Electromechanical equation of piezoelectric crystal stack is derived from the piezoelectric equations of constant D and constant stress,but the acoustic speed of under the constant E is used in design in practical transducer design.

• 推导晶堆的机电状态方程时 ,选用的是恒定电位移及恒定应力时的压电方程 ,最后设计计算时却又用的是恒定电场下的声速。