Understanding a Universal Testing Machine Motor Control System

The mechanical properties of a material are determined by using a testing machine to push, pull or twist a sample of the material. Many materials are strain rate sensitive which means their properties vary with test speed. A valid comparison of mechanical properties between suppliers can only be achieved if the same test speed is used by all.

The American Society of Testing and Materials (ASTM) and the International Standard Organization (ISO) are two organizations that govern mechanical test specifications. Each specification requires that the force be applied at a specific strain, crosshead position or stress rate. One function of the testing machine controller is to ensure that the specified test rate is accurately maintained throughout the test. Universal testing machines are electromechanically or hydraulically actuated. Here, we will consider an electromechanical testing machine that uses a motor control system for force actuation. ADMET's MTESTQuattro(R) Materials Testing System controller is part of the motor control system and is responsible for regulating the speed of the motor. A schematic diagram of the motor control system is shown in Figure 1. See link to Full Article below Figure 1, 2 & 3.