Investigation of exact analytical solutions for composite laminates under pin-bearing loading

Abstract

A number of analytical, experimental as well as numerical methods are available for designing mechanically fastened composite joints. In the present paper, exact analytical solutions previously introduced in literature for the case of a pin-loaded composite laminate are investigated. Experimental testing in a single-lap pin-bearing setup accompanied by digital image correlation of quasi-isotropic and highly-orthotropic CFRP laminates is conducted. Additionally, 3D finite element modeling is performed for detailed analysis of the test specimens on lamina level. Within a preliminary study, it is concluded that application of either of the analytical solutions leads to quantitative as well as qualitative differences in the resulting stress fields, thus, indicating that the choice of model is critical for subsequent failure analysis. Qualitative as well as quantitative comparisons of 2D strain fields on laminate level confirm the high prediction quality of certain analytical solutions. However, there are analytical solutions, some of which are implemented in commercial composite design software, that exhibit significant deviations from experimental and numerical data. These observations are further extended by detailed stress analysis down to lamina level. The results show that certain exact analytical solutions exhibit very good stress prediction qualities for w/d ratios as low as 3 and thus can be recommended for preliminary design purposes.