Solidwork Meshing

Meshing

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Learning Objectives After completing this chapter, you will be able to: •

·         Understand the concepts of generating a mesh •

·         Generate mesh for complex models •

·         Refine the mesh •

·         Apply local mesh control to a mesh •

·         Check mesh quality •

·         Optimize the mesh quality of a model

Concept of mesh

INTRODUCTION 

Meshing is the process of subdividing a model, also called discretization, into a number of small pieces having

·         simple shape,

·         same size, and

·         connected at common points.

A component discretized into a number of small elements of defined size is referred to as mesh. These simple shapes are called elements and the common points where these elements are connected are known as nodes.

Meshing is an important step in design analysis. The automatic mesher in SOLID- WORKS Simulation generates a mesh based on

·         global element size,

·         tolerance,

·          local mesh control specifications, and 

·         contact specifications. 

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Mesh control lets you specify different sizes of elements for components, faces, edges, and vertices. 

In FEA, element size plays an important role. Result of an analysis and the time consumed in it change with the changes done in the element size.

Smaller elements may give more accurate results but increase the computation time.

Solidworks simulation mesh elements

SOLIDWORKS Simulation lets you create a mesh of solid elements

·         (3D tetra- hedral),

·         shells (2D triangular), or

·         beam (1D linear).

A mesh consists of elements of one type unless a mixed mesh type is specified.

·         Solid mesh is appropriate for bulky or complex 3D models.

·       Shell elements are suitable for thin parts like sheet Metal components.

·         Beam and truss elements are suitable for modeling structural members.

The accuracy of the solution depends on the quality of the mesh.

& Mesh Quality Depend on method

Different methods of meshing are discussed next. 

 Solid Meshing 

Solid meshing is generally used for bulky models.

 Each node in a solid element has three translational degrees of freedom in three orthogonal directions.

 SOLID- WORKS Simulation uses the X, Y, and Z directions of the global cartesian coor- dinate system in formulating FEA problems.

In solid meshing,

the mesh elements have tetrahedral shape.

The tetrahedral ele- ments are classified into two types:

1.       linear solid elements and

2.       parabolic solid elements.

The software generates one of the types of element based on the active mesh option specified for the analysis.

Draft Quality Solid Mesh

 In draft quality solid mesh -- linear tetrahedral shaped elements are generated.

Linear elements are also known as first order or lower order elements.

A linear tetrahedral element is defined by four corner nodes connected by six straight edges. 

High Quality Solid Mesh 

In high quality solid mesh,

Parabolic tetrahedral shaped elements are generated. 

Parabolic elements are also known as second order or higher order elements.

A parabolic tetrahedral element is defined by

·         four corner nodes,

·         six mid-side nodes, and six edges

In general, for same mesh density, parabolic elements provide better results than linear elements. This is because

·         parabolic elements represent curved boundaries better and hence produce better mathematical approximation. 

·         But they require more computation time than linear elements.

Note -It is highly recommended to use the high quality option for final results and for models with curved geometry. Draft quality meshing can be used for quick evaluation.

Shell Meshing 

Shell elements are suitable for thin parts (like sheet metals, surface bodies).

In shell meshing, the program determines the shell thickness of the sheet metal component and automatically creates mesh on the mid surface.

 Shell elements are 2D elements capable of resisting membrane and bending loads.

SOLIDWORKS Simulation automatically generates triangular shell elements.

                                                                       

These triangular ele-ments may be linear or parabolic depending upon the active meshing options for the study.

Types of shell meshing are discussed next.

Draft Quality Shell Mesh In draft quality shell mesh, linear triangular elements are generated, refer to Figure 3-5. A linear triangular shell element is defined by three corner nodes con- nected by three straight edges.  

High Quality Shell Mesh In high quality shell mesh, parabolic triangular ele- ments are generated, refer to Figure 3-6. A parabolic triangular element is defined by three corner nodes, three mid-side nodes, and three parabolic edges. The shape of parabolic triangular element is shown in

 Note A fine draft quality mesh and a high quality mesh pro- vide similar results when the number of elements is same. The results differ if the model includes a curved geometry.

Beam Meshing 

Beam meshing is used for meshing structural members and weldment structures.

You can treat an extrusion (meshes with solid elements by default) as a beam by right-clicking on the part node in the Simulation Tree and choosing the Treat as Beam option from the shortcut menu displayed.

Mixed Meshing 

SOLIDWORKS Simulation automatically uses a mixed mesh when different geometries are present in the model.