Investigation of exact analytical solutions for circular notched composite laminates under tensile loading

Abstract

For the design of composite structures with circular cut-outs analytical, experimental and numerical methods are available. This paper investigates numerous exact analytical methods introduced in literature as an example of the Airbus Industries Test Method for determination of open hole tensile strength, conforming to AITM 1-0007. Experimental testing accompanied by digital image correlation of unidirectional 0° and 90° laminates as well as quasi-isotropic CFRP laminates with width-to-diameter (w/d) ratios of 3 and 5 is conducted. In addition, 3D finite element models of the test specimens are created for detailed analysis on lamina level. A preliminary study on numerous analytical methods introduced in literature shows that application of any of those methods results in one of two possible stress distributions. A qualitative comparison of 2D strain fields on laminate level reveals the high prediction quality of the analytical solutions. Furthermore, a detailed stress analysis on lamina level by comparison to a validated FE model is conducted. The results show that exact analytical solutions exhibit a satisfactory stress prediction quality for w/d ratios as low as 3 and thus can be recommended for preliminary design purposes.