两端固定双晶片变形特性的实验研究

为利用压电双晶片构造高位移分辨力的小型运动装置,实验测试了8种不同厚度组合的接收型双晶片在两端固定条件下的变形特性.样片为矩形,尺寸70 mm×20 mm.组建了专门的测试系统,手工变换悬挂载荷后,由计算机控制自动逐级加载电压和记录数据,分别测试了负载特性、滞环特性、蠕变特性、重复特性等.实验结果表明:负载特性曲线初始段较软,负载超过某一临界点后变硬;相同电压下,金属层加厚变形减小,压电层加厚变形增大;四层压电片的复合晶片是双晶片输出推力的1.5~2倍;滞环分布范围与压电叠堆相似,在8%~16%之间;同等"伸长"条件下,两端固定双晶片的蠕变量小于叠堆.双晶片(d31)在两端固定条件下,其中心部位的变形特性和压电叠堆(d33)端部的变形特性具有可比性,可以满足亚微米级精度的定位/驱动场合对力和变形的要求.

Experimental study on displacement characteristics of piezoelectric bimorphs fixed by two tips

In order to develop a new type of miniature locomotive platform with high resolution actuated by piezoelectric bimorphs,some of the bimorph’s characteristics should be mastered.The size of the receiving type bimorph is 70 mm×20 mm and combines to obtain 8 kinds of samples according to different thickness of PZT and metal plate.In a special testing system,some items such as displacement output,hysteresis curve,worming effect and repetition characteristics versus voltage and burden have been obtained under which the boundary conditions are fixed by two tips.The curve of displacement output is soft under light load and then becomes rigid when the load increases over a critical value.The bending displacement decreases with the increase of the metal plate thickness,while increases with the increase of the PZT layer thickness.The multi-morph of 4 PZT layers is 1.5～2 times of bimorph on force output.Compared bimorph with stack,the hysteresis curve is similar and both vary from 8% to 16% and the worming effect is also resembled.In fact,the worming effect of bimorph is even smaller than that of stack under the same "elongation".The above results prove that the central part of bimorph(d31) has the same property as that of the tip of stack(d33).So,the fixed manner of bimorph can meet the requirements to force and displacement of precise positioning or actuation fields on the submicron order.