Detail Design Evaluation of Extruded Sections on a Body-in-White Concept Model

Topology optimization allows for the design of structures with an optimum distribution of material for a given set of load cases. In the past, it has been shown that topology optimization can be implemented for a design space representing a body-in-white vehicle structure undergoing multiple load requirements. Using a Hybrid Cellular Automata algorithm along with a scaled energy weighting approach, both the objective of maximizing stiffness as well as maximizing compliance can be considered concurrently for multiple load cases. This methodology using LS-TaSCTM generates the optimum load paths for the design space subjected to the defined load cases. However, designers are often interested in applying local manufacturing constraints, such as extrusion constraints, on specific portions of the larger design space. This can be achieved by defining multiple design spaces and placing constraints as needed to represent these known manufacturing constraints. In this case, a full body-in-white design space is defined using multiple connected design spaces with an extrusion constraint applied to the side sill structure. The load paths are then generated for the overall requirements of the body-in-white. The results obtained from the initial topology optimization are used to extract the outer boundary of the extruded side sill. These results generate a base model design space to perform a localized topology optimization for the side sill. To successfully solve for the optimal cross-section design of the side sill, this local design space is significantly refined from the original design space definition and subjected to load cases specific to this extruded section. This subsequent topology optimization then solves for the detailed structure of the side sill component. The results from the second stage are interpreted as a shell representation in order to perform a size optimization on the extruded structure. Such a three-staged optimization process enables the designer to obtain design recommendations that originates from a global design domain and finally helps develop a detailed local design.