E n g i n ee e e r i n g A n a l y s i s u s i n g S im i m u l at a t io i o n (S W ) The process of dividing the model into small pieces is called m e s h i n g . The behavior of each element is well-known under all possible support and load scenarios. The finite element method uses elements with different shapes. Elements share common points called n o d e s .
U p l o a d i n g S i m u l a t io i o n ( SW SW )
S W S im i m u l a ti ti o n Designer (SW Simulation) Linear static load analysis (SimulationXpress) (Includes many limitations)
Professional (SW Simulation Professional) Linear static load analysis, Thermal analysis, Buckling analysis, Frequency analysis, Drop test analysis, Fatigue analysis Optimization analysis
Advance Professional (SW Simulation Premium) Premium) The features of the Professional package plus: Nonlinear analysis and Dynamic loading condition
S o l i d W o r k s S im i m u l a t io i o n - A d v a n c e Pr Pr o f e s s i o n a l
Select New Study
P lo lo t T y p e O p t i o n s Safety factor applied to strength, less than 1
Right click on results and select plot types 2008 2009
S W Si S i m u l a ti t i o n P r o f es es s i o n a l
S t r es e s s a n a l y s i s d u e t o s t a t i c l o a d s - Static studies calculate displacements, reaction forces, strains, stresses, and factor of safety distribution. A distribution. A factor of safety safety less than unity indicates part failure. Large factors of safety in a contiguous region indicate low stresses and that you can probably remove some material from this region.
tends to vibrate Frequ Fre qu ency (Vibr (Vibr ation ) analys is - A body in motion tends at certain frequencies called natural frequencies. The lowest natural frequency is called the fundamental frequency. frequency. For each natural frequency, frequency, the body takes a certain shape called mode shape. Frequency analysis calculates the natural frequencies and the associated mode shapes. High stresses are produced if a body is subjected to a dynamic load vibrating at one of its natural frequencies. This phenomenon is called
S W Si S i m u l a ti t i o n P r o f es es s i o n a l
T h e r m a l a n a ly l y s i s - Thermal studies calculate temperatures, temp. gradients, and heat flow considering heat generation, conduction, convection, and radiation conditions. Thermal studies can help in avoiding undesirable thermal conditions like overheating and melting.
B u c k l i n g a n al a l y s i s - Slender structures, called columns, subject to axial loads can fail due to buckling at load levels lower than those required to cause material failure. Buckling can occur in different modes. In many cases, only the lowest buckling load is of interest.
O p t i m i z a t i o n - Optimization studies automate the search for the optimum design based on a geometric design. The software is
S W Si S i m u l a ti t i o n P r o f es es s i o n a l
F at a t i g u e a n a l y s i s - Repeated (cyclic) loading weakens objects over time even when the induced stresses are considerably less than allowable stress. The number of cycles to failure depends on the material and the stress fluctuations. This information, is provided by a curve called the S-N curve (stress vs number of cycle to failure). Fatigue studies evaluate the consumed life of an object based on fatigue events and S-N curves.
D r o p T e s t S t u d i e s - Drop test studies evaluate the effect of dropping the design on a rigid floor floor.. The dropping distance or the velocity at the time of impact, in addition to gravity, gravity, can be specified. The program solves a dynamic problem as a function of time. Due to the large amount of data, the program saves results at certain instants and locations as instructed
S W Si S i m u l a ti t i o n P r o f es es s i o n a l
N o n l i n e ar a r a n a l y s i s - When the assumptions of linear static analysis do not apply, apply, you can use nonlinear studies to solve the problem. The main sources of nonlinearity are: large displacements, nonlinear material properties, and contact. Nonlinear studies calculate displacements, reaction forces, strains, and stresses at incrementally varying levels of loads and restraints. Nonlinear studies refer to nonlinear structural studies. For thermal studies, the software automatically solves a linear or nonlinear problem based on material properties and thermal restraints and loads. Solving a nonlinear problem requires much more time and resources than solving a similar linear static study study..
M es e s h E le l e m e n t s u s e d b y S W Si S i m u l a t io io n
• Beam elements (1D)
Draft quality
• Shell elements (2D)
• Solid elements (3D)
High quality
M es e s h E le l e m e n t s u s e d b y S W S im i m u l a ti ti o n Draft quality
High quality
Certain shapes can be modeled using either solid s olid or shell elements such as a plate.
) N o d a l D eg e g r e e o f F r e ed e d o m (D O F The model's degrees of freedom (DOF) are assigned at the nodes. Usually solid elements have three DOF, all translational . Rotations are accomplished through translations of a node relative to another node. Shell elements, on the other hand, have six DOF per node: three translations and three rotations. The addition of rotational DOF allows for evaluation of bending stresses due to rotation of one node relative to another. This bypasses the necessity of modeling the physical thickness. The assignment of nodal DOF also depends on the class of analysis. For a thermal analysis, only one temperature DOF
M es e s h T y p e i n S W Si S i m u l a ti ti o n Solid Use the solid mesh for bulky models. All elements are tetrahedral with straight or curved edges Node
M es e s h T y p e i n S W Si S i m u l a t io io n Shell mesh using mid-surfaces Use this option for s h e e t m e t al a l s a n d s i m p l e t h i n s o l i d p a r t s made made of a single material. During meshing, the software creates shell elements based on midsurfaces. The thickness of elements is calculated automatically based on a i l ab a b l e f o r a s s e m b l i e s a n d s u r f ac ac e m o d e l s surface pairs. T h i s o p t i o n i s n o t a v ai and can fail to generate the proper mesh for complex parts and parts with intersections. View the mesh and see if it represents the actual model before proceeding with the solution.
M es e s h T y p e i n S W Si S i m u l a ti ti o n Shell mesh using surfaces es This option allows you to create shells on selected f a c e s o r s u r f a c es . For each shell, you can specify thickness, t hickness, material, and formulation. It is available for solid parts, solid assemblies, and surface models. Shell elements are placed such that the associated face or surface is located at the t he middle of the element across the thickness.
M es e s h T y p e i n S W Si S i m u l a ti ti o n Beam Mesh Use this option to simulate frames, and truss structures. The program creates elements automatically from weldments or you can define elements manually . A beam element is a line element defined by two end points and a cross-section. cr oss-section. Beam elements elements are capable of resisting axial, bending, shear shear,, and torsional loads. Trusses resist axial loads only.
Mixed Mesh This option is available only if you have a s o l i d b o d y in the document. It is possible to create shells as well as solids. When meshing, the software creates shells with shell elements and solids with tetrahedral solid elements. U s e t h i s o p t i o n i f t h e m o d e l i n c l u d e s b u l k y a s w e l l as as t h i n o b j e c t s .
A u t o m a t ic i c M es es h i n g
When you mesh a model, the software generates a mixture of solid,
shell, spring, and contact elements based on the created geometry.. The program automatically creates the following geometry meshes:
Solid mesh
Shell mesh
Beam
Mixed mesh
SW Simulation’s Help SW Simulation provides extensive on-line help and tutorials
S W Si S i m u l a t io i o n M en en u Tool bars
Main
Loads
S W S i m u l at at i o n To start analyzing the model, you should start st art with the definition of a study. Select S t u d y
Study name Mesh type, not in 2009, selection is done automatically by the program
Select analysis type
S W Si S i m u l a t io i o n –O p ti ti o n m en u Set Mesh quality to H i g h
C r ea e a t in i n g M es es h Use the bar to set the mesh density Right click the M e s h folder to display the pop-up menu.
Select Create Mesh
Effect of Mesh Siz Size e
Coarse
Medium
Fine
M es e s h C h a r ac ac t e r i s t i c s A u t o m a t i c t r an an s i t i o n - the
Global element size Tolerance is set at 5%. Nodes are merged if the distance between them is less than 5% of the element size.
Increasing the tolerance may resolve meshing problems
program automatically applies mesh controls to small features, holes, fillets, and other fine details of your model. Uncheck A u t o m a t i c t r a n s i t i o n before meshing large models with many small features and details to avoid generating a very large number of elements.
M es e s h C h a r ac ac t e r i s t i c s
Parabolic bolic elemen elements ts can map map J a c o b i a n P o i n t s - Para curved geometry much more accurately than linear elements of the same size. In extremely sharp or curved boundaries, it is possible to generate distorted elements with edges crossing over each other causing the mesh generation to fail. The Jacobian check is based on a number of points located within each element. The default value of 4 should be fine for most applications. Increase that for extremely curved surfaces.
M es es h Q u a l i t y
The ideal shape of a tetrahedral element is a regular tetrahedron with the a s p e c t r a t i o o f 1 . Analogously,, an equilateral triangle is the ideal Analogously shape for a shell element.
Sometimes, Irregular tetrahedra are created by the program. These distorted elements have high aspect ratio. An aspect ratio that is too high causes element degeneration, which in turn affects the quality of the results.
A s p e c t R at at i o
Right click the M e s h icon and select Create Mesh Plot
at i o Select A s p e c t r at
SW A u t o m es h e r
M es e s h Q u a l i t y – A u t o m e s h e r ( S W ) S t an an d a r d m e s h (a u t o m e s h e r ) It is preferred to use the Standard automesher (default). The program uses the Voronoi-Delaunay Voronoi-Delaunay meshing technique, it is faster than t han the Curved-based mesh method (Alternate automesher). By far the most popular of the triangle (2D) and tetrahedral (3D) meshing techniques are those utilizing the Delaunay criterion. c riterion. The Delaunay criterion, sometimes called the "empty sphere" property. Simply stated, it says that any node must not be contained within the circumcircle of a triangle or circumsphere of any tetrahedral within the mesh Delaunay triangulations maximize the minimum angle of all the angles of the triangles in the triangulation. The process avoids narrow triangles, as they have large circumcircles compared to their area
Triangle element
The Delaunay triangulation with all the circumcircles and
M es e s h Q u a l i t y – A u t o m e s h e r ( S W ) The Delaunay criterion in itself, is not an algorithm for generating a mesh. It merely generates a set of existing points in space. As such it is necessary to provide a method for generating node locations within the geometry. A typical approach is to first mesh the boundary of the geometry to provide an initial set of nodes. The boundary nodes are then triangulated according to the Delaunay criterion. Nodes are then inserted incrementally into the existing mesh, redefining the triangles or tetrahedra locally as each new node is inserted to maintain the Delaunay criterion. It is the method Connecting the centers of the that is chosen for defining where to locate the circumcircles produces the interior nodes that distinguishes one Delaunay Voronoi diagram (in red) algorithm from another. A Voronoi segment can be defined as the line segment segment between the circumcircle centers of two adjacent triangles or tetrahedra. The new node is introduced at a point along the Voronoi Voronoi segment in order to satisfy the best local size criteria.
M es e s h Q u a l i t y – A u t o m e s h e r ( S W ) ) C u r v e d B a s ed e d m e s h (A l t e r n a t e au au t o m e s h e r The Curved based mesh method uses the Advancing Front meshing technique. The mesher creates more elements in higher-curvature areas automatically (without (without need for mesh control). The technique technique disregards disregards the mesh control and automatic transition settings. It should only be used when the Standard automesher fails Another very popular family of triangle and tetrahedron tetrahedron mesh generation algorithms is the advancing front, or moving front method. Two Two of the main contributors to this method are Rainald Lohner at George Mason University and S. H. Lo at the University of Hong Kong. In this method, the tetrahedra are built progressively inward from the triangulated surface. An active front is maintained where new tetrahedra are formed. The figure shows a simple two-dimensional example of the advancing front, where triangles have been formed at the boundary. boundary. As the algorithm progresses, the front will advance to fill the remainder of the area with triangles.
S W Si S i m u l at a t i o n - M at a t er e r i al al s Right click on the material icon to edit
To assign material select Material and choose Apply Material to All
T y p e o f R es e s t r a in i n t s (s u p p o r t s ) Select the Fixtures (Restraints) option Fixtures menu
Standard option: Fixed support Sliding support Pin support
T y p e o f R es e s t r a in i n t s (s u p p o r t s )
Advanced supports
T y p e o f R es e s t r a in i n t s (s u p p o r t s ) Fixed (no rotation and translation) This is used for build-in or rigid supports. For solid elements, this restraint type sets all translational degrees of freedom to zero (solid elements do not have rotational degrees of freedom). For shell elements, it sets the translational and the rotational degrees of freedom to zero. When using this restraint type, no reference geometry is needed. Selectable entities: vertices, edges, and faces
Immovable (no translation) – translation) – SW 2008 This restraint type sets all translational degrees of freedom to zero. This is the same as fixed If solid elements are used. The rotational degrees of freedom are not constrained for shell elements. No reference geometry is used.
T y p e o f R es e s t r a in i n t s (s u p p o r t s ) Symmetry For shell models, symmetry requires that faces coinciding with planes of symmetry should be prevented from moving in the normal direction and rotating about the other two orthogonal directions. Symmetry requires that geometry, geometry, restraints, loads, and material properties be symmetrical. In general, using symmetry is not recommended for buckling and frequency studies.
Plane of symmetry
You can use symmetry to analyze a portion of the model instead of the full model. When appropriate, taking advantage of symmetry can help you reduce the size of the problem and obtain more accurate results. The procedures to apply the symmetry restraint type to s o l i d m e s h e
T y p e o f R es e s t r a i n t s – S y m m e t r y (S ( S o l i d M es es h ) The model
DOFs restrained for solid meshes: 1 translation
Plane of symmetry
Analyze one one half of the model by applying applying the Symmetry constrained to the faces of
T y p e o f R es e s t r a i n t s – S y m m e tr t r y (S ( S o l i d M es es h )
The model is symmetrical with respect to two planes
Analyze one quarter of the model by applying the S y m m e t r y constraint to the faces of symmetry.
) T y p e o f R es e s t r a i n t s – S y m m e t r y (S o l i d M e s h DOFs restrained for solid meshes: 1 translation
Axisymmetrical model, use a wedge, apply the Symmetry restraints to
) T y p e o f R es e s t r a i n t s – S y m m e t r y (Shell Mesh For studies created with Shell mesh using mid-surfaces, mid-surfaces , symmetry restraints are applied on the faces coinciding with the planes of symmetry of the model along the model thickness.
Axial symmetry symmetry
Mid-Surface element Rotation about radial and axial directions are restrained. Displacement (translation) n o r m a l to the face is restrained, circumferential direction
The axisymmetrical model can be studied by analyzing a wedge of the model
) T y p e o f R es e s t r a i n t s – S y m m e t r y (Shell Mesh Planar symmetry
Mid-Surface element
) T y p e o f R es e s t r a i n t s – S y m m e t r y (Shell Mesh For studies created with Shell mesh using surfaces, surfaces , symmetry restraints are applied manually on shell edges located on the planes of symmetry of the model
Surface model with Axial Symmetry
Select the axis of the shell as a reference and set the rotations about radial and axial and translation in the circumferential directions to zero on the vertical edges..`
Type of Restraints Roller/Sliding Use the Roller/Sliding restraint to specify that a planar face can move freely on its plane but CANNOT move in the direction normal to its plane. The face can shrink or expand under loading.
Hinge Use the Hinge restraint to specify that a cylindrical face can ONLY rotate about its own axis. The radius and the length of the cylindrical face remain constant under loading. This condition is similar s imilar to selecting the On cylindrical face restraint type and setting the radial and axial components to zero.
T y p e o f R es e s t r a i n t s – O n C y l i n d r i c a l Fa Fa c e You can use this option only when all the selected faces are cylindrical. Each face can have a different axis. The radial, circumferential, and axial directions for each face are based on its own axis.
DOFs restrained for solid meshes: 3 translations DOFs restrained for shell meshes: 3 translations and 3 rotations
T y p e o f R es e s t r a i n t s – On Fla Flatt Face You can use this option only when all the selected faces are planar. planar. Each face can be in a different plane. Each face is restrained relative to its own directions (Direction 1, Direction 2, and Normal).
The selected face can only slide in the direction shown (dashed red line). Translation in the other two directions, Dir. 2 and Normal are set to zero
T y p e o f R es e s t r a in i n t s - O n F la l a t Fa Fa c e The selected face can slide in the directions 1 and 2. Translation in the normal direction is set to zero.
T y p e o f R es e s t r a in i n t s - O n F la l a t Fa Fa c e It is required to have the inner slider free to slide along the direction shown
Use the On Flat Face restraint and specify zero displacement along Face Dir 2 and Normal to the face. The face is allowed to move in Fa Face ce Di Dirr 1.
T y p e o f R es e s t r a in i n t s - O n F la l a t Fa Fa c e
The desk is free to slide on the ground (dashed red arrows) arrows ) but not to move up and down (normal direction, blue arrow)
The selected flat faces can slide freely f reely in Dir 1 and Dir 2 but are restrained in the Normal direction
T y p e o f R es e s t r a i n t s – O n S p h e r i c a l F ac ac e You can use this option only when all the selected faces are spherical. Each face can have a different center. center. The radial, longitude, and latitude directions for each face are based on its own center.
The spherical face of the reflector can only rotate in the latitude direction. Set the translations in the other two directions to zero to achieve this.
T y p e o f R es e s t r a i n t s – O n S p h e r i c a l F ac ac e
A handle
T y p e o f R es e s t r a i n t s – Use Refe R eferenc renc e Geom etry You can use a selected reference geometry to apply restraints. The reference can be a plane, axis, edge, or face. Using this option you can prescribe restraints on vertices, edges, and faces. Reference plane
T y p e o f R es e s t r a i n t s – Use Refe R eferenc renc e Geom etry You can use an axis as a reference to apply restraints. You can prescribe the translations in the radial, circumferential, circumferential, and axial directions. directions. For shell meshes, you can prescribe rotations in reference to these directions.
The selected face of the cylindrical hole can rotate about or move along the reference axis (in blue)
T y p e o f R es e s t r a i n t s – C y c l ic ic S y m m et r y Cyclic symmetry allows you to analyze a model with circular patterns around an axis by modeling a representative segment. The segment can be a part or an assembly . The geometry, geometry, restraints, and loading conditions must be similar for all other segments making up the model. Turbine, fans, flywheels, and motor rotors can usually be analyzed using cyclic symmetry. Model one sixth of the wheel and apply Cyclic Symmetry to the cut faces
S t re r e s s A n a ly l y s i s - E x am am p l e e w S t u d y from the toolbar or Simulation menu Select S t u d y an and d ch choo oose se N ew
Name the study
Select study type, Static
S tr t r e s s A n a ly l y s i s - M at a t er e r i al a l s e l ec ec t i o n Simulation menu→ choose Apply Material.
Create a new material by specifying it’s mechanical properties or edit the exciting one in the library.
S t r es e s s A n a ly l y s i s - M at a t er e r i al a l s e l ec ec t i o n From Library files select 1023 steel
S tr t r e s s A n a l y s i s – Restraint Selectio Se lectio n Select the desired type of restraint (support), fixed. Symbols used to show translational and rotational restraints
Rotation
Select the entity, face
Translation
S t re r e s s A n a l y si s i s - A p p l y L o a d (F o r c e ) Select the type of load, location, direction, and magnitude. magnitude.
S t re r e s s A n a l y si s i s - A p p l y L o a d (F o r c e )
Select the edge for load location
Specify value, units and direction of the force
Choose the direction of the load by selecting the edge
S t re r e s s A n a ly l y s is is - Ru n Co m m an d After selecting study type, mesh type, material, load, and restraints, you are ready to run the solver.
Select Run
S t re r e s s A n al a l y s is i s - R es es u l t s Stress distribution Yield strength = 282.7 MPa, max. stress around the hole = 14030 MPa
S t re r e s s A n al a l y s is i s - R es es u l t s Displacement Maximum deflection at the tip is 16.45 mm.
S tr t r e s s A n a ly l y s i s – M es es h C o n t r o l Mesh control refers to specifying different element sizes at different regions in the model. A smaller element size in a region improves the accuracy of results in that region. You You can specify mesh control at vertices, v ertices, edges, faces, and components
From the SolidWorks Simulation manager, select Mesh and right click
Choose Apply Mesh Control option
S tr t r e s s A n a ly l y s i s – M es es h C o n t r o l Select the edges of the two holes (max. stress location) to create finer mesh.
S tr t r e s s A n a ly l y s i s – M es es h C o n t r o l Finer mesh at the hole With mesh control
S tr t r e s s A n a ly l y s i s – M es es h C o n t r o l
Max. stress = 14030 MPa, without finer mesh around the holes
Max. stress = 14370 MPa, with finer mesh around the holes, 2.5% higher.
S tr t r e s s A n a l y s i s – E f f ec e c t o f R es es t r a i n t T y p e Change the back face restraint from fixed to immovable.
No change in max. stress
