Adaptive control of a materials-testing machine

Testing is vital in the search for better materials, for quality control in manufacture, and for assurance about the life-time of components when subjected to cyclic loading. The adaptive control of servohydraulic materials testing machines is the subject of this paper. The machines described typically use sampling rates of 5kHz, have bandwidths of up to 500Hz, and control powers of many tens of kW. Standard servohydraulic systems can apply alternating loads at frequencies up to 300Hz superimposed on mean tensile or compressive loads.