Measurement of yield points of high polymers with resistance-wire dynamometer

A new load dynamometer utilizing electricresistance wire consists of a cylinder around which the resistance wire is coiled tightly. When the cylinder is compressed axially and deforms elastically, the resistance wire is strained an amount equal to the circumferential strain of the cylinder resulting from Poisson's ratio. The dynamometer is designed with attention to electrical insulation, rate of heat dissipation, compensation for temperature change of electric resistance and material for the stressed body. The reading of this load dynamometer is not affected by the bending moment due to eccentric loading, and the bridge unbalance to be measured is larger than by any other type of strain gage utilizing resistance wire. This load dynamometer can be applied to the measuring of dynamic or transient changes in load. As one example, the tardy yielding phenomenon of thermosetting cast resins has successfully and reasonably been measured by this dynamometer without any inertia effect.