Date of Award

7-2008

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Mechanical Engineering

Advisor

Ayalew, Beshah

Committee Member

Ziegert , John

Committee Member

Daqaq , Mohammed

Abstract

One of the goals of automotive lightweight engineering is to achieve reduction in mass, cost, and complexity of vehicle components, subsystems and systems without sacrificing functionality and expected performance. This thesis addresses functionally integrated suspension systems that could lead to reduction in part count and mass and save packaging space. It deals with the analysis of multi-link suspensions that combine the function of energy storage and the mechanism of wheel location and guidance within individual compliant links and members.
To explore possibilities, a generic kinematic model of an independent five-link suspension was built in the MSC.ADAMS multi-body dynamics simulation environment. Models of the compliant energy storage and kinematic guidance members were created using a finite element analysis package and interfaced with the MSC.ADAMS environment. Then, the main spring, and individual and multiple rigid links of the reference suspension were replaced with compliant members, and subsequently, the resulting kinematic characteristics of the compliant multi-link suspension were compared against those of the reference rigid multi-link suspension. Under certain achievable assumptions and a suitable choice of the dimensions of the compliant links, it was found that similar kinematic characteristics as the reference suspension could be achieved by variants of the compliant multi-link suspension consisting of compliant links.
The analysis was also applied to the development of a compliant suspension concept for an existing high performance vehicle. Model validation data were obtained from actual tests conducted on a kinematic and compliance test rig. Evaluation of possible compliant variants of the rear suspension for this vehicle led to the replacement of the upper control arm of the original suspension with a ternary-link compliant member. The kinematic and compliance characteristics of this modified suspension were thoroughly analyzed through simulations and some of the characteristics were validated with tests conducted using a test-fixture employing many parts of the actual suspension and an aftermarket composite member for the compliant ternary-link.
The compliant suspension concepts evaluated in both phases use fewer parts, and therefore exhibit reduced mass and complexity. Further research and development is required to comprehensively optimize the design of the compliant links for certain desired response attributes, such as better toe control.

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