Abstract
Degradation, damage evolution, and fatigue models in the literature for various engineering materials, mostly metals and composites, are reviewed. For empirical models established under the framework of Newtonian mechanics, Gurson–Tvergaard–Needleman (GTN) type model, Johnson-Cook (J-C) type damage model, microplasticity model, some other micro-mechanism based damage models, and models using irreversible entropy as a metric with an empirical evolution function are thoroughly discussed. For Physics-based models, the development and applications of unified mechanics theory is reviewed.
Highlights
When the strain rate is around 10−6 to 10−5 s−1, creep can be a dominant mechanism; when around 10−4 to 10−3 s−1, it is defined as a quasi-static process; when above 103 s−1, it is usually regarded as a high strain rate, where inertia effects, thermal effects and wave propagation influences must be taken into account [1]
The results show that compared to local damage model, the proposed non-local model predicts an initial stage of stable crack tip blunting followed by a distinct point of crack initiation
Wu et al [63] modeled the low cycle fatigue of 1.4848 cast austenitic steel at temperatures ranging from room temperature to 1173 K and at strain rate from 2 × 10−4 to 2 × 10−2 s−1 based on the integrated creep-fatigue theory (ICFT)
Summary
Review of Damage, Void Evolution, and Fatigue Life Prediction Models. The degradation, damage evolution, and fatigue behavior of materials are closely related to structural performance and safety. The physics-based models, on the other hand, as the name suggests, are based on the physical foundations and do not require curve fitting empirical functions to test data They can be classified under the framework of Unified Mechanics Theory (UMT), incorporating the second law of thermodynamics directly into Newton’s laws at the ab-initio level [7]. The UMT based models are pure physics-based and do not need curve fitting to any test data for the evolution of void/damage. They do require deriving analytical thermodynamic fundamental equations of the material without curve fitting.
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