A review of failure modes and fracture analysis of aircraft composite materials. (September 2020) - Zimmermann, Natalie
Highlights: Analyzing composite material fractures is more complex than of metallic fractures. The failure analysis of composite materials presents a vast body of knowledge. The composite structure and its failure mode influence the fractographic features. Studying failed composite structures is crucial to aircraft accident analysis. Abstract: Composite material-based structures have become increasingly common for aircraft construction. While a large number of researches focused on the understanding of composite materials and structures' behavior under a variety of scenarios to determine their performance when being exposed to flight loads, it is also critical to consider how these materials fail and fracture, especially in an aircraft accident. In this study, tension, compression, bend, impact, and fatigue fracture analysis of composite laminates and sandwich structures are reviewed, and the failure modes and characteristics of adhesively and mechanically fastened joints are analyzed. Furthermore, aircraft accidents in which composite materials failed are described to highlight the significance of the understanding of composite materials failure modes and fracture analysis on the overall aircraft accident investigation process. Thus, the presented study has a twofold purpose. To provide an all-encompassing review of current research in the area of composite material failure modes and fracture analysis, as well as presenting exemplary cases of aircraft accidents in which the composite material failure modes and fracture analysis body of knowledge has been practically applied. Three overarching themes were observed during the study. First, the complexity of composite material fracture analysis when compared to metallic material fracture analysis. Second, the relationship and dependency between fractographic features of composite materials and the composite structure itself and the failure mode. Lastly, the study and further investigation of composite material failures are found to be critical for aircraft accident investigations. The results from this review can be applied to identify areas of future development concerning composite material failure modes and fracture analysis, especially with applications to material analysis during aircraft accident investigations.