Automated Computer Controlled Ultrasonic Adhesive Bond Evaluation Technique.

摘要

An inspection procedure for a step-lap joint problem is reviewed in detail in this report. Rather than study the mechanics of bonding and the relationship of performance to many manufacturing and service variables, it is proposed to examine the potential of selected ultrasonic signal features and their ability for predicting performance of an adhesively bonded structure. Emphasis is placed on studying the disbond type problem. Adhesive problems are considered; not cohesive. The adhesive problem is the one termed most critical with respect to inspection difficulty as mentioned by many individuals in Air Force and other government and industrial agencies. Adhesive or surface preparation problems on either one or both sides of a test specimen will be considered with emphasis being placed on the establishment of a one-sided inspection approach, because of the practical value of this inspection procedure. A completely automated data acquisition and analysis procedure is developed, not only because of the fast convenient automation process, but because of its necessity in noise reduction and test repeatibility in advancing the state of the art in this critical inspection problem. Complete information in a RF ultrasonic waveform is considered in this study with significant advancements being made in the application of Fourier transform procedures. In addition, several concepts and philosophies in pattern recognition are introduced, combined with various options and flexibilities in employing probability density function curves. Mechanics is used in the study by way of shear distribution analysis and theoretical wave interaction analysis with various models in assisting the pattern recognition program of study. (MM).