A Novel Compliance Constrained Mass Optimization Framework
for Vehicle Suspension Subframe Structures 2019-01-0838
Traditional vehicle suspension mass optimization process is achieved by an iterative process which is usually conducted with virtual test using an initial flexible suspension structure while satisfying compliance constraints via multi-body dynamic simulation software. Ideally, with an adequate vehicle suspension model, to formulate and solve this design problem via a traditional optimization procedure is possible. In reality, with such complex flexible model, this optimization process is in general extremely cumbersome and time-consuming. Furthermore, the search solution is not always guaranteed to be an optimal one. In this paper, a novel rapid and accurate design framework is presented for vehicle suspension subframe structural mass optimization. The framework consists of four main components: (1) A meta-model is constructed to directly approximate the relationship between the subframe geometry and compliance characteristics of the corresponding suspension. (2) Discriminant classification analysis is used to model the compliance constraint as a function of subframe stiffness at the attachment point, which is a result of a real bushing element and equivalent stiffness due to the flexibility of the subframe. The equivalent stiffness of the flexible subframe is determined from the finite element analysis based on the geometry. (3) An optimization search is performed on the meta-model directly to identify the subframe geometry with minimal mass and compliance constraint satisfied. In the meta-model, the geometric dimensions of the subframe and suspension compliance are treated as design variables and constraints, respectively. (4) In addition, global sensitivity analysis is also performed to reduce the insignificant design variables of the meta-model. The results indicate that despite the initial design and constraint level, reduction in mass of the optimized geometry can be always achieved.