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Preliminary Examination of Ply Cracking and Delamination in a Tapered Chevron Notch Laminate Subjected to Tensile Loading



New composite airframes have integrated design features for improved performance not necessarily related to structural efficiency. In many cases, such as on the wing, the panels are an integral part of the primary structure, and thus accurate strength predictions of these specially notched laminates are crucial for platform structural integrity management. Experimental and numerical studies were conducted to determine the effect of these specially shaped notches on the laminate tensile strength and in particular how sub-critical damage evolved to final failure. High definition video and high-speed video with contrast enhancement and thermal stress analysis were used to characterise failure mechanisms and measure the full field stress. The results showed that significant stress concentrations exist around the notch root leading to sub-critical damage evolution. The overall strength, however, was similar to an open-hole notch specimen. The work provides an experimental and numerical foundation for the further development of strength prediction techniques that model directly the onset and progression of sub critical damage and predict failure.

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