MSC NASTRAN patran Progressive Failure and Delam 021712

SECTION 3 Progressive Ply Failure and Delamination Modeling

Composites Technology Day, January February2012 2012 Copyright 2012 MSC.Software Corporation

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Composites Failure Modeling • Look at types of problems you can solve today with MSC’s composite failure technology • Examples demonstrating how to apply this technology and how it works

Composites Technology Day, January 2012 Copyright 2012 MSC.Software Corporation

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Composite Fuselage Example • Composite aircraft fuselage – Light weight composite components – Constructed from layered composite material – Bonded and/or fastened together

Composites Technology Day, February 2012 Copyright 2012 MSC.Software Corporation

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A Closer Look

Simulate delamination?

Frame

Stringers

Shear clips Skin Composites Technology Day, February 2012 Copyright 2012 MSC.Software Corporation

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Composites Damage and Manufacturing Defect Examples


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Composites Failure Examples


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First-Ply-Failure Analysis • First-Ply Failure (FPF) – Linear analysis based on failure theory – Compute failure index or strength ratio for the ply material – Optimization of ply angle/thickness

Critical Margin of Safety


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Going Beyond FPF • Evaluate the load redistribution in a composite structure as the plies fail progressively • Simulate delamination growth from initial flaw • Study crack propagation to design for fail-safe structures


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Going Beyond FPF Ply Material Failure

Delamination

CZM

VCCT

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PFA Delamination Composites Technology Day, February 2012 Copyright 2012 MSC.Software Corporation

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Breaking Glue

FAQ: What Element types are supported? • Composite failure modeling is supported in both shell and solid elements Shell element

Solid element Layered Composite definition

Solid Shell element Composites Technology Day, February 2012 Copyright 2012 MSC.Software Corporation

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Composites Failure Modeling - PFA

VCCT

CZM

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Breaking Glue


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Progressive Failure Analysis (PFA) • Also known as Progressive Ply Failure (PPF) • Select a failure criterion • Select a degradation option • The composite is failed on a layer by layer basis • Upon failure, the elastic properties are scaled down

Pin bearing on hole Composites Technology Day, February 2012 Copyright 2012 MSC.Software Corporation

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Composite Failure Criteria Composite Failure •

Most of the criteria are semi-empirical in nature

Composite Failure on Layer Basis • • • • • • • • • •

Maximum Stress Maximum Strain Hill Hoffman Tsai-Wu Hashin Puck Hashin-Tape Hashin-Fabric User defined (UFAIL)


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PFA Options Progressive Composite Failure options •

Flagged through the MATF entry (ITYPE = 2 or 3)

•

Up to three failure criteria can be selected

•

Only the primary failure criterion is used for PFA

•

The other two are only used to calculate failure indices

•

The behavior up to the failure point is linear elastic

•

Upon failure… – When failure index is larger than one, degrade material moduli – Selective degradation – if matrix fails, do not change fiber properties – Stiffness drops gradually or immediately


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MSC Nastran Input Data Format

ITYPE: 0 – No PFA; 2 – Gradual Selective; 3 – Immediate Selective

Criterion: 1 – Max. Stress; 2 – Max. Strain; 3 – Hill; 4 – Hoffman; 5 – Tsai-Wu; 7 – Hashin; 8 – Puck; 10 – Hashin-Tape;11 – HashinFabric; 13 – User Subroutine


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PFA Example – Fuselage Damage Rigid elliptical cylinder hitting composite shell 5-layered composite Puck criterion, gradual option Damage of outer ply


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PFA Example – Wing Damage


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Micromechanical Failure model • Traditional approach computes composites failure based on ply-level failure properties • The Micromechanical approach gets down to the fiber and matrix level and looks at the failure mechanism at the constituent level • MSC has partnered with Firehole to bring the Helius MCT micromechanical failure technology to our users


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Composites Failure Modeling - VCCT

VCCT

CZM

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Breaking Glue


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VCCT • In linear fracture mechanics, a crack starts to grow when – Total G > Gc – G is the energy release rate – Gc is the fracture toughness

• The VCCT is one of the methods used to compute the energy release rate.


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VCCT (Virtual Crack Closure Technique)

• FEM approximation: Use consistent nodal force at tip and crack opening at first crack segment • Energy release rate: G = Fu/2a • Growth method • Release glued contact • Grow along element edge Marc Only • Remeshing Composites Technology Day, February 2012 Copyright 2012 MSC.Software Corporation

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VCCT • Supported in both Marc and MSC Nastran • Supported crack types are shown below

line crack – 2D or shell

face crack – shell to shell

line crack – shell edge to solid or shell Composites Technology Day, February 2012 Copyright 2012 MSC.Software Corporation

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face crack – 3D solid

face crack – shell to solid

Modes of Crack Extension • All three modes of crack extension are supported

Mode I: Opening Composites Technology Day, February 2012 Copyright 2012 MSC.Software Corporation

Mode II: Sliding S3-23

Mode III: Tearing

VCCT Example – Release glued contact • Skin-Stringer Delamination – Wagner/Balzani, Computers & Structures 2008 – Stringer glued to skin

stringer

initial crack front

skin

Initial delamination

fixed stringer

push skin downward

VCCT key ingredients: - Initial crack Composites Technology February 2012 - Define crackDay, front nodes Copyright 2012 MSC.Software Corporation

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VCCT Example – Release glued contact

Animation shows glued region

Animation shows region released from glued


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VCCT Example – Release glued contact • Benchmark Problems

DCB

DCB


DCB

SLB S3-26

VCCT Example – Release glued contact • 4-Ply Composite modeled with 2 layers of solid elements

Embedded circular defect

• Defect between 3rd and 4th ply • Glue parts together, except at defect

F Buckling Delamination


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F

VCCT Example – Release glued contact


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VCCT Example – Grow Along Element Edge Growth direction: maximum hoop stress criterion

Initial crack


clamped

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VCCT Example – Grow Along Element Edge

Quad mesh

Tria mesh

Remesh Composites Technology Day, February 2012 Copyright 2012 MSC.Software Corporation

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VCCT Example – Crack Bifurcation • New technology – Crack tip automatically generated as the crack reaches the stiffener 8 layers 4 layers

glued

shell thickness with offsets

elastic orthotropic material composite with four layers: [-45/90/0/45]


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VCCT Example – Crack Bifurcation • Growth through composite skin with stiffeners


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VCCT Example – Crack Bifurcation

Courtesy of Dr. Kim Parnell Composites Technology Day, February 2012 Copyright 2012 MSC.Software Corporation

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Composites Failure Modeling - CZM

VCCT

CZM

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Breaking Glue


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Cohesive Zone Modeling (CZM) • Cohesive Zone Modeling (CZM) is a technique used to simulate delamination growth.

• The implementation of CZM is based on: • Library of special interface elements • Material model to characterize the interface behavior

Interface Element


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Cohesive Zone Modeling (CZM) • The constitutive behavior of these elements is expressed in terms of tractions versus relative displacements between the top and bottom edge/surface of the elements • Top and bottom faces may coincide

V is the effective opening displacement


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Cohesive Zone Modeling (CZM) • Material models • Bilinear • Exponential • Linear-exponential

• Material behavior

8

4 n

 t

5 1

• Initially reversible • Irreversible if v > vc


top face 7

 s

3 bottom face

6 2

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top and bottom face may coincide (zero thickness)

CZM – Example • Lap-Shear Joint: Plates

Adhesive Region

•

Reference: M.N. Cavalli, M.D. Thouless and Q.D. Yang, Cohesive-Zone Modeling of the Deformation and Fracture of Weld-Bonded Joints; Welding Journal Vol. 83, no. 4, 2004


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CZM – Example • Finite element model: – Mesh plates and adhesive layer independently using higher order elements – Utilize the contact option to glue the adhesive layer to the plates


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CZM – Example


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Composites Failure Modeling – Breaking Glue Contact

CZM VCCT

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Breaking Glue

PFA Composites Technology Day, February 2012 Copyright 2012 MSC.Software Corporation

Delamination S3-41

Breaking Glued Contact • Release glued contact when the following stress criterion is met User specified

User specified

• Use contact normal and tangential stresses • After break, do regular contact with friction and separation Composites Technology Day, February 2012 Copyright 2012 MSC.Software Corporation

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Example - Breaking glued contact • Coating debonding • Load with rigid body


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Example - Breaking glued contact • Coating debonding • Load with rigid body


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Composites Failure Modeling – Delamination (Marc only)

CZM

VCCT

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Breaking Glue

PFA Composites Technology Day, February 2012 Copyright 2012 MSC.Software Corporation

Delamination S3-45

Delamination • Split up mesh between materials or within a material when the following stress criterion is met

• Use stresses normal and tangential to interface


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Delamination Examples


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Delamination with CZM • Option to insert interface element where mesh is split – Fully automatic


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Delamination Example: Plate impact • Composite plate, 8 layers, [0/45/45/90]s • Stacked solid shell elements – One element per layer – No double nodes

• Clamped edges, prescribed downward motion of circular region in the center


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Delamination Example: Plate impact • View quarter model • Outline plot • Delamination between layers (mesh splitting) • Contact occurs between layers


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Delamination Example: Plate impact • Automatic insertion of interface elements • Self contact not needed • Show only interface elements


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Summary • Progressive Failure Analysis (PFA) • Virtual Crack Closure Technique (VCCT) – Fracture mechanics

• Cohesive Zone Model (CZM) – Interface elements

• Breaking glued contact – Stress Criterion 52

• Delamination – Stress Criterion Composites Technology Day, February 2012 Copyright 2012 MSC.Software Corporation

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End of Section 3


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MSC NASTRAN patran Progressive Failure and Delam 021712

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