Investigation of corrosion in aluminum/adhesive lap-splices using pulse-echo ultrasonic techniques

摘要

In this paper we have shown that aluminum skin samples corroded in the laboratory by an electrochemical process are similar to corrosion that occurs naturally. Incorporating the corroded skins into several sets of characterized aluminum/adhesive lap-splices with first and second layer corrosion defects, we have shown qualitative agreement in PP signal amplitude between a low frequency ultrasonic model and experiment. The model suggests, and the experimental evidence agrees, that the trailing signal PP amplitude of a low frequency tri-polar pulse can be used to discriminate metal thinning in the second layer due to corrosion. Further work is in progress to address the issues of frequency selection and errors caused by layer parameter approximation. 6 refs, 7 figs.