Development of empirical models for estimation polymer indentation fatigue and validation with finite element simulation models

Multi-cycle micro-indentation tests were conducted on three polymers: Poly-ether-ether-ketone (PEEK), Poly (methyl methacrylate) (PMMA), and Poly (tetra-fluoroethylene) (PTFE). The load-displacement curve obtained from the indentation technique was used to evaluate the mechanical properties of these polymers. This study employed multi-cyclic indentation to establish a polymer fatigue model utilizing the indentation load-displacement curve. Currently, researchers are investigating fatigue life studies using stress- and energy-based approaches. Two empirical models for each approach were developed using the least-square curve-fitting method in this study. A simulation model based on finite element analysis has been utilized to verify the accuracy of these fatigue models for Vickers indentation. During the validation process, both models had a maximum error value of 2% compared to the experimental data, indicating a strong agreement with the simulation results. The generated models can evaluate polymer fatigue using non-destructive methodology.