ANSYS12.0官方培训教程 Explicit_Dynamics_Chapter 6_Explicit_Meshing.pptVIP

What is required of Meshes for Explicit Applications? Uniform element size (in finest zoned regions) Smallest element size controls the time step used to advance the solution in time Explicit analyses compute dynamic stress waves that propagate throughout the entire mesh Element size controlled by the user throughout the mesh Not automatically dependent on geometry Implicit analyses usually have static region of stress concentration where mesh is refined (strongly dependent on geometry) In explicit analyses, the location of regions of high stress constantly change as stress waves propagate through the mesh Mesh refinement is usually used to improve efficiency Mesh transitions should be smooth for maximum accuracy Hex-dominant meshing preferred More efficient Sometimes more accurate for slower transients Mesh Meshing Methods Meshing Methods – Solid Bodies Tetrahedrons Advantages An arbitrary volume can always be filled with tetrahedra Can be generated quickly, automatically, and for complicated geometry Disadvantages Element and node counts are higher than for a hex mesh with a similar mesh density Generally not possible to align the cells with a flow direction Not well suited for thin solids or annuli due to non-isotropy of geometry and nature of element Meshing Methods – Solid Bodies Meshing Methods – Solid Bodies Meshing Methods – Solid Bodies Meshing Methods – Sweeping Multizone Direct decomposition of complex geometries at the time of meshing to create a hex mesh Meshing Methods - Solid Bodies Meshing Methods – Surface Bodies (Shells) Meshing – Line Bodies (Beams) Mesh Sizing Sizing can be applied to Body Face Edge Vertex Three options Element Size (Body, Face, Edge) Number of Divisions (Edge) Sphere of Influence (Body, Face, Edge, Vertex) Mesh Sizing Element Size Element Size specifies average element edge length for bodies, faces or edges Often will also improves mesh quality Mesh Sizing Number of Divisions Sp