Abstract
The present author tried to detect and succeeded in determening the actual deflection phenomena of a rotary bending test piece by means of the so-called air condnser method. Namely, the distance between a rotating bending piece and a fixed plate, which is not constant under a constant loading, was made clear at any instant by application of the so-called modulation method of a high frequency circuit connected to the gap (namely, equivalent to the deflection of the test piece) of the air condenser. Results thus obtained give us a clear idea that a rotary bending fatigue specimen under a constant loading do not show uniform constant deflection around the circumference of the piece as it is usually supposed to occur, but always show non-uniform deflection, which also is of a completely cyclic state just the same as the cycle of the rotary piece. These results give us a new foundation to the idea that, a direct measurement about deflection of a rotary bending piece could,at any instant of its rotation, be obtained using a reading microscope, if we would observe under a strobo-glow lamp illumination excited by a circuit of the same cycle as the rotary piece. By this new method, observations of the deflection of a rotary piece were carried out; these observations were easily made as a simple statical measurement. Also, by a successive change of the phase of the strobo (neon) lamp illumination by a cam apparatus, the deflection at various phases of rotation of a rotary piece was equally measured; thus the distribution of deflection around the circumference of the piece could easily be determined. These results will give a new information about the actual features of an actual fatigue fracture. Moreover, by this author’s new method, deflection phenomena which may be brought about by the effect of the speed of the load application and of the shape of the notch of a fatigue specimen (i.e. actual fatigue resisting strenth) may equally be traced by the results of this same measurement.
