Analysis of Piezoelectric Benders Used As Knock Sensors

Resonant piezoelectric benders are analyzed by use of a lumped-parameter equivalent circuit, each mode being described by a frequency of resonance, an equivalent mass, a mechanical resistance and electromechanical coupling. The bandwidth of the sensor can be controlled by controlling the coupling through the dimensions of the bender. Examples of the temperature dependence of the sensitivity, bandwidth, and frequency of peak sensitivity illustrate the effects of different piezoceramic materials, load resistances and electromechanical couplings.