Suppression of initial failure at tapered end-closure sandwich panel joint by taper angle change

To examine the configuration of CFRP face plates/foamed plastic core sandwich panel joints, a tapered end-closure-type joint is selected and studied. In this type of joint, the sandwich panel is tapered to form a solid laminate comprising two face plates near the joint, and the two panels to be joined are mechanically fastened at the solid laminate with a splice plate. This type of joint may be suitable for aircraft panels because a flat surface can be obtained at the joint, which is advantageous from an aerodynamic viewpoint. However, in a previous study on such a joint, it was found that a delamination crack initiated from the tapered core end and propagated through the interface between the two face plates as an initial failure mode at a much lower tensile load than the final failure load in a tensile strength test. In this study, the angle of the tapered panel was focused on and the effect of changing the taper angle on suppressing the initial failure was investigated through experiments and numerical analysis. It was found that a smaller taper angle is more effective for suppressing the initial failure.