同面阵列电容成像传感空/满场设定方法研究

Method of Setting Empty/Full Field for Coplanar Capacitance Array Imaging Sensor

同面阵列电极电容成像技术应用于工件缺陷无损检测时,因电极布置在同一平面内,若采用常规的单一介质作为空场或满场时,往往导致测量精度不高等问题。提出了一种空场/满场的相对设定方法,同时采用空气和被测材料两种介质作为空场和满场设定条件,通过分别改变两种介质的空间位置和大小,实现空场/满场可调节且不唯一;阐述了同面阵列电容传感器的工作原理,并以隔热材料和环氧树脂作为测量物场,通过有限元仿真获取了灵敏度矩阵。针对空场和满场的设定方法进行了电容成像实验研究,结果表明该方法可改善成像效果,能够反映出被测物体中缺陷的平面位置信息,验证了该方法的有效性。

Using a conventional single dielectric medium as empty or full field often leads to the low measurement accuracy when the planar array electrode capacitance imaging technology is applied to nondestructive testing of defects, because electrodes are arranged in the same plane. A method of setting the relative empty/full field using air and tested material as dielectric is proposed. The capacitance value of empty/full field is adjustable and non-unique by changing the spatial position and size of the two kinds of medium, respectively. The working principle of the planar array capacitance sensor is described and the sensitivity matrix is obtained by means of finite element simulation for measure field made up of heat insulating material and epoxy resin. Experimental study on capacitance imaging is conducted for empty and full field setting method. The results show that the imaging quality can be improved, the plane position information of defects in the object is given, and the validity of the method is verified.