This work presents a critical assessment of wear volume determination methods for ball-on-flat linear reciprocating sliding tribological tests. It revealed that the ASTM D7755-11 standard leads to ...the highest relative errors (up to 106%) and deviations (up to 27%) depending on the regularity of the wear track shape. The present study suggests improvements for the ASTM D7755-11 wear computation, which can reduce errors from 106% to 17% when analysing irregularly shaped wear tracks. In addition, a five-year period review of two relevant tribology journals revealed that the most used methods for wear determination, namely three-dimensional (3D) profilometry (46%) and nonstandard profile-based methods (36%), are overall reported with incomplete procedural information for wear computation. Furthermore, as many as 8% of the papers specify no data regarding the computation method and only 3% explicitly cited and followed the existing standards (ASTM D7755-11 or G133-05). The present study highlights the importance of the correct selection, implementation, and reporting of wear volume computation method and quantifies the potential errors.
•Wear computation strictly following G133 and D7755 standards rarely reported (3%).•3D Topography (46%) is the most used method, but is not unambiguously reported.•The 3D topography method reported the most robust and accurate results.•ASTM D7755-11 presented the highest relative errors and variations.•The suggested guidelines decrease errors from 106% to 17% when using ASTM D7755-11.
•Fluid–structure interaction methodology for predicting residual stress distribution.•Jet configuration plays a significant role in the residual stress distribution.•Volumetric radiation can be ...neglected for low thickness and high cooling rates.•Local flow behaviour becomes irrelevant below a critical temperature.
In this paper a novel numerical methodology for calculating non-uniform residual stress distributions during the glass tempering process is presented. Tempering techniques lead to non-uniform heat transfer rates causing residual stress inhomogeneities, which consequently have a direct impact on the structural behaviour of components. Nevertheless, most works in the literature do not consider the influence of local flow phenomena during thermal calculations, resulting in non-representative residual stress distributions. In this context, a novel generalised methodology based on a fluid–structure interaction one-way approach to sequentially couple the thermal and mechanical fields is presented. In this way, the unsteady and non-uniform heat transfer rate is coupled with the Narayanaswamy model to predict the non-homogeneous residual stress pattern. The obtained numerical results for the analysed impinging jet array case are in good agreement both quantitatively and qualitatively, exhibiting an average error below 10% with respect to previous experimental investigations. Finally, efforts are made to reduce the computational time. Therefore, the proposed methodology proves to be an efficient tool for understanding the underlying mechanisms and predicting the residual stress distributions during glass tempering.
•A coupled fretting wear and fatigue numerical methodology is proposed in a single numerical model.•Wear simulation is a key factor not to overestimate the fretting wear life prediction.•The coupled ...architecture accounts the evolution of the slip regime during simulation.•The presented methodology shows a mean error of 33% compared to the experimental lives.
This work presents a numerical procedure for combined fretting wear and fretting fatigue problems. It combines the Archard wear model and the Smith-Watson-Topper fatigue indicator parameter with the Miner damage rule for crack nucleation estimation. The eXtended Finite Element Method (XFEM) is then used in combination with the Archard wear model for crack propagation prediction. This procedure was validated in 12 experimental tests taken from the literature, and a good correlation was found. The procedure allows a detailed study of the interaction between the crack and fretting contact in combination with wear. The results show that the relative slip decreases and changes its distribution unevenly when the crack grows, and highlight the key importance of accounting for wear in order to obtain non-conservative predictions.
Radial fretting is defined as the damage caused by the relative motion of a ball under a variable normal load. The conducted experimental tests proved the existence of this damage even in contacting ...bodies with similar materials and elastic properties; however, the reviewed analytical methods do not predict damage under these conditions, and the numerical methods are time-consuming, especially when the investigation requires the analysis of several loading cases or during large number of cycles. The main objective of this work was to develop a fast analytical method to analyse radial fretting wear. For this purpose, a novel formulation for contact displacements under a normal variable load was built and merged to different contact mechanic formulas. For validation purposes, false brinelling in thrust bearings was used as a representative industrial example. The results were compared with a FEM model showing a relative difference under 9% and a massive reduction of the calculation time of more than 30 000 times, moreover experimental tests were carried out, showing a good agreement between the density of friction energy and the obtained fretting damage what endorse the use of this formulation for the analysis of a large number of cycles and loading cases.
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•An analytical new formulation for radial fretting wear simulation.•An experimental and numerical validation of the proposed methodology.•An industrial application to false brinelling in stationary thrust bearings under variable loading conditions.•An alternative fretting method to FEM simulations with a massive time reduction of 30 000 times.
This work analyses the viability of the theory of critical distances (TCD) using mesh control for fretting fatigue lifetime assessment. More than seven hundred sets of simulations were performed by ...taking seventy different experimental tests reported previously in the literature. The outcome of the present study suggests that the TCD mesh control method can be extended to fretting fatigue problems by the reasonable assumption of setting the right element size proportional to critical distance. In this study, a significant computational time reduction of up to 97% was obtained. Thus, this study provides a simple method to design complex 3D industrial components subjected to fretting fatigue phenomena using finite element analysis efficiently without requiring complex remeshing techniques.
•Investigation of the viability of “TCD with Mesh Control” for fretting fatigue.•“TCD with Mesh Control” and traditional TCD, similar SWT and life predictions.•97% less computational time than the traditional TCD in fretting fatigue.•Potential to effectively study complex 3D components subjected to fretting.
This work presents a critical analysis of coefficient of friction derivation methods for fretting under gross slip regime. A mass review of tribology journals revealed that 41% of papers did not ...specify the derivation method used and 37% employed the least effective methods. Following an analytical and experimental study, the use of the geometric independent coefficient of friction method (GICoF) is suggested for gross slip regime due to its robustness, followed by the energy method (ECoF). This study highlights the importance of the correct selection of the coefficient of friction method and it quantifies potential errors.
•GICoF and ECoF derivation methods gave the best results.•A mass review showed that 41% of the analysed papers did not specify the CoF derivation method used.•37% of the reviewed papers employed the least effective CoF derivation methods.
•Fatigue performace of cast components is mainly affected by porosity.•An alternative fatigue procedure that accounts the effect of porosity was developed.•The model presented an average logarithmic ...error below 2% and absolute below 16%.•The required porosity parameters can be obtained by computed tomography.•In high series sectors, a statistical store with fracture surface data could be used.
Porosity is one of the main parameters in the fatigue life of cast alloys as it affects both crack initiation and propagation phases. However, most fatigue assessments present a lack of accuracy as they only consider the effect of the initial pore on the fatigue limit. Therefore, in the present study, first, the effect of the main porosity characteristics on the crack initiation and propagation phases is evaluated. Then, an alternative fatigue assessment model is proposed and implemented for Low Pressure Die Casting (LPDC) A356-T6 aluminium alloy. The model accounts for the effect of the initial pore size and distance to surface on the initiation phase as well as fractographic porosity and average pore size on the fracture surface on the propagation phase. Finally, the model was validated by means of experimental tests. Results have shown that the proposed model is able to qualitatively predict the scatter trend of samples tested at the same load. In addition, the model presents high quantitative accuracy in life estimation with an average logarithmic error below 2% and an absolute average error below 16%.
•Numerical analysis of crack path prediction is performed using X-FEM.•Results obtained through crack path prediction criteria are compared.•The (Δτ)min criterion shows a low average deviation in ...stage II.•The (Δσn,eff)max criterion shows an erratic zigzag behaviour.
In this work the suitability of the criterion of maximum effective amplitude of the normal stress (Δσn,eff)max and the criterion of minimum shear stress range (Δτ)min for 2D cylindrical plain fretting contact condition has been analysed. The numerical analysis has been performed by means of the extended finite element method, which takes into account the contact between crack faces during the closing part, and the results have been compared with experiments reported in the literature. Results show that overall the (Δτ)min criterion predominates in intermediate stage, while the (Δσn,eff)max shows less deviation in the final stage. However, the predicted crack path by the latter criterion shifts toward the outer side, which do not correlate with the experimental results reported in the literature. Additional studies should investigate the variables that are affecting this change in the behaviour along the crack in order to set a criteria that is able to predict the plain fretting condition crack paths accurately.
Many mechanical components such as, bearing housings, flexible couplings and spines or orthopedic devices are simultaneously subjected to a fretting wear and fatigue damage. For this reason, the ...combined study on a single model of wear, crack initiation and propagation is of great interest. This paper presents an all-in-one 2D cylinder on flat numerical model for life assessment on coupled fretting wear and fatigue phenomena. In the literature, two stages are usually distinguished: crack nucleation and its subsequent growth. The method combines the Archard wear model, a critical-plane implementation of the Smith-Watson- Topper (SWT) multiaxial fatigue criterion coupled with the Miner-Palmgren accumulation damage rule for crack initiation prediction. Then, the Linear Elastic Fracture Mechanics (LEFM) via eXtended Finite Element Method (X-FEM) embedded into the commercial finite element code Abaqus FEA has been employed to determine the crack propagation stage. Therefore, the sum of the two stages gives a total life prediction. Finally, the numerical model was validated with experimental data reported in the literature and a good agreement was obtained.
•An improved coupled 3D fretting wear and fatigue numerical procedure is proposed.•Crack initiation locations were predicted accurately.•The contact stiffness is a key factor in replicating the ...contact behavior during wear process.•A novel damage interpolation scheme, coined as CCPM, is proposed.
This work presents a coupled 3D wear and fatigue numerical procedure for fretting problems in ultra-high strength steel wires that combines Archard’s wear equation with the Smith–Watson–Topper parameter to predict crack nucleation. For total life prediction, a mode I crack propagation based on the weight function method was used. To assess fretting fatigue lifetime, several experimental campaigns were run. The numerical results were in good agreement with the fretting fatigue experimental results. Thus, this study provides a 3D numerical methodology to study the combined effects of wear and fatigue in fretting with a case study in ultra-high strength steel wires.
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