Rapid fatigue failure testing

Abstract

Fatigue testing machines may be classified from different viewpoints such as purpose of the test, type of stressing, means of producing the load, operation characteristics, type of load, etc. A machine belongs either to a constant-stress amplitude type or to the constant-strain amplitude type, although some machines may easily be transformed from one type to the other. The aim of this project is to design a fatigue testing apparatus which can be readily and cheaply built for carrying out small scale tests in research and teaching laboratories. The principle of the fatigue testing apparatus is that the specimen is caused to vibrate, in an oscillating magnetic field, at its natural frequency of vibration, thus reducing the power required. The result in a devide that can produce fatigue failure rapidly and allows the determination of an S/N curve in a short time. The apparatus may have a wide application in the teaching laboratory where the principles of fatigue failure can be easily demonstrated in a few minutes.