Abstract

In a high speed repeated torsion tester of constant stress range type designed by the author, the test piece is to be chucked one end on the armature of an oscillating motor and the other end to the torsion bar. The torsion bar is used to measure repeated torque by the method of lamp and scale. The constructions of the oscillating motor is the same as an ordinary D. C. motor, and if alternating current or pulsating current of any frequency is supplied to the armature while direct current being supplied to the field coils, the armature will exert alternating or pulsating torque on the test piece. So-called rapid method proposed by Gough can also be carried out simply and accurately by this machine, (but the author could not find out such a fatigue limit as found by Gough.) On carrying out the endurance test, it is advisable to use the resonance phenomena of torsional vibration, because in the vicinity of that frequency the armature current decreases and the wave form of repeated torque becomes more regular. Adding some simple attachments to this machine, ordinary simple torsion test can also be carried out. The test pieces to suit this machine can be made simply and accurately by means of a milling machine giving rotation and axial feed to the test pieces.