Notched fatigue behavior of PEEK

Abstract

Poly(ether-ether-ketone) (PEEK) has been used as a load bearing orthopaedic implant material with clinical success. All of the orthopaedic applications contain stress concentrations (notches) in their design; however, little work has been done to examine the fatigue behavior of PEEK in the presence of a notch. This work examines both stress-life (SN) fatigue behavior and the fracture behavior of unfilled PEEK under tension tension loading in circumferentially grooved round bar specimens with different elastic stress concentration factors. It was found that the majority of the loading was elastic in nature, and that there was only a small portion on the lifetime where there was a detectable change in structural behavior prior to gross fracture. Fractographic analysis via SEM further elucidated the potential fracture micromechanisms. Additional analysis was conducted to estimate the percent of the lifetime spent in crack initiation vs propagation, and it was found that the specimens spent the majority of the time in the crack initiation phase.

Mechanical properties and stem cell adhesion of injection‐molded poly(ether ether ketone) and hydroxyapatite nanocomposites

“…Saib et al ., for example, observed that after a thermal treatment of PEEK notched samples, the ones with the highest amount of crystallinity had the highest crack growth strength; this was probably due to the increase in the orientation and number of crystallites, which required more energy to deform and fracture. On the other hand, in another study, Sobieraj et al . observed that most of the fatigue energy was expended to initiate the crack; that is, when the fatigue life was highest, the ratio between the number of cycles necessary to initiate the crack and the number of cycles necessary to propagate the crack was highest.…”

Ceramics and ceramic coatings in orthopaedics

“…10(b) is a representative microstructure of these types of Al 2 O 3 -ZrO 2 nano-composites. For reference purposes, fatigue testing has been conducted for most of the biomaterials of Table 1a, and the reader is referred to selected publications for Al 2 O 3 [357][358][359][360][361][362], Mg-PSZ [363][364][365], Ce-TZP [366,367], Y-TZP [346,[368][369][370], Ce-and Y-ZTA [212,348,355,371,372], ATZ [211], Si 3 N 4 [344,354,373,374], CoCr [375], Ti6Al4V [376,377], PEEK [378][379][380], and cortical bone [381][382][383].…”

Evaluation of multiaxial fatigue life prediction criteria for PEEK

“…Tang et al [39] investigated the HA/PEEK composites subjected to tension-tension fatigue under load-controlled load, they found that all of the specimen could withstand 50% ultimate tensile strength, which they attribute to the polymer chain re-orientation and stress-induced crystallization. The fatigue behavior of PEEK in the presence of a notch is studied by Sobieraj et al [40,41] by examining both stress-life fatigue behavior and the fracture behavior. It is found that most of the lifetime was spent on initiation of cracks rather than propagation.…”