Investigation of fracture of ‘PEEK-CF-prepreg’ US-consolidated lap joints

Abstract

In this paper, the effect of ultrasonic welding (USW) parameters on the tensile strength of the polyetheretherketon (PEEK) lap joints is reported. The adhesion levels between the joined parts were varied due to different thicknesses and properties of prepreg, as well as some features of the implemented USW procedures. To identify the key resulting factors, computer simulation of the process was applied. The stress-strain state parameters in the lap joints under tension were determined by the author’s software package based on the flat statement of the elasticity theory solved using the finite element method. Changes in the properties of the materials and their delamination were taken into account in the applied algorithms. It was shown that the main parameters influencing the tensile strength of the US-welds were the adhesion level and the number of contact points at the interface. Both macro- and micro-bending of the lap-joints were revealed. Their values depended on the thickness and properties of the interfaced layers (adherends) and affected the tensile strength of the US-welds.