A Basic Study on Fatigue Gauge Made of Copper Electroplating. 3rd Report. Evaluation of Equivalent Stress from the Density of Recrystallized Grains under the Variable Stress Condition.

Abstract

The possibility of measuring the magnitude and number of stress cycles of the machine parts subjected to service loading was examined by the fatigue gauge, made of electroplated copper. It is found that the recrystallized grains formed by cyclic stresses in the foil can be utilized as a measure for stress determination under both constant and variable amplitude stresses. This method is shown enough accurate to evaluate constant stress amplitude. In case of variable stress amplitude, the fatigue damage is correlated with that of the constant stress amplitude in terms of a equivalent stress. This equivalent stress is expressed by (Σ σαiNi/Σ Ni)1/α, where σi, Ni. and α are the stress amplitude, the number of stress cycles of σi and the material constant of the gauge, respectively.