Deformation and ductile fracture characterization and modelling of Poly-Ether-Ether-Ketone.

Abstract

Poly-Ether-Ether-Ketone (PEEK) offers a viable option for biomedical applications due to its excellent combination of physical and mechanical properties, and biocompatibility. This paper investigates the PEEK material's deformation behaviour and fracture mechanism under varying strain rates and temperatures. A new extended constitutive-damage model was developed based on the Zhu-Ou-Popov (ZOP) constitutive model and the Gurson-Tvergaard-Needleman (GTN) damage model to accurately represent the mechanical response and predict the fracture of PEEK by characterising void nucleation, growth, and fracture. Mechanical testing and microscopic observation showed a strong link between the strain rate, temperature, and PEEK fracture mechanism. Fractographic observations show a clear correlation between the ratio of ductile and brittle regions of PEEK fracture surfaces and the tensile testing conditions. Hence the fracture void volume fraction can be determined using this ratio from different testing conditions. The results also demonstrate that the ductile fracture of PEEK can be accurately predicted using the new constitutive-damage model, in which the GTN damage parameters are defined as functions of strain rate and temperature.