tailieunhanh - Using an electro mechanical system to investigate the influence of the fatigue on the energy dissipated per cycle due to the hysteresis damping

The energy dissipated per cycle due to the hysteresis damping is one of the criteria for determining the vibration system. The experimental results reveal that the energy dissipated per cycle increases versus the cycles to fatigue of the rotating-beam steel specimen. | Vietnam Journal of Mechanics, VAST , Vol. 26 , 2004, (237 - 24G) USING AN ELECTRO-MECHANICAL SYSTEM TO INV ESTIGATE THE INFLUENCE OF THE FATIGUE ON THE EN ERGY DISSIPATED PER CYCLE DUE TO THE HYSTERESIS DAMPING VAN Huu THINH1, NGUYEN HuNG2 1 University of Technical Education HCM city 2 Institute of Applied M echanics HCM city ABSTRACT. The energy dissipated per cycle due to the hysteresis damping is one of the criteria for determining the vibration system. The experimental results reveal that the energy dissipated per cycle increases versus the cycles to fatigue of the rotating-beam steel specimen. 1 Int roduction To determine the energy dissipated per cycle of t he rotating-beam steel specimens, we manufactured and performed the experiments on an electromechanical system as shown in Fig . 1. The electromechanical syst em consists of a DC motor, a flexible coupling, a revolution counter , bearing housings, ·a ·hydraulic jack, and t he specimen . In t he electromechanical system, the turning on t he motor rotates t he specimen, and under t he load from the hydraulic jack, the specimen is applied a pure bending moment. As t he specimen rotates at a point on its outer surface the bending stress varies cont inuously from maximum tension to maximum compression. Thus this electromechanical system is a type of the rotating-beam fatigue-testing machine. The specimen is a fat igue-test ing specimen. To evaluate the fat igue failure, we can base on one of the following fat igue criteria: the stress-strain criterion, the energy criterion, and the fatigue crack criterion. In other words, according to vibration of compliant mechanisms we can consider the specimen as a forced vibration system with hysteresis damping. By measuring its vibration signals, we can determine its response and the energy dissipated per cycle. The amount of energy dissipated per cycle equals the area of the hysteresis loop, and t he hysteresis loop relates to the fatigue strengt h of the .