Micro-plastic strain accumulation via ratcheting at the scale of the carbide microstructure is proposed to be the underlying mechanism for cyclic hardening.
The model is based on a damage mechanics approach, wherein the evolution of fatigue damage in the adhesive is defined as a power law function of the micro-plastic strain.
Interrupted tensile testing with corresponding surface analysis using scanning electron microscopy (SEM) was carried out to clearly demarcate the micro-mechanisms operative in various plastic strain regimes.
Utilizing the variation in micro-Vickers hardness with depth for both virgin and plastically deformed PGMs, representative plastic strain, and well established hardness-yield strength relationships, the constitutive response of the PGM is uniquely determined.
Two main mechanisms determined polymer wear: a) abrasion, by second-body action of counterface metal asperities and by third-body debris; b) adhesion/fatigue, disclosed by micro-scale ripples, resulting from cyclic plastic strain accumulation.
Under the rolling-sliding contact condition, the distribution of micro-hardness was affected by the equivalent plastic strain and tangential stress.
The micro-structure was obviously refined due to the ultra-high plastic strain induced by multiple LSP impacts.
Under the pure rolling contact condition, the distribution of micro-hardness was almost identical to that of the equivalent plastic strain.
It was found that the micro-structure was obviously refined due to the ultra-high plastic strain induced by multiple LSP impacts.
Electron backscatter diffraction (EBSD) is combined with high spatial resolution digital image correlation (HR-DIC) to explore full field plastic strain distributions, together with finite element modelling, to understand the micro-crack nucleation mechanisms.
The results of SEM, FEM, and micro-hardness tests indicated that under the pure rolling contact condition, the maximum plastic strain was approximately 200 400 μm below the contact surface.
