Experimental testing and numerical modelling of ductile fracture of PEEK in incremental sheet forming process

Abstract

Abstract. This research investigates the use of Hooputra-based damage model to predict fracture of polyether-ether-ketone (PEEK) material and its application to single point incremental forming (SPIF) process under different conditions. Flat PEEK sheets are used to examine the influence of temperature changes on the Hooputra fracture strain-stress triaxiality damage curve and to verify the capability of the Hooputra ductile damage model in predicting fracture in uniaxial tensile tests and the SPIF process. The research showed that the formulas used to calculate stress triaxiality based on geometric dimensions are insufficient with notched samples because the radius of the notched sample is no longer circular after plastic deformation. Temperature alters the Hooputra damage curve; therefore, the Hooputra ductile damage formula should be developed to consider the effect of temperature. When the Hooputra damage curve is established according to the temperature effect, the uniaxial fracture is precisely predicted at different temperatures. Hooputra ductile damage model could be developed to capture the fracture initiation and propagation in SPIF process.