Patran 2012 Laminate

MSC Laminate Modeler

Version 2012 User’s Guide

Corporate

Europe

MSC.Software Corporation MSC.Software GmbH 2 MacArthur Place Am Moosfeld 13 Santa Ana, CA 92707 USA 81829 Munich, Germany Telephone: (800) 345-2078 Telephone: (49) (89) 43 19 87 0 Fax: (714) 784-4056 Fax: (49) (89) 43 61 71 6

Asia Pacific MSC.Software Japan Ltd. Shinjuku First West 8F 23-7 Nishi Shinjuku 1-Chome, Shinjuku-Ku Tokyo 160-0023, JAPAN Telephone: (81) (3)-6911-1200 (3)-6911-1200 Fax: (81) (3)-6911-1201 (3)-6911-1201

Worldwide Web www.mscsoftware.com

Disclaimer This documentation, as well as the software described in it, is furnished under license and may be used only in accordance with the terms of such license. MSC.Software Corporation reserves the right to make changes in specifications and other information contained in this document without prior notice. The concepts, methods, and examples presented in this text are for illustrative and educational purposes only, and are not intended to be exhaustive or to apply to any particular engineering problem or design. MSC.Software Corporation assumes no liability or responsibility to any person or company for direct or indirect damages resulting from the use of any information contained herein. User Documentation: Copyright 2010 MSC.Software Corporation. Printed in U.S.A. All Rights Reserved. This notice shall be marked on any reproduction of this documentation, in whole or in part. Any reproduction or distribution of this document, in whole or in part, without the prior written consent of MSC.Software Corporation is prohibited. The software described herein may contain certain third-party software that is protected by copyright and licensed from MSC.Software suppliers. Contains IBM XL Fortran for AIX V8.1, Runtime Modules, (c) Copyright IBM Cor poration 1990-2002, All Rights Reserved. MSC, MSC/, MSC Nastran, MD Nastran, MSC Fatigue, Marc, Patran, Dytran, and Laminate Modeler are trademarks or re gistered trademarks of MSC.Software Corporation in the United States and/or other countries. NASTRAN is a registered trademark of NASA. PAM-CRASH is a trademark or registered trademark of ESI Group. SAMCEF is a trademark or registered trademark of Samtech SA. LS-DYNA is a trademark or registered trademark of Livermore Software Technology Corporation. ANSYS is a registered trademark of SAS IP, Inc., a wholly owned subsidiary of ANSYS Inc. ACIS is a registered trademark of Spatial Technology, Inc. ABAQUS, and CATIA are registered trademark of Dassault Systemes, SA. EUCLID is a registered trademark of Matra Datavision Corporation. FLEX lm is a registered trademark of Macrovision Corporation. HPGL is a trademark of Hewlett Packard. PostScript is a registered trademark of Adobe Systems, Inc. PTC, CADDS and Pro/ENGINEER are trademarks or registered trademarks of Parametric Technology Corporation or its subsidiaries in the United States and/or other countries. Unigraphics, Parasolid and I-DEAS are registered trademarks of UGS Corp. a Siemens Group Company. All other brand names, product names or trademarks belong to their respective owners.

P3:V2012:Z:LAM:Z: DC-USR-PDF

Corporate

Europe

MSC.Software Corporation MSC.Software GmbH 2 MacArthur Place Am Moosfeld 13 Santa Ana, CA 92707 USA 81829 Munich, Germany Telephone: (800) 345-2078 Telephone: (49) (89) 43 19 87 0 Fax: (714) 784-4056 Fax: (49) (89) 43 61 71 6

Asia Pacific MSC.Software Japan Ltd. Shinjuku First West 8F 23-7 Nishi Shinjuku 1-Chome, Shinjuku-Ku Tokyo 160-0023, JAPAN Telephone: (81) (3)-6911-1200 (3)-6911-1200 Fax: (81) (3)-6911-1201 (3)-6911-1201

Worldwide Web www.mscsoftware.com

Disclaimer This documentation, as well as the software described in it, is furnished under license and may be used only in accordance with the terms of such license. MSC.Software Corporation reserves the right to make changes in specifications and other information contained in this document without prior notice. The concepts, methods, and examples presented in this text are for illustrative and educational purposes only, and are not intended to be exhaustive or to apply to any particular engineering problem or design. MSC.Software Corporation assumes no liability or responsibility to any person or company for direct or indirect damages resulting from the use of any information contained herein. User Documentation: Copyright 2010 MSC.Software Corporation. Printed in U.S.A. All Rights Reserved. This notice shall be marked on any reproduction of this documentation, in whole or in part. Any reproduction or distribution of this document, in whole or in part, without the prior written consent of MSC.Software Corporation is prohibited. The software described herein may contain certain third-party software that is protected by copyright and licensed from MSC.Software suppliers. Contains IBM XL Fortran for AIX V8.1, Runtime Modules, (c) Copyright IBM Cor poration 1990-2002, All Rights Reserved. MSC, MSC/, MSC Nastran, MD Nastran, MSC Fatigue, Marc, Patran, Dytran, and Laminate Modeler are trademarks or re gistered trademarks of MSC.Software Corporation in the United States and/or other countries. NASTRAN is a registered trademark of NASA. PAM-CRASH is a trademark or registered trademark of ESI Group. SAMCEF is a trademark or registered trademark of Samtech SA. LS-DYNA is a trademark or registered trademark of Livermore Software Technology Corporation. ANSYS is a registered trademark of SAS IP, Inc., a wholly owned subsidiary of ANSYS Inc. ACIS is a registered trademark of Spatial Technology, Inc. ABAQUS, and CATIA are registered trademark of Dassault Systemes, SA. EUCLID is a registered trademark of Matra Datavision Corporation. FLEX lm is a registered trademark of Macrovision Corporation. HPGL is a trademark of Hewlett Packard. PostScript is a registered trademark of Adobe Systems, Inc. PTC, CADDS and Pro/ENGINEER are trademarks or registered trademarks of Parametric Technology Corporation or its subsidiaries in the United States and/or other countries. Unigraphics, Parasolid and I-DEAS are registered trademarks of UGS Corp. a Siemens Group Company. All other brand names, product names or trademarks belong to their respective owners.

P3:V2012:Z:LAM:Z: DC-USR-PDF

Contents MSC Laminate Modeler User’s Guide

1

Overview Purpose

2

MSC.Laminate Modeler Product Information What is Included with this Product?

3

4

MSC.Laminate Modeler Integration with Patran What is MSC.Laminate Modeler?

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5

6

Tutorial Introduction

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Composite Materials and Manufacturing Processes Composite Materials 11 Common Material Forms 11 Common Manufacturing Forms 12

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Composites Design, Analysis and Manufacture 15 The Development Process 15 Requirements of CAE Tools for Composites Development Development Composites Development Within the Patran Environment Draping Simulation (Developable Surfaces) Definition of Developable Surfaces 21 Example of Waffle Plate 21 Benefits of MSC.Laminate Modeler 23

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Draping Simulation (Non-Developable Surfaces) Definition of Non-Developable Non-Developable Surfaces 24 Benefits of MSC.Laminate Modeler 29 Building Models using Global Layers 30 Global Layer Description of Layup 30 Example of a Top Hat Section 31 Benefits of MSC.Laminate Modeler 33

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15 19

6 MSC Laminate Modeler User’s Guide

Results Processing 34 Recovering Results by Global Layer Example of a Top Hat Section 34 Benefits of MSC.Laminate Modeler

34 37

Structural Optimization 38 Introducing Iteration to the Development Process Example of a Torque Tube with a Cutout 38 Glossary

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Using MSC.Laminate Modeler Procedure

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Element Library 46 Supported Element Topologies 46 Supported Element Types 46 Supported Element Property Words 46 Initialization

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Creating Materials 49 Create LM_Material Add Form Modify LM_Material Form 52 Show LM_Material Form 53 Delete LM_Material Select Form

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Creating Plies 55 Create LM_Ply Add Form (Draping) Create LM_Ply Add Form (Projection) Modify LM_Ply Form 71 Show LM_Ply Graphics Form 72 Delete LM_Ply Select Form 73

56 70

Creating a Layup and an Analysis Model Create LM_Layup Add Form 75 Modify LM_Layup Add Form 82 Show LM_Layup Exploded View Form 83 Show LM_Layup Cross Section Form 84 Show LM_Layup Element Form 85 Show LM_Layup Element Info Form 86 Transform LM_Layup Mirror Form 87 Delete LM_Layup Select Form 88

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Creating Solid Elements and an Analysis Model

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CONTENTS

Create Solid Elements LM_Layup Form

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Creating Laminate Materials 91 Create Laminate LM_Layup Form 92 Show Laminate Form 94 Delete Laminate Select Form 95 Delete Property Set Select Form 96 Creating Sorted Results 97 Create LM_Results LM_Ply Sort Form 98 Create LM_Results Material ID Sort Form 99 Creating Failure Results 100 Create LM_Results Failure Calc Form

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Creating Design and Manufacturing Data Create Ply Book Layup Form 104 Importing Plies and Models Import Plies File Form 106 Import Model File Form 107

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Importing and Exporting Laminate Materials Import Laminate LAP Form 109 Export Laminate LAP Form 110 Setting Options 111 Set Export Options Form Set Display Options Form Session File Support Public PCL Functions Data Files

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112 114 118 119

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Example:Laminated Plate Overview

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Model Description Modeling Procedure Step-By-Step

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8 MSC Laminate Modeler User’s Guide

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Theory The Geometry of Surfaces

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The Fabric Draping Process Results for Global Plies Composite Failure Criteria

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Bibliography

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Chapter 1: Overview MSC Laminate Modeler User’s Guide

1

Overview



Purpose



MSC.Laminate Modeler Product Information



What is Included with this Product?



MSC.Laminate Modeler Integration with Patran



What is MSC.Laminate Modeler?

2 3

4

6

5

2

MSC Laminate Modeler User’s Guide Purpose

Purpose Patran comprises a suite of products written and maintained by MSC.Software Corporation. The core of the product suite is Patran, a finite element analysis pre and postprocessor. Patran also includes several optional products such as application modules, advanced postprocessing programs, tightly coupled solvers, and interfaces to third party solvers. This document describes one of these application modules. For more information on the Patran suite of products, see the Patran Reference Manual. MSC.Laminate Modeler is a Patran module for aiding the design, analysis, and manufacture of laminated composite structures. The user can simulate the application of layers of reinforcing materials to selected areas of a surface to ensure that a design is realizable. Layers are then used to build up the composite construction in a manner that reflects the manufacture of the structure. Finite element properties and laminated materials are automatically generated so that accurate models of the structure can be evaluated rapidly. Alternative solutions can be compared to optimize the structure at an early stage of the development process.

Chapter 1: Overview 3 MSC.Laminate Modeler Product Information

MSC.Laminate Modeler Product Information MSC.Laminate Modeler is a product of MSC.Software Corporation. The program is available on all Patran supported platforms and allows identical functionality and file support across these platforms.

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MSC Laminate Modeler User’s Guide What is Included with this Product?

What is Included with this Product? The MSC.Laminate Modeler product includes all of the following items: 1. PCL command and library files which add the MSC.Laminate Modeler functionality definitions into Patran. 2. An external executable program for Layup manipulation and composite ply generation. 3. This Application Preference User’s Guide is included as part of the product. An online version is also provided to allow the user direct access to this information from within Patran.

Chapter 1: Overview 5 MSC.Laminate Modeler Integration with Patran

MSC.Laminate Modeler Integration with Patran Figure 1-1 indicates how the MSC.Laminate Modeler library and associated programs fit into the Patran

environment.

Figure 1-1

MSC.Laminate Modeler Integration with Patran Environment

6

MSC Laminate Modeler User’s Guide What is MSC.Laminate Modeler?

What is MSC.Laminate Modeler? MSC.Laminate Modeler is a Patran module for aiding the design, analysis, and manufacture of laminated composite structures. By enabling the concept of concurrent engineering, MS C.Laminate Modeler allows the production of structures which take full advantage of these materials in the aerospace, automotive, marine, and other markets. The quality of the development process can be greatly improved because of the rigorous and repeatable manner in which MSC.Laminate Modeler defines fibre orientations. MSC.Laminate Modeler incorporates two key functionalities: simulation of the manufacturing process, and storage and manipulation of composite data on the basis of global layers.

Process Simulation Process simulation methods include draping of fabrics using various material and manufacturing options, in addition to the more conventional techniques of projecting fibre angles onto a surface. These options allow the use of MSC.Laminate Modeler for various production methods including manual layup of pre preg materials, Resin Transfer Moulding (RTM) and filament winding. Furthermore, MSC.Laminate Modeler reflects the open systems philosophy of Patran and can cater to customized simulation methods developed by customers.

Composite Data Management All data produced by the manufacturing simulation are s tored together and referenced as a single data entity. This structured representation allows efficient data handling in the actual design environment. For example, to apply predefined layers to an analysis model, the user simply adds them to a table in a process which reflects the real-world manufacture of the finished component. Alternative layups can be generated and evaluated rapidly to allow the designer to optimize the composite structure using existing structural analysis tools. The process of defining layups is inherently traceable, unlike the situation in conventional composites analysis where data is reduced to an unstructured element-based level which has no physical analogy. The functions available within MSC.Laminate Modeler allows the designer to visualize the manufacturing process and estimate the quantity of material involved. Representative analysis models of the component can be produced very rapidly to allow effective layup optimization. Finally, a “ply book” and other manufacturing data can be produced. These functions promise a significant increase in the efficiency of the development process for high performance composite structures.

Chapter 1: Overview 7 What is MSC.Laminate Modeler?

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MSC Laminate Modeler User’s Guide What is MSC.Laminate Modeler?

Chapter 2: Tutorial MSC Laminate Modeler User’s Guide

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Tutorial

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Introduction

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Composite Materials and Manufacturing Processes

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Composite Materials and Manufacturing Processes

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Composites Design, Analysis and Manufacture

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Draping Simulation (Developable Surfaces)

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Draping Simulation (Non-Developable Surfaces)

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Building Models using Global Layers

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Results Processing

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Structural Optimization

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Glossary

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34 38

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MSC Laminate Modeler User’s Guide Introduction

Introduction This manual is intended to introduce the reader to the most common methods of composite manufacture, and define what is required of an effective tool for simultaneous composites engineering. Thereafter, some examples of the use of the MSC.Laminate Modeler are presented to illustrate the usefulness of this module in the composites development process.

Chapter 2: Tutorial 11 Composite Materials and Manufacturing Processes

Composite Materials and Manufacturing Processes Composite Materials Composite materials are composed of a mixture of two or more constit uents, giving them mechanical and thermal properties which can be significantly better than those of homogeneous metals, polymers and ceramics. An important class of composite materials are filamentary composites which consist of long fibres embedded in a tough matrix. Materials of this type include graphite fibre/epoxy resin composites widely used in the aerospace industry, and glass fibre/polyester mixtures which have wide applicability in the marine and automotive markets. Because of their predominance in high-quality structures which need to be analyzed before manufacture, the term composite material will refer to a filamentary composite having a resin matrix in this document. Furthermore, it will be as sumed that the composite is manufactured in distinct layers, which is appropriate for almost all filamentary composite materials. By decreasing the characteristic size of the microstructure and providing large interface areas, the toughness of the composite material is improved significantly compared with that of a homogeneous solid made of the same material as the fibres. In addition, the manufacturing processes of many components can be simplified by applying the fibres to the component in a manner which is compatible with its geometry. These and other considerations mean that composite materials are an effective engineering material for many types of structure. However, filamentary composite materials are often characteri zed by strongly anisotropic behavior and wide variations in mechanical properties which are a direct result of the manufacturing route for a component. In addition, the cost of a composite component is highly dependent on the w ay the fibres are applied to a surface. This means that designers must be aware of the consequences of manufacturing considerations from the beginning of the development phase.

Common Material Forms Filamentary composite materials are usually placed in components as tows (bundles of individual fibres) or as fabrics which have been processed in a separate operation.

Tows A large proportion of commercially-produced components are built up from layers of fibre tows laid parallel to each other. Each tow consists of a large number of individual fibres as each fiber is usually too thin to process effectively. For example, graphite tows typically contain between 1000 to 10000 fibres. Tows containing many fibres result in cheaper components at some expense of mechanical properties. Composite structures built up from tows have the greatest volume fraction of fibres which usually lead to the most favorable theoretical mechanical properties. They are also characterized by extreme anisotropy. For example, the strength and stiffness of a resulting layer may be ten times greater in the direction of the fibres compared with an orthogonal direction.

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MSC Laminate Modeler User’s Guide Composite Materials and Manufacturing Processes

Fabrics Individual tows may also be woven or stitched into fabrics which are used to form the component. This method effectively allows much of the fibre preparation to be completed under controlled conditions, while components can be rapidly built up from fabric during the final stage of manufacture. Composite structures built up from fabrics are generally easier to manufacture and exhibit superior toughness compared with those built up from tows, with some loss in ultimate mechanical properties.

Mixed Some processing methods allow the user to mix tows and fabrics to achieve optimum performance. An example of this is a composite I-beam, where the shear-loaded web consists of a fabric, while the axiallyloaded flanges have a high proportion of fibres oriented along the beam.

Common Manufacturing Forms Composite structures are manufactured using a wide variety of manufacturing routes. The ideal processing route for a particular structure will depend on the chosen fiber and matrix type, processing volume, quality required, and the form of the component. All these issues should be addressed right from the beginning of the development cycle for a component or structure. A feature of almost all the manufacturing processes is that the fibres are formed into the final structure in layers. The thickness of each layer typically ranges between 0.125 mm (0.005”) for aerospace-grade pre-pregs up to several millimeters for woven rovings (say, 0.25”). This means that a component is usually built up of a large number of layers which may be oriented in different directions to achieve the desired structural response. Another consequence of layer-based manufacturing is that a laminated area is usually thin compared with its area. This means that the dominant loads are in the plane of the fibres, and that classical lamination theory (which assumes that through-thickness stresses are negligible) and shell finite elements can be used to conduct representative analyses. In contrast, in particularly thick or curved skins, inter-laminar tensile and shear stresses can be significant. This can seriously compromise static and fatigue strength and may require the use of through-thickness reinforcement. Another consequence of thi ck laminates is that the analyst must use special thick shell or solid elements to model the stress fields correctly.

Wet Layup In the wet layup process, fibres are placed on a mould surface in fabric form and manually wetted-out with resin. Wet layup is widely used to make large structures, like the hulls of small ships. This process is amenable to high production rates but results in wide variations in quality. In particular, the inability to control the ratio of fibres to resin means that the mechanical properties of the laminate will vary from point-to-point and structure-to-structure.

Chapter 2: Tutorial 13 Composite Materials and Manufacturing Processes

Pre-Preg Layup In this process, tows or fabrics are impregnated with controlled quantities of resin before being placed on a mould. Pre-preg layup is typically used to make high-quality components for the aerospace industry. This process results in particularly consistent components and structures. Because of this, pre-preg techniques are often associated with sophisticated resin s ystems which require curing in autoclaves under conditions of high temperature and pressure. However, the application of pre-preg layers to a surface is highly labor-intensive, and can only be automated for a small class of simple structures.

Compression Moulding Compression moulding describes the process whereby a stack of pre-impregnated layers are compressed between a set matched dies using a powerful press, and then cured while under compression. This method is often used to manufacture small quantities of high-quality components such as crash helmets and bicycle frames. Due to the use of matched dies, the dimensional tolerances and mechanical properties of the finished component are extremely consistent. However, the requirement to trim the component after curing and the need for a large press means that this method is extremely expensive. Also, it is very difficult to make components where the plies drop off consistently within the component.

Resin Transfer Moulding (RTM) / Structural Reaction Injection Moulding (SRIM) Here, dry fibres are built up into intermediate preforms using tows and fabric held together by a thermoplastic binder. One or more preforms are then placed into a closed mould, after which res in is injected and cured to form a fully-shaped component of high quality and consistency. The in-mould cycle time for RTM is of the order of several minutes, while that for SRIM is measured in seconds. As fibres are manipulated in a dry state, these processes provide unmatched design flexibility. RTM produces good-quality components efficiently but incurs high initial costs for tooling and development. As a result, there is often a cross-over point between pre-preg layup and RTM for the manufacture of high-quality components like spinners for aero engines. At a lower level, SRIM is used for the manufacture of automotive parts which have a lower volume fraction of fibres.

Filament Winding In this method, tows are wet-out with resin before being wound onto a mandrel which is rotated in space. This process is used for cylindrical and spherical components such as pipes and pressure vessels. Winding is inherently automated, so it allows consistent components to be manufactured cheaply. However, the range of component geometries amenable to this method is somewhat limited.

Automated Tow Placement This development of filament winding utilizes a computer-controlled 5-axis head to apply individual tows to a mandrel rotating in space. This allows the manufacture of complex surfaces, such as entire helicopter body shells with speed and precision.

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MSC Laminate Modeler User’s Guide Composite Materials and Manufacturing Processes

Of course, the equipment required for manufacture is extremely expensive, being of the order of $1 million. In addition, the possibilities for fibre placement are so controllable that no component can possibly make use of the capabilities of the process at present. However, the development of CAE tools for optimized design of composite structures will increase its usefulness in the future.

Chapter 2: Tutorial 15 Composites Design, Analysis and Manufacture

Composites Design, Analysis and Manufacture The Development Process The development process for any component consists of design, analysis and manufacturing phases, which are sometimes undertaken by separate groups within large organizations. However, for composites, these functions are inextricably linked and must be undertaken simultaneously if the component is to be manufactured economically. Thus, the principles of concurrent engineering must be followed particularly closely for composites development. In general, the development process incorporates three phases: Conceptual Development - here, the development team generates a number of conceptual solutions based on their interpretation of the requirements and knowledge of composite materials and processes. Outline Development - thereafter, surface geometry is defined, a preliminary layup determined and analysis undertaken. Based on the interpretation of analysis results, the outline design may be modified through several iterations before an acceptable solution is reached. Detailed Development - detailed drawings of the structure and required tooling are prepared together with plans for production.

Requirements of CAE Tools for Composites Development The outline development process is the most critical phase in refining a design solution. Composite components and structures can be an order of magnitude more complex than items made of homogeneous materials. It is, therefore, essential to automate many repetitive tasks using computer-based tools. Depending on the application, these tools should have one or more of the features defined below.

Integration of CAD/CAE/CAM Systems It is important to integrate all tools for composites engineering within a single environment to allow simultaneous development of a product (see Figure 2-1). Furthermore, all design and manufacturing information should be readily transferable to and from a CAD system so that the intent of an optimized design can be realized.

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MSC Laminate Modeler User’s Guide Composites Design, Analysis and Manufacture

Figure 2-1

Integrated Composites Development Environment

Layer-Based Modeling The fundamental requirement is that the CAE tools treat the composite structure in a manner which reflects the real-world structure. In particular, many conventional CAE tools store and manipulate data on the basis of laminate materials as shown in Figure 2-2. This representation means that the model becomes extremely complicated as soon as the layers making up the structure overlap. In contrast, all CAE tools should store the data describing the structure in terms of its constituent layers. This ensures that the construction is always representative of the manufacturing method, making the model easy to understand. Furthermore, changes are easily effected by adding and removing layers.


Figure 2-2

Comparison of Global Layer and Laminate Material Descriptions for a Simple Structure

Layer-Based Results Processing Any optimization during the development process is likely to involve the interpretation of results for various analyses. These results should be interpreted on the basis of layers, in the same way that the component is manufactured. Furthermore, it should be possible to visualize results in the reference system of the material making up a layer, even where this reference system changes constantly over a surface.

Mass and Cost Calculation The cost of composites materials are generally high. A CAE tool should allow the designer to interrogate the materials usage and approximate cost at any point in the development cycle.

Visualization Tools Sufficient visualization tools should be provided to ensure that the form of the structure is easily checked and communicated. Such tools would include the ability to interrogate the extent and orientation of

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layers, generate core samples at various points, generate cross sections along arbitrary lines, and generate a layer sequence table.

Manufacturing Guides Any CAE tool should produce fool-proof manufacturing guides, so that the design and analyses components are actually manufactured. For structures manufactured from sheet materials, this could take the form of a “ply-book” which has a page for every layer. This should present the cutout shape, views of the three-dimensional moulded shape and other essential information.

Mould Surface and Insert Shape Definition Typically, layers will be placed on a male or female mould surface. If the mould tool is closed. The software should calculate the exact thickness of the laminate stack which has been defined. This should include the effect of thickening which can occur as woven material is sheared to conform to a surface. Thereafter, a second mould surface should be defined which is offset from the original surface by the correct amount. It should also be possible to define a secondary mould surface, and automatically define the cutout shapes of individual plies required to fill the entire mould.

Materials Data Management Because composite materials are generally anisotropic, and have more variability in their properties than homogeneous materials, it is important to store and manipulate materials data in a consistent manner throughout the design process. In particular, the same data should be used for all subsequent analyses, s o that any change is reflected throughout the entire cycle. The state of composite materials can also be highly dependent on temperature, moisture content, and even the degree of shear which might be induced in a manufacturing process. This means that all data should be stored as a function of state, and the correct information retrieved for any analysis. Because of the wide variety of states possible, material property data will only be available for a few states. It is, therefore, necessary to interpolate material property data for intermediate states in a rational and repeatable manner. For example, if the properties of fabric a re known when the warp and fill fibers are 90 and 60 degrees apart, the software should also calculate equivalent properties for 75 degrees separation.

Drape Analysis A large proportion of composite structures are manufactured by placing essentially two-dimensional sheets of fabric onto three-dimensional surfaces. If the surface has curvature, then the shape of the sheet cannot be inferred directly from a projection of the surface onto a plane. Therefore, the draping simulation software must produce the cutout shape of the layer before it is applied to the surface. If the surface is doubly-curved at any point, it is non-developable. In this case, the sheet material must shear in its plane to allow it to conform to the surface. The software must illustrate the degree of shearing in the sheet, and update the material property references to account for the changed material state. The


shearing also means that the orientation of the material changes dramatically over a curved surface. The correct orientations must therefore be passed through transparently t o all relevant analysis codes. Sheet material can be extremely expensive. Therefore, so-called nesting software should be used to minimize the material required by aligning and placing the cutouts in an optimum way.

Structural Analysis Any composite part must be thoroughly analyzed to ensure that it will withstand service loads. Many composite components are relatively thin so that through-thickness stresses are low. This means that shell elements can be used to model the structure adequately. However, to model through-thickness stresses, solid elements must be used. For some problems, such as investigating through-thickness stresses at edges, many high-order elements will be required through the thickness of t he laminate to model stresses at all reasonably. A major concern with composite materials are their resistance to damage, as the degradation of the material is very complex and not well understood. It is, therefore, important that the structural analysis codes provide for modelling the initiation, growth and effects of defects.

Resin Flow Analysis Resin flow should be analyzed for processes such as RTM to ensure that pockets of air are not trapped in the moulding, causing defects. In addition, resin flow has a dominant effect on cycle time, with its ongoing effect on manufacturing cost.

Cure Analysis The curing of a composite component should be analyzed to dete rmine the cycle time of the process. Also, it is essential to determine the extent of springback in the cured component.

Mould Tool Analysis Mould tool analysis is required to estimate deflections in the tool where small tolerances are required. The thermal behavior of the mould can also have a significant effect on the cutting of a composite component.

Composites Development Within the Patran Environment The Patran environment provides a rich core environment for the development of composite structures. Existing links are readily used to import geometry from leading CAD systems including CATDirect, CADDS 5, Unigraphics, Pro/ENGINEER and Euclid 3. Meshing and other general pre and postprocessing functions are available within Patran itself. Finally, the preference system enables the seamless use of a variety of analysis systems which would be useful for composites development.

MSC.Mvision MSC.Mvision allows the user to store and handle complex materials data such as that required for composites development.

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MSC.Laminate Modeler The MSC.Laminate Modeler adds dedicated layer-based modeling and results processing functionality to Patran. This support greatly improves the ability of the user to define and modify representative composite structures, and then analyze their behavior using analysis packages supported by preferences. The module also includes a drape simulation facility which can handle non-developable surfaces. This allows the user to understand the deformation required of a sheet of fabric to cover a s urface, predicts realistic material orientations over individual elements, and produces cutout shapes for use by CAM systems.

Patran FEA This general-purpose finite element analysis solver includes QUAD4/8 and TRI3/6 laminates shell elements which account for bending and extension deformation of a shell. The linear strain elements also model the transverse shear flexibility of the laminate. HEX8/20 and WEDGE6/15 elements are available to model the flexibility of a laminate in all directions. All composite elements provide the facility for inputting nonlinear material properties.

Patran Composite This specialized finite element analysis solver is used for detailed analysis of laminates with complex fibre geometry or unusual material behavior. It utilizes a family of elements with tri-cubic interpolation functions, with up to HEX64 topology. These allow the calculation of high stress gradients, such as occur at free edges or in components which suffer severe thermal stress during processing.

Chapter 2: Tutorial 21 Draping Simulation (Developable Surfaces)

Draping Simulation (Developable Surfaces) Definition of Developable Surfaces An important subset of curved surfaces is developable surfaces. These surfaces can always be manufactured using sheet materials without the material needing to shear. At any point, there will be no curvature in one direction and maximum curvature in the orthogonal direction. Mathematically, this means that these surfaces are characterized by zero Gaussian curvature over their entire area. Cylinders are one example of developable surfaces found in many structures. Note that all developable surfaces are ruled surfaces. However, not all ruled surfaces are developable. For example, a hyperbola of one sheet (such as a cooling tower shape) is not developable. Although many CAD systems have provision for developing flat patterns from developable surfaces, the definition of material orientation is not trivial, particularly when the curvature is great. The draping process for development is unique. That means that the cutout profile is always the same, and that definition of fibre orientation at any point uniquely describe the fibre orientations at all other points on the surface.

Example of Waffle Plate One example of a developable surface with complex fibre orientations is a waffle plate used as a core for sandwich structures. A typical geometry for a circular sandwich structure is shown in Figure 2-3. As the core is predominantly loaded in shear, it would be if the majority of fibres lay in the +/-45 directions along the webs. However, if these directions are ideal for one web, they will obviously not be the same for other webs.

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MSC Laminate Modeler User’s Guide Draping Simulation (Developable Surfaces)

Figure 2-3

Geometry of a Curved Waffle Plate

The MSC.Laminate Modeler can be used to quantify the effect of varying fibre orientation both qualitatively and quantitatively. For example, if a piece of woven fabric is draped from the middle rib so that the average angle is +/-45 along the webs of the central rib, we see that the angle on the webs near the edge of the plate are more like 0/90. This latter direction will obviously result in poor shear s tiffness and strength in this direction. Having understood this limitation, the designer can then make an informed decision whether to specify a quai-isotropic layup for the whole of the waffle plate, or to make the waffle plate out of several different plies oriented in different directions. Both alternatives can be modeled and analyzed rapidly using the MSC.Laminate Modeler, and an informed choice made on the basis of analysis results.

Chapter 2: Tutorial 23 Draping Simulation (Developable Surfaces)

Figure 2-4

Variation of Fibre Angles over Waffle Plate

Benefits of MSC.Laminate Modeler 1. Visual feedback of fibre orientation. 2. Accurate orientation data for analysis model. 3. Exact flat-pattern generation.

24

MSC Laminate Modeler User’s Guide Draping Simulation (Non-Developable Surfaces)

Draping Simulation (Non-Developable Surfaces) Definition of Non-Developable Surfaces Non-developable surfaces are those which cannot be formed from sheet material without the material shearing in its plane. Surfaces of this type have curvatures in two different directions (they are therefore often called doubly-curved surfaces). Although these surfaces are usually more difficult to manufacture than flat or developable surfaces, their form gives them great stiffness and strength. Because composite materials can often shear during the manufacturing process, they are more suitable for manufacturing these shapes than conventional materials like aluminium. This magnifies the advantage of laminated composite materials for many classes of structure.

Gaussian Curvature The extent of double curvature at any point is reflected in a value called the Gaussian curvature. This is the product of the curvatures in the principal directions at any point on a surface. The Gaussian curvature reveals many of the characteristics of a surface. Positive Gaussian curvature means that the surface is locally dome-shaped, with the curvatures in the same direction with respect to the surface normal. In contrast, negative Gaussian curvature implies saddle-shaped topology, with curvatures in opposite directions. Finally, zero Gaussian curvature is characteristic of a developable area. Note that surfaces often have varying Gaussian curvature over their extent. As an example, a torus (donut) is saddle-shaped on the inside (negative Gaussian curvature) but dome-shaped on the outside (positive Gaussian curvature). Gaussian curvature can be given a physical significance by drawing geodesic lines on a surface. (Geodesic lines are straight in the plane of the surface at any point; meridians are geodesic, but lines of latitude are constantly turning in one direction with respect to the surface.) A pair of lines which are initially parallel will tend to converge on surfaces of positive Gaussian curvature, but will diverge on a surface of negative Gaussian curvature. In contrast, the lines will remain parallel on the surface until they reach an edge if the surface is developable. Another interpretation of Gaussian curvature is the extent of misfit in the surface. Consider a circular disk made up of several flat segments. This necessarily has zero Gaussian curvature even if it is bent along the joints between segments. However, if one of the segments is removed and the neighboring segments joined, the disk will adopt a dome-like shape which is indicative of positive Gaussian curvature. In contrast, adding a segment will result in the disk forming a saddle-like shape with negative Gaussian curvature.

Drape Simulation for Non-Developable Surfaces Draping of non-developable surfaces is an extremely difficult task. Essentially, this process involves extremely large geometric and, perhaps, material nonlinearities. A direct consequence of this is that there is no unique solution for the draping process . The draped shape is highly dependent on the point at which the draping starts, the directions in which the draping proceeds and the properties of the material itself. In addition, if there is interaction between different layers, friction between them would have a

Chapter 2: Tutorial 25 Draping Simulation (Non-Developable Surfaces)

significant effect. A detailed analysis of the draping process for arbitrary geometries is therefore a considerable analysis task in itself. This difficulty in analysis reflects a real-world difficulty in manufacturing complex composite components consistently. Engineering drawings of composite components typically specify fibre angles within a tolerance of 3 degrees. In practice, if there is significant curvature in a surface, the manufacturing tolerance could easily reach 15 degrees or more. These problems can be mitigated to a large extent by limiting the degree of shear developed wi thin reinforcing layers during the manufacturing process. The degree of shear is primarily dependent on the Gaussian curvature and the area of a layer. Therefore, a design incorporating two layers of excessive shear can be replaced by three smaller layers with less shear and greater quality. The MSC.Laminate Modeler employs a rapid draping module which allows the designer to investigate the likely degree of shear, and make rational engineering decisions on the basis of manufacturing simulations. Whatever simulation process is used, two different levels of draping should be considered. Local Draping reflects the behavior of an infinitesimal material element applied to a point on a surface having general curvature. This is a material characteristic and is determined from tests on material s. In contrast, Global Draping considers how the many material elements are placed on a surface, and is dependent on the manufacturing process used.

Local Draping Models Local draping is concerned with fitting a small section of material to a generally-curved surface. If the surface has nonzero Gaussian curvature, the material element must shear in its plane to conform to the surface. This deformation is highly dependent on the microstructure of the material. As a result, local shearing behavior can be regarded as a layer material property.

Figure 2-5

Scissor Draping Mechanism

26


Figure 2-6

Slide Draping Mechanism

MSC.Laminate Modeler currently supports two local draping algorithms: scissor and slide draping. For scissor draping (Figure 2-5), an element of material which is originally square shears in a trellis-like mode about its vertices to form a rhombus. In particular, the sides of the material element remain of constant length. This type of deformation behavior is characteristic of woven fabrics which are widely used to manufacture highly-curved composite components. For slide draping ( Figure 2-6), two opposite sides of a square material element can slide parallel to each other while their separation remains constant. This is intended to model the application of parallel strips of material to a surface. It can also model, very simply, the relative sliding of adjacent tows making up a strip of unidirectional material. When draping a given surface using the two different local draping algorithms, the shear in the layer builds up far more rapidly for the slide draping mechanism than for the scissor draping mechanism. This observation is compatible with actual manufacturing experience that woven fabrics are more suitable for draping curved surfaces than unidirectional pre-pregs. For small deformations, the predictions of the different algorithms are practically identical. Therefore, it is suggested that the scissor draping algorithm be used in the first instance.

Global Draping Models Global draping is concerned with placing a real sheet of material onto a surface of general curvature. This is not a trivial task as there are infinite ways of doing this if the surface has nonzero Gaussian curvature at any point. Therefore, it is important to define procedures for the global draping simulation which are reproducible and reflect what can be manufactured in a production sit uation. As a result, global draping behavior can be regarded as a manufacturing, rather than material, property. The MSC.Laminate Modeler currently supports three different global draping algorithms: Geodesic, Planar and Energy. For the Geodesic global draping option, principal axes are drawn away from the starting point along geodesic paths on the surface (i.e., the lines are always straight with respect to the surface). Once these principal axes are defined, there is then a unique solution for draping the remainder of the surface. This may be considered the most “natural” method and appropriate for conventional laminating methods. However, for highly-curved surfaces, the paths of geodesic lines are highly dependent on initial conditions and so the drape simulation must be handled with care.


For the Planar global draping option, the principal axes may be defined by the intersecti on of warp (and weft for scissor draping) planes which pass through the viewing direction. This method is appropriate where the body has some symmetry, or where the layup is defined on a space-centered rather than a surface-centered basis. Finally, the Energy global draping option is provided for draping highly-curved surfaces where the manufacturing tolerances are necessarily greater. Here, the draping proceeds outwards from the start point, while the direction of draping is controlled by minimizing the shear strain energy along each edge.

Example of a Pressure Vessel Many pressure vessels are made of composite materials, particularly via the filament winding process. However, it is often necessary to add woven reinforcements to the shell. In this case, it is vital to understand the mechanics of the draping process because the curvature of the surface varies so much. In particular, the body of a pressure vessel is developable and has zero gaussian curvature. In contrast, the ends have constant positive Gaussian curvature. If draping begins at the pole of the vessel ( Figure 2-7), the shear in the material increases rapidly away from the start point due to the severe curvature. The amount of shearing is indicated by the color of the draping pattern lines. Note that the degree of shear is zero along the principal axes, which are defined by geodesic lines. The draping algorithm stops where the shear reaches the cutoff value for the material, or the override value defined in the Additional Controls form. This gives an indication of where the material would fold when being formed.

28


Figure 2-7

Fibre Directions for Draping Starting at the Pole of the Vessel

To cover the same area, it is also possible to begin draping on the cylindrical part of the surface (Figure 2-8). Because this region is developable, there is no shear deformation until the end cap is reached. This means that the average degree of shear on the surface is much lower, which should lead to better quality and better mechanical performance.


Figure 2-8

Fiber Directions for Draping Starting on the Cylindrical Part of the Vessel

Benefits of MSC.Laminate Modeler 1. Visual feedback of fibre orientation. 2. Visual feedback of material shear. 3. Orientation data for analysis model. 4. Flat pattern generation.

30

MSC Laminate Modeler User’s Guide Building Models using Global Layers

Building Models using Global Layers Global Layer Description of Layup The model is built up from predefined layers using a spreadsheet. This mirrors the use of layup tables in the final drawings of a component. The models are easily modified by defining, adding and deleting new layers to or from the layup.

Figure 2-9

Spreadsheet For Defining the Layup Using Predefined Layers

Chapter 2: Tutorial 31 Building Models using Global Layers

Example of a Top Hat Section A typical top-hat section subjected to pressure and bending load will be used to illustrate the building of models using global layers. The model itself consists of a total of 52 global layers arranged in 4 different laminates. To model this structure properly, using conventional methods, would require the definition of 11 different property regions containing between 16 and 48 layers each. This would be tedious to define, and almost impossible to modify if the user wished to conduct a rapid sensitivity analysis.

Figure 2-10

Geometry of the Top Hat Section

32

MSC Laminate Modeler User’s Guide Building Models using Global Layers

Figure 2-11

Lamination Specification of the Top Hat Section

In contrast, the MSC.Laminate Modeler user simply needs to define four layers which cover the areas of each laminate. Then, multiples of these layers are added to the model, using the layup spreadsheet. Because the surface is developable, it is permissible to use the Angular Offset option to modify the orientation of the plies at 45, 90 and -45 to the original layers. All the generation of representative property regions would be handled completely automatically by the software.

Chapter 2: Tutorial 33 Building Models using Global Layers

Figure 2-12

Visualization of Geometry Covered by Layer_3

The greatest benefit would, of course, accrue if the model needed to be changed after a preliminary analysis. For example, the user may wish to define localized reinforcement at the attachment end of the section. This could be completed in a matter of minutes by defining additional layers and adding them to the layup.

Benefits of MSC.Laminate Modeler 1. Rapid layer-based generation and modification of model.

34

MSC Laminate Modeler User’s Guide Results Processing

Results Processing Recovering Results by Global Layer Conventional systems present stresses on the basis of a particular layer on individual elements. If any element is reversed, or there are ply drop-offs on the surface, the produced results cannot be interpreted meaningfully. In contrast, the MSC.Laminate Modeler rearranges analysis results stored in the database so that they refer to global layers defined in the layup spreadsheet. This means that the results for a physically meaningful piece of fabric are presented together. This is a unique capability for the maj ority of codes that store composite data on the basis of laminate materials.

Example of a Top Hat Section Fringe plots for stresses along the fibres are presented for global layers 1, 17, 21 and 33 for the top-hat section model. Using conventional post-processors, this would give misleading results due to the variation of layup over the model. In contrast, all stresses presented here are continuous, indicating that the correct results have been grouped for each global layer.

Figure 2-13

Chapter 2: Tutorial 35 Results Processing

Figure 2-14

Layer Results

36

MSC Laminate Modeler User’s Guide Results Processing

Figure 2-15

Layer Results

Chapter 2: Tutorial 37 Results Processing

Figure 2-16

Layer Results

Benefits of MSC.Laminate Modeler 1. Flexible layer-based results processing.

38

MSC Laminate Modeler User’s Guide Structural Optimization

Structural Optimization Introducing Iteration to the Development Process The ability to modify a composite model rapidly and asses results on a realistic basis opens up many opportunities for the optimization of composite structures. This is essential to compete with highlyoptimized structures made of conventional materials, and bring the cost of composite structures down to a competitive level.

Example of a Torque Tube with a Cutout A tube subject to torsional loading and having a large cutout is representative of a number of structures, including the chassis of a single-seater racing car. A layup was defined, using two global layers covering the entire surface, and the rim around the cutout respectively as shown in Figure 2-17 and Figure 2-18.

Figure 2-17

Analysis Model of Torsion Tube

Chapter 2: Tutorial 39 Structural Optimization

Figure 2-18

Stiffened Collar

Models were built with a uniform layup, and including layer_2 reinforcement around the cutout. Analyses were then conducted for both configurations. As shown in the deformation plot in Figure 2-19, the torsional load generates substantial out-of-plane deflections around the cutout. Therefore, it is to be expected that reinforcing the cutout edge will have a significant effect on the structural performance of the tube.

40

MSC Laminate Modeler User’s Guide Structural Optimization

Figure 2-19

Deformed Shape of Analysis Model

The analysis results for both models are summarized in the table below.

Property

Uniform Layup

Reinforced Layup

Difference

Layup

layer_1 (0/45/-45/90) layer_1 (90/-45/45/0)

layer_2 (0/45/-45/90) layer_1 (0/45/-45/90) layer_1 (90/-45/45/0) layer_2 (90/-45/45/0)

layer_2 (0/45/-45/90) layer_2 (90/-45/45/0)

Mass

4.826 kg

5.035 kg

0.209 kg (+4.3%)

Rotation

0.143

0.118

-0.025 (-18%)

Max. Deflection

2.817 mm

1.800 mm

-1.017 mm(-36%)

Max. Tensile Fiber Stress

165 MPa

122 MPa

43 MPa (-26%)

Max. Compressive Fiber Stress

186 MPa

121 MPa

65 MPa (-35%)

This clearly shows that the addition of local reinforcing in highly-loaded areas can have an extremely significant effect on overall structural performance. By allowing the designer to quantify the effects of localized reinforcement, the MSC.Laminate Modeler will enable the development of more efficient structures.

Chapter 2: Tutorial 41 Structural Optimization

Benefits of MSC.Laminate Modeler Rapid modify-analyze-interpret cycle allows optimization.

42

MSC Laminate Modeler User’s Guide Glossary

Glossary (ISO 10303 equivalent terms in parentheses) layer (Ply)

An area on a surface having consistent material properties, fiber orientation and thickness. A layer is analogous to one or more pieces of fabric which are applied to a surface adjacent to each other and in a similar way.

layup sequence (Layup_ply_table)

An assembly table which provides an ordered list of layers.

layup (Ply_laminate)

A collection of one or more layers which mate with one another.

Chapter 3: Using MSC.Laminate Modeler MSC Laminate Modeler User’s Guide

3

Using MSC.Laminate Modeler



Procedure



Element Library



Initialization



Creating Materials



Creating Plies



Creating a Layup and an Analysis Model



Creating Solid Elements and an Analysis Model



Creating Laminate Materials



Creating Sorted Results

97



Creating Failure Results

100



Creating Design and Manufacturing Data



Importing Plies and Models



Importing and Exporting Laminate Materials



Setting Options



Session File Support



Public PCL Functions



Data Files

44 46

48

127

49

55

111 118 119

74

91

103

105 108

89

44

MSC Laminate Modeler User’s Guide Procedure

Procedure The MSC.Laminate Modeler is a specialized tool for the creation and visualization of a ply-based laminated composite model. An analysis model consisting of appropriate laminate materials and element properties can be generated automatically for a number of different analysis codes. Following analysis, specific composite results can be calculated to verify the performance of the model. The general process for generating a laminate composite model is as follows: 1. Create Homogeneous Materials (Patran) Materials are typically orthotropic, and the user should specify failure coefficients when defining materials. 2. Create Mesh (Patran) The surface on which the composite layup is to be built is defined by the shell elements of the finite element mesh in the Patran database. The user should generate a mesh of sufficient resolution for both drape simulation and analysis purposes. It is a requirement that the meshing is completed before starting a session. Use the tools in the Finite Element application to verify the element normals and the free edges of the model before creating a new Layup file. 3. Create Ply Materials (MSC.Laminate Modeler) These materials are analogous to raw ply materials and include a reference to a homogeneous material for specifying mechanical properties, as well as manufacturing related information like thickness. 4. Create Plies (MSC.Laminate Modeler) Create plies in a manner which reflects the manufacturing process. 5. Create a LM_Layup and an Analysis Model (MSC.Laminate Modeler) A layup, or sequence of plies, is defined, allowing the creation of corresponding laminate materials and element properties required to define an analysis mode.. 6. Analyze (Patran and analysis code) The analysis is submitted in the usual way. The user may have to explicitly request layered composites results from the analysis code. 7. Create Results (MSC.Laminate Modeler) The user may sort results on the basis of physical plies or define new ones based on a failure analysis. These operations are summarized schematically overleaf.

Chapter 3: Using MSC.Laminate Modeler 45 Procedure

Overview

Figure 3-1

Overview of MSC.Laminate Modeler Process

46

MSC Laminate Modeler User’s Guide Element Library

Element Library Standard shell elements define the surfaces used in the MSC.Laminate Modeler module. The standard Patran geometry and mesh generation commands can be used to create a valid model. The elements in the Patran database are used to define the draping surface in addition to acting as analysis elements

Supported Element Topologies

Figure 3-2

Element Types

After the laminate descriptions have been generated they are applied to the Finite Element model in a controlled manner. The user is allowed to select the type of element for the currently selected analysis preference.

Supported Element Types 1. Property selection and generation has been significantly enhanced from previous versions. MSC.Laminate Modeler is no longer restricted to generati ng the data for MSC’s own preferences. Any suitably customized database will allow the generation of the required laminate materials and properties. 2. Selection of the thermal composite elements is now possible because of the redesign. 3. SAMCEF is supported by writing an external file for inclusion into the BACON BANQUE file.

Supported Element Property Words The routine for creating properties extracts the data from the database and compares it against values that are consistently used for the type of data required by MSC.Laminate Modeler. The PROP_IDS that are recognized are:

Chapter 3: Using MSC.Laminate Modeler 47 Element Library

PROP IDS

DESCRIPTION

DATA TYPE

ID_PROP_MATERIAL_NAME(13)

Laminated material name generated by MSC.Laminate Modeler.

MATERIAL_ID(5)

ID_PROP_ORIENTATION_ANG(20)

This will be set to 0.0. The Laminate materials are built to reflect the different relative angles.

REAL_SCALAR(1)

ID_PROP_ORIENTATION_SYS(21)

This prop_id is used to allow the creation of COORD_ID(9) additional reference coordinate frames. Users are prompted whether or not they wish to create the frames.

ID_PROP_ORIENTATION_AXIS(1079)

The property call is made reflecting the occurrence of this prop_id.

INTEGER_SCALAR(3)

If the applicable data type for the prop_ids described is not available, then the MSC.Laminate Modeler cannot generate the required property cards.

48

MSC Laminate Modeler User’s Guide Initialization

Initialization The initialization form controls the opening of the current MSC.Laminate Modeler database (Layup) file and the resultant display of the main Action Object Method control forms. To display the initialization form, select MSC.Laminate Modeler from the Tools menu.

Chapter 3: Using MSC.Laminate Modeler 49 Creating Materials

Creating Materials When using MSC.Laminate Modeler there are three levels of material generation. 1. Patran homogeneous materials should be generated using standard Patran functionality. These contain mechanical, thermal or physical data which can be manually input or imported Using Patran Materials (p. 10) in the Patran Materials Enterprise . 1. MSC.Laminate Modeler ply materials. These ply materials have thickness and manufacturing data in addition to a reference to an appropriate material in the Patran database. These ply materials are used to create plies in the MSC.Laminate Modeler module. 1. Patran laminate materials which are built up from Patran homogeneous materials by the MSC.Laminate Modeler software on the basis of the user-specified layup sequence, offsets and tolerances.

Patran Homogeneous Material Definition The main description of the materials is done using the standard Patran methods of definition. The Materials form can be used to generate the required materials. Methods available include user input, external definition and Patran Materials.

MSC.Laminate Modeler Ply Material Definition The homogeneous materials created, within the standard Patran form, are referenced within the MSC.Laminate Modeler Create LM_Material Add form to generate ply materials with extended property sets which include thickness and manufacturing data, such as the maximum strain allowable during draping.

Material Application Types Ply materials are categorized by the way in which they are applied to a selected surface. They reference particular types of Patran homogeneous materials. • Painted

Isotropic materials are supported for Painting . • Projected

2D/3D orthotropic and anisotropic materials are supported for Projecting . • Scissor Draped

2D/3D orthotropic and anisotropic materials are supported for Scissor Draping . • Slide Draped

2D/3D orthotropic and anisotropic materials are supported for Slide Draping .

50

MSC Laminate Modeler User’s Guide Creating Materials

Additional Ply Material Parameters • Thickness • The thickness of a single ply of the material before it is sheared. • Maximum Strain

The allowable strain value before the material “locks” (i.e., the material can no longer conform to the surface by shearing). This is measured in degrees. • Initial Warp/Weft Angle

This value describes the original undeformed angle between warp and weft yarns in a fabric. This value can be overridden on the Create LM_Ply Add, Additional Parameters form. This allows deformation of the fabric before it is placed on the model, which may achieve better draping. This angle is measured in degrees.

Paint

Project

Scissor

Slide

Thickness

Yes

Yes

Yes

Yes

Maximum Strain

No

No

Yes

Yes

Initial Warp/Weft Angle

No

No

Yes

No


Create LM_Material Add Form This form allows the user to generate MSC.Laminate Modeler ply materials which reference Patran homogenous materials and contain additional thickness and manufacturing data.

52


Modify LM_Material Form


Show LM_Material Form

54


Delete LM_Material Select Form

Chapter 3: Using MSC.Laminate Modeler 55 Creating Plies

Creating Plies What is a Ply? A ply is an area of LM_Material which is stored and manipulated as a single entity. A ply represents a piece of reinforcing fabric which is cut from sheet stock and placed on a mould during the manufacturing process. A ply is fully characterized by the LM_Material it is made of, the area it covers, and the way in which it is applied to the surface. The latter is particularly important for non-developable surfaces where there are many different ways of placing the fabric on a surface.

Figure 3-3

LM_Ply Description

Why use Plies? Plies allow easy manipulation of complex data when you assemble and/or modify the layers to form the complete layup. The physical representation of a ply is a piece of fabric.

56

MSC Laminate Modeler User’s Guide Creating Plies

Create LM_Ply Add Form (Draping)

Application type. Options include: Drape (Scissor), Drape (Slide), Projected, Painted. Existing LM_Plies of the selected type. Unique name used to reference the ply. The default name is of the form:

Ply_1 After a new ply is created, the numerical suffix (if any) of the name is identified and incremented by one, e.g. Ply_1 to Ply_2

Existing LM_Materials of the selected type. If only one material exists, then it is automatically selected.

Elements or Surfaces defining the extent of a ply. Starting point of the application method. Reference direction for the application method. Reference direction for the application method. Reference angle between the reference direction and the initial warp orientation at the starting point. Additional parameters required by the application method.

Application Direction

Start Point Reference Angle Reference Direction

Note:

When a ply is created, a group of the same name and containing the Area Definition entities is created.


Input Data Definitions Start Point

This defines the starting point of the drape simulation process. It is analogous to the point at which a ply is first attached to a mould surface during manufacture. As the distortion usually increases away from the starting point, it is best to begin draping near the center of a region to minimize shear distortion. If the start point coordinates do not lie on the selected surface, the coordinates are projected onto the surface along the application direction vector. The start point must lie on the s elected area. Application Direction

The application direction defines the side of the surface area on which a ply is subsequently added when the final layup is defined. The “Top” of the surface covered by the ply is defined as the s ide on which the ply is originally applied when created. When defining a layup, the ply can be added to the “Top” or “Bottom” side of the mesh. It follows that the “Top” side is the same side as the application direction used to define the ply, whereas the “Bottom” side is the side opposit e the application direction.


Top

Top For the same element, it is possible for different plies to have a different definition of the top side of the element depending on the application direction.

Application Direction The concept of side is very important as composite structures are often built using molds or forms, limiting the side of application to a single direction. The plies of reinforcing fabric can be added to either the outside of a male mould or the inside of a female mould. When defining plies and a layup, it is useful to consider the manufacturing process. The application direction is also used to project the start point and reference direction onto the surface.

58


Reference Direction

The reference direction is used to specify the initial direction of the fabric. The input vector is projected onto the surface along the application direction to define the principal warp axis of the material at the start point. Note that the direction of the material wi ll usually change away from the starting point if the surface is curved. Reference Angle

The principal warp axis of the material on the surface can be rotated from the reference direction by inputting a non-zero reference angle. This rotation is counterclockwise when viewed along the application direction.

Viewpoint 1

Viewpoint 2

(a)

Figure 3-4

Reference Direction

(b)

Effect of Application Direction on Warp Orientation

Note that the application direction is used to project the start point and reference direction vector onto the selected surface. This means that the same start point and reference direction vector results in different values when projected onto the surface along different application directions, as shown in Figure 3-4. It follows that the start point and reference direction should be defined as close to the surface as practical, while the application direction should be defined as perpendicular to the surface as possible.


Side Definition

Figure 3-5

Projection of Reference Direction

60


Example of Starting Definitions


Start Point

Reference Direction

Start Point

[24.999996 49.999996 0.] Application Direction

<0.1 -1.0 0.> Reference Direction

<1. 0. 0.> Reference Angle

0.

This example shows the view as it would appear in the viewport in addition to the input that would appear on the Create LM_Ply Add form.

Axis Type The principal warp and weft axes are the paths the warp and weft fibers follow along the surface away from the start point. By defining the paths of the principal axes, it is possible to constrain the ply uniquely in the region bounded by the principal axes.


Boundary of uniquely constrained region Principal weft axis Start point Principal warp axis The principal axes can be defined in different ways: • None

No principal axes are defined, draping proceeds using the extension method only. • Geodesic

The principal axes are defined by geodesic lines from the start point. • Planar

The principal axes are defined by the intersection of planes defined by the start point, application direction and reference direction rotated about the application direction through the reference angle. Extension Type

The extension type controls the draping process if no axis type is defined, or the draping extends beyond the region uniquely defined by the principal axes. In this case, the material cells on each edge are kinematically unconstrained, and so some extension type must be specified to control the extension of the fabric.

Boundary of region uniquely constrained by principal axes.

Free edge extending in accordance with the extension type. The extension mechanism can be defined in different ways: • Geodesic

The fiber closest to the principal axis is identified and extended along the surface along a geodesic path. The adjacent fabric cells are then uniquely constrained. Note that the geodesic extension method yields an identical result to that produced using geodesic principal axes, followed by geodesic extension where necessary.

62


• Energy

The mechanism defined by the free edge cells is rotated in such a way as to minimize the shear strain energy in that free edge, using the assumption that the shear load-deflection behavior is linear (this could be extended for nonlinear response). • Maximum

The mechanism defined by the free edge cells is rotated in such a way as to minimize the maximum shear strain in that free edge. Optimised Energy and Optimised Maxshear modes use a "circula r" extension strategy to model the hand layup of woven fabrics. The Tape modes use a "strip" extension strategy to simulate the application of tape in a way which accurately reflects the real-world application of butted tapes of material onto a surface by manual means. This is also likely to reflect butted tape laying via automated means, subject to the fact that the t he detailed characteristics of the tape laying machine m achine are not known by AFM. Circular Propagation Modes

In the "circular" extension modes (Energy and Maxshear), free edges in the warp and weft directions are extended alternately so that the ply extends uniformly in all directions away from the Seed Point. This models the operator progressively smoothing the fabric onto the mould away from the Seed Point.

Strip Propagation Modes

In the "strip" extension mode (Tape), the first tape is extended from the Seed Point in the warp direction all the way to the ply boundary in both the positive and negative warp directions. Only once this first tape is laid are additional tapes abutted against the free weft edges of the preceding tapes. For each new tape, the material strain is set to zero at the point of first application, which is defined as the point in the most negative warp direction. This reflects the fact that the material is unsheared at the point of first application

Chapter 3: Using Using MSC.Laminate MSC.Laminate Modeler 63 Creating Plies

on a surface. The rate of increase of shear along the tape depends on the width of the tape and the Gaussian curvature of the surface.

64


Additional Controls Form - Geometry

Sets the axis type for the draping simulation. None:There None:There are no principal axes, and draping proceeds by extension only. Geodesic:Principal Geodesic:Principal axes are geodesic lines from the start point. Planar:Principal Planar:Principal axes are intersection of principal planes with the surface. Manual:Define Manual:Define principal axes by selecting element edges.

Sets the extension type for the draping simulation. Energy is the default. Energy:Draping Energy:Draping proceeds from start point minimizing shear strain deformation energy. Maximum:Draping Maximum:Draping proceeds from start point minimizing the maximum shear. Geodesic:The Geodesic:The first extension yarn lies in a geodesic direction nearest the principal axis. Sets the step length for the application simulation. Implicit: Input value multiplies default step length Explicit:Input Explicit:Input value used for step length


Additional Controls Form - Material

66


Additional Controls Form - Boundaries

Chapter 3: Using Using MSC.Laminate MSC.Laminate Modeler 67 Creating Plies

Figure Figure 3-6

Note:

Split Example Example

Avoid starting to drape near split definitions to prevent ambiguous draping results.

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Additional Controls Form - Order of Draping


Note:

This capability is particularly useful when draping over a series of conical sections. First drape the most critical section, ensuring minimal shear. Thereafter, drape peripheral areas.

70


Create LM_Ply Add Form (Projection)


Modify LM_Ply Form

72


Show LM_Ply Graphics Form


Delete LM_Ply Select Form

Note:

When an LM_Ply is deleted, the group of the same name created at LM_Ply creation time will also be deleted.

74

MSC Laminate Modeler User’s Guide Creating a Layup and an Analysis Model

Creating a Layup and an Analysis Model The individual LM_Plies are used to define the model LM_Layup using the Create LM_Layup Add form. When this form is selected, a spreadsheet for the Layup definition and forms for the relevant tolerances can be accessed. The forms are described on the following pages. These forms are used to create and maintain the analysis layup. As well as providing tools to modify and redefine the layup, the forms will generate the correct laminate materials and apply the correct properties to the model. If all other operations are complete (i.e., Loads/BC addition), the model is ready for analysis after these forms have been applied.

Chapter 3: Using MSC.Laminate Modeler 75 Creating a Layup and an Analysis Model

Create LM_Layup Add Form

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Layup Definition Form

The spreadsheet is used to specify which of the previously defined LM_Plies are used in the generation of the model LM_Layup. The form allows the selection and ordering of the required LM_Plies. Manipulation of the LM_Plies within the spreadsheet is used to create different stacking sequences and layups. Select the specific LM_Ply from the definitions in the Existing LM_Plies frame The method of application of that LM_Ply to the existing layup is controlled by the LM_Layup Controls. Continue by Adding, Inserting, and Deleting LM_Plies until the LM_Layup is finished. LM_Plies can be added to the layup at any time to reinforce the model between analyses. The ability to redefine laminates rapidly is one of the key features of the MSC.Laminate Modeler. The spreadsheet works in two distinct but connected modes. They are called “Expanded” and “Compressed.” In expanded mode, the multiplier column on the spreadsheet is always set equal to 1. This enables you to work at the level of single LM_Plies and the Delete and Replace commands will only act on the single LM_Ply selected. In compressed mode, the Delete and Replace commands can be used to


do multiple “single actions” at the same time. For example, if a row is specified as having a multiplier of 10, then a replace instruction will replace all 10 rows with the new LM_Ply. The same is true for delete. You can switch between the two methods at any time and take advantage of the quicker set up time of the stack building, while still being able to modify the LM_Ply sequence at the single LM_Ply level if required. Make current definition a total definition.

Make the current definition symmetrical by copying LM_Plies.

Make the current definition symmetrical about the bottom LM_Ply.

Split the current definition in half.

Split the current definition in half as if the current definition is symmetrical about a mid-LM_Ply.

Cut data from selected spreadsheet cells.

Copy data from selected spreadsheet cells

Paste data cut or copied from selected spreadsheet cells

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Paste mirrored data cut or copied from selected spreadsheet cells

Undo the last command for the LM_Layup definition spreadsheet.

Figure 3-7

Icons on LM_Layup Create Spreadsheet


Offset Definition Form

Important:

Ignore Offsets is required for analysis preferences like ABAQUS and Patran Advanced FEA which do not allow any offset definition for composite shells. This is not the same as having an offset = 0.0. An offset with a specified value will cause an error as it is interpreted as a set value.

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Select Element Type Form


Tolerance Definition Form

82


Modify LM_Layup Add Form

As only a single layup is allowed in a single Layup file, the form for layup modification is identical to that for layup creation.


Show LM_Layup Exploded View Form

This capability allows the user to verify the definition and application direction of the plies defined in a layup.

Patran 2012 Laminate

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