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The purpose of this paper is to investigate the effect of different wedge shapes on the performance of air foil thrust bearing (AFTB).

During the study, a bump foil stiffness model considering slip deformation and a two-dimensional sheet top foil model is established, and the Reynolds equation and film thickness equation is solved using the finite difference method and finite element method. The static performance such as load carrying capacity, friction torque and power loss of AFTB under different taper parameters is obtained. The influence of different pitch ratio, film thickness ratio and wedge shapes on the bearing characteristics is studied.

There is an optimal height and a pitch ratio for the taper of AFTB with certain tile number. Compared to the plane and concave wedge shape, the upper convex shape can enhance the convergence effect of the wedge region, increase the effective film pressure distribution area of the bearing and reduce the local concentrated load of the top foil, which is more conductive to the increase of load capacity.

The wedge shape parameters bring a fundamental difference in the static performance of AFTB. The results are expected to be helpful to bearing designers, researchers and academicians concerned.

The purpose of this paper is to maximize the load-carrying capacity (LCC) of a rotating ring, a numerical model optimizing both the surface and bottom shape of its surface textures is proposed.

The Reynolds equation is used to evaluate the film pressure and LCC obtained by integrating the film pressure is set as the objective function. Around the center of the computational domain, radial lines with an equal angle between adjacent ones are produced and the surface contour of textures is obtained by connecting the endpoints using a spline curve. The bottom profile is then obtained by connecting the endpoints of two vertical lines at the circumferential ends of textures. Lengths of these lines are set as design variables and genetic algorithm is used to solve optimization models.

Results show that optimum textures have an “apple-like” surface contour and a “wedge-like” bottom profile, which are both expressed by smooth spline curves. Optimum wedge-bottom textures generate higher LCC than optimum flat-bottom textures. Moreover, the optimum textures have the highest LCC compared with optimum grooves proposed previously, which validates the practical value of the current optimization model.

This work presents a comprehensive optimization method of texture geometry, which provides a new idea of the design of surface textures.

This paper aims to research the effect of the different structures of dimpled textures on the rod bearing surfaces on improving the engine’s lubrication efficiency and friction power loss (LE-FPL).

Based on the hydrodynamic model of the rod bearing, the effect of different structures of dimpled surfaces including circular dimples (CD), square dimples (SD), wedge-shaped dimples (WSD), circular-square dimples (CSD) and square-wedge-shaped dimples (SWSD) on ameliorating the LE-FPL is analyzed under the different operating conditions of the engine. The oil film pressure (p), asperity contact force (W_ac), friction force (F_f) and coefficient of friction (COF) of the rod bearing are chosen to evaluate the LE-FPL.

The SD’s performance on improving the LE-FPL is better than all other structures of the CD, WSD, CSD and SWSD. Particularly, the average values of W_ac, F_f and COF with the SD is significantly reduced by 14.5%, 28.5% and 33.3% compared to the optimal dimensions of the rod bearing; and by 26.4%, 34.5% and 43.7% compared to the optimal CD (n = m = 6).

The generated friction between surfaces of rod bearings of the engine not only reduces the engine power but also affects the durability of the structures. Thus, the optimal design of the SD to further improve the LE-FPL is very necessary.

Hydrostatic thrust bearing is a key component of the vertical CNC machining equipment, and often results in friction failure under the working condition of high speed and heavy load. The lubricating oil film becomes thin or breaks because of high speed and heavy load and it affects the high precision and stable operation of the vertical CNC machining equipment; hence, it is an effective way of avoiding friction failure for achieving the oil film shape prediction

For the hydrostatic thrust bearing with double rectangular cavities, researchers solve the deformation of the friction pairs in hydrostatic bearing by using the computation of hydrodynamics, elasticity theory, finite element method and fluid-thermal-mechanical coupled method. The deformation includes heat deformation and elasticity deformation, the shape of gap oil film is got according to the deformation of the friction pairs in hydrostatic bearing, and gets the shape of gap oil film, and determines the influencing factors and laws of the oil film shape, and achieves the prediction of oil film shape, and ascertains the mechanism of friction failure. An experimental verification is carried out.

Results show that the deformation of the rotational workbench is upturned along its radial direction under the working condition of high speed and heavy load. However, the deformation of the base is downturned along its radial direction and the deformation law of the gap oil film along the radius direction is estimated; the outer diameter is close but the inner diameter is divergent wedge.

The conclusion can provide a theoretical basis for the oil film control of hydrostatic thrust bearing and improve the stability of vertical CNC machining equipment.

This study aims to probe customers’ expectations and explore discrepancies across various domestic kids’ ready to wear (RTW) apparel brands for measurements, fit, shape and labelling/nomenclature.

Data were collected through qualitative and quantitative methods. Interviews were held with the consumers to understand their perceptions and expectations with the kids’ wear brands for measurements, fit and labelling. The approach had a twofolded purpose of addressing the consumers’ dissatisfaction and the apparel manufacturer’s perspective.

The results indicated that 87% of consumers gave importance to well-fitted apparel. The apparel brands considered for the study showed inconsistency and discrepancies in the measurements, leading to consumer dissatisfaction and frustrations.

The findings of the study may be useful for fashion academia, kids RTW apparel manufacturers and designers who can relate to the role of standard measurements and the varying body shapes in RTW apparel. They can work closer to develop innovative practices focusing on the fit challenges in kids RTW apparel.

The implication of the lack of any standard measurement for Indian kids for apparel is well-established in the study.

A stage has now been reached in the development of rocket propulsion where, with moderate advances in technique, it becomes possible to produce a manned satellite vehicle and later to proceed to interplanetary flight. It is, in fact, evident that some work is already in progress to develop the satellite vehicle for military purposes, but exclusive military exploitation of space‐flight would be deplorable and it is desirable that a project, for purely scientific purposes, should come into being under a civilian authority.

In high voltage direct current cable systems, cable joints are known as the least reliable components due to the use of multiple dielectrics. Resulting from the electric field and temperature depending conductivity of the different dielectrics, field enhancement at critical areas, e.g. triple points, may result in accelerated aging and the failure of the component. To reduce the stress, different field grading techniques are applied. The purpose of this study is to investigate different grading techniques for cable joints. Different shapes of the electrode and a varying nonlinear conductivity of field grading materials (FGM) are used for the simulation of the electric field.

Coupled electro-thermal field simulations are applied for different joint geometries, to obtain the stationary electric field. Electric field simulations in cable joint using geometric and nonlinear field grading techniques are shown.

Using the geometric field grading, the shape of the stress cone determines the field values in critical areas (triple points). High stress reduction is obtained for a certain curvature of the stress cone. For the nonlinear stress control, materials with a higher conductivity in comparison to the cable and the joint material are used. A field reduction is obtained by increasing the total conductivity. On the other hand, this is also increasing the insulation losses within the total FGM. More applicable is the decrease of the switching field or the increase of nonlinearity, which is only locally increase the conductivity and the insulation losses. Furthermore, simulations results show that an approximately constant field reduction is obtained, if the nonlinearity is above a certain threshold.

This study is restricted to a field dependency of FGM only. For impulse voltages, high temperature and electric conductivity values my result in a thermal runaway. Furthermore, only direct current field grading techniques are studied.

The field grading of cable joints, using geometric and nonlinear techniques, is analyzed. A comparison between the electric field, by varying the curvature of the ground stress cone or the FGM conductivity constants in a complex joint geometry is novel. With its effect on the electric fields, general requirements for the geometry (geometric field grading) or the values of the FGM constants (nonlinear field grading) are defined to obtain a sufficient field grading.

To solve the problem of oil film thinning when hydrostatic thrust bearings are overloaded or rotating at high speed, the dynamic pressure formed by tiny oil wedges is used to compensate, and the optimum height of oil wedges is determined by the compensation rate to improve the bearing capacity of hydrostatic thrust bearings.

This research method is aimed at the new type of double rectangular cavity static bearing with microbevel surface of q1-205. The wedge parameters of oil film were defined. The oil film lubrication performance of the bearing with the wedge parameters of 0, 0.02, 0.04, 0.06, 0.08 and 0.10 mm was simulated by the finite volume method, the comprehensive influence law of the wedge-shaped parameters on the vorticity and flow rate of the oil cavity pressure fluid was revealed. Finally, the oil cavity pressure changes of oil films with different wedge parameters under certain load and speed were tested by design experiments, and the theoretical analysis and simulation were verified.

This study found that the oil film wedge shape can well compensate the static pressure loss caused by the high-speed or heavy-duty operation of the bearing, but the dynamic pressure effect of the wedge shape does not always increase with the increase of the wedge height. The oil film exhibits superior lubrication performance in the range of 0.06–0.08 mm.

The original hydrostatic oil pad was designed as a microinclined plane, and the dynamic pressure caused by the microwedge of the oil pad was used to compensate the static pressure loss of the bearing. The lubrication performance of the oil film under the condition of varying viscosity was obtained by using the simulation method.

An area navigation system, RNAV, has dual way‐point selection for advance flight programming and tenth unit readouts for better navigation accuracy. Slant range corrected, linearised horizontal guidance circuits provide constant course widths regardless of distance from VOR stations. Course width (full scale needle deflection on course deviation indicator) is ±5 miles in the ENROUTE Mode and ±1·25 miles in the APPROACH Mode. Distance‐proportional, zero‐time‐lag filtering is included to provide instantaneous course deviation data in cross track manoeuvres.

This paper aims to investigate spontaneous movement of single droplet on chemically heterogeneous surfaces induced by the net surface tension, using the improved three-dimensional (3D) lattice Boltzmann (LB) method.

D3Q19 Shan-Chen LB model is improved in this paper. Segmented particle distribution functions coupled with the P-R equation of state are introduced to maintain the higher accuracy and greater stability. In addition, exact difference method (EDM) is adopted to implement force term to predict the droplet deformation and dynamics.

The numerical results demonstrate that spontaneous movement of single droplet (=1.8 µm) along wedge-shaped tracks is driven by net surface tension. Advancing angle decreases instantaneously with time, while receding angle changes slightly first and then decreases rapidly. Wetting length is affected by vertex angle and wetting difference, whereas the final value is only dependent on the stronger wettability. Although the velocity of single droplet on wedge-shaped tracks can be increased by the larger vertex angle, it has a negative influence on the displacement. For the same wetting difference, vertex angle equal to 30º is an optimization strategy in this model. If the simulation length is extended enough, then the smaller vertex angle is beneficial for the droplet movement. In addition, a larger wetting difference is beneficial to spontaneous movement, which can speed up the droplet movement.

The proposed numerical model of droplet dynamics on chemically heterogeneous surfaces provides fundamental insights for the enhancement of drop-wise condensation heat transfer.