High power piezoelectric axial shockwave generation

Shock wave generationby piezo-stacks33.1 The piezo-stack: an active barA piezo-stack can be described as a solid bar ofPZT-ceramics. When this PZT bar is electricallycharged sufficiently fast, the internal stress jumpsinstantaneously to a high level:The initial pressure is the blocking pressure, causingnow an accelerated expansion of the PZT-stack:a shock is created. By coupling the PZT rod toanother solid body, the shock impulse can betransferred and a shock wave is propagating.In this terminology a PZT-stack is an "active bar",generating inherently mechanical shock pulses byelectrical pulse excitation.Because the active bar is at rest, two pulses aregenerated propagating in opposite direction tobalance the total impulse to zero.This kind of pulse generation is called to be "superelastic",because the kinetic energy of the systemafter the shock generation is higher than before theshock event.This situation is similar to the use of an explosive.6