finite element analysis of the steel horse rear suspension presented by: erika ramirez april 29,...
TRANSCRIPT
Finite Element Analysis of the Finite Element Analysis of the Steel Horse Rear SuspensionSteel Horse Rear Suspension
Presented by:Presented by:
Erika RamirezErika Ramirez
April 29, 2003April 29, 2003
Problem StatementProblem Statement
The rear suspension of The rear suspension of any mini baja car must be any mini baja car must be able to withstand the able to withstand the rough terrains associated rough terrains associated with the competition’s with the competition’s motor cross track. motor cross track.
The objective of this The objective of this project is to successfully project is to successfully analyze the rear analyze the rear suspension with an suspension with an impact load at the rear of impact load at the rear of
the tire.the tire.
Problem FormulationProblem Formulation
The rear suspension The rear suspension to be analyzed is a to be analyzed is a single a-arm. It is single a-arm. It is made out of 4130 made out of 4130 Chromoly tubing with Chromoly tubing with an outer diameter of an outer diameter of 1” and thickness 1” and thickness of .058”.of .058”.
Impact Force Impact Force Impact Force Impact Force Another car traveling at 30 mph hits our car and comes to rest at one Another car traveling at 30 mph hits our car and comes to rest at one
second or the car hits an object traveling at 30MPH form the side:second or the car hits an object traveling at 30MPH form the side:
Vi=30 MPH Vi=30 MPH Vf=0 MPH Vf=0 MPH
t=1s t=1s m=600lb m=600lb
Vf=Vi+atVf=Vi+at
a(impact)=Vf-Vi/ta(impact)=Vf-Vi/t
F=m*a(imp)F=m*a(imp)
F = 820 lbfF = 820 lbf
Worst Case ScenarioWorst Case Scenario
The car lands in one tire.The car lands in one tire.Weight of the vehicle (600 lbs)Weight of the vehicle (600 lbs)
The tire hits a rock, bump, etc.The tire hits a rock, bump, etc. Use the 820 lbf loadUse the 820 lbf load
Use an Actuator to model the motor – cross Use an Actuator to model the motor – cross tracktrack
Material PropertiesMaterial Properties
DensityDensity .284 lb/in^3.284 lb/in^3
Modulus of ElasticityModulus of Elasticity205 GPa205 GPa
Yield StressYield Stress8e8 Pa8e8 Pa
UTSUTS9.65e9 Pa9.65e9 Pa
Pro-E ModelPro-E Model
REVOLUTE JOINTS
ACTUATOR
IMPACT FORCE = 820 lb
SPRING/DAMPER (SHOCK) – 175 lb/in and C=10.2
Finite Element Modeling (Stresses)Finite Element Modeling (Stresses)
Concentration of Stresses located at the revolute joints. Concentration of Stresses located at the revolute joints.
DisplacementsDisplacements
Max Displacement occurs at the Hub tabs near the tire – also at one of the revolute joints.
Factor of SafetyFactor of Safety
Making the ends .01” thickerMaking the ends .01” thicker
Von Misses Stresses
Modified DisplacementsModified Displacements
Modified Factor of SafetyModified Factor of Safety
Comparing StressesComparing Stresses
The Maximum Principle Stresses are greatly reduced by making the revolute joints .01 thicker.
Comparing DisplacementsComparing Displacements
Displacements were increased a little from .75891 to .82149 in.
Von Misses StressesVon Misses Stresses
Von Misses stresses were also reduced.
Comparing Factor of SafetyComparing Factor of Safety
Minimum Factor of Safety was increased – and there are less areas of concern.
Comments / SummaryComments / Summary
H-Adaptivity was not used because of the H-Adaptivity was not used because of the complexity of the part.complexity of the part.
The Mesh size used was .02 Feet, this The Mesh size used was .02 Feet, this was done after converging on the same was done after converging on the same maximum value of stresses (no significant maximum value of stresses (no significant change for a smaller mesh size). change for a smaller mesh size).
A simple way to reduce the stress A simple way to reduce the stress concentrations would be to introduce more concentrations would be to introduce more material on the revolute ends. material on the revolute ends.
Questions?Questions?