Numerical Simulation of Flaw Detection with a Capacitive Array Sensor Using Finite and Infinite Elements

Capacitive array sensors are one among many electromagnetic techniques that can be used to detect flaws or other irregularities at or near the surface of materials. Capacitive sensors have an advantage over inductive sensors in that insulating materials may be interrogated as well as conducting materials. These sensors have seen some application in nondestructive evaluation, including flaw detection, the monitoring of porosity and thickness of thermal barrier coatings, dielectric cure monitoring, and robotic proximity sensing [1, 2]. Only surface features can be examined on metallic plates because the accumulation of surface charges blind the capacitive probe to interior features. In dielectric materials, both surface and subsurface features can be examined.