3D Beam Large Deflection Analysis ME 501 Tim Allred Jon Bell June 20, 2001.
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Transcript of 3D Beam Large Deflection Analysis ME 501 Tim Allred Jon Bell June 20, 2001.
3D Beam Large Deflection Analysis
ME 501
Tim Allred
Jon Bell
June 20, 2001
Overview
• Objective• Problem Definition• Analysis• Results• What we learned• Conclusion
Project Objective
• Model this mechanism in 3D
• Compare deflection and stress results using large deflection analysis to:– Approximate 2D pseudo
rigid body model
– 2D beam model
– 3D beam model using small deflection analysis
Problem DefinitionOriginal Suspension Compliant Suspension
14.6
16
6.5
500 lbs.
Designed for 8 inches of vertical motion for 500 lb force input.
Cross-Sectional Shape
2.0 X 0.215 in.
Material: Carbon/Epoxy Composite
SUT: 330 ksi
E: 20.6 Mpsi
1
5
2
76
4
3
Analysis Models
• 2D beam large deflection
• 3D beam small deflection• 3D beam large deflection
9
8
76
5 4
321
Results 3D w/ large
displacements3D w/ small
displacements2D model Psuedo-rigid body
results
Displacement at node 7
9.7 inches 7.4 inches 8.6 inches 8 inches
Maximum Stress
182 ksi 171 ksi 177 ksi N/A
Displacements
3D large displacement model 3D small displacement model 2D model
9.7 “ 7.4 “8.6 “
Stresses
3D large displacement model 3D small displacement model 2D model
Stress distributions change
Stressmax=182 ksi Stressmax=171 ksi Stressmax=177 ksi
What we learned about ANSYS!• 2 Plane Bending• 3D beam Torsional Moment of
Inertia– With no input, ANSYS
automatically inserts polar moment of inertia or
Ixx +Iyy
• Maximum Stress includes only Bending + Axial Stresses– Shear Stress due to Torsion
not included– For correct failure analysis,
user would need to calculate shear stress by hand
MR
Conclusions
• 3D modeling with large displacement is necessary for accurate results on this particular problem due to the torsion introduced on the compliant member
• ANSYS is very useful in predicting results and learning about the important parameters of the problem
• Prototype would need to be built for accurate verification of results