1. Key Lab of Measurement Technology and Instrumentation of Hebei Province, Yanshan University, Qinhuangdao, Hebei 066004, China
2. Institute of Defense Science and Technology,Yanshan University, Qinhuangdao, Hebei 066004, China
Abstract 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.
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2018, Vol. 39 
