Comparative assessment of dissipated energy and other fatigue criteria☆

Abstract

Amongst a large number of fatigue criteria proposed for the prediction of crack initiation in thermomechanical fatigue, various approaches have been found to be particularly useful for certain categories of material over specific domains of temperature and cyclic strain. However, no particular approach appears to give invariably better predictions than others, so that the choice of the lifing model must be based on validation for the relevant circumstances.In this paper the focus is placed on the Energy Dissipation Criterion (EDC). We present physical arguments in favour of this approach's versatility, and illustrate its performance by the application of this approach both in the macroscopic and micromechanical context.Firstly, by way of illustration we consider cyclic deformation of a Ramberg-Osgood material, with a view to establish the equivalence between the EDC and some selected classical criteria. For this simple but analytically tractable case several interesting results can be established, including the equivalence between EDC and both stress range and strain range lifing criteria.Secondly, we consider fatigue loading of polycrystalline FCC material deforming by the combination of anisotropic linear elasticity and crystal slip. Energy dissipation density in this case is location-dependent even for a polycrystal subjected to macroscopically uniform stress and strain. Crack initiation then is predicted to occur at the 'weakest link' location corresponding to the most intense dissipation.The above two versions of energy dissipation criteria are each compared against experimental data. The comparative performance of Walker strain, Smith-Watson-Topper (SWT) and EDC lifing methods is assessed. It is concluded that EDC provides improved reliability, particularly for cases of complex loading paths and mechanisms interactions.

Micro-scale testing and micromechanical modelling for high cycle fatigue of CoCr stent material

“…Another study established the usefulness of p for predicting the experimentally-observed FCI sites for explicit ferritic steel microstructures under four-point bending fatigue [24]. The second FIP used is a crystallographic work parameter [26], W, which sums strain energy dissipation over all slip systems:…”

“…A crystallographic work parameter [26], W, has also been successfully used to predict the experimentally-observed FCI site for an austenitic steel [27].…”

On the Necessary but Sufficient Amount of Grease to Obtain Fully Lubricated Fretting Regime in Moist Air for SUJ2 Bearing Steel against S15C Carbon Steel

“…Then the slip ratio ( Fig. 2) can be defined as the ratio of the slip and displacement amplitudes [1][2][3][4][5]. However, from an experimental standpoint, by neglecting the end effects at the extremities of the hysteresis loop, the slip ratio can be also calculated as the ratio between the dynamic and static friction forces ( Fig.…”

“…Depending on the loading conditions, material properties and environment, fretting can cause fretting wear, which combines all four basic mechanisms (oxidative, adhesive, surface fatigue and abrasive), or fretting fatigue, which combines surface and bulk fatigue [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. Fretting wear and fatigue severely decrease the life of machine elements (e.g., rolling element bearings, screw and rivet assemblies, etc.)…”

Using machine learning and a data-driven approach to identify the small fatigue crack driving force in polycrystalline materials

“…In the last decades, many analytical surrogate metrics for the small crack driving forces, which are commonly known as fatigue indicator parameters, have been postulated, 21,[32][33][34][35] albeit seldom of these theories have been directly compared to 3D experimental data. [36][37][38] Due to the nature of their construction, these fatigue metrics would benefit from a systematic analysis of the variables possibly influencing the small crack propagation process.…”