压电陶瓷预应力
压电陶瓷与所有陶瓷一样，抗拉强度低。因此，为防止陶瓷在超声振动时受损，必须避免其承受任何净拉应力。为此，必须对陶瓷施加静态压应力（预应力）。该静态压应力必须大于陶瓷中预期的最大超声拉应力。这种预应力通常由叠堆螺栓施加，将陶瓷压紧在后驱动块与前驱动块之间。
也称为预载荷（preload）或偏置载荷（bias load）。
Piezoelectric ceramic prestress
Piezoelectric ceramics, like all ceramics, are weak in tension. Therefore, in order to prevent damage to the ceramics as they vibrate ultrasonically, they must be prevented from experiencing any net tensile stress. Thus, a static compressive stress (prestress) must be applied to the ceramic. This static compressive stress must be larger than the largest expected ultrasonic tensile stress in the ceramic. This prestress is commonly applied by stack bolt(s) that compress the ceramics between the back driver and front driver.
Also called preload or bias load.