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1 – 10 of 101Yinkai Niu, Heyun Bao, Wei Huang, Wuzhong Tan and Rupeng Zhu
During the operation of a wet clutch, there are fluctuations in speed and torque, which have an impact on the stability of the clutch and the strength of the friction plate and…
Abstract
Purpose
During the operation of a wet clutch, there are fluctuations in speed and torque, which have an impact on the stability of the clutch and the strength of the friction plate and the spline pair of the dual steel plate. The purpose of this study is to investigate the vibration characteristics of the wet clutch and the dynamic load characteristics of the spline pairs.
Design/methodology/approach
The spline pair model is established by the piecewise linear function method, and on this basis, dynamic equations considering the spline pair of dual steel plates and friction plates are established. Considering that the wet clutch has multiple spline pairs, an equivalent model of the number of teeth and the equivalent model of the tooth width were proposed, and the Runge-Kutta numerical method was used for the wet clutch for these two models.
Findings
The research results show that the equal tooth number model has greater meshing stiffness and smaller fluctuation than the constant tooth width model, which shows that increasing the meshing stiffness of the system is beneficial to reduce system fluctuation and improve system stability.
Research limitations/implications
The friction plate has the system that multiple splines are independent of each other, which is relatively complicated. Therefore, an equivalent calculation is performed on multiple pairs of steel plates (friction plates) to simplify the calculation of the spline pairs.
Social implications
This paper provides a theoretical basis for further dynamic characteristics analysis of wet clutch and reducing fluctuation of speed and torque.
Originality/value
Dynamic equation considering the spline pair of the dual steel plates and the friction plates is established to study the vibration characteristics of the wet clutch and the dynamic load characteristics of the spline pair, etc.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-03-2023-0078/
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Zhi Li, YiYuan Du, Zhiming Xu, Xuqian Qiao and Hong Zhang
The purpose of this study is to investigate the influence of surface texture on the subsurface characteristics of contact interfaces under elastohydrodynamic lubrication…
Abstract
Purpose
The purpose of this study is to investigate the influence of surface texture on the subsurface characteristics of contact interfaces under elastohydrodynamic lubrication condition. As a typical contact form of gears and bearings, the optimization of friction characteristics at the elastohydrodynamic lubrication (EHL) interface has attracted the attention of scholars. Laser surface texturing is a feasible optimization solution, but there have been concerns about whether the surface texture of high-pair parts will affect their fatigue life.
Design/methodology/approach
To examine the impact of texture preparation on the subsurface characteristics of high-pair interfaces under EHL conditions, a point contact EHL model is developed that takes into account the effect of textured surface topography. The pressure and thickness of the oil film are calculated as input parameters under different loads and entrainment velocities. The finite element method is used to simulate the impact of textures with varying diameters, densities and depths on the subsurface characteristics of the elastohydrodynamic interface. According to ISO 25178, analyze the relationship between 3D topography parameters and subsurface characteristics and study the trend of friction characteristics and subsurface characteristics based on the results of the ball on disc friction tests.
Findings
The outcomes suggest that under different rotational velocity and load conditions, the textured surfaces exhibit improved friction reduction effects; however, the creation of textures can result in significant subsurface plastic deformation and local peeling. The existence of texture makes the larger stress zone in the subsurface layer closer to the surface, leading to fatigue failure near the surface. Reasonable design parameters can help enhance the attributes of the subsurface. A smaller Sa and a Str greater than 0.5 can achieve ideal subsurface properties on the textured surface.
Originality/value
This paper investigates the influence of surface texture on the friction and subsurface characteristics of EHL interfaces and analyzes the impact of surface texture on interface contact performance while achieving lubrication improvement functional characteristics. The results provide theoretical support for the optimization design and functional regulation of surface texture in EHL interfaces.
Peer review
The peer review history for this article is https://publons.com/publon/10.1108/ILT-10-2023-0324/
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Xuying Li, Yanbin Liu, Jie Huang, Deyu Sang, Kun Yang and Jinbo Ling
This paper aims to reveal the influence of the grooved texture parameters on the lubrication performance of circular pocket-roller pairs in cylindrical roller bearings.
Abstract
Purpose
This paper aims to reveal the influence of the grooved texture parameters on the lubrication performance of circular pocket-roller pairs in cylindrical roller bearings.
Design/methodology/approach
In this paper, the thermal elastohydrodynamic lubrication mathematical model of the grooved texture circular pocket-roller pair was established, the finite difference method and successive over-relaxation method were used to solve the model, the influence of texture quantity, texture depth and texture area ratio on circumferential bearing capacity, friction coefficient, maximum temperature rise, stiffness and damping of the circular pocket-roller pairs were analyzed.
Findings
The results show that texture quantity, texture depth and texture area ratio significantly influence the static and dynamic characteristics of circular pocket-roller pairs. The suitable surface groove texture parameters can dramatically improve the circumferential bearing capacity, reduce the friction coefficient, inhibit the maximum temperature rise and increase the stiffness and damping of the circular pocket-roller pairs.
Originality/value
The research in this paper can provide a theoretical basis for the optimization design of pockets in cylindrical roller bearings to reduce friction and vibration.
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Minglang Zhang, Xue Zuo and Yuankai Zhou
The purpose of this paper is to reveal the dynamic contact characteristics of the slip ring. Dynamic contact resistance models considering wear and self-excited were established…
Abstract
Purpose
The purpose of this paper is to reveal the dynamic contact characteristics of the slip ring. Dynamic contact resistance models considering wear and self-excited were established based on fractal theory.
Design/methodology/approach
The effects of tangential velocity, stiffness and damping coefficient on dynamic contact resistance are studied. The relationships between fractal parameters, wear time and contact parameters are revealed.
Findings
The results show that the total contact area decreases with the friction coefficient and fractal roughness under the same load. Self-excited vibration occurs at a low speed (less than 0.6 m/s). It transforms from stick-slip motion at 0.4 m/s to pure sliding at 0.5 m/s. A high stiffness makes contact resistance fluctuate violently, while increasing the damping coefficient can suppress the self-excited vibration and reduce the dynamic contact resistance. The fractal contact resistance model considering wear is established based on the fractal parameters models. The validity of the model is verified by the wear tests.
Originality/value
The results have a great significance to study the electrical contact behavior of conductive slip ring.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-09-2023-0300/
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Youjie Chen, Rong Fu, Junying Yang, En Zhang, Linlin Su and Fei Gao
This study aims to clarify the relationship between the coefficient of friction (COF) and temperature of aluminum-based brake discs.
Abstract
Purpose
This study aims to clarify the relationship between the coefficient of friction (COF) and temperature of aluminum-based brake discs.
Design/methodology/approach
Three friction blocks with different COFs are examined by a TM-I-type reduced-scale inertial braking dynamometer. On this basis, the thermo-mechanically coupled model of friction pairs is established to study the evolution of brake disc temperature under different COFs using ADINA software.
Findings
Results indicate that the calculated disc temperature field matches the experimental well. The effect of COF on the peak temperature is magnified by the braking speed. With the COF increasing, the rise rate of instantaneous peak temperature is accelerated, and the dynamic equilibrium period and cooling-down period are observed in advance. The increase in COF promotes the area ratio of the high-temperature zone and the maximum radial temperature difference. When the COF is increased from 0.245 to 0.359 and 0.434 at 140 km/h, the area ratio of high-temperature zone increases from 12% to 44% and 49% and the maximum radial temperature difference increases from 56°C to 75°C and 83°C. The sensitiveness of the axial temperature difference to the COF is related to the braking time. The maximum axial temperature difference increases with COF in the early stages of braking, while it is hardly sensitive to the COF in the later stages of braking.
Originality/value
The effect of COF on the aluminum-based brake disc temperature is revealed, providing a theoretical reference for the popularization of aluminum-based brake discs and the selection of matching brake pads.
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Xu Zhang, Kangjie Tang, Yingyu Wang and Dongying Dong
The purpose objective of this study is to identify the friction coefficient and friction effect in electromagnetic upsetting (EMU) high-speed forming process.
Abstract
Purpose
The purpose objective of this study is to identify the friction coefficient and friction effect in electromagnetic upsetting (EMU) high-speed forming process.
Design/methodology/approach
Based on numerical simulation and upsetting experiment of 2A10 aluminum alloy bar, the friction coefficient between contact surfaces is obtained by combining the fitting displacement distribution function and the electromagnetic-mechanical coupling numerical model, and the influence of friction effect is analyzed.
Findings
The maximum impact velocity and acceleration during EMU are 13.9 m/s and −3.3 × 106 m/s2, respectively, and the maximum strain rate is 7700 s−1. The functional distribution relationship between friction coefficient combination (FS, FD) and characteristic parameters [upper diameter (D1) and middle diameter (D2)] is established. The values of FS and FD are 0.1402 and 0.0931, respectively, and the maximum relative error is 2.39%. By analyzing the distribution of equivalent stress and strain, it is found that plastic deformation has obvious zoning characteristics and there is serious failure concentration in the strong shear zone.
Originality/value
Friction coefficient significantly affects stress or strain distributions in material forming process, but it is difficult to obtain friction coefficients through experimental tests in the high-speed forming process. In this paper, a multi-field coupling numerical model is proposed to determine friction coefficients and applied to the electromagnetic impact loading process (a high-speed forming process).
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-05-2024-0154/
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Min Li, Hangxuan Liu, Xingquan Zhang, Hengji Yang, Lisheng Zuo, Ziyu Wang, Shiwei Duan and Song Shu
The purpose of this paper is to investigate the effect of laser peening (LP) on mechanical and wear properties of 304 stainless steel sheet.
Abstract
Purpose
The purpose of this paper is to investigate the effect of laser peening (LP) on mechanical and wear properties of 304 stainless steel sheet.
Design/methodology/approach
Three-dimensional morphology, micro-hardness and micro-structure of shocked samples were tested. The wear amount, wear track morphology and wear mechanism were also characterized under dry sliding wear using Al2O3 ceramics ball.
Findings
The LP treatment generates deformation twins that contribute to the grain refinement and hardness increase. The wear test displays that the wear mechanism of samples is mainly abrasive wear and oxidation wear at 10 N load. While at 30 N, the delamination and adhesion areas of treated sample are reduced visibly compared to untreated ones.
Originality/value
This study specifically investigates the mechanical and wear properties of 304 stainless steel after the direct action of LP on its surface, which shows an effective improvement on the wear resistance. For example, the wear loss of processed sample is reduced by 19% at 30 N, the friction coefficient decreases from 0.4714 to 0.4308 and the groove depth is reduced from 78.1 to 74.4 µm under same condition.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-01-2024-0007/
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Shi Chen, Zhiyong Han, Qiang Zeng, Bing Wang, Liming Wang, Liuyang Guo and Yimin Shao
Hydro-viscous drive (HVD) clutches are widely used in equipment requiring soft start, such as fans and pumps, to transmit torque and adjust speed by changing the gap distance…
Abstract
Purpose
Hydro-viscous drive (HVD) clutches are widely used in equipment requiring soft start, such as fans and pumps, to transmit torque and adjust speed by changing the gap distance between friction pairs. This paper aims to propose a novel two-parameter evaluation method for HVD during the mixed lubrication stage. The objective is to develop an effective model that establishes the relationship between these parameters and the actual surface topography.
Design/methodology/approach
In the presented methods, the fractal features of the real manufacturing surface are calculated based on the power spectrum function by the ultra-depth three-dimensional microscope. After that, the hybrid friction model of the friction plate is established based on mixed elasto-hydrodynamic lubrication theory, boundary friction model and fractal theory. Then the torque and load bearing characteristics of the clutch are obtained, and the influences of the surface fractal features are investigated and discussed. Finally, the Weierstrass–Mandelbrot function is adopted for the surface topography characterization and evaluation.
Findings
The results indicate that the proposed method exhibits good accuracy, while the speed difference between the friction pair exceeds 2,500 rpm. It is concluded that this paper proposed a way to evaluate the torque and loading capacity of HVD considering the real manufacturing surface topography and is helpful for surface optimization.
Originality/value
The originality and value of this study lie in its development of a novel torque and load bearing capacity evaluation method for HVD in mixed lubrication stage, considering manufacturing surface topography and describing the real manufacturing surface.
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Jingjing Zhao, Yuan Li, Liang Xie and Jinxiang Liu
This study aims to propose an optimization framework using deep neural networks (DNN) coupled with nondominated sorting genetic algorithm II and technique for order preference by…
Abstract
Purpose
This study aims to propose an optimization framework using deep neural networks (DNN) coupled with nondominated sorting genetic algorithm II and technique for order preference by similarity to an ideal solution method to improve the tribological properties of camshaft bearing pairs of internal combustion engine.
Design/methodology/approach
A lubrication model based on the theory of elastohydrodynamic lubrication and flexible multibody dynamics was developed for a V6 diesel engine. Setting DNN model as fitness function, the multi-objective optimization genetic algorithm and decision-making method were used to optimize the bearing pair structure with the goal of minimizing the total friction loss and the difference of the average values of minimum oil film thickness.
Findings
The results show that the lubrication state corresponding to the optimized bearing pair structure is elastohydrodynamic lubrication. Compared with the original structure, the optimized structure significantly reduces the total friction loss.
Originality/value
The optimized performance and corresponding structural parameters are obtained, and the optimization results were verified through multibody dynamics simulation.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-12-2023-0417/
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Zhixiong Chen, Weishan Long, Li Song and Xinglin Li
This paper aims to research the tribological and dynamic characteristics of aeroengine hybrid ceramic bearings through wear experiments and simulation analysis.
Abstract
Purpose
This paper aims to research the tribological and dynamic characteristics of aeroengine hybrid ceramic bearings through wear experiments and simulation analysis.
Design/methodology/approach
First, the authors carried out wear experiments on Si3N4–GCr15 and GCr15–GCr15 friction pairs through the ball-disc wear test rig to explore the tribological properties of their materials. Second, using ANSYS/LS-DYNA simulation software, the dynamic simulation analysis of hybrid bearings was carried out under certain working conditions, and the dynamic contact stress of all-steel bearings of the same size was simulated and compared. Finally, the change of the maximum contact stress of the main bearing under the change of load and rotation speed was studied.
Findings
The results show that the Si3N4–GCr15 pair has better tribological performance. At the same time, under the conditions of high speed and heavy load, the simulation analysis shows that the contact stress between the ceramic ball and the raceway of the ring is smaller than the steel ball. That is, hybrid bearings have better transient mechanical properties than all-steel bearings. With the speed increasing to 12,000 r/min, the maximum stress point will shift in the inner and outer rings.
Originality/value
In this study, the tribological and transient mechanical properties of Si3N4 material were comprehensively analyzed through wear experiments and dynamic simulation analysis, which provided a reference for the design of hybrid bearings for next-generation aeroengines.
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