Simplified system efficiency functions for linear phased-array transducers
Computer models are often used to simulate ultrasonic inspections of industrial components. One ingredient of such simulations is a frequency dependent function which describes the efficiency of the inspection system for converting electrical energy to sound and vice versa. For a phased‐array transducer there are many such efficiency functions, namely one for each independent pair of piezoelectric elements. In this paper we describe a simplified, approximate approach for specifying these functions. Element‐to‐element differences are accounted for by two “residual” parameters: (1) a strength factor which describes the relative “hotness” of an element compared to its peers; and (2) a time delay which describes the extent to which an element fires later or earlier than its peers when all elements are instructed to fire in unison. These residuals are used to relate the system efficiency function for any pair of elements to that of an average efficiency which can be readily measured. The use of this approach is demonstrated using front‐wall and back‐wall responses from a stainless steel block, as acquired using a 5‐MHz, 32‐element, linear phased‐array transducer. Good agreement was found between measured and simulated surface responses.