A crystal plasticity based methodology for fatigue crack initiation life prediction in polycrystalline copper

Abstract

Fatigue failure is the dominant mechanism that governs the failure of components and structures in many engineering applications. In conventional engineering applications due to the design specifications, a significant proportion of the fatigue life is spent in the crack initiation phase. In spite of the large number of works addressing fatigue life modelling, the problem of modelling crack initiation life still remains a major challenge in the scientific and engineering community. In the present work, we present a methodology for estimating fatigue crack initiation life using macroscale loading conditions and the microstructural phenomenon causing crack initiation. Microstructure sensitive modelling is used for predicting potential crack initiation life by employing randomly generated representative microstructures. The microstructural parameters contributing to crack initiation life are identified and accounted for by computing lattice level energy dissipation during fatigue crack initiation. This model is coupled with experimental results to improve the predictive capabilities and identification of potentially damaging weak points in the microstructures. The estimated values for crack initiation life were found to be in good agreement with the experimentally observed values of initiation life. The results have shown that this kind of approach could be successfully used to predict crack initiation life in polycrystalline materials. This work successfully provides an approach for estimating crack initiation life based upon numerical computations accounting for the microstructural phenomenon.

Investigating the Difference in Mechanical Stability of Retained Austenite in Bainitic and Martensitic High-Carbon Bearing Steels using in situ Neutron Diffraction and Crystal Plasticity Modeling

“…3, we can see that the onset of RA transformation into product martensite for each specimen, B1, B2 and M1, coincides with its corresponding macroscopic yield point from the true stress and true strain curve. This can be attributed to the fact that under uniaxial tension, the specimens are more susceptible to undergoing an austenite transformation that is strain-induced or strainassisted, as hypothesized and discussed in prior works in literature [31][32][33].…”

In-situ neutron diffraction and crystal plasticity finite element modeling to study the kinematic stability of retained austenite in bearing steels

“…Several groups have developed fatigue initiation parameters (FIP) using CPFE models to facilitate a relative comparison between different application loads [13][14][15]. Recently, Voothaluru and Liu [16] used CPFE models to predict the micro-mechanical response and also the potential fatigue life of copper [17] and iron microstructures [18]. Alley and Neu [19,20] developed a hybrid crystal plasticity formulation to predict rolling contact fatigue life in high-carbon steels.…”

Material characterisation and finite element modelling of cyclic plasticity behaviour for 304 stainless steel using a crystal plasticity model

“…Fine and Bhat [10] proposed an energy approach to estimate the number of cycles to initiate microcracks in single crystal iron and copper, by balancing the energy required to form the crack surfaces and the energy released from storage. Voothaluru and Liu [11] applied the energy method into the crystal plasticity framework to predict crack initiation life for the randomly generated grain microstructures of a polycrystalline copper, and to identify the potential weak sites in fatigue behaviour. Tanaka and Mura [12] proposed a crack nucleation life rule based on the assumption that microcracks were initiated by irreversible dislocation pile-ups in PSB.…”