Mechanical Lock Joint for Effective In-Plane Application of Concentrated Loads to Thin Polymer Matrix Laminates

Means of in-plane loading of thin laminates with concentrated loads are of high practical importance. The purpose of this work was to investigate experimentally and numerically the mechanism of load transfer, load capacity, damage and associated failure modes of a specific, mechanical lock joint intended for in-plane loading of thin laminate plates with concentrated loads. The experimental investigations were carried out with the digital image corelation (DIC) and computed tomography (CT), and numerical ones with the help of a non-linear FE modelling, accounting for progressive damage. For this purpose, a special algorithm was developed accounting for a continuous degradation of the stiffness moduli of the laminate with strains according to the custom defined degradation law. Due to the specific design, the joint loaded a laminate plate with its front and rear parts, unlike a typical bolt joint transferring a load only by contact pressure developed at the front side of a bolt. Due to this feature, the load capacity of the joint was almost two times higher than that of a typical bolt joint of the same relevant dimensions.