Inverse Transfer Function Techniques Applied to Laboratory-Based Vehicle Dynamics Simulations

Friday, January 28, 2000 - 10:10am - 11:00am
Vincent 570
Robin Tuluie (MTS Systems Corporation)
Laboratory simulation methods have been used for many years in the automotive, aerospace and materials testing industries to accelerate durability testing of structures and systems. In the test lab, computer controlled, servo-hydraulic actuators are used to apply forces, moments or motions to the test specimen. The loading and motion of the instrumented specimen is reproduced in the lab from the acquired, actual usage time histories. The RPC (Remote Parameter Control) process is used to reproduce this measured, real-life loading. This 6-step process involves measurement of the system FRF (frequency response function), a linear model of the transfer function of the system. Physically, the FRF characterizes how the specimen transducers respond to each applied input. Even though the FRF is a linear system model, an iterative procedure allows the user to recreate non-linear events accurately. Through a series of nested loops composed of iterated events, a test sequence can then be established.

After an introduction to the RPC the process and definition of the FRF, some examples of this process are presented: (1) Re-creation of an automobile proving ground road surface in the lab with a full vehicle simulator for the purposes of accelerated durability testing. (2) Ride Comfort analysis for a motorcycle using the NASA model. (3) Measurement and calculation of rigid body properties using the FRF and modal analysis techniques.