Nonlinear ultrasonic inspection of cohesive failure in adhesive due to contaminants in the manufacturing process

Do-Kyung Pyun; Lucas W. Koester; Daniel J. Barnard; Leonard J. Bond

doi:10.1117/12.2612271

18 April 2022 Nonlinear ultrasonic inspection of cohesive failure in adhesive due to contaminants in the manufacturing process

Do-Kyung Pyun, Lucas W. Koester, Daniel J. Barnard, Leonard J. Bond

Author Affiliations +

Proceedings Volume 12047, Nondestructive Characterization and Monitoring of Advanced Materials, Aerospace, Civil Infrastructure, and Transportation XVI; 1204709 (2022) https://doi.org/10.1117/12.2612271
Event: SPIE Smart Structures + Nondestructive Evaluation, 2022, Long Beach, California, United States

Abstract

Adhesive joints have been an effective alternative to conventional mechanical fasteners for joining similar and dissimilar materials in the aerospace industry. Adhesive joints have various advantages, including uniform stress distribution, lower weight, and design flexibility, but quality issues and possible defects in these joints have limited wider use. In this study, contaminants mixed into the epoxy-adhesive, which cause cohesive failure, were investigated. In the manufacturing process there can be various contaminants, such as release agents, oils, and moisture. Since release agents are essential materials during the manufacturing process, these were used in this study. A nonlinear ultrasonic technique was employed to evaluate the micro-scale defects in the adhesive due to contaminants. The experiments measured the nonlinearity parameter, with varying the contamination level, at 0, 0.5, 1.0, and 1.5% of the total weight of the epoxy mixture. The nonlinearity parameter exhibited higher sensitivity than the sound velocity, which is a conventional linear ultrasonic parameter, for the differentiation of the contamination levels in the adhesive. Furthermore, differential scanning calorimetry (DSC) and Rockwell hardness testing were conducted to monitor changes in chemical and mechanical properties respectively, with varying degrees of the contamination. It is shown that using the correlation between the nonlinearity parameter and chemical, and mechanical properties of the adhesive, there is the basis for an advanced inspection system, which has potential to improve the detectability of micro-scale defects in adhesively jointed structures.

Conference Presentation

Citation Download Citation

Do-Kyung Pyun, Lucas W. Koester, Daniel J. Barnard, and Leonard J. Bond "Nonlinear ultrasonic inspection of cohesive failure in adhesive due to contaminants in the manufacturing process", Proc. SPIE 12047, Nondestructive Characterization and Monitoring of Advanced Materials, Aerospace, Civil Infrastructure, and Transportation XVI, 1204709 (18 April 2022); https://doi.org/10.1117/12.2612271

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