FATIGUE TESTER CONSTITUTED BY BUILDING MECHANICAL VIBRATION SYSTEM INCLUDING FATIGUE TEST PIECE IN FEEDBACK LOOP OF VIBRATING DEVICE

摘要

PURPOSE:To measure variation in the rigidity of a test piece without interrupting a fatigue test by placing a repetitive load of invariably the same vibration frequency with the natural vibration of a mechanical vibration system on the fatigue test piece. CONSTITUTION:One end of the fatigue testing piece 1 is fixed to a test base 2 and an exciter 3 fixed to the test base 2 as well displaces the free end of the test piece 1 vertically to place the repetitive load on the test piece 1. The vertical displacement of the test piece 1 is transduced by a transducer 4 into an electric signal, which is amplified by a nonlinear amplifier 5 and fed back to the exciter 3 to cause stable self-vibration. Consequently, the repetitive load of the same vibration frequency as the natural vibration frequency is placed on the test piece 1, so the vibration frequency of the self-vibration is measured to find the relation between the number of times of the repetition of loading and a decrease in rigidity without interrupting the fatigue test.