PVDF piezoelectric voltage coefficientin situmeasurements as a function of applied stress

Direct piezoelectricg31voltage coefficient was measuredin situas a function of applied tensile stress for films of polyvinylidene fluoride (PVDF). Measurements were performed under quasi‐static conditions with applied strain rates of 0.5–1.5 mm/min for strains up to 12%. Open‐circuit voltage was measured with a contact‐less electrostatic voltmeter. Obtained results show a strong dependence of theg31coefficient of mono‐oriented PVDF films on the applied stress, with a maximum value of the coefficient in the transition region between elastic and plastic deformation zones. The effect of sample geometry on the apparentg31coefficient is shown and discussed. The anisotropy of the piezoelectric effect is studied by means ofg31andg32measurements.