tailieunhanh - Vehicle Crash Dynamics P5

A crash pulse is the time history of the response of a vehicle system subjected to an impact or excitation. The dynamic characteristics of the system can be described by using a “hardware” or a “software” model. A “hardware” model is a system consisting of masses interconnected by energy absorbers (springs and dampers). This will be presented in Chapters 4 and 5. The present chapter covers the use of a “software” model utilizing digital convolution theory for crash pulse prediction. In a study by Eppinger and Chan [1], the concept of a finite impulse response (FIR) model based on. | CHAPTER 3 CRASH PULSE PREDICTION BY CONVOLUTION METHODS INTRODUCTION A crash pulse is the time history of the response of a vehicle system subjected to an impact or excitation. The dynamic characteristics of the system can be described by using a hardware or a software model. A hardware model is a system consisting of masses interconnected by energy absorbers springs and dampers . This will be presented in Chapters 4 and 5. The present chapter covers the use of a software model utilizing digital convolution theory for crash pulse prediction. In a study by Eppinger and Chan 1 the concept of a finite impulse response FIR model based on convolution theory is used to assess thoracic injury in a side impact. Using accelerometer data from both the impacting side rib cage and the non-impacting side spine of a thorax the torso dynamic system is characterized by a set of FIR coefficients . a transfer function. Then under a different impact condition the torso response in the non-impacting side can then be predicted by convoluting the FIR coefficients with the accelerometer data for the impacting side of the thorax. The basic operation of convolution theory the derivation of the transfer function and an algorithm using a snow-ball effect to increase the computation efficiency are discussed. Cases are presented which include but are not limited to the 1 Use of transfer functions in assessing the occupant response prediction using various crash pulse approximations 2 Characterization of truck body mounts by FIR coefficients and the prediction of body pulses with different frame pulses 3 Evaluation of the performance of air bag and steering column restraint systems for both unbelted and belted occupant responses and 4 Assessment of sled test pulses and the prediction of its occupant crash severity in a barrier test condition. In body-on-frame vehicles two types of body mounts using man-made or natural rubbers are evaluated for their transient transmissibility TT the .