Investigation of subsurface fatigue crack in PEEK shaft under one-point rolling contact by using 2.5D layer observation method

Hitonobu Koike,Yuji Kashima,Koshiro Mizobe,Genya Yamaguchi,Katsuyuki Kida

doi:10.1051/matecconf/201713009001

Hitonobu Koike, Yuji Kashima + Show 3 more

Open Access

https://doi.org/10.1051/matecconf/201713009001

Copy DOI

Abstract

Subsurface fatigue cracks under rolling contact area of the PEEK shaft against an alumina bearing’s ball were investigated for application of frictional part in mechanical element in special situations such as chemical environments. In order to explore the flaking process of the PEEK shaft, the rolling contact fatigue tests were carried out by using a one-point radial loading rolling contact machine. The flaking occurred on the rolling track of the PEEK shaft at approximate 4⨉10 5 fatigue cycles. The subsurface fatigue crack propagation was investigated by using 2.5-Dimension layer observation method. The flaking was caused by the propagations of surface cracks and subsurface shear cracks, and the flaking shape was half-ellipse. Moreover, beach marks as fatigue crack propagation in the flaking were observed.

Highlights

Lightweight function parts using premium plastic are extended in various mechanical elements under special situation such as chemical, medical, space or flying devices [1,2]
We reported that the subsurface crack propagated along the PEEK shaft rolling direction in terms of fatigue failure mechanism when cyclic compressive stress was applied to the PEEK shaft [9]
The PEEK shaft after the test was cut along the rolling track, in order to observe the subsurface of the PEEK shaft

Summary

Introduction

Lightweight function parts using premium plastic are extended in various mechanical elements under special situation such as chemical, medical, space or flying devices [1,2]. Researchers investigated tribological failures of PEEK materials for frictional parts [3,4,5,6]. Hoskins et al stated that in the PEEK twin disc test, failure including melting was observed on the contact surfaces in severe high slip-ratio, high load conditions [4]. Fridrich et al investigated various failure patterns through their works They stated that Mode I fatigue was not the dominant mechanism from results of the brock on ring wear tests of PEEKs with different molecular weight against hard steels [6]. The one-point loading rolling contact fatigue (one-point RCF) tests under an oil lubricant condition were performed, in order to explore the subsurface fatigue crack and flaking failure mechanism of the PEEK shaft against an alumina ball

PEEK shaft

One-point rolling contact fatigue test

Fatigue fracture of PEEK shaft under rolling contact

Subsurface crack propagation