INFLUENCE OF WRINKLE ON THE TENSILE PROPERTIES OF COMPOSITE LAMINATES: EXPERIMENTS AND NUMERICAL MODEL

Defects are usually introduced into composite laminates during manufacturing process, and wrinkle of fiber is one of the most common defects in engineering. In order to investigate the influence of wrinkles on the mechanical properties of composite laminates along fiber direction, specimens without defects and specimens with 4 types of wrinkles are manufactured. Moreover, quasi-static tensile tests are carried out for the manufactured 5 groups of specimens, and the displacement and strain are measured by digital image correlation (DIC) technology. The influences of wrinkles on the static strength and failure pattern are studied through experimental tests. The results indicate that the static tensile strength along fiber direction of composite laminates with wrinkles is reduced by more than 40% compared to the static strength of composite laminates without wrinkle. Moreover, greater heigh-to-width ratio and bigger wrinkle angle will lead to smaller static tensile strength. At the same time, it can be found that the failure patterns of the composite laminates have been changed due to wrinkles, and breakage failure and blowout failure of fibers occur at the same time, while only blowout failure is present for the composite laminates without wrinkle defect. In addition, in order to describe the relationship between the static strength and geometry parameters of wrinkles (heigh-to-width ratio and angle), an influence model of wrinkle on static strength of composite laminates is built by employing a multi-fidelity machine learning algorithm, so the influence of different wrinkles on static strength can be predicted by using limited experimental data. The results indicate that the built model can accurately describe the influence of heigh-to-width ratio and angle of wrinkle on the tensile strength of composite laminates with a few of experimental data, therefore, the suggested model can be taken as a novel strategy for mechanical property investigation of composite laminates with defects.