Stress intensity factor measurement of cracks using piezoelectric element

A stress intensity factor (SIF) measurement method for cracks using a piezoelectric element and an electrostatic voltmeter is presented. In this method, an isotropic piezoelectric element is first attached near the tip of the crack. Then surface electrodes are attached to three different positions on the piezoelectric element. The electric potentials of the surface electrodes, which are proportional to the sum of the stress (sigma(x) + sigma(y)) on the structural member, are measured by an electrostatic voltmeter during load cycling. The mode I and mode II SIFs of the crack are estimated using the relationship between the SIF and (sigma(x) + sigma(y)). The applicability of the proposed method is examined through experiments and numerical analysis.