1. 1 sphere_derror.sldprt at 100MPa pressure Should be zero Should be 78540N Should be zero Should be 78540N

2. 2 sphere_derror.sldprt 100MPa pressure

3. 3

4. 4 VERIFICATION AND VALIDATION OF FEA RESULTS

5. 5 REALITY verification validation MATHEMATICAL MODEL FEA MODEL RESULTS Discretization error Modeling error Solution error VERIFICATION AND VALIDATION OF FEA RESULTS

6. 6 Sinking of Sleipner A platform Failure occurred due to discretization error; model was not verified. http://www.ima.umn.edu/~arnold/disasters/sleipner.html VERIFICATION AND VALIDATION OF FEA RESULTS

7. 7 Hartford Civic Centre Arena roof collapse. Failure occurred due to modeling error; model was not validated. http://www.eng.uab.edu/cee/faculty/ndelatte/case_studies_project/Hartford%20Civic%20Center/hartford.htm#Top VERIFICATION AND VALIDATION OF FEA RESULTS

8. 8 TYPICAL DISCLAIMER NOTE

9. 9 MODELING TECHNIQUES

10. 10 REALITY MATHEMATICAL MODEL FEA MODEL RESULTS Discretization error Modeling error Solution error FEA MODELING PROCESS Modeling error is controlled by out understanding of the analyzed problem Modeling error is controlled by using good modeling practices

11. 11

12. 12 Credo A model can never be accepted as a final and true description of the system. Rather, it can at best be regarded as a good enough description of certain aspects that are of particular interest to us.  Our objective is to make the design decision. FEA model should be only good enough to make that decision with a reasonable confidence. Modelling tips Spend enough time preparing and planning your analysis.  Define restraints and loads before working on geometry.  Keep it in mind that very detailed representation of geometry is often not worth the effort.  Concentrate modelling detail in the regions of most structural concern.  Do not make solid elements your first choice, consider using shells or beams in the place of solids Understand your structure and understand elements you use, create the mesh so it can model the real stress field MODELING PHILOSOPHY

13. 13 Before meshing, the following should be known: Geometry  required modelling approach (solids, shells)  required element types (first order, second order, …)  required element size (global, local)  any symmetries or anti- symmetries? Loads and restraints  elastic support spring stiffness?  restraints in local coordinate systems?  any rigid body motions? Required results (each analysis type may require a different mesh)  global displacements ?  local stress concentrations ?  modes of vibration ?  temperature distribution ? Stress distribution in the structure to be meshed That exact stress distribution is, of course, unknown prior to analysis. However, we should have some idea of stress pattern to create the proper mesh BEFORE YOU MESH

14. 14 MODELLING APPROACHES DICTATED BY ANALYSIS OBJECTIVE Shell model can be used for displacement and modal analysis Solid model should be used for analysis of stress concentrations

15. 15 MODELLING APPROACH DICTATED BY THE NATURE OF GEOMETRY Stamped steel pulley requires shell element modeling Injection molded pulley requires solid element modeling no matter what is the objective of analysis

16. 16 model fileec044 model typesolid materialaluminum alloy 1060 restraintsfixed to I.D. symmetry boundary conditions loadpressure to produce 1,000N reaction force objectives use symmetry boundary conditions for solid elements pressure load reaction forces Pressure 10,000,000Pa Fixed support ec044ALUMINUM PULLEY Symmetry boundary conditions

17. 17 Displacements results confirm that symmetry boundary conditions have been correctly defined. ec044ALUMINUM PULLEY Max. von Mises stress 84 MPa

18. 18 ec043STAMPED STEEL PULLEY model fileec043 model typeshell materialAlloy steel shell thickness3mm restraintsbuilt-in to I.D. symmetry boundary conditions loadpressure to produce 1,000N objectives symmetry boundary conditions for shell elements meshing surface geometry with shell elements properties of shell elements Pressure applied Symmetry boundary conditions Built-in support

19. 19 ec043STAMPED STEEL PULLEY Solid geometry suitable for solid element meshing Shell geometry suitable for shell element meshing

20. 20 ec043STAMPED STEEL PULLEY Symmetry boundary conditions defined for shell elements (6 D.O.F.)

21. 21 ec043STAMPED STEEL PULLEY Bottom of shell elements (green) Top of shell elements (gray)

22. 22 ec043STAMPED STEEL PULLEY P1 stress on bottom of shell elementsP3 stress on top of shell elements

23. 23 TORSION BAR Model fileTORSION BAR.sldprt Model typesolid MaterialAlloy Steel Restraintsfixed to the far end anti - sym. b.c. to the axial cross-section Loadcouple of forces 1,000 N Objectives demonstrate the need for defeaturing modeling simplifications demonstrate anti - symmetry boundary conditions limitations of linear analysis Anti symmetry boundary conditions 1000 N Fixed restraint 1000 N Note: shaft is shown shorter than in model