TORSION FATIGUE TESTING DEVICE

PURPOSE:To enlarge torsion resonance frequency and to quicken a testing speed by a simple structure, by connecting a vibration load device and a mean load device through a torsion elastic body, making a spring constant of a torsion elastic body lower than a spring constant of the vibration load device, and setting the magnitude of inertia moment so that resonance frequency of the mean load device becomes lower than resonance frequency of the vibration load device. CONSTITUTION:When a variable speed motor 50 is rotated by frequency in the vicinity of a resonance point of a vibration load device 22 containing a test piece 26, vibration load of several times through scores of times of compelling force generated by an exciter 46 can be applied to the test piece 26, and resonance magnification can be varied by changing the rotational frequency of the variable speed motor 50 and varying magnitude of compelling force of the exciter 46 and the frequency. Load amplitude operating on the test piece 26 is measured by a load cell 30, is compared with a set value from a setting device 56 by a comparator 54, and in case when there is a difference, a controller 52 changes a speed of the variable speed motor 50, and maintains the load amplitude operating on the test piece 26 at a desired value.