Measurement of Biaxial Stress Using Electrodeposited Copper Foil with a Microcircular Hole (Effect of Frequency and Wave Form on Strain Sensitivity)

Abstract

In order to examine the effects of frequency and the wave form of cyclic stress on the strain sensitivity of biaxial stress measurement method using an electrodeposited copper foil with microcircular holes, pulsating tension tests are done to the stainless steel specimen glued the copper foil and recrystallized copper foil. The higher the frequency becomes, the lower the strain sensitivity becomes.And in the case of sine wave, the relationship between stress amplitude σph0.5 corresponding to slip occurrence rate of 50% at the periphery of micro circular holes and the mean strain rate 4nσph0.5/Eper one forth cycle, where n is the frequency expressed by Hertz and K is Young's modulus of the material stress measured, is expressed as σph0.5=.4109 (4nσph0.5/E) +B. So, σph0.5 to optional frequency can be estimated by this equation. Also, the strain sensitivity is affected by wave form and it becomes highest in the case of square wave and becomes lower in ramp wave than sine wave. If the copper foil is recrystallized, the strain sensitivity increases but the effect of the difference of wave form decreases.