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In this paper, a new calculation method of relative fatigue life considering surface texture on high-speed and heavy-load ball bearing is presented. Rolling bearing quasi-dynamics, micro-TEHL analysis, non-Gaussian surface simulating technique and stress analysis with FEM are combined to obtain the relative fatigue life. The maximum subsurface stress with the new method are compared with data in inference, the relative error is 3.9%, which caused by decreasing surface stress under high speed. The non-Gaussian surface textures effect on surface pressure and shear stress are studied, which show transverse texture perpendicular to entrainment direction is helpful to form film because of the increasing hydrodynamic effect, and decrease the pressure and shear stress, but longitudinal texture has an opposite effect. Non-Gaussian parameters effects on relative fatigue life are researched, which display relative fatigue life increase with the increase of transverse texture, and decrease with the increasing longitudinal texture. The increasing skewness and curtosis can bring the decrease of relative fatigue life, but the relative fatigue life is beneficial as skewness is negative and curtosis is small, which is helpful for bearing life. Finally, the whole relative fatigue life of inner race and balls are given. [ABSTRACT FROM AUTHOR]

• A tribo-dynamic analysis procedure is developed for the predictions of the aero ball bearing with 3D measured roughness. • The influences of structure parameters and running conditions on the bearing dynamic performance have been discussed. • The roughness effects on lubrication state and friction-temperature of the aero ball bearing are investigated. • The 3D dynamic subsurface stress of the aero ball bearing has been researched. Tribological failures, like wear, scuffing and pitting, etc, often occur in aero ball bearings due to large dry contact area, high friction-flash temperature and stress concentration at the interface between the contacting ball and race. In this paper, a numerical tribo-dynamic analysis procedure is developed for the predictions of dynamic performance, lubrication state, friction-temperature, and subsurface stress of the aero ball bearing with 3D measured roughness. The numerical model is verified by comparing the friction coefficients with the testing results, which show well agreements and proves the presented model is available. The dynamic performance of bearing at different azimuth angle are studied, which indicate the increasing radial load and speed result in more asymmetric distributions of the contact load, stress and slide-roll ratio, the maximum values and the unloaded-region become larger. With the increase of the inner race groove coefficient and the contact angle, the pv value and the radial stiffness decrease clearly. The tribology behaviors of the ball bearing are also investigated, the obtained results indicate that the heavy-load and low-speed lead to large dry contact areas, high friction-temperature, and high local stress peaks, the lubrication state become worse, which may further cause the failures of mass wear, scuffing and micro-pitting. [ABSTRACT FROM AUTHOR]

The timing gears of the ship internal combustion engine usually undergo dynamic loading conditions, and often work in a mixed lubrication state. In this study, by considering the three-dimensional (3D) machined roughness, an integrated model with the analysis of mixed lubrication state and dynamic-meshing performance for the spur gear is developed. The model is verified by comparing its results with the predictions using the typical line-contact EHL formulas. The machined roughness apparently affects the local 3D distributions of the film pressure and thickness. The shaved surfaces have the minimum film thickness ratio and the worst lubrication state, while the polished surfaces can improve the lubrication performance of the timing gear pairs greatly. Under the conditions of heavy-load and low-speed, almost all of the Hertzian contact zone appears to be in contact with 0 film thickness, and the local maximum pressure may lead to serious stress concentration, film breakdown, and excessive wear, etc. By optimizing the gear module and pressure angle, the loading capacity of the timing gear is promoted and the contact area gets reduced, the lubrication state improves significantly from mixed lubrication to full film lubrication. • An integrated model with the mixed lubrication and dynamic-meshing performance for the spur gear is developed. • The mixed lubrication model of the timing gear pairs with 3D real roughness is built. • The effects of machined process on mixed lubrication state of the timing gears have been researched. • The ways to improve lubrication by optimizing the gear modulus and pressure angle are investigated. [ABSTRACT FROM AUTHOR]

• A comprehensive stiffness model of intermediate bearing is presented. • A reduced model of dual rotor-bearing-casing coupling system is developed. • The effects of typical parameters on the vibration of the system are discussed. • The mechanism of the comprehensive stiffness and system vibration is revealed. This paper focuses on the vibrational properties of a dual rotor-casing coupled system with nonlinear clearance in the intermediate bearing, considering both the oil film stiffness and Hertzian contact stiffness between rolling elements and raceways. A comprehensive stiffness model for the intermediate bearing has been developed based on elastohydrodynamic lubrication (EHL) and Hertz contact theory. Subsequently, a dynamical model of the dual rotor-bearing-casing system is established using the finite element method, thereby verifying the feasibility of simulating the casing with beam elements. The dimensionality of the system equation is reduced using the fixed-interface component mode synthesis (CMS) method, and the resulting reduced-dimensionality equation is solved using the improved Newmark- β method. The effects of casing support, rotational speed, and radial clearance on the vibration characteristics of the system are investigated. Then, the comprehensive stiffness and coupled vibration characteristics of the system are analyzed to elucidate its intrinsic mechanism. Finally, the contact characteristics within the intermediate bearing under dynamic load are also studied. The results indicate that the support stiffness of the casing has a more significant impact on the second resonance caused by both the inner and outer rotors. The system is prone to experiencing varying compliance (VC) resonance at low rotational speeds. The excessive bearing clearance leads to complex vibrational characteristics of the system, making it challenging to predict its motion. The impact of minor changes in stiffness on system vibration is small when the comprehensive stiffness is large. At this time, the limited effect of oil film stiffness allows it to be disregarded in terms of comprehensive stiffness. Furthermore, the speed significantly influences the contact characteristics within the intermediate bearing under the unbalanced force of the rotor and gravity. [ABSTRACT FROM AUTHOR]

The aim of the present study was to establish a prediction index (PI) model for the 5-year survival rate of patients with hepatitis B-related hepatocellular carcinoma (HCC) after radical resection, and to evaluate the effect of prophylactic transcatheter arterial chemoembolization (TACE). A total of 201 patients with hepatitis B-related HCC who had undergone radical hepatic resection at The First Affiliated Hospital of Xinjiang Medical University (Xinjiang, China) were enrolled, and the clinical, pathological and complete follow-up data were collected. Univariate and multivariate Cox regression analyses were performed to identify which clinicopathological factors were considered significant risk factors and the PI model was established based on these factors. The receiver operating characteristic curve was generated, and the area under the curve (0.841) and the cut-off value for PI were calculated. A Kaplan-Meier plot was used for survival analysis and the log-rank test was used to determine differences in survival. Cox regression analysis demonstrated that there were seven independent factors that may have affected the 5-year survival of HCC patients: Neutrophil-to-lymphocyte ratio (NLR), maximum size of tumor (MTS), tumor histological grade (HG), positive resection margin (PRM), microvascular invasion (MVI), the amount of tumor (AT), and antivirus therapy (AVT). A PI model on 5-year survival was established based on these factors, which was PI=0.32 × NLR + 0.39 × HG (high=1, medium=2, low=3) + 0.92 × PRM (yes=1, no=0) + 0.87 × MVI (yes=1, no=0) + 0.73 × AT (single=0, many=1) + 0.53 × MTS (≥5 cm=1, <5 cm=0)-0.87 × AVT (yes=1, no=0). PI was an independent predictor for survival, with a cut-off value of 2.75. For low-risk patients (PI <2.75), there was no significant difference in cumulative survival between TACE and non-TACE. For high-risk patients (PI >2.75), the cumulative survival rates showed significant differences among patients who had received ≥3 TACE procedues, patients who had received <3 TACE procedures, and patients who had not undergone TACE. The PI model predicts the 5-year survival rate of patients with hepatitis B-related HCC. For high-risk patients with a PI >2.75, if they had received ≥3 prophylactic TACE procedures, they demonstrated a more favorable outcome. For low-risk patients (PI <2.75) with 1 or 2 risk factors, TACE is recommended 1–2 times after surgery. TACE treatment is not required for low-risk patients without any risk fctors. These results may contribute to the decision-making process for whether prophylactic intervention is recommended after radical resection of HCC. [ABSTRACT FROM AUTHOR]

Highlights • The coated asperity contact behaviors are studied for the soft coating cases under frictionless and friction condition. • The effect of the strain hardening exponent of the coating, besides the Young's modulus, yield strength and original thickness on the contact behaviors is explored. • The expressions of the contact area and the coating thickness leading to the maximum weakening effect in the loading process is obtained. • An inflection point of the maximum von Mises stress curve in the coating is found, which is related to the locations of maximum stresses. The expressions of the dimensionless von Mises stress and the interference at the inflection point are acquired. Abstract The contact between a rigid flat and a coated asperity is studied using the finite element method under frictionless and friction condition. The soft coating and hard substrate of the asperity are both considered as the power-law hardening elastic–plastic material, which is commonly used in main bearing of the marine engine. The effect of the material and geometrical properties of the coating, including Young's modulus, yield strength, hardening exponent and original coating thickness, on the contact behaviors is studied under the frictionless condition. The change of the contact area and coating thickness in the loading process is explored, and the expressions of the coating thickness which leads to the maximum weakening effect are obtained. The von Mises stress distribution at yield inception and the maximum stress in the loading process in the coating are researched respectively. Also, the friction effect on the contact parameters was considered by integrating the empirical friction coefficient value into the contact model. This work would be helpful to find the optimal material and geometrical properties for the soft coating on the hard substrate which are power-law hardening elastic–plastic materials. [ABSTRACT FROM AUTHOR]

The damage evolution induced by three types of carbides in M50 bearing steel is studied in this paper. Stress distribution in the micro-domain is initially obtained to calculate the damage accumulation of the elements. Subsequently, the process of the butterfly generation is simulated. It can be seen that the butterfly wings are generated at the sites where maximum stress appears. The irregular shape carbide seems to be most harmful to the bearing material. Finally, the effect of residual stress on damage evolution induced by the carbides is investigated. The result shows that higher temperature, smaller balls and ion implantation are beneficial for the strengthening of residual stress and hence damage accumulation rate is reduced. [ABSTRACT FROM AUTHOR]

This paper focuses on the crack nucleation and crack propagation induced by a cluster of carbides. The morphology of the carbides is extracted from scanning electron microscope images of M50 bearing steel. Subsequently, a continuum damage accumulation model is incorporated into the Voronoi finite element model to investigate the damage evolution in the material. It can be observed that nearly all the micro-cracks nucleate on the boundary of the carbide and propagate through the bearing material matrix around those carbides until they become large enough to coalesce to failure. With the increasing of friction coefficient, cracks gradually grow to the contact surface. The result also shows that the carbides deeper than a certain depth are not harmful to the material. [ABSTRACT FROM AUTHOR]

Abstract: In this work, we demonstrated the effect of crystal defects on the photoelectrochemical properties of ZnO nanorod arrays (NRAs). Vertically aligned ZnO NRAs with different defect contents were grown on F doped SnO2 (FTO) glass substrate via facile electrochemical process and annealing treatement. [Copyright &y& Elsevier]