1. ME 501 Final Project: Analysis of Ford Expedition Frame Crossmember June 20, 2001 John Smart Andy Stansel Courtesy Ford Motor Company Used without permission

2. Presentation Outline Project Background and Objective Modeling—meshing, boundary conditions. 3 loading conditions Results Conclusions

3. Project Objective

4. Modeling—ProE Model Both crossmembers were created in Pro/E Frame rails OEM Crossmember New crossmember New crossmenber dimensions

5. Modeling—Ansys Model Export Pro/E model as an IGES file Import the IGES file into ANSYS Set element type as “Shell 63” (3D, 4 node element, 6 DOF per node) Set shell thickness to.125” Material properties of steel (E=30 Mpsi, =.27) 1040 Steel, Sy = 86 kpsi

6. Modeling—Meshing Several different meshes were tested Coarse & fine free meshing 4 elements thick Fine mapped meshing 2,544 elements 2,546 nodes 15,276 DOF (unconstrained)

7. #1 Fixed #2 Chase boundary Modeling—Boundary Conditions Two separate boundary conditions were tested OEM crossmember symmetry Difference of 8 kpsi

8. Difference of 2 psi! Therefore, we used fixed-fixed conditions Modeling—Boundary Conditions Two separate boundary conditions were tested New crossmember #1. Fixed, fixed #2. Quasi-simply supported

9. Loading Condition #1 Vehicle at rest, or driving straight, or landing from jump. Fixed 1,000 lbs. New crossmemberOEM crossmember Fixed Rollers 1,000 lbs

10. Loading #1— Results OEM crossmember Maximum deflection=.022” New crossmember Maximum deflection=.0335” Y-displacement Bulges out here

11. Loading #1— Results New crossmember Max eq. stress: 34 kpsi Factor of safety: 2.5 Max eq. stress: 47 kpsi Factor of safety: 1.8 OEM crossmember

12. Loading Condition #2 Frame rails twist due to terrain. This induces torsion in the crossmember. fixed 500 ft-lbs OEM crossmember fixed 500 ft-lbs New crossmember

13. Loading #2—Results OEM crossmember New crossmember Max deflection: 0.0325”Max deflection: 0.0308”

14. Loading #2—Results New crossmember Max eq. stress: 8.8 kpsi Factor of Safety: 9.7 OEM crossmember Max eq. stress: 7.6 kpsi Factor of Safety: 11.3

15. Loading Condition #3 Pure bending in crossmember fixed 1,000 lbs fixed 1,000 lbs OEM crossmember New crossmember

16. Loading #3—Results OEM crossmember New crossmember Max deflection: 0.972”Max deflection: 0.897”

17. Loading #3—Results Max eq. stress: 59.1 kpsi Factor of safety: 1.4 OEM crossmember New crossmember Max eq. stress: 92.8 kpsi Factor of safety: 0.92 Mad stress concentration

18. Loading #3—Results OEM crossmember New crossmember  Z (normal) Neutral axis

19. Summary of Results Safety factors Load caseOEMNew 1 (shear) 1.82.5 2 (torsion)11.39.7 3 (bending) 1.40.9

20. Model Limitations Difficult to model frame rail interaction— boundary conditions Difficult to know magnitude of loading conditions No detailed models of weld joints, body mounts, gussets, or rounds

21. Conclusion Our simple analysis shows: The new crossmember is less stressed than the OEM version for typical “around town” loading conditions (load case 1) However, for extreme off-road type load conditions, the new crossmember is inferior to the OEM (load cases 2,3) Further analysis and prototype testing should be done before going into production.

22. What we learned 3D importing 3D meshing Effects of different boundary conditions FEA is not a “black box”