Virtual testing of brakes 2000-05-0234

The development of a "Virtual Brake Testing" concept is presented in the paper, showing how a "virtual disc brake prototype" may be subject to "virtual testing" for performance and reliability evaluation. For this purpose, a large experience accumulated throughout many years of testing of various vehicle brakes by means of a couple of full-scale inertia dynamometers was collected in an appropriate Knowledge Database. It is used in this project to enable (i) to create the test schedule, (ii) to model the braking cycle influencing factors, and (iii) to model factors expressing brake performance and reliability for application within an advanced computer simulation.

The development of the virtual disc brake model that was then subject to virtual testing was based on integrating Pro/Engineer & Pro/Mechanica parametric design capabilities, while subsequent virtual testing was performed by means of Pro/Motion. Such integration is directed towards creation of possibilities to predict performance and reliability of brakes, thus enabling radical reduction of the amount of testing of physical prototypes on inertia test benches.

Virtual brake testing designates "virtual test bench," where computer is used to enable a designated brake application to be performed. The observed brake disc, "loaded" with appropriate inertia, at prescribed initial interface temperature, is driven to reach the prescribed initial speed. After short speed stabilization period, brake is actuated with predetermined initial control force/pressure. That is how a brake is decelerated to the requested final speed, or even to the full stop.

A set of predetermined initial brake test condition parameters (speed, pressure, temperature) under virtual brake testing was subject to anticipated variations caused by friction. It would make a brake to perform similarly to the way it would behave if a physical model were tested.

The speed, pressure and temperature changes are represented by means of appropriate analytical or numerical forms or "drivers," and these were used to simulate initial test condition parameters, and to duplicate their changes during braking. That is how virtual testing differs from real dynamometer tests, where these parameters are subject to direct influence of friction and its changes. The braking torque was also modeled in addition to friction that develops during braking, so as to enable different "if-then" scenarios to be used for virtual evaluation of brake performance and reliability.