A Study Of Stiffness In Control Arms Utilizing Inner Webbed Structures To Minimize Deflections

Open Access
Anderson, James W
Area of Honors:
Mechanical Engineering
Bachelor of Science
Document Type:
Thesis Supervisors:
  • Amit Banerjee, Thesis Supervisor
  • Ronald Walker, Honors Advisor
  • Issam Abu Mahfouz, Faculty Reader
  • Control Arms
  • Webbed Structures
  • Aluminum Arms
Millions of vehicles traverse our roads every day and automobile safety is ever more important. Automotive control arms are an essential component of a vehicles suspension system and their design and construction can directly affect vehicle safety. The purpose of this thesis is to evaluate control arm deflections and if using a specific cross sectional shape for a machined inner structure, determines the increase in stiffness of aluminum control arms. Aluminum control arms made from a 6061 alloy, utilizing a machined inner bracing were manufactured and tested until failure occurred. Various control arms were machined each using a different cross sectional shape as the bracing which composed the inner webbed structure. The arms were then strategically tested and monitored to determine if stiffness can be reliably improved. Using a specially designed jig and a universal testing machine the arms were individually subjected to a steadily increasing load at the tip of the control arm. Using a Linear Variable Differential Transducer, strain gages and the tensile tasting machine’s computer interface the deflections, load and stresses were recorded and monitored for comparison. The results will provide a determination that a specific cross sectional shape can be used to better increase a control arms resistance to deflections. The thesis provides an in-depth study of deflections in planar control arms to be used by automotive engineers. The results are particularly interesting to light weight sport compact, hybrid and racecar suspension designers. The experimental results in some cases compared favorably with the associated FEA simulation results. Although, the numerical values did not agree, the general trends were consistent in both the experimental portion and the FEA Simulation. The patterns were similar and consistent considering there was an acceptable amount of experimental error. The results proved that some cross sectional shapes used in the bracing members performed better in certain situation. It was found that decreasing the amount of deflection in the test specimen was more so dependent on the trajectory of the cross bracing. The bracing trajectory had a larger influence on the associated deflection than the cross sectional shape of the bracing itself. It was also observed, that in some trajectories of the cross bracing the load at which the specimen failed changed very little in comparison to the unbraced arm. However, the associated deflections varied quite drastically.