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The objective of this paper is to determine fretting parameters of hoisting rope according to the hoisting parameters in coalmine and to explore the effect of contact load on fretting-fatigue behavior of steel wires.

Based on the mechanical model of hoisting rope in coalmine, the dynamic tension simulation of hoisting rope was performed. Static equations of hoisting rope under tension and torsion and theories of contact mechanics were applied to obtain fretting parameters. Fretting-fatigue tests of steel wires at different contact loads were conducted using a fretting-fatigue test rig. The fretting regime, normalized tangential force and fretting-fatigue life were studied. The morphologies of fretting contact scars and fracture surfaces were observed by scanning electron microscopy and optical microscopy to examine wear and failure mechanisms.

Dynamic tension changes from 0 to 30,900 N. In outer strand layer, contact loads between steel wires in certain wire layers are 60.5 and 38.3 N compared with 378 and 102.7 N between wire layers; relative displacements between wires are 62.5 and 113.2 μm, respectively. Mixed fretting regimes develop in all cases. Increasing contact load decreases the stabilized relative slip and normalized tangential force, reduces the fretting fatigue life, induces accelerated adhesive wear and fatigue wear and results in rougher fracture surface topographies. In all cases, fretting zone induces crack initiation; crack propagation and rupture zones present brittle cleavage and longitudinal splitting, respectively.

This paper presents the systemic study on determination of fretting parameters of hoisting rope according to the hoisting parameters in coalmine and the fretting-fatigue behavior of its internal steel wires. The results of fretting-fatigue tests show that the increase of contact load decreases the stabilized relative slip in mixed fretting regime and normalized tangential force, reduces the fretting fatigue life, induces accelerated adhesive wear and fatigue wear and results in rougher fracture surface topographies.

The authors warrant that the paper is original submission and is not being submitted to any other journal. And the research does not involve confidentiality, copyright infringement, leaks and other issues, all the responsibilities that the authors will take.

Optimisation of grinding processes involves enhancing the surface quality and reducing the cost of manufacturing through reduction of power consumptions. Recent research works have indicated the minimum quantity lubrication (MQL) system is used to achieve near dry machining of alloys and hard materials. This study aims to provide an experimental analysis of the grinding process during machining of aluminium alloy (Al6061-T6). MQL nanofluid was used as the lubricant for the grinding operations. The lubricant was formed by suspending silicon dioxide nanoparticles in canola vegetable oil. The effect of input parameters (i.e. nanoparticle concentration, depth of cut, air pressure and feed rate) on the grinding forces and surface quality was studied. Adaptive neuro-fuzzy inference system (ANFIS) prediction modelling was used to predict the specific normal force, specific tangential force and surface quality, the ANFIS models were found to have prediction accuracies of 97.4, 96.6 and 98.5 per cent, respectively. Further study shows that both the specific grinding forces and surface roughness are inversely proportional to the nanofluid concentration. Also, the depth of cut and table feed rate were found to have a directly proportional relationship with both the grinding forces and surface roughness. Moreover, higher MQL air pressure was found to offer better delivery of the atomised nanofluid into the grinding region.

Grinding experiments were performed using MQL nanofluid as the lubricant. The lubricant was formed by suspending silicon dioxide nanoparticles in canola vegetable oil. The effect of input parameters (i.e. nanoparticle concentration, depth of cut, air pressure and feed rate) on the grinding forces and surface quality has been studied.

The grinding process parameters were optimised using Taguchi S/N ratio analysis, whereas the prediction of the response parameters was done using ANFIS modelling technique. The developed ANFIS models for predicting the specific normal force, specific tangential force and surface quality were found to have prediction accuracies of 97.4, 96.6 and 98.5 per cent, respectively. Further findings show that both the specific grinding forces and surface roughness are inversely proportional to the percentage of nanoparticle concentration in the lubricant. Also, the depth of cut and table feed rate were found to exhibit a direct proportional relationship with both the grinding forces and surface roughness, while high MQL air pressure was observed to offer more efficient delivery of the atomised nanofluid into the grinding region.

The work can applied into manufacturing industries to prevent unnecessary trials and material wastages.

The purpose of this study is to develop an artificial intelligent model for predicting the outcomes of MQL grinding of the aluminium alloy material using ANFIS modelling technique.

The purpose of the paper is to present a novel cross-modal sensor whose tactile is computed by the visual information. The proposed sensor can measure the forces of robotic grasping.

The proposed cross-modal tactile sensor consists of a transparent elastomer with markers, a camera, an LED circuit board and supporting structures. The model and performance of the elastomer are analyzed. Then marker recognition method is proposed to determine the movements of the marker on the surface, and the force calculation algorithm is presented to compute the three-dimension force.

Experimental results demonstrate that the proposed tactile sensor can accurately measure robotic grasping forces.

The proposed cross-modal tactile sensor determines the robotic grasping forces by the images of markers. It can give more information of the force than traditional tactile sensors. Meanwhile, the proposed algorithms for forces calculation determine the superior results.

The purpose of this paper is to investigate the two-dimensional problem in couple stress thermoelastic medium for a half space is established and state space approach has been applied to solve the problem.

Normal mode analysis is used to obtain the exact expressions for normal stress, tangential stress and couple stress. Numerical calculation is prepared for these quantities and depicted graphically for a special model.

The expressions for normal stress, tangential stress and couple stress are obtained numerically and depicted graphically to see the couple stress effect.

It is found that couple stress effect decrease the value of normal stress components for circular frequency equal to 0.5 for small values of the wave number and then increases whereas the values of normal stress components decrease first and then increase monotonically for circular frequency equal to 0.1 when the force is applied in normal direction and the values of tangential stress components and couple stress components decrease for all values of wave number. But the values for normal stress components, tangential stress components and couple stress components increase when the force is applied in tangential direction.

The purpose of this paper is to develop a discrete element (DE) and multiscale modeling methodology to represent granular media at their particle scale as they interface solid deformable bodies, such as soil‐tool, tire, penetrometer, pile, etc., interfaces.

A three‐dimensional ellipsoidal discrete element method (DEM) is developed to more physically represent particle shape in granular media while retaining the efficiency of smooth contact interface conditions for computation. DE coupling to finite element (FE) facets is presented to demonstrate initially the development of overlapping bridging scale methods for concurrent multiscale modeling of granular media.

A closed‐form solution of ellipsoidal particle contact resolution and stiffness is presented and demonstrated for two particle, and many particle contact simulations, during gravity deposition, and quasi‐static oedometer, triaxial compression, and pile penetration. The DE‐FE facet coupling demonstrates the potential to alleviate artificial boundary effects in the shear deformation region between DEM granular media and deformable solid bodies.

The research is being extended to couple more robustly the ellipsoidal DEM code and a higher order continuum FE code via overlapping bridging scale methods, in order to remove dependence of penetration/shear resistance on the boundary placement for DE simulation.

When concurrent multiscale computational modeling of interface conditions between deformable solid bodies and granular materials reaches maturity, modelers will be able to simulate the mechanical behavior accounting for physical particle sizes and flow in the interface region, and thus design their tool, tire, penetrometer, or pile accordingly.

A closed‐form solution for ellipsoidal particle contact is demonstrated in this paper, and the ability to couple DE to FE facets.

In customized production such as plate workpiece grinding, because of the diversity of the workpiece shapes and the positional/orientational clamping errors, great efforts are taken to repeatedly calibrate and program the robots. To change this situation, the purpose of this study is to propose a method of robotic direct grinding for unknown workpiece contour based on adaptive constant force control and human–robot collaboration.

First, an adaptive constant force controller based on stiffness estimation is proposed, which can distinguish the contact of the human hand and the unknown workpiece contour. Second, a normal vector search algorithm is developed to calculate the normal vector of the unknown workpiece contour in real-time. Finally, the force and position are controlled in the calculated normal and tangential directions to realize the direct grinding.

The method considers the disturbance of the tangential grinding force and the friction, so the robot can track and grind the workpiece contour simultaneously. The experiments prove that the method can ensure the force error and the normal vector calculating error within 0.3 N and 4°. This human–robot collaboration pattern improves the convenience of the grinding process.

The proposed method realizes constant force grinding of unknown workpiece contour in real-time and ensures the grinding consistency. In addition, combined with human–robot collaboration, the method saves the time spent in repeated calibration and programming.

Compared with other related research, this method has better accuracy and anti-disturbance capability of force control and normal vector calculation during the actual grinding process.

This paper aims to investigate the mechanisms lying behind the cycloidal rotor under hovering status.

Experiments were conducted to validate the numerical simulation results. The simulations were based on unsteady Reynolds-averaged Navier–Stokes (URANS) equations solver and the sliding mesh technique was used to model the blade motion. 2D and 2.5D simulations were made to investigate the 3D effects of turbulence. The effects of pressure and viscosity were compared to study the significance of the blade motion on force generation.

The 2.5D numerical simulation cannot produce more accurate results than the 2D counterpart. The pitching motion of the blade results in dynamic stall. The dynamic stall vortices induce parallel blade vortex interaction (BVI) upon downstream blades. The interactions between the blades delay the stall of the blade which is beneficial to the thrust generation. The blade pitching motion is the dominant contributor to the force generation and the turbulence is the secondary. Strong downwash in the rotor cage varied the inflow velocity as well as the effective angle of attack (AOA) of the blade.

Cycloidal rotor is a propulsion device that can provide omni-directional vectored thrust with high efficiency and low noise. To understand the mechanisms lying behind the cycloidal rotor helps the authors to design efficient cycloidal rotors for aircraft.

The authors discovered that the blade pitching motion plays primary role in force generation. The effects of the dynamic stall and BVI were studied. The reason why cycloidal rotor can be more efficient was discussed.

The purpose of this paper is to investigate the effects of liquid carbon dioxide (LCO₂) on grinding of stainless steel.

A factorial experimental approach was used to compare the LCO₂'s performance against grinding under dry air and emulsion coolants.

The experimental results have a great use to practitioners. It was found that under special conditions, LCO₂ proves to be an alternative coolant for grinding of temperature sensitive materials. Furthermore, grinding under LCO₂ conditions produced the lowest tangential force, while the normal forces were close to the values found under emulsion fluid environment. When compared to grinding under dry conditions, LCO₂ coolant was successful in reducing the work piece temperatures. LCO₂ and emulsion conditions inhibit work hardening by reducing material deformation at the grinding zone.

The paper shows that sub‐zero temperature coolants have the ability to bring about lower grinding temperatures than what is typically achieved under conventional fluids.

The purpose of this paper is establish a model of the equations of a two‐dimensional problem of fluid saturated porous medium for a half space.

A state space approach has been applied to solve the problem. Normal mode analysis is used to obtain the exact expressions for normal stress, tangential stress and pore pressure.

A computer programme is developed and numerical results are obtained for normal stress, tangential stress and pore pressure and depicted graphically for a special model. A particular case of interest has also been deduced from the present investigation.

The disturbance due to force in normal and tangential direction and porosity effect have been observed by the method of normal mode analysis.

The purpose of this paper is to develop a numerical approach to solve the transient rolling contact problem with the consideration of velocity dependent friction.

A three dimensional (3D) transient FE model is developed in elasticity by the explicit finite element method. Contact solutions with a velocity dependent friction law are compared in detail to those with the Coulomb’s friction law (i.e. a constant coefficient of friction).

The FE solutions confirm the negligible influence of the dependence on the normal contact. Hence, analysis is focussed on the tangential solutions under different friction exploitation levels. In the trailing part of the contact patch where micro-slip occurs, very high-frequency oscillations are excited in the tangential plane by the velocity dependent friction. This is similar to the non-uniform sliding or tangential oscillations observed in sliding contact. Consequently, the micro-slip distribution varies greatly with time. However, the surface shear stress distribution is quite stable at different instants, even though it significantly changes with the employed friction model.

This paper proposes an approach to solve the transient rolling contact problem with the consideration of velocity dependent friction. Such a problem was usually solved in the literature by the simplified contact algorithms, with which detailed contact solutions could not be obtained, or with the assumption of steady rolling.