Predictive Methodology for Delamination Growth in Laminated Composites Part 1: Theoretical Development and Preliminary Experimental Results

https://doi.org/10.21949/14045821998PDFTech Reporthttp://www.tc.faa.gov/its/worldpac/techrpt/ar97-87.pdfDOT/FAA/AR-97/87LaminatesTest proceduresDelaminationGraphiteEpoxy resinsFinite element methodMixed-modeCrack tip elementUnited StatesWilliam J. Hughes Technical Center (U.S.)Davidson, BarrySyracuse University. Dept. of Mechanical, Aerospace and Manufacturing EngineeringUnited States. Federal Aviation Administration. Office of Aviation ResearchNTL-AVIATION-AVIATIONNTL-AVIATION-Aviation Safety/AirworthinessUS Transportation CollectionA methodology is presented for the prediction of delamination growth in laminated structures. The methodology is aimed at overcoming computational difficulties in the determination of energy release rate and mode mix. It also addresses the issue that many laminated composites exhibit large-scale crack tip damage zones and, as such, a singular field-based mode mix decomposition may not accurately account for the dependence of toughness on the loading. In the methodology, the toughness versus mode mix relation, and the definition of mode mix itself, is first determined experimentally. The definition of mode mix is found from the results of a series of delamination toughness tests and is obtained within the construct of a crack tip element analysis. Next, the structure of interest is analyzed using the crack tip element analysis and the experimentally determined definition of mode mix, and delamination growth assessments are performed. This approach also obviates the need for locally detailed two- and three-dimensional finite element analyses