Research On Product Family Based Body Structure Conceptual Design

In other to meet the demand of passenger car consumers, product family design is an efficient way to reduce development and manufacturing costs, rich product diversity, which enhances the competitiveness of enterprises. Global car makers generally present their product family design strategy. Body structure design should base on this strategy. Its design task changes to divide the platform and add-on modules, perform a series of conceptual design and detailed design to obtain 3D models of each part.This study focuses on the conceptual design stage. Referring to examples of body structure conceptual design practice and the condition of an A00-class electric vehicle, a body structure conceptual design process was presented. Loads and performance indexes in static stiffness are discussed, which included in to 2 stages of topology and size optimization. Crash safety cases were considered as static stiffness cases for equivalence. Constraints and the objective function in topology optimization phase were discussed in detail. In order to avoid the weight ratio determination of multi-objective optimization, strain energy was put into constraints rather than objective function, which a simple example was performed to prove the equivalence.Using the body structure conceptual design process, a body structure conceptual design of this vehicle was made. Performance indexes were determined in optimal design referring similar maturity models. According to the profile characteristics, design variables were defined as both continuous and discrete variables in size optimization phase. The optimization process leads to more efficient load transfer path and more reasonable material distribution. The resultant structure outperforms the original one in many structure responses and most significantly, it reduces weight by 30%, which demonstrates the efficiency of the proposed method.Based on product family design, a body structure conceptual design of this vehicle was made. Product family design is a tradeoff between universal level and product performance. Derived ways of car models were discussed in the context of the body structure. The division of the platform and add-on modules was taken in topology optimization stage and load transfer paths of platform and various add-on modules were obtained. The amount of common parts reflects universal level. The selection strategy of common parts was focused in size optimization phase. Different amount of common parts was defined in the process of size optimization to realize a set of body structure conceptual designs in different universal level. The design results reflect the compromise relationship between universal level and product performance, which can be decided by engineers.