In this study, acoustic emission was evaluated as a supplementary nondestructive testing method for detecting damage initiation and progression, identifying the site of damage, and anticipating ultimate fracture in notched full-scale honeycomb sandwich composite fuselage panels using redundant arrays of different acoustic emission sensor models. Each panel contained different damage scenarios and was subjected to combinations of quasi-static hoop and longitudinal loads. Damage progression and location were characterized with various inspection techniques, and the acoustic emission results were correlated with photogrammetric strain fields. Applying post-test signal processing, acoustic emission accurately detected notch tip damage initiation and tracked its progression to ultimate failure.
The acoustic emission method was applied during the testing of six full-scale sandwich composite aircraft fuselage panels containing through-the-thickness notches. The panels were subjected to different combinations of quasi-static internal pressure, the corresponding hoop loads, and longitudinal loads. The applicability of conventional acoustic emission signal feature analysis to identify the dominant modes of failure and extraneous emission in large composite structures was investigated. It was concluded that no clear distinction could be made among the different failure mechanisms based on the conventional acoustic emission signal features alone. Further, emission generated by fretting, either among fracture surfaces or of loading fixtures, has acoustic emission signal waveform features that are similar to those of damage-generated emission signals.
This paper evaluates the ability of progressive damage analysis (PDA) finite element (FE) models to predict transverse matrix cracks in unidirectional composites. The results of the analyses are compared to closed-form linear elastic fracture mechanics (LEFM) solutions. Matrix cracks in fiber-reinforced composite materials subjected to mode I and mode II loading are studied using continuum damage mechanics and zero-thickness cohesive zone modeling approaches. The FE models used in this study are built parametrically so as to investigate several model input variables and the limits associated with matching the upperbound LEFM solutions. Specifically, the sensitivity of the PDA FE model results to changes in strength and element size are investigated.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.