tailieunhanh - Vehicle Crash Dynamics P1

A basic characteristic of a vehicle structural response in crash testing and model simulation is the “crash signature,” commonly referred to as the crash pulse [1] (numbers refer to references at the end of each chapter). This is the deceleration time history at a point in the vehicle during impact. The crash pulse at a point on the rocker panel at the B-pillar is presumed to identify the significant structural behavior and the gross motion of the vehicle in a frontal impact. Other locations, such as the radiator and the engine, are frequently chosen to record the crash pulse. | CHAPTER 1 CRASH PULSE AND KINEMATICS INTRODUCTION A basic characteristic of a vehicle structural response in crash testing and model simulation is the crash signature commonly referred to as the crash pulse 1 numbers refer to references at the end of each chapter . This is the deceleration time history at a point in the vehicle during impact. The crash pulse at a point on the rocker panel at the B-pillar is presumed to identify the significant structural behavior and the gross motion of the vehicle in a frontal impact. Other locations such as the radiator and the engine are frequently chosen to record the crash pulse for component dynamic analysis. The nature of the crash response depends on the mass structural stiffness damping at that location and on external interactions from neighboring components. In this chapter techniques for analyzing the basic vehicle occupant and restraint system interactions digital filtering and the crash pulse are reviewed also applications of the kinematic relationships in the analysis of restraint coupling and ridedown efficiency 2-5 are covered. Case studies involving air bag crash sensing deployment and crash recorder data analysis are also presented. VEHICLE IMPACT MODES AND CRASH DATA RECORDING Figs. and show two structure types commonly found in vehicles. These types are unitized-body and body-on-frame structures. The unitized-body vehicle has no separate frame or steel girders. It has comparatively thin pieces of body sheet metal which are stamped into complex shapes and welded together to provide the strength required for the chassis. The resultant structure is usually stiffer and lighter than one using separate frame and body construction. Unitized bodies are commonly found on small and compact vehicles. Fig. Unitized Body Vehicle Fig. Body-on-Frame Vehicle The disadvantages of unitized body construction are that 1 more road noise and vibration are transmitted 2 a serious safety problem is posed if .