A bio-mechanics based methodology to optimize vehicle front profile for pedestrian safety

Car front design is based on performance and passenger safety requirements by regulatory and rating tests. Pedestrian safety tests are mandatory in regions like European Union and Japan while other regions do not have such regulations. These tests involve impacts of head-form, upper leg-form and lower leg-form to simulate collisions with bumper, bonnet edge and bonnet regions while excluding regions like windscreen. In this paper, we address this issue by the interaction of a complete human body model and not just independent “body-forms”. The focus is to study the human body interaction with the complete front end profile and addressing the front end shape in the perspective of injury reduction. In this process, kinematics of vehicle-pedestrian crash is considered on the basis of a multi-body simulation using MADYMO software. Four different body dimensions are analyzed comprising of one child dummy and 3 adult dummies. The optimization of vehicle shape is based on an “injury cost” measure as a single objective function using indicative cost for various body segments from leg to head. A genetic algorithm based optimization was implemented in MATLAB/MADYMO environment. Constraints of the optimization process denote the geometric limits of the specific car segment. This process has the objective of supporting the initial concept stage of a vehicle design process. An optimization at this stage allows the design to be more pedestrian friendly without compromising the rating and mandatory requirements.