Study Of Deformation Control In Vehicle Structural Design For Occupant Protection In Frontal Impact

Occupant protection in vehicle full frontal impact is a very important research topic in crashworthiness. In this work, the front crash test data, including that of mini-bus, minivan and passenger cars, is studied and summarized. A kinematic model based on crash pulse is established for simulating vehicle and occupant motions and restraint system interactions in vehicle frontal crash collision. This model uses four key parameters to describe the non-linear impact process, including the vehicle acceleration enlargement factor, the crash pulse duration, the specific stiffness and the slack of the occupant restraint system. The study provides a quantitative and qualitative relationship of these factors, establishes a way for coupling the vehicle deceleration and the occupant restraint system, and creates a process for designing and improving vehicle frontal crash performance.Stable folding mode of vehicle front rails during frontal impact is the key to achieve desired deceleration pulse. Using finite element simulation and test validation, bending stiffness of thin-wall square tubes and the characteristics of the deformation initiators are studied for achieving appropriate energy absorption. A new constrained-initiated square tube is designed for front frame deformation. It may provide better protection in oblique frontal impact and may also be beneficial for vehicle lightweight design.To meet crash pulse target and requirement of occupant compartment integrity, the maximum dynamic crush, the collapse mode of structure, the sequence of structure collapse and the structure failure should be controlled during a front crash event. The methods to control vehicle structural deformation during a frontal impact are also put forward in this work. A guideline for vehicle front structural design and collapse mode control is established.As an application and demonstration of the methods developed in this study, the HAISE minibus and SUZUKI minivan made in China were significantly improved on frontal impact performance without using airbags. After the structural changes, all these vehicle models have met the Chinese safety regulation. The application of themethods has been an achievement in design and research capabilities in the Chinese automotive industry.