In calculation, adopted load-unload criterion of stress wave propagation was to decide load-unload state of element and to adjusts and transfers internal stress for tensile failure element as well.

The greater the amplitude change of head wave of transverse velocity is, the severer the damage is, the later the arriving time of the first wave hollow and the longer the damaged element will be.

The results for element input impedance, radiation efficiency of space wave, directivity and radiation pattern are presented.