FLEXIBLE ULTRASONIC TRANSDUCER ARRAYS FOR NONDESTRUCTIVE EVALUATION APPLICATIONS .1. THE THEORETICAL MODELING APPROACH

This paper presents the development of a theoretical modeling strategy to be used in the design of flexible ultrasonic transducer arrays. Th ese new types of array device are intended for those applications wher e surface conformity is desirable. Such array structures allow much mo re efficient and effective coupling of acoustic energy between the tra nsducer and test specimen than would have been otherwise possible with an equivalent rigid device. The objective of this work is to provide the transducer designer with a set of design tools that will permit th e analysis of different material configurations and various transmit-r eceive aperture designs. Linear systems modeling is used to evaluate, and consequently optimize, the transduction performance, while a surfa ce scattering model has been developed to facilitate the analysis of d ifferent transmit-receive aperture configurations. In Part I of this w ork, a theoretical modeling approach for flexible arrays is developed and where necessary, the validity confirmed by experimental measuremen t. This theoretical approach is then employed in an accompanying paper (Part II) to compare and assess different array structures for nondes tructive evaluation (NDE) imaging applications.