G is a material constant equal to 0.055 V-m/N for quartz in compressive stress and 0.22 V-m/N for polyvinyl lidene fluoride in axial stress.
a. A force sensor uses a piezoelectric quartz crystal as the sensing element. The quartz element is 0.25 in thick and has a rectangular cross section of 0.09 in2. The sensing element is compressed and the output voltage measured across the thickness. What is the output of the sensor in volts per new ton?
b. A polyvinyl lidene fluoride film is used as a piezoelectric load sensor. The film is 30 µm thick, 1.5 cm wide, and 2.5 cm in the axial direction. It is stretched by the load in the axial direction, and the output voltage is measured across the thickness. What is the output of the sensor in volts per new ton?