| 摘要 |
PURPOSE:To stably control dynamic load to an actual use condition, in a fatigue testing apparatus for applying average load and dynamic load to an object to be tested, by generating dynamic load by a DC motor and detecting the rotary speed of said motor to compare the same with a reference value. CONSTITUTION:An object 1 to be tested is held by a fixed end 2 at the upper part thereof and by a vibration stand 4 at the lower end thereof. The internal stress of the object 1 to be tested is set to a desired value by operating the setting knob 33 of an average load motor 7 and a dynamic load motor 12 is started by a start switch 34 and the rotary speed thereof is brought to a desired value by operating a mannal setting knob 35 while a rotary speed display circuit 36 is looked. In this state, a test is performed until the object 1 to be tested is broken and the number of vibrations are cumulated and displayed by a vibration number display circuit 37. Because the motor 12 is a DC servo motor and the output of a rotary speed detector 21 is compared with that of a reference voltage generation circuit 46 by a comparing circuit 45 and controlled by a control circuit 34 so as to be made constant, dynamic load is stabilized over a long time. |
