Modeling the pulse-echo response of a two-dimensional phase-insensitive array for NDE of layered media

The use of a pulse-echo phase-insensitive array as the approach for the NDE (nondestructive evaluation) of uneven bondlines in the Space Shuttle Solid Rocket Motor is discussed. Experimental results with a scanned-element pseudoarray indicate that the sensitivity of detecting total disbonds at a rough interface between two rubberlike materials can be improved by more than a factor of 2 by using phase-insensitive detection. Computer simulations are being used to evaluate the pulse-echo characteristics of various arrangements of pulse-echo arrays with coplanar interspersed transmitting and receiving elements. This approach allows flexibility for exploring various array configurations, and as well as independent selection of materials for optimizing transmit and receive characteristics