MPDB工况下碰撞兼容性的基本问题与车体设计原则

2021版中国新车评价规程(C-NCAP)首次引入了正面50％重叠可渐近变形移动壁障碰撞工况(MPDB)用于评价车辆的碰撞兼容性.为了提高试验车在MPDB工况中的碰撞兼容性表现,得到影响碰撞兼容性的关键车体结构和基本的结构设计原则,应用对碰理论分析MPDB工况的2个基本物理问题——壁障与车体的吸能关系和运动变形关系.基...

Basic Problems of Crash Compatibility in MPDB Test and Compatibility Design Principles of Vehicle Structures

The frontal 50% overlapping mobile progressive deformable barrier test (MPDB) has been introduced in the 2021 version of China new car assessment program (C-NCAP) to assess the crash compatibility of car. In order to improve the crash compatibility performance of cars in the MPDB test, find out the key structure affecting crash compatibility, and acquire the basic principle of structure design, the present work utilized the car-to-car impact theory to analyze two fundamental physics relations between the barrier and the car in the MPDB test: the energy absorption relation and the kinetics-deformation relation. The design space of energy absorption for cars was derived from the allocation of the impact energy between the barrier and cars according to the energy absorption relation. Based on the kinetics-deformation relation, a design strategy for crash compatibility was originally proposed by applying the “butterfly graph”, leading to some suggestions for structure improvement to control the accelerations and deformations of the barrier and the car. Additionally, an equivalent impact velocity, which generalizes MPDB test to the frontal impact tests, was derived from the “butterfly graph” for the purpose of estimating the impact severity. The contributions of the car's mass, elastic resilience, structural strength and number of the energy-absorbing paths on the occupant load criteria (OLC) were analyzed. By dividing a typical front-structure of cars into four areas, the key structures within and in between these four areas which affect the standard deviation (SD) and bottoming out of the barrier were revealed. The validity of the above theoretical analyses and the feasibility of the proposed design principles were proved by an optimization of a mass-produced car. The present analyses highlighted that the matching of the front-structure of cars to the barrier was of the most essential and the basic design principle of the MPDB test.