Flaking of PEEK under one-point rolling contact fatigue using Al2O3 ball

Hitonobu Koike,Koshiro Mizobe,Katsuyuki Kida,Genya Yamaguchi,K Kida

doi:10.1051/matecconf/201926401004

Hitonobu Koike, Koshiro Mizobe + Show 3 more

Open Access

https://doi.org/10.1051/matecconf/201926401004

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Abstract

The growth of flaking as tribological fatigue failure in PEEK was investigated through the one-point type rolling contact fatigue test between a machined PEEK polymer shaft and an alumina bearing's ball. Due to Hertzian contact of cyclic compressive stress, the subsurface fatigue cracks in the PEEK shaft propagated in rolling and axial directions. When the rolling fatigue life of the PEEK shaft reached 106 fatigue cycles, many narrow angled cracks occurred in the near-surface of the rolling track without flaking. On the other hand, when the flaking ocuurred on the PEEK shaft before 106 fatigue cycles, semicircular surface and subsurface crack propagations were observed. From these observations, it was found that micro-flaking occurred due to the linkages between subsurface and surface cracks. Flakingdeveloped due to the accumulation of these micro-flakings.

Highlights

Lightweight function parts using premium plastics are extended in various mechanical elements under special chemical environments [1,2]
The machined PEEK shaft with a 290 mm length and a 17 mm diameter was used for the one-point Rolling Contact Fatigue (RCF) test
The rolling track was concentrated on only one line on the PEEK shaft under a radial load

Summary

Introduction

Lightweight function parts using premium plastics are extended in various mechanical elements under special chemical environments [1,2]. Kida et al performed RCF test using Si3N4 balls and Si3N4 plates with an artificial pit, and investigated the fatigue crack propagation under the rolling track [12]. They proposed that the subsurface crack propagation depended on the mode ΙΙ or mode ΙΙΙ crack propagation after the surface crack propagation in sliding-rolling contact [12]. In order to explore the flaking mechanism under rolling contact between machined PEEK shaft and alumina ball, one-point Rolling Contact Fatigue (RCF) tests were performed. The internal fatigue crack propagation in early stages of the flaking was observed

PEEK shaft specimens

One-point rolling contact fatigue test

Contact surface of PEEK shaft under onepoint RCF

Crosssection of PEEK shaft under one-point RCF

Growth of flaking of PEEK shaft under onepoint RCF