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The paper aims to deal with shape optimization of a novel thermoelastic clutch working on the principle of induction heating. The clutch consists of a driving part, with a ferromagnetic ring, and a driven part. The driving part rotates in a static field produced by appropriately arranged static permanent magnet. Currents induced in the rotating ferromagnetic ring cause its temperature to rise and increase its internal and external radii. As soon as its external diameter reaches the diameter of head of the driven part, it starts also rotating because of mechanical friction between both parts.

Presented is the complete mathematical model of the device, taking into account all relevant nonlinearities (saturation curve of the processed steel material and temperature dependences of its physical parameters). The forward solution is realized by the finite element method, and the shape optimization is solved using heuristic algorithms.

The clutch was found to be fully functional and may be used in applications with limited access into the device.

The coefficient of expansion of material of the driven part must be substantially lower than the same coefficient of the driving part to keep the necessary friction torque. The clutch can be only used in applications where higher temperatures (such as 300°C) are not dangerous to the environment.

The presented model and methodology of its solution may represent a basis for design of devices for transfer of generally mechanical forces and torques.

This paper presents an idea of induction-produced thermoelastic connection of two parts capable of transferring mechanical forces and torques.

The purpose of this study is to investigate the flexible dynamic characteristics about hydro-viscous drive providing meaningful insights into the credible speed-regulating behavior during the soft-start.

A comprehensive dynamic transmission model is proposed to investigate the effects of key parameters on the dynamic characteristics. To achieve a trade-off between the transmission efficiency and time proportion of hydrodynamic and mixed lubrication, a multi-objective optimization of friction pair system by genetic algorithm is presented to obtain the optimal combination of design parameters.

Decreasing the engagement pressure or the ratio of inner and outer radius, increasing the lubricating oil viscosity or the outer radius will result in the increase of time proportion of hydrodynamic and mixed lubrication, as well as the transmission efficiency and its maximum value. After optimization, main dynamic parameters including the oil film thickness, angular velocity of the driven disk, viscous torque and total torque show remarkable flexible transmission characteristics.

Both the dynamic transmission model and multi-objective optimization model are established to analyze the effects of main design parameters on the dynamic characteristics of hydro-viscous flexible drive.

The purpose of this paper is to present a new device (thermoelastic actuator) for accurate control of position whose principle is based on thermal dilatation of its working unit brought about by induction heating.

The device must satisfy the prescribed operation parameters (mainly the above thermal dilatation). The task to find them is a multiply coupled problem (interaction of electromagnetic field, temperature field and field of thermoelastic displacements) that is solved by the finite element method supplemented with a number of other procedures.

The control of position based on the described thermoelastic effect is very accurate and ranges from 1×10⁻⁶ to 1×10⁻³ m.

The device also contains two self‐locking friction clutches of conical shapes whose purpose is to fix the position of the plunger in the prescribed position. Further attention should be paid to their dynamic behaviour during the process of fixing.

The device can be used in various technical domains such as optics and laser or microscope techniques.

The principal part of the device contains no movable element, which is a substantial advantage in comparison to other systems based on mechanical, hydraulic or pneumatic principles working with movable elements or media.

The purpose of this paper is to present an approach to compute accurately the distributions of the frictional heat generated, contact pressure and thermal stresses at any instant during the sliding period (heating phase) of the single-disc friction clutch system works in the dry condition and the complex interaction among them.

Numerical work was achieved using the developed elastic and thermal finite element models (axisymmetric models) to simulate the engagement of the single-disc friction clutch system.

The change of distribution of contact pressure during the sliding period (heating phase) affects significantly the magnitude and distribution of the produced thermal stress. The high local heat generated appeared in the contacting surfaces because of the non-uniformity of the distribution of contact pressure during the heating phase (sliding time) and this will dramatically increase the thermal stresses.

Sequentially coupled thermal-mechanical approach was developed to investigate the thermal stresses problem in automotive clutches under dry conditions. This approach is considered a promising approach to investigate the effect of material, sliding time, torque function, etc., on the thermal stresses of different types of friction clutch.

This paper aims to introduce the moment of inertia of the driving and driven end of the clutch into the analysis of the transient temperature field of a friction plate and studied the influencing factors on that, especially to a marine gearbox.

A three-dimensional transient heat transfer analysis model of a wet clutch friction plate used in a marine gearbox is developed, and the transient characteristics of the temperature field during engagement are analyzed with taking account of the influence factors such as the sliding friction coefficient, engaging revolving speed, moment of inertia and applied engagement pressure.

The paper found out that the hot spot appears on the surface of the friction plate, taking account of the effect of radial slots and spiral groove. To avoid damage to the friction plate as a result of overheating, the appropriate sliding friction coefficient, lower engaging revolving speed and reasonable selection of applied engagement pressure curve can ensure a favorable heating situation of the friction plate. The reasonable structural design for the clutch with a bigger moment of inertia of driving end and smaller moment of inertia of driven end can reduce the engaging time effectively and decrease the peak temperature of the friction plate.

This paper fulfils a method to study the transient temperature field of a wet clutch friction plate, especially used in a marine gearbox.

The purpose of this paper is to reveal the mechanism of effect of surface groove on speed‐regulating start.

This paper investigates numerically and analytically the torque transfer and load capacity of oil film between separator and friction disc with grooves commonly used at present by solving simultaneous equations: modified Reynolds, energy, and temperature‐viscosity equations.

The results show friction discs with wider and deeper groove are not suitable for speed‐regulating start. To improve performance of speed‐regulating start, distribution and size of surface groove should be designed to obtain ascending trend of oil film load capacity during startup process.

This paper reveals the mechanism of effect of surface groove on speed‐regulating start and facilitates the conceptual design of speed‐regulating start control system.

The purpose of this paper is to study the influence of different cross-sectional shapes (rectangular, trapezoidal, oval and triangular) and layout forms of oil grooves (radial, circumferential, inclined, compound, helical and double-helical), and determine the optimal section shape and layout form of oil grooves on the temperature field.

Heat conduction theory model was established based on startup characteristics and friction heat principle of hydro-viscous clutch (HVC), and then the theoretical expression of angular velocity of the friction pair and control pressure were deduced, and the heat flux and its distribution on friction disk and separator disk were calculated. Finally, the finite element method was used to solve the temperature field of the friction pair.

The studies show that the circumferential oil groove got the highest temperature, and on the surface of all other structures, hot spots appear with different sizes and temperatures, and the maximum temperature difference in the friction zone is about 3°C, and in the oil groove zone is about 16°C, wherein the compound oil groove has the lowest average temperature. This research shows that the compound oil groove with rectangular cross-section is the best choice for the friction pair.

In this paper, it was found that the compound oil groove with rectangular cross-section is the best choice for the friction pair, and it provided a favorable theory reference and technical support for the structural design of the friction pair and optimized design of the high-power HVC.

The hydro-viscous drive (HVD) has been widely used in fan transmission in vehicles, fans, and scraper conveyors for step-less speed regulating and soft starting. It is an efficient method to save energy and reduce consumption. This study aims to analyze the influencing factors of oil film shear torque accurately.

The shear torque calculation model of double arc oil groove friction pairs was established. The influence of groove structure parameters on shear torque was analyzed. The interaction between viscosity temperature and shear torque was considered. Meanwhile, the equivalent radius was calculated when the rupture of oil film appeared. Finally, the test rig of torque characteristics was set up. The variance of shear torque with the input rotation speed under different oil film thickness, different oil temperature, and different flow rate was seen.

The results show that the shear torque increases with the growth of rotation speed. However, the increase of torque is quite gradual because of the effect of the change of viscosity, which is caused by the rise of temperature. The shear torque increases with the decrease of thickness, the increase of inlet flow rate, and the decrease of inlet oil temperature. Meanwhile, when the feeding flow rate is less than the theoretical, the oil film gets ruptured and the shear torque decreases sharply.

The influence on shear torque during full film shear stage in HVD can be achieved much more accurately through both experimental research and theoretical modeling in which groove parameters, influence of temperature, and oil film rupture are considered. Therefore, the shear torque of HVD can be predicted by theoretical model and experimental research in full film shear stage.

This paper aims to study and compare the friction stability of wet paper-based clutches with regard to the radial grooves (RG) and waffle grooves (WG).

This paper presents an experimental study of a wet clutch concerning the effect of groove patterns on the friction torque and surface temperature. The friction stabilities of RG and WG are investigated with the applied pressure, rotating speed and automatic transmission fluid (ATF) temperature taken into consideration.

The friction torque and surface temperature of WG are larger than those of RG under the same operating condition. The friction torque difference between RG and WG grows with the increase of applied pressure and narrows with the increase of ATF temperature. Additionally, their temperature difference expands via increasing the rotating speed and ATF temperature or reducing the applied pressure; in this way, not only the variable coefficient difference between RG and WG can be narrowed, but also the friction stability of the clutch can be improved dramatically.

This paper explains the thermodynamic differences between RG and WG; moreover, it is verified experimentally that WG has a better friction stability than RG.

The purpose of this paper is to study the dynamic transmission of the oil film in soft start process of hydro-viscous drive (HVD) between the friction pairs with consideration of surface roughness, and obtain the distribution law of temperature, velocity, pressure, shear stress and viscous torque of the oil film.

The revised soft-start models of HVD were derived and calculated, including average Reynolds equation, asperity contact model, load force model and total torque model. Meanwhile, a 2D model of the oil film between friction pair was built and solved numerically using computational fluid dynamics (CFD) technique in FLUENT.

The results show that the maximum temperature gradually reduces from the intermediate range (z = 0.5 h) to the inner side of the friction pair along the direction of oil film thickness. As the soft-start process continues, pressure gradient along the direction of the oil film thickness gradually changes to zero. In addition, tangential velocity increases and yet radial velocity decreases with the increase of the radius.

In this paper, it was found that the viscous torque calculated by the numerical method is smaller than that by the CFD model, but their overall trend is almost the same. This also demonstrates the effectiveness of the numerical simulation.