Road Load Data Estimation on Multiaxial Test Rigs for Exhaust System Vibrations 2002-01-0805

Road inputs are one of the most significant components of operational loading of motor vehicles and their exhaust systems. Even if road profiles remain the same, the response spectrums measured on exhaust system components vary for different vehicle and exhaust system combinations.

Existing exhaust system product development and design approval procedures require multi-channel data acquisition on vehicles under specified driving conditions and at proving grounds to cover all representative customer usage events. After analysis and reduction, damage relevant sections of this data package will be used for test lab simulation purposes. This vehicle instrumentation and data acquisition process is very time consuming and cost intensive.

The method presented here is based on the calculation of the dynamic characteristics of each road segment, or road events using road measured acceleration time histories, and lab measured transfer functions of vehicle body and suspension. This calculated road profile can replace the on vehicle road data acquisition and can be used for any other vehicle to predict the response spectrum of exhaust components. Additionally, drive files will be generated using this profile for experimental road load simulation on a multi channel servo hydraulic full system exhaust simulator. For this purpose the necessary individual transfer functions of vehicle and exhaust components can easily be measured on full vehicle hydraulic shakers (4 poster test rig) in the test lab.

The advantages of the presented methodology are significant time and cost savings. Particularly the time saving is a very significant tool to shorten the product development cycle in today's very competitive business world.