The Application of Continuum Damage Mechanics to Fatigue Failure Mechanisms

Abstract

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Modelling Damage Growth and Failure in Elastic Materials with Random Defect Distributions

“…(2) The assumption that damage remained uncoupled from elastic properties until complete failure for a particular plane is justifiable only for materials that show a sudden loss in stiffness near failure, which is the case for polymethylmethacrylate [14] and for fatigue of many other materials. For this type of behaviour, an uncoupled model has been shown to give equivalent results to continuously coupled models with the benefit of reduced computational time [20]. (3) The form of the damage evolution equation considers only maximum tensile stress and thus neglects the possibility that compressive stress could affect damage accumulation (e.g.…”

Interface damage model for fatigue-driven fracture

“…As shown by Eqs. (8) and (10), the evolution of is set by the local, relative crack face displacements in a material point of the crack. The upper expression in Eq.…”

“…The crack driving force can be straightforwardly established for a single crack with a well-defined crack tip, but cannot be uniquely computed in case of complex fracture patterns characterized by (various) crack coalescence and crack bifurcation events. In order to circumvent this problem, various investigators have defined the fatigue growth rate as a function of the local deformation in a material point of the crack [9][10][11][12]. In the approach of Khoramishad et al [9,12], the resulting fatigue damage parameter degrades the static traction-separation diagram that is used for computing the traction and the effective damage under the actual cyclic loading conditions applied.…”

Analysis of Casting Materials under Thermal Fatigue

“…There are several key features to characterize the fatigue damage. They include the proportionality of fatigue damage rate to stresses [5,8,13], to accumulated inelastic strains [13,14], inelastic strain rates [1,8,13,14] and differs for compression and tension regimes [1,8]. Accordingly to these features assumptions the fatigue damage evolution equation is postulated in the following form:…”

“…To analyze the saturated state we set β = 0 in the hardening evolution equation (13). As a result the saturated value of the backstress can be obtained…”