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 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.


Figure 1

figure 1

Follow these menus to find where to tune the gains settings in MTESTQuattro. If you do not understand gains tuning, please consult our Gains Tuning White Paper(download below) or call 1-800-667-3220 for ADMET technical support.

Figure 2 gains servo menu


Figure 3

control panel gains shortcut resized 600

While the test is running, choose the highlighted button on the control panel. Click edit to make changes. You will see results on the next cycle on the top graph.

Gains button on control panel resized 600

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