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The attractive specifications of vertical axis wind turbine (VAWT) are its operating with low noise and wind in various directions. To achieve a higher performance of these turbines, modeling of a curved‐blade VAWT by the modified double multiple streamtube (DMST) method and optimizing this wind turbine are performed. The power coefficient and the total normal force acting on blades were selected as two objective functions. Minimizing the normal force acting on turbine blades as the second objective function was not observed in the open literature. The amount of normal force is crucial in the structural design of VAWT because it generates both the bending moment on blades and forces on supporting arms of VAWT. Another innovation of this study is to consider the shape coefficient parameter that determines the shape of the rotor geometry as a design variable in optimization procedure. A 3 m height curved‐blade VAWT type was optimized by this multi‐objective optimization technique. The optimum values of the design variables obtained by the Genetic Algorithm were selecting an elliptical rotor geometry, pitch angle −1.4°, diameter/height 1.3, blade aspect ratio 19.8, tip speed ratio 4.3 and selecting three blades which could provide a power coefficient of 0.49 and a normal force of 158.7 N. [ABSTRACT FROM AUTHOR]

The main core of the semi-active friction damper is the control unit of normal force, which often comprises a piezoelectric actuator with a high dynamic response frequency. However, the telescopic range of the piezoelectric actuator is very limited, so the magnitude of the normal force generated by this actuator is also limited. Moreover, the actuator is sensitive to abrasion and deformation of the friction surface, which affects the friction accuracy of such dampers. To ameliorate these problems, this study proposes a modified semi-active friction damper with a new control mechanism for normal force. The aim is to improve the controllability of the friction damper and reduce its sensitivity to the abrasion, deformation, temperature and speed of the friction surface. Test results show that the three characteristics of this proposed control mechanism are as follows: (1) The internal strain energy is not transformed when the normal force is changed. Therefore, this proposed mechanism can operate without an energy supply; (2) It has flexibility, allows abrasion and deformation of the friction surface, and can still maintain good accuracy; (3) This proposed mechanism provides a closed loop driver and high control accuracy. [ABSTRACT FROM AUTHOR]

In order to investigate the influence of sepiolite minerals on the normal force of magnetorheological grease (MRG), a mixed sample (ALCH) on the basis of preparing an aluminum–lithium-based magnetorheological grease (base sample ALC), containing sepiolite was further prepared. The field-dependent normal force of the two samples was tested using a rotational rheometer, considering conditions such as magnetic field, time, strain amplitude, frequency, and temperature, and the results were compared. The results indicate that sepiolite limits the field dependent normal force of the magnetorheological grease under steady state shear, and is unaffected by magnetic field, time, temperature, and shear rate. Sepiolite has minimal impact on the transient response of the magnetorheological grease. Under oscillatory shear, the magnetic field is an important factor influencing the field-dependent normal force response of the sepiolite-magnetorheological grease (ALCH). At low magnetic fields, the field-dependent normal force of the sepiolite-containing sample (ALCH) is greater than that of the base sample (ALC), while this relationship is reversed at high magnetic fields, unaffected by other factors. Under long-term shear conditions, both samples exhibit good shear stability, as well as consistency at different frequencies and strain amplitudes. However, an increase in shear rate reduces the normal force, and temperature also affects the field-dependent normal force. The patterns of variation in steady-state and oscillatory shear modes are not entirely the same, but both exhibit a characteristic decrease with increasing temperature under high magnetic field intensities. Sepiolite can reduce the temperature sensitivity of the normal force of the magnetorheological grease. In conclusion, the introduction of sepiolite is beneficial for the application of magnetorheology in high-precision devices. [ABSTRACT FROM AUTHOR]

The mechanical and hydrodynamic phenomena occurring in the refining zones of disc refiners cause fibres to undergo fibrillation. This paper presents a study of the changes occurring during fibre fibrillation as expressed in terms of the fibrillation index when refining pulp with a 10%, 15%, and 20% consistency. The influences of the tangential force of a circular bar and a straight bar on fibre fibrillation were compared. The changes in the tangential force are shown to depend on the angle between the tangent to the cutting edge and the radius from the centre of the disk to the tangency point. Increasing the angle between the tangent to the cutting edge and the radius from the centre of the disk to the tangency point gives higher fibrillation index values. The study revealed a relationship between fibre fibrillation and the strength characteristics of handsheets. [ABSTRACT FROM AUTHOR]

The aim of the study was to characterize raw aqueous extracts from Plantago ovata husk in terms of molecular chain mass, osmotic, hydrodynamic, and rheological properties. The raw extracts used in this study have not been yet investigated in the indicated research area. Determination of the molecular weight of the chains present in the extract was performed by gel permeation chromatography (GPC). Osmotic properties were characterized using membrane osmometry. Rheological properties were investigated via classical rotational rheology with normal force measurements, as well as less common but equally important measurements of extensional viscosity. Two types of chains with an average molecular mass of 200 and 1780 kDa were found. The values of the first virial coefficient (B2) indicate the predominance of biopolymer-biopolymer interactions. The hydrodynamic radius established at 25 and 30 °C was 74 and 67 nm, respectively, and lower than at 40 °C (>600 nm). The first critical concentration was determined: c * = 0.11   g · dL − 1 . The dominance of negative normal force values resulting from the formation of a pseudo-gel structure of the heteroxylates was demonstrated. Extensional viscosity measurement results revealed that the studied extracts cannot be treated as simple shear-thinning fluids, as indicated by shear flow, but should be considered as viscoelastic fluids. [ABSTRACT FROM AUTHOR]

Wood friction welding is a green and pollution-free wood processing technology. Research on wood friction welding mainly focuses on the influence of wood type, welding process, and welding interface additives on welding interface strength. However, studies on the tribological properties of wood friction welded interface and its effect on the strength of the welded interface are few. In this article, chemical additives in wood were added to the interface. The frictional force, normal force, microstructure, and chemical composition of the welding interface, and their effects on the strength of the welding interface were studied. In the rotating friction welding of wood, frictional force increased gradually with friction welding. Approximately 2 s after welding, the frictional force achieved a stable state. Normal force increased and then gradually decreased. No considerable changes in frictional force and interface strength were observed and interface strength increased with normal force. The interface strength of glucose and rosin increased, whereas that of N2 protection showed little change. The interface strength of tung oil, cellulose, and guaiac decreased. This study provides a basic reference for the further industrial application of wood friction welding technology. [ABSTRACT FROM AUTHOR]

To solve the problem of springback in traditional multi-point forming (MPF), a new multi-point forming process, namely, multi-point forming with individually controlled force–displacement (MPF-ICFD), is proposed. In this manuscript, traditional MPF and MPF-ICFD are compared. Taking the cylindrical surface as the research object, the change in the springback of a plate is analysed by experiments, and the distribution of the strain and wall thickness of the plate is analysed by numerical simulation. Theoretical analysis is used to calculate the forming window for the MPF-ICFD process, and the results from theoretical analysis are verified by experiments and numerical simulation. The results show that the springback of 1060 aluminium alloy and Q295 for MPF-ICFD can be decreased by 73.8% and 45.5%, respectively, compared with traditional MPF. In traditional MPF, the strain uniformity of the plate is poor, and the maximum thinning rate is 4.5%. For MPF-ICFD, the strain is relatively uniform, and the maximum thinning rate is 0.25%. For an aluminium alloy sheet with a wall thickness of 1.5–3 mm, the upper and lower limits of the forming force for a single head are observed to change linearly from 6.3 to 12.6 kN and from 0.5 to 1 kN, respectively. [ABSTRACT FROM AUTHOR]

Cutting using an abrasive water jet is a complex process involving several physical phenomena. This research studies some of them, mostly the influence of selected variables on the measured forces and vibrations. The traverse speed represents one of the key parameters when cutting using the AWJ. In the presented research, a set of experiments was performed on twelve different metal samples, while the force sensor measured the exerted forces and accelerometers measured the vibrations. Ten different types of steel samples of the same dimensions were cut applying five different traverse speeds. The data obtained during these measurements show that an increase in the traverse speed leads to an increase in the measured forces and vibrations. An analogous experiment performed on bronze and duralumin samples of the same dimensions, having applied higher speeds to compensate for the difference in the material structure and properties, completes the presented data. The most important results of the research are that exerted forces in the z-axis are higher than those in the x-axis, whereas measured vibrations are higher in the x-axis. According to our research, the elemental structure, especially the carbide formation, affects the measured forces and vibrations substantially. [ABSTRACT FROM AUTHOR]

The tribocorrosion behaviour of Ti-6Al-4 V exposed to phosphate buffered saline was investigated under a range of normal forces in both cathodic and anodic regions to provide a basis for properly deriving the tribological constants of this alloy. To achieve this, a new customised tribotester was designed and manufactured to rub the Ti-6Al-4 V disks against zirconia balls. The tests were conducted at a sliding frequency of 1 Hz and a sliding distance of 4.8 mm under various normal forces and potentials as 17.5, 10.8, 6, 3.5 N, and − 1.2, − 0.6, 0, 0.4, 0.8 V/VAg/AgCl, respectively. The damaged surfaces were characterised by scanning electron microscopy and energy-dispersive X-ray spectroscopy, profilometer, and micro-hardness tester. The post analyses confirmed the appearance of some minor cracks together with third-body wear particles. No significant changes in the hardness were detected after the tribocorrosion tests. The results of profilometry and electrochemical current indicated that in the anodic region the chemical losses accounted for a significant proportion (up to 36%) of the total loss. The proportional chemical loss increased with the potential; however, neither direct nor reverse relationship was found with the normal force. Overall, in the anodic domain, the material loss increased with the potential level due to the formation of oxide layer which may induce more shear cutting. In the cathodic domain, hydrogen embrittlement changed the properties of the interface and thus, the amount of material loss. Both the mechanical and chemical wear were described by an existing tribocorrosion theory; thereby, the theory was equipped with its tribocorrosive constants for future analyses on the tribocorrosion of this alloy extensively used in various applications including biomedical implants. [ABSTRACT FROM AUTHOR]

Nowadays, many scholars have been studied the normal force of MRF in the uniform magnetic field. However, the research on the normal force of MRF in the non-uniform magnetic field is relatively limited. The non-uniform magnetic field can cause the MRF to generate normal force of different sizes and directions to cope with different working conditions, thus the normal force generated in the non-uniform magnetic field require more attention. In this paper, a theoretical model of the normal force of MRF in the non-uniform magnetic field was developed based on the enhanced magnetic dipole model. The normal force of MRF within a unit area can be calculated based on this theoretical model. However, the magnetic induction intensity is different at different locations of the non-uniform magnetic field, which leads to the normal force generated by the MRF are not accurately calculated. Therefore, it is necessary to use COMSOL to establish the material model of the MCR-302 plate rheometer and MRF to verify the accuracy of the proposed model. Then a flat-plate rheometer was used to test the static normal force of the MRF in the non-uniform magnetic field. Finally, the simulation and experimental data were compared. The results show that the simulation result with the experimental data is a good agreement, which verifies the reliability of the theoretical model. The static normal force of the MRF increases with the increase of volume fraction and magnetic field intensity. [ABSTRACT FROM AUTHOR]

In this paper, a kind of magnetorheological fluid, containing nano‐Fe3O4, was prepared in order to study the influence of nano‐Fe3O4 content on its normal force characteristics. Firstly, the microscopic force model is constructed and the microscopic static analysis is carried out. Secondly, the force of the magnetic chain under impacted is simulated by using the numerical simulation method of ANSYS finite element analysis and a plate‐to‐plate shear test system is established. The results show that the normal force of the magnetic chain is enhanced by the supporting force of the nano iron powder embedded in the magnetic chain. At the same magnetic induction intensity, the normal force of the magnetorheological fluid gradually increases with the increase of the mass fraction of nano‐particles. When the mass fraction of the nanoparticles is 7 %, the normal force reaches the maximum. [ABSTRACT FROM AUTHOR]

This purpose was to investigate developed seat-cover assemblies' effect on decreasing the fluctuation of the shear force exerted onto the buttocks as the factors causing decubitus ulcers when the back-support was inclined. The participants were 10 wheelchair users. The force plate was used to measure the horizontal force as the shear force. The back-support was inclined at increasing angles, starting from the upright position (IUP), then proceeding to a fully reclined position (FRP), and returning to the upright position (RUP). The experimental conditions were two conditions; the seat-cover assembly conditions and without the seat-cover assembly as the control conditions. The average values in the seat-cover assembly condition were 14.4 ± 3.3, 13.9 ± 2.3, and 17.3 ± 3.3% body weight in the IUP, FRP, and RUP, respectively. The average values in the control condition were 14.8 ± 2.6, 11.4 ± 1.7, and 24.0 ± 6.7% body weight in the IUP, FRP, and RUP, respectively. In the FUP and the RUP, there were significant differences between two conditions (p <.01). These results suggested that the shear force exerted onto the buttocks may to be decreased by using novel seat-cover assembly. It is possible to decrease the fluctuations in the shear force by moving the body up and down according the novel seat-cover assembly attached the back-support incline. Disabled, older individuals can be provided with a comfortable life on a reclining wheelchair while preventing decubitus ulcers. [ABSTRACT FROM AUTHOR]

• Normal force oscillation in single-wheel testbeds adds artifacts to timeseries data. • Normal force oscillation does not significantly affect average experimental results. • Acceleration related to vertical wheel motion cannot explain normal force variation. • Normal force oscillations are mainly caused by friction in vertical sliders. • A 4-bar mechanism essentially removes normal force oscillation. This work reviews wheel load application methods in single-wheel testbeds (SWTBs), used widely to study terramechanics. Normal force oscillations have been reported in SWTBs, and visible in time-series data when provided. This has usually been attributed to grousers, but is also visible for wheels without grousers suggesting other system dynamics (e.g. friction in the vertical axis) are the cause. Furthermore, accelerations related to periodic vertical displacements of the wheel (whether caused by grousers or otherwise) cannot explain more than a small fraction of the amplitude of normal force variations. In this work, a 4-bar mechanism was developed that balances the normal load and ensures that a constant (not oscillating) normal force is achieved throughout terramechanics experiments. System behaviour with and without the 4-bar mechanism was assessed, highlighting the need for a 4-bar mechanism or other method of balancing normal loads if a constant normal force is desired. No significant effects on average experimental results were observed due to normal force oscillation, but artifacts were observed in the time-series data. Comparisons of results with a system where wheel load is applied pneumatically and characterization of friction in each testbed provide further support to the conclusion that normal force oscillations are mainly caused by friction in the vertical axis. [ABSTRACT FROM AUTHOR]

The Poynting effect generically manifests itself as the extension of the material in the direction perpendicular to an applied shear deformation (torsion) and is a material parameter hard to design. Unlike isotropic solids, in designed structures, peculiar couplings between shear and normal deformations can be achieved and exploited for practical applications. Here, a metamaterial is engineered that can be programmed to contract or extend under torsion and undergo nonlinear twist under compression. First, it is shown that the system exhibits a novel type of inverted Poynting effect, where axial compression induces a nonlinear torsion. Then the Poynting modulus of the structure is programmed from initial negative values to zero and positive values via a pre‐compression applied prior to torsion. The work opens avenues for programming nonlinear elastic moduli of materials and tuning the couplings between shear and normal responses by rational design. Obtaining inverted and programmable Poynting effects in metamaterials inspires diverse applications from designing machine materials, soft robots, and actuators to engineering biological tissues, implants, and prosthetic devices functioning under compression and torsion. [ABSTRACT FROM AUTHOR]

We report the real time characterization and measurement results of a new tri-axial capacitive sensing array. Each unit cell of the Kapton based sensor has an overlapping electrode geometry that allows for the measurement of normal and shear force magnitudes, and the estimation of the 2D and 3D angle of the shear force. The use of a patterned Ecoflex dielectric layer further improves the shear force response and the tunability of the sensor. A custom readout circuit was developed to selectively read the differential capacitances in the sensor array. The local (unit cell) and global (array) force response of the sensor was characterized using a tilt stage, allowing us to determine both the normal and the shear response at different angles in the range of 0-20N. The results show that the Unit Cell response is uniform in the linear range of 0-10N for normal forces (4.6fF/N for all four differential capacitances) and shows good sensitivity for shear forces (1.4 fF/N difference between the right and left differential capacitances at the minimum) and low cross talk. Similar results were seen when a global force was applied across the sensor array. 2D and 3D models were developed to extrapolate the shear force angle from the capacitance data. We also characterized the flexible patterned dielectric layer to understand the effect of its structural dimensions on the effective relative permittivity and developed an analytical model to easily calculate the effective relative permittivity, which showed excellent correlation with the experimentally obtained results. [2020-0382] [ABSTRACT FROM AUTHOR]

From paints to food products, solvent evaporation is ubiquitous and critically impacts product rheological properties. It affects Newtonian fluids by concentrating any nonvolatile components and viscoelastic materials, which harden up. In both of these cases, solvent evaporation leads to a change in the volume of the sample, which makes any rheological measurements particularly challenging with traditional shear geometries. Here, we show that the rheological properties of a sample experiencing "slow" evaporation can be monitored in a time-resolved fashion by using a zero normal force controlled protocol in a parallel-plate geometry. Solvent evaporation from the sample leads to a decrease of the normal force, which is compensated at all times by a decrease of the gap height between the plates. As a result, the sample maintains a constant contact area with the plates, despite the significant decrease of its volume. We validate the method under both oscillatory and continuous shear by accurately monitoring the viscosity of water–glycerol mixtures experiencing evaporation and a relative volume decrease as large as 70%. Moreover, we apply this protocol to drying suspensions. Specifically, we monitor a dispersion of charged silica nanoparticles undergoing a glass transition induced by evaporation. While the decrease in gap height provides a direct estimate of the increasing particle volume fraction, oscillatory and continuous shear measurements allow us to monitor the evolving viscoelastic properties of the suspension in real time. Overall, our study shows that a zero normal force protocol provides a simple approach to bulk and time-resolved rheological characterization for systems experiencing slow volume variations. [ABSTRACT FROM AUTHOR]

The effect of contact forces on rail uneven longitudinal wear was investigated using three series of rolling tests, including tests with the same tangential force and varying normal force, tests with the same normal force and varying tangential force, and tests with varying tangential and normal forces. Results indicated that the effect of tangential force on rail uneven longitudinal wear was greater than that of normal force. When the tangential force was the same, rail uneven longitudinal wear occurred under the small normal force condition. As the normal force increased, the wear rate decreased. With the same normal force, rail uneven longitudinal wear occurred under the large tangential force condition. The main damage of the unevenly worn rail was oxidative wear and fatigue wear. The oxidative wear and ploughing were more severe at the crest. Plastic deformation, the degree of grain refinement and fatigue cracks were more severe at the trough. More severe fatigue cracks at the trough lead to more severe wear and then the aggravation of rail uneven longitudinal wear. • The influence of normal force and tangential force on rail uneven longitudinal wear was studied. • The effect of contact forces on rail uneven longitudinal wear was quantified. • The wear and rolling contact fatigue behaviors of rail were investigated in detail. • The damage mechanism of rail uneven longitudinal wear was proposed. [ABSTRACT FROM AUTHOR]

The working temperature of a bituminous pavement can typically range from 75 ∘ C to − 20 ∘ C. Bitumen shows a wide spectrum of mechanical behaviour in this temperature range and these include those of a viscoelastic fluid, a viscoelastic solid and an elastic solid. Due to the amorphous nature of the material, the transitions between such mechanical responses are gradual. This investigation focuses on the transition between the viscoelastic solid and the viscoelastic fluid state of a wide class of bitumens with regard to unaged and short-term aged conditions. An unmodified binder and three modified binders were subjected to temperature sweep and frequency sweep in the viscoelastic regime across a wide range of temperatures. Depending on the material and the post-processing method followed, one could discern a viscoelastic fluid and a viscoelastic solid regime and a frequency-dependent mixture regime consisting of a viscoelastic solid and a viscoelastic fluid, across the tested temperatures and frequencies. It is shown in this investigation that parameters such as G ′ –G ′′ crossover and frequency independence of tan δ cannot be used to estimate the temperatures corresponding to the onset of either fluid-like or solid-like behaviour of the body as the temperature varies. It is also shown that the time–temperature superposition principle does not hold good in the temperature regime tested (75–25 ∘ C) due to the viscoelastic transitions exhibited by bitumen and modified bitumen. [ABSTRACT FROM AUTHOR]

By discretizing the contact area between the external retainer plate and the external spherical hinge, a mathematical model for the force relation of an arbitrary contact point in the external return spherical bearing pair was established and a mathematical expression for the friction power of the external return spherical bearing pair was deduced. The influences of the slant inclination of the external swash plate, pump shaft rotating speed, eccentricity, spring force and number of discrete contact points on the friction power were also analysed. The results show that the power fluctuation amplitude of the discrete contact point in the external return spherical bearing pair increases with increasing slant inclination of the external swash plate, pump shaft rotating speed and spring force; the total friction power was found to increase linearly. However, the power fluctuation amplitude of the discrete contact point in the external return spherical bearing pair was found to decrease with increasing eccentricity, with the total friction power decreasing nonlinearly until reaching a certain value. The distribution shape of the friction power of the discrete contact point is only affected by eccentricity. If the eccentricity is large, the friction power of the discrete point presents a double-peak distribution, whereas if it is small, a multiple-peak distribution is observed. [ABSTRACT FROM AUTHOR]

In order to fast calculate the thrust force and normal force of linear induction motor (LIM) for low-speed maglev train under overall conditions including traction and braking, this paper proposes an improved equivalent circuit (EC) method. Firstly, the improved equivalent circuit model is proposed based on the traditional one by adopting a precision correction factor, which can accurately consider the transverse edge effect of cap-shape secondary conducting sheet. Moreover, the permeability of back-iron and magnetic inductance are amended considering the saturation effect. The corresponding calculation procedure is given out. Then, the precise correction factor is investigated based on 2D finite element (FE) model. By comparison with the traditional Russell and Norsworthy correction factor (RNF), the precision correction factor is proved to be more suitable to LIM with wide-range slip frequency. Finally, the thrust force and normal force of LIM with different slip frequency are predicted under braking and traction conditions by improved EC method. The predicted results and the proposed method are validated by 3D FE method and experiment results. [ABSTRACT FROM AUTHOR]

Phase-shift or pole-shift method can reduce the detent force of the double-sided permanent magnet linear synchronous motor (DS-PMLSM) dramatically. However, this method causes a decrease in thrust and an increase in normal force simultaneously. To overcome this drawback, a novel slot-shift structure whose slots on the two sides of the primary component are staggered by an optimal distance is proposed in this paper. The models of the detent force including the end force and cogging force is established theoretically, and then verified by finite element analysis. The windings in the upper primary and the lower primary are arranged differently to improve the average thrust. The thrust characteristics of the DS-PMLSM under different shifted distances are analyzed and compared in detail. Furthermore, the primary component employing two kinds of core laminations is proposed to reduce both the dc component and ripple of the normal force. Finally, a DS-PMLSM prototype is tested, and the experimental results are compared with the analytical results to verify the effectiveness of the theoretical and simulation research. [ABSTRACT FROM AUTHOR]

During the last decades, the use of connectors in electrical devices for automotive has significantly increased. This raise in the number of electrical and electronic devices on board has led to a growing number of breakdowns. Indeed, this connectors need to keep a low and stable electrical contact resistance (ECR) but due to engine vibrations, fretting wear damage occur. Characterized by small oscillatory motions, fretting induces wear and oxide debris layer (third body) decaying the electrical contact resistance. The aim of this work is to study the effects of two main factors, which are the normal contact force and the displacement amplitude. In this study, a silver-plated contact (2 µm of thickness) was investigated applying various loading parameters: 2 N < P < 6 N and ±3 µm < δ* < ±20 µm. Results show that the ECR endurance decreases when the displacement amplitude increases regardless of the normal force. However, a non-monotonic evolution is found regarding normal force effect. Indeed, for a given displacement amplitude, a rise of the normal force tends to increase the contact pressure but at the same time induces a reduction of the effective sliding amplitude due a larger tangential accommodation. Hence, by coupling a friction energy density approach with a basic compliance description, the synergic effect of the normal force and the displacement amplitude is described and the ECR endurance predicted. • The influence of the normal force on the electrical endurance was clarified. • Reduction of the sliding amplitude when the normal force increases (accommodation). • Fretting maps of endurance and friction energy were developed. • The higher the friction dissipation, the lower the electrical endurance. • Prediction of the electrical endurance based on a friction density approach. [ABSTRACT FROM AUTHOR]

This paper presents an experimental method to investigate the effect of nanomagnetic particle on mechanics performance of magneto-rheological (MR) fluid, including the normal force and shear torque. Under different currents, the mechanics performance of a series of MR fluids with different quantities of nanomagnetic particles (0%, 4%, 7%, 12%, and 16% respectively) are measured by the plate-on-plate shearing test rig. The experimental results indicate that, with an increasing quality percentage of nanomagnetic particles, in a small range of currents (0-1.5 A), the mechanics performances are increasing, but their increment is no longer obvious when the current is above 1.5 A. [ABSTRACT FROM AUTHOR]

Abstract Wind tunnel experiments were performed at Re = 6.5 × 104 to measure the mean drag and normal forces, mean bending moment, and vortex shedding frequency for surface-mounted finite-height cylinders. The cylinder aspect ratio was varied in small increments between AR = 0.5 and 11, and two different boundary layer thicknesses were used, δ / D = 0.6 and 1.9. Small increments in AR and use of a single Re helped clarify some AR effects for finite cylinders. The data allowed a more precise definition of the familiar critical aspect ratio to be set, based on the behaviour of the mean aerodynamic forces and the point of action of the mean drag force. A second change in behaviour of the aerodynamic forces with AR was also identified; this transition was related to changes in the vortex formation length, the development of the near-wake recirculation zone, and the influence of the two main near-wake vortex structures, with AR. The general effects of increasing δ / D are to lower the force and moment coefficients and Strouhal number, increase the critical AR, and increase the AR where the second transition occurs. Highlights • Exploration of how C D , C N , C My , and St behave with AR and δ / D for surface-mounted finite-height cylinders. • The critical AR can be defined based on the behaviour of the aerodynamic forces and the point of action of the drag force. • A second change in the behaviour of the forces with AR may be attributed to changes in the near-wake recirculation zone. [ABSTRACT FROM AUTHOR]

Hard and brittle materials, such as optical glass, engineering ceramics, and silicon-based materials, are widely used in high-tech fields, such as optical engineering and integrated circuits, because of their good physical and chemical properties. Their low plasticity and high brittleness lead to low efficiency and poor surface quality during cutting. A model of wire saw velocity and normal cutting force in the cutting process of diamond wire saw is established, and a minimum variance self-tuning controller is designed for controlling the cutting force on-line in real-time. The experimental results show that the minimum variance self-tuning controller can be used to reduce the fluctuation of cutting force on the slice in the wire saw cutting system, and make the cutting force tend to be stable. Compared with the slice cutted under the condition of the constant parameters, the surface of work-piece finished using the minimum variance self-tuning control strategy is relatively smooth, and the surface roughness is decreased by about 30% [ABSTRACT FROM AUTHOR]

Abstract In this paper a semi-analytical solution for transverse vibrations induced by a moving oscillator is derived and validated. It is assumed that the oscillator is moving uniformly on an infinite beam, which may be subjected to a normal force, and is supported by a two-parameter visco-elastic foundation. Full evolution of deflection shapes is derived with the help of integral transforms and methods of contour integration. Analytical solution of the problem is presented in the Laplace domain. In the time domain, vibrations are given by a sum of truly steady-state part, induced harmonic part and transient vibration that has generally low importance and rapidly decreasing tendency. Except for the transient vibration, solution is expressed as a finite sum of analytical expressions (sum of residues), of which each has at most one parameter that has to be obtained numerically. With the help of iterative techniques proposed in this paper, these parameters can be easily determined with any precision. These parameters are named as the induced frequencies and as such can identify the onset of unstable behaviour. Thus, derivations in this paper allow to predict not only the onset of instability, but also its severity, which is important for mitigation measures. Transverse vibrations obtained for infinite beams are validated by analyses on long finite beams, exploiting a program written in Matlab software, that was previously validated by finite element software LS-DYNA. The effects of the normal force, Pasternak modulus, harmonic component of the vertical force and foundation damping are discussed. Highlights • New form of a semi-analytical solution for moving oscillator problem on infinite beams. • Analysis and determination and of induced frequencies. • Identification of the source of the transient part of the solution and its analysis. • Investigation of the critical frequency of the harmonic force. • Determination of the onset of instability and its severity. [ABSTRACT FROM AUTHOR]

Slot milling of unidirectional carbon fiber reinforced polymer (CFRP) laminates in four directions relative to fiber orientation is conducted to effectively study the machinability of CFRP composites with respect to process parameters and fiber orientation angle (relative to cutting speed) simultaneously and fiber orientation angle can vary from 0 to 180∘ continuously. First, slot milling experiments with a full factorial design are conducted to include all fiber orientation angles from 0 to 180∘. Then, the cutting forces with respect to fiber orientation angle and chip thickness are decoupled and results are analyzed. The results show that both fiber orientation angle and chip thickness have significant effect on cutting forces and the specific cutting forces with respect to chip thickness are governed by power law for fiber orientation angle lower than 135∘. [ABSTRACT FROM AUTHOR]

The two aims of this publication are to introduce a new and rheometer-independent rheometric tool for measuring the axial normal force in oscillatory shear rheology and to study the normal forces of polyolefin melts under large amplitude oscillatory shear (LAOS). A new plate geometry with an incorporated highly sensitive piezoelectric normal force sensor was designed for a rotational rheometer. The new geometry was used to investigate normal forces of polyethylene (PE) melts under LAOS. The resulting stress and normal force data was compared with the data from measurements in commercial high performance rotational rheometers. The stress and the normal force response were Fourier-transformed and their resulting spectra were analysed. The non-linear contributions to the FT-magnitude spectra (i.e. the intensities of the higher harmonics) were analysed using the framework of the Q-parameter, Q=I3/1/γ02 for both the stress spectrum and the normal force spectrum, resulting in the strain-dependent Qγ0 and QNFγ0, respectively. The newly designed normal force geometry had a sensitivity in the measurement starting from 5×10−5 N up to 20 N, and respectively a signal-to-noise ratio (SNR) of 1: 16.000, which is about a factor of 1.8 times better than the best performing commercial rheometers. The new geometry was used to determine Qγ0 and QNFγ0, to characterize the shear rheological behaviour of the PE melts. Even rather simple rheometers, those without normal force detection, can be extended utilizing the here presented tools for high sensitive FT-rheology analysing the normal forces. [ABSTRACT FROM AUTHOR]

This paper presents the analyses and experimental results of a single-sided linear induction motor (SLIM) thrust and normal force for the propulsion of semi-high-speed magnetic levitation (maglev) trains. These trains are composed of a levitation system that uses electromagnetic suspension and a propulsion system that uses SLIMs. The propulsion system of maglev trains using SLIMs has better low noise and dynamic characteristics compared with those using rotators. However, it has nonlinear characteristics due to the effect of slip that occur in the secondary eddy-current induction process; the normal force generated by the SLIM can negatively affect the levitation control. Therefore, a new slip-control algorithm is proposed for the safe operation of maglev trains, reflecting the normal force of the motor in propulsion control. First, the SLIM thrust and normal force are analyzed through the finite-element method (FEM) for a precise analysis of the slips. Furthermore, a slip range with a low normal force was derived based on the FEM analysis results, and these results are reflected in the propulsion control algorithm. Finally, the new algorithm was validated by an application to a full-sized testing apparatus. [ABSTRACT FROM AUTHOR]

In the static test, the deformation of wing with high-aspect-ratio will increase with loading level increment and the normal force direction of the wing will change at the same time. Taking the wing as the research object and considering the nonlinear deformation of feature, this paper proposes a kind of tracking loading technology in order to improve the accuracy of the wing's normal force under the condition of large deformation. With the deformation of the wing, the direction of the actuator's normal force is adjusted to ensure that the loading is always in the normal direction. The verification test is designed to validate the tracking loading technology in the end. The results show that the tracking loading technology can be used for the large deformation wing under normal force, which provides a new method for the wing static test. [ABSTRACT FROM AUTHOR]

For understanding the long term fretting mechanism, the effect of normal force on the fretting wear behavior of 690 TT heat transfer tube against 304 stainless steel (SS) ball in simulated secondary water with 10 6 total fretting cycles was studied. The changes of the friction coefficients can be divided into five stages: small and slowly increase stage, sharply increase to a peak point, dramatically decrease to a steady value, steady stage, and continuously increase stage. And the friction coefficient decreases with the increase of the normal force. The morphologies of the worn scars under different normal forces are quite different. A stratified layer structure is formed on the 690 TT surface during the fretting wear process when the normal force is 60N. [ABSTRACT FROM AUTHOR]

Linear flux‐switching permanent‐magnet (LFSPM) machines exhibit significant potential in many applications. A double‐sided sandwiched LFSPM (DSSLFSPM) machine with high thrust force capability is investigated in this study. After being optimised for optimal thrust force using Maxwell 2D, this machine is found to deliver higher thrust force when compared with an optimised conventional 12/14 LFSPM machine. However, low thrust force ripple is also required in many applications. Thus, in order to reduce the thrust force ripple, the DSSLFSPM machine is improved by a staggered stator teeth structure and an end permanent‐magnets method, then, two improved machines are obtained. The improved machines can reduce the thrust ripple to a very low level without thrust force density decrease. Further, the stator yoke thickness of the improved machines is optimised to reach optimal thrust force density. Finally, the performance of the DSSLFSPM‐ST machines is analysed including the normal force, the efficiency and the power factor. It shows that the improved DSSLFSPM machines exhibit relatively low normal force and high thrust force density as well as low thrust ripples, indicating that they are suitable for long‐stroke applications. [ABSTRACT FROM AUTHOR]

In this paper the new semi-analytical solution for the moving mass problem, published by the author of this paper, is extended to account for the non-homogeneous initial conditions. Derivations are presented for infinite homogeneous beams placed on a two-parameter visco-elastic foundation. Methods of integral transforms and contour integration are exploited to obtain the final closed-form solution, which is presented in form of a sum of the truly steady-state part, mass induced harmonic part, initial conditions induced harmonic part and transient vibration. Except for the transient part that is obtained by numerical integration, full evolution of the transversal vibrations can be quickly and accurately obtained by simple evaluation of the presented closed-form results. Newly derived formulas for infinite beams are validated by analysis of long finite beams, where the problem is solved by the eigenmode expansion method. Excellent agreement between the results is obtained validating the new formulas. [ABSTRACT FROM AUTHOR]

This article deals with the challenges of semi‐integral construction of long viaducts. The main characteristic of semi‐integral bridges is the monolithic connection of most parts of the substructure with the superstructure. This leads to complex load‐bearing behavior, in which several structural components interact with each other. Because of the longitudinal movement of the superstructure, constraint forces and moments occur in the piers. They induce additional stresses in the structure compared to conventionally supported bridges. An important issue during the design process is the choice of the pier cross section. The stiffness and ductility of the piers influence the constraint moments and failure behavior of the pier. This is the reason why the detailed investigation into the influencing parameters (normal‐force utilization, reinforcement ratio, and width‐to‐height ratio) described in this paper was carried out. In this investigation, the moment–curvature relationship was used and the failure behavior as well as the constraint moments in the structure were evaluated. [ABSTRACT FROM AUTHOR]

The friction between an elastomer and a rigid substrate may depend on a large number of system and loading parameters. Based on a general structure of the law of friction, we propose a generalized master curve procedure for elastomer friction where the significant governing parameter – indentation depth (or normal force) was taken into account. Unlike the generation of the classical master curve by horizontal shifting of dependence “friction - logarithm of velocity” for different temperatures, in the case of various indentation depth the shifting in both horizontal and vertical direction is required. We experimentally investigated coefficient of friction of elastomer on sliding velocity for different indentation depths and temperatures, and generated a ‘master curve’ according to this hypothesis. [ABSTRACT FROM AUTHOR]

Based on HSR-2M high-velocity reciprocating friction and wear tester, 45 steel and GCr15 steel friction pair performance test was carried out. Inside the permanent magnet magnetic field working environment, the effects of sliding velocity, normal force and other parameters on the friction coefficient and wear rate were studied. By analyzing wear scar morphology, the wear mechanism was studied and the results with and without magnetic field were contrastively analyzed. The results show that the magnetic field can reduce the friction coefficient and wear rate to some extent. With the sliding velocity increase, the friction coefficient and wear rate was reduced. With the normal force increase, the friction coefficient was reduced, but the wear rate was increased. Magnetic field can improve the friction and wear performance of 45 steel and GCr15 steel friction pairs. Without any magnetic field, the wear was typical abrasive wear, worn surface was obvious furrows, and the wear system shows greater wear rate and friction coefficient. [ABSTRACT FROM AUTHOR]

At present, researches about surface roughness mainly focus on the measurement methods and the relation between wood surface roughness and adhesion strength as well. It is well known that some sanding parameters are considerably key factors for analyzing the cause of surface roughness. However, only a few research studied the relations among surface roughness, sanding parameters, sanding pressure and wood texture direction. Back-propagation network ( BP network) system was applied to simulate and predict the surface roughness value during the sanding process. The aim of this study was to determine the effects of sanding parameters on surface roughness of pinus koraiensis and the relation between sanding pressure and surface roughness, and finally establish the model of surface roughness combined with wood texture characteristic of pinus koraiensis through neural network system. The results showed that All values of surface roughness had a “vacuum belt” when λ  = 0° and λ  = 45°, but it did not appear when λ  = 90° ( λ refers to the angle between the feeding direction and the wood grain). The confidence of the fitting surface roughness results was 97% by BP network model and the average error was 5.8%, which can simply and successfully predict surface roughness during sanding process. [ABSTRACT FROM AUTHOR]

This paper presents the theoretical modeling and numerical simulation of the probe tip based nanochannel scratching. According to the scratching depth, the probe tip is modeled as a spherical capped conical tip or a spherical capped regular three side pyramid tip to calculate the normal force needed for the nanochannel scratching. In order to further investigate the impact of scratching speed, scratching depth and scratching direction on the scratching process, the scratching simulation is implemented in LS-DYNA software, and a mesh-less method called smooth particle hydrodynamics (SPH) is used for the sample construction. Based on the theoretical and simulated analyses, the increase of the scratching speed, the scratching depth and the face angle will result in an increase in the normal force. At the same scratching depth, the normal forces of the spherical capped regular three side pyramid tip model are different in different scratching directions, which are in agreement with the theoretical calculations in the d 3 and d 4 directions. Moreover, the errors between the theoretical and simulated normal forces increase as the face angle increases. [ABSTRACT FROM AUTHOR]

In this paper a new semi-analytical solution for the moving mass problem is presented. Firstly, the problem of a mass traversing a finite beam on an elastic foundation is reviewed and some new aspects are added. Then, the new semi-analytical solution is deduced for an infinite beam. The semi-analytical solution of the displacement under the mass is derived with the help of integral transforms and the full deflection shape is obtained by linking together two semi-infinite beams. An iterative procedure is suggested for the determination of the frequency of the oscillation induced by the moving mass. Results deduced for infinite beams are confirmed by analysis of long finite beams, with the help of derivations given in the first part of this paper. Convergence analysis on finite beams is also presented, and, in addition, the effects of the normal force, of the harmonic component of the vertical force and of the foundation damping are discussed. [ABSTRACT FROM AUTHOR]

Although there are evidences that most, if not all, soil physical and mechanical processes on larger scales have their origin in processes and properties at the microscale, the range of methods to investigate micro-scaled soil behavior directly is limited. One method to detect flow and deformation behavior under steady and transient stresses is rheometry. This method is well established by means of the amplitude sweep test (AST) to detect viscoelastic properties of soils, i.e. stress-strain relationships under transient stresses that occur due to wheeling or trampling. This test is based upon a soil sample positioned between two parallel plates, where the upper plate rotates in an oscillatory manner with increasing stress or strain amplitude, and the lower plate is fixed. Depending on the retardation of the sample's shear stress reaction, viscous and elastic strain proportions are defined with the help of storage and loss modulus (G′ and G″), and their ratio (tan δ). However, the AST is strongly susceptible to sample preparation and the vertical force of the upper plate. Either a low force (e.g. 1 N) was applied or samples with forces beyond a critical limit (e.g. 12–15 N) were excluded. We used controlled force of 1, 3 and 10 N, equivalent to compressive stresses of 2.04, 6.11 and 20.37 kPa, to find the optimum settings to run the AST. The selected forces/stresses are either low, intermediate or high compared to those observed under undefined conditions in two South Brazilian soils (A and B horizon of a Typic Hapludox – Oxisol, and an Oxyaquic Hapluderts – Vertisol). Furthermore, field density and a common (high) density were applied to the homogenized soil material. The variability of the results generally decreased with increasing compressive stress level, and at highest stress variability was lower than under variable force/stress. The microaggregation of the Oxisol based upon iron oxides and hydroxides (pseudosand) and high kaolinite content in the B horizon resulted in a smaller range of recoverable elasticity than in the Vertisol. However, at large strains the elasticity was higher in the Oxisol, while the Vertisol exhibited alignment of the soil particles. The Oxisol generally showed a brittle rupture by means of a maximum shear stress; while in the Vertisol yielding occurred due to expandable clay. High compressive force and density simultaneously reduced the share of elastic deformation and promoted plastic yielding. The results do not allow yet defining an optimum compressive stress. Thus, we suggest investigating further force or stress levels and to test more soils, e.g. of high soil organic matter content and/or high or low clay, silt or sand content. [ABSTRACT FROM AUTHOR]

A newly magnetorheological fluid based honing process is developed for internal surface finishing of ferromagnetic cylindrical workpiece as existing magnetorheological fluid based finishing processes are not found suitable to finish the ferromagnetic internal surfaces. The performance of the present developed finishing process in terms of reduce wear and improve the functional application of cylindrical components, mainly depends on the normal force acting on abrasive particles due to magnetic behavior of carbonyl iron particles in magnetorheological polishing fluid. Also, it depends on shear force acting on surface by abrasive particles due to translational and rotational motion of tool as similar to the honing operation. For the newly developed finishing process, the modeling of surface roughness with the effect of induced magnetic field and magnetic normal force for different finishing cycles have been proposed. To validate the model and understand the wear mechanism during finishing, the experiments have been performed on the internal surface of cylindrical ferromagnetic workpiece with the three different sets of finishing cycles. The surface roughness of cylindrical workpiece has experimentally measured with Mitutoyo SJ-400 surftest. Also, to understand wear mechanism during finishing, the scanning electron microscopy has been performed. The theoretical calculated values of surface roughness with number of finishing cycles are validated with experimentally obtained surface roughness values for the same number of finishing cycles and conditions. Both were found in close agreement within 5.88%. Thus, the present developed finishing process is found suitable to reduce wear on internal surface of cylindrical components which leads to saving in service, energy consumption, maintenance costs, and improves its functional applications as compared to traditional finishing techniques. [ABSTRACT FROM AUTHOR]

This paper describes the development and precise positioning control of a thin and compact linear switched reluctance motor (LSRM). The LSRM that has been developed has a mover that is easy to fabricate and can be disposable. The mover can be easily separated from the stator, allowing it to be changed frequently or discarded in a hazardous application. The prototyped LSRM mover is only 0.128 mm thick with the stator measuring 2.0 mm at its thickest point. These features are highly desirable for space savings while being cost-effective. However, the LSRM has a strong nonlinear driving characteristic that presents a challenge with respect to precision control. In order to overcome this problem and achieve precision positioning, a linearizer unit was designed and integrated into the controller to compensate for the nonlinear relationships among the effective thrust force, mover position, and excitation current. The usefulness of the designed controller was examined experimentally. The experimental positioning results show that the steady-state errors were all less than 1 μm in the working range of the LSRM. In addition, the redesign for the improvement of thrust characteristic and easy fabrication of the LSRM is explained. [ABSTRACT FROM AUTHOR]

The harsh operating environments of many electronic systems, such as in the automotive and aerospace applications, make the semi-permanent connector terminal susceptible to intermittent failure or high contact resistance. Fretting, small cyclic movements at the contact interface, is exacerbated by oxidation to cause fretting corrosion, resulting in these types of failures. However, due to the fretting action, the contact does not remain in the failed state but often recovers to low contact resistance for a period before the next failure event. Improvements in reliability can be achieved by specific design considerations, either increasing the normal force of the contacts, or increasing the number of contacts per terminal or both. This paper shows the optimum design for the ratio of the total normal force ( F) of all contacts and the number of contacts ( n) per terminal, for one of the most popular contact materials used in connector technology. A model is developed, the optimum F/ n Model, incorporating failure and recovery rates based on a theoretical understanding of the contact interface and experimental investigations. This is used to select the appropriate ratio between normal force and number of contacts per terminal (force/multi-contact, F/ n) ratio for optimised reliability. A minimum in the unreliability function is found for particular values of force and contact number and recommended for optimum performance for the tin-plated system. [ABSTRACT FROM AUTHOR]

Fretting wear experiments have been performed in high temperature water with a range of normal forces to investigate the wear behavior of Alloy 690TT tube sections oscillating against stainless steel Type 304 plates. Alloy 690TT is a Ni-based alloy containing Fe, Cr, and other minor additions. Results of tests conducted in an autoclave chamber in pressurized 288 °C water, indicated that fretting wear processes mainly consisted of adhesive wear, abrasive wear, delamination, material transfer, and oxidation. As normal force increased, the initial contact area also increased, resulting in the increase of wear area as well as wear depth. Fretting wear promoted the oxidation of fresh material, and the mechanism corresponded in certain aspects to static oxidation. That is, the outermost surface layer consisted of an Fe-rich spinel, while Cr 2 O 3 existed in the inner layer after fresh materials were exposed to the testing environment. [ABSTRACT FROM AUTHOR]

Initially uncracked push-off specimens were tested to investigate shear transfer in recycled aggregate concrete with concrete grade, normal force and the replacement level of recycled aggregates being the variables. A marginal increase in normalized shear strength was noted when the natural coarse aggregates were replaced with the recycled aggregates. Normal force and concrete grade had the most significant effect on the measured strengths and predictions obtained from modified Zia failure criterion were in good agreement with the experimental results of the natural as well as the recycled aggregate concretes. Selected shear strength models in the literature have been reviewed for their predictive efficacy and in the context of design, the PCI code gave reasonably accurate and conservative predictions of the measured shear strengths of both the concrete types. [ABSTRACT FROM AUTHOR]

• A mechanical model of monocrystalline silicon modified-substrate layer structure based on two-dimensional green's function was established. • The correctness of the mechanical model is proved by the nanoindentation-scratch experiment combined with the phase transition of monocrystalline silicon. • Using this mechanical model to draw the stress component contour diagram and interface stress distribution diagram of monocrystalline silicon modified-substrate layer structure, the internal stress state of the material when the surface is stressed is obtained. It provides a reference for the formulation of process parameters of chemical mechanical micro-grinding process. The application and demand of monocrystalline silicon components are becoming more and more urgent for many advanced applications like solar cells. Chemical-mechanical micro-grinding is one of the effective methods for processing such components. However, the theory of chemical-mechanical micro-grinding of monocrystalline silicon has not been fully established, and the mechanism of material removal is still unclear. In this paper, the monocrystalline surface is modified by catalytic modification, resulting in a modified-substrate layer region. A model is proposed to study and analyze force conditions based on Green's function for modified-substrate layer region under the action of normal force and tangential force. The nanoindentation, XPS, and Raman spectroscopy have been done to verify the theoretical model and explore the phase change process of monocrystalline silicon. The results showed that the established mechanical model can predict the stress distribution at the interface between the surface modification layer of the monocrystalline silicon material and the substrate layer. Furthermore, the internal stress distribution of the surface of the monocrystalline silicon material that has undergone surface chemical modification under load can be obtained. Therefore, the recent paper provides a theoretical basis for the optimization of the process of chemical-mechanical micro-grinding of monocrystalline silicon. [Display omitted] [ABSTRACT FROM AUTHOR]

• Exploration of the mean pressure distribution on the free end of a finite-height square prism. • Systematic changes are made in aspect ratio (AR) and incidence angle (α), and results are shown for two different boundary layer thickness (δ / D). • The locations of the conical delta-wing vortices, as well as the value of the mean normal force coefficient due to pressure, are sensitive to AR, α , and δ / D. In this experimental study, the mean pressure distribution was measured on the free end of a surface-mounted finite-height square prism for different aspect ratios, incidence angles, and boundary layer thicknesses. The Reynolds number based on the width of the prism was kept constant at Re = 6.5 × 104, the aspect ratio of the prism was changed from AR = 1 to 11, and the incidence angle was varied in small increments from α = 0° to 45°. The thickness of the boundary layer on the ground plane relative to the prism width was either δ / D = 0.8 or δ / D = 2.6, representing a thin or thick boundary layer. When the prism was oriented at α = 0°, distinct mean pressure distributions were observed for prisms nearly or completely immersed in the boundary layer, and also for the very slender high-aspect ratio prisms. The mean normal force coefficient steadily increased with the aspect ratio but its value decreased in the presence of the thicker boundary layer. When the prism was oriented at α = 45°, strong pressure gradients were encountered near the leading edges for prisms nearly or completely immersed in the boundary layer, and the conical vortex angles increased with aspect ratio. For intermediate aspect ratios, these pressure gradients weakened and the vortex angles became insensitive to AR. When the incidence angle was between 0° and 45°, the asymmetric mean pressure distribution meant that the conical vortices were located at different angles. The position of the conical vortex located more centrally above the free end was more sensitive to changes in aspect ratio. The influence of the boundary layer on the vortex angles was more pronounced for smaller aspect ratios. In addition, the behaviour of the normal force coefficient with incidence became more complex for higher aspect ratios. [ABSTRACT FROM AUTHOR]

This paper studies the tribocorrosion behaviour of Ti-6Al-4 V in phosphate buffered saline under reciprocating frequencies of 1, 5, 10, 15, 20, and 25 Hz at different normal forces of 3.5, 6, 10.8, and 17.5 N using a customised ball-on-disk test set-up. The tribocorroded scars were then post-assessed by scanning electron microscopy and energy dispersive x-ray spectroscopy, atomic force microscopy, profilometry, and confocal microscopy. The results demonstrated a unique pattern for the total volume loss versus frequency such that the loss was maximum at 5 Hz with a subsequent reduction from 5 to 15 Hz, and a final stabilisation beyond 15 Hz. Compared to the total and chemical losses, mechanical volume loss showed more significant variations with frequency. The results indicated complex interactions between the normal force and frequency in relation to the total material loss from the alloy. These findings challenge the general understanding of an increase in the total loss with increasing frequency. • Tribocorrosion of Ti-6Al-4 V was studied under various normal forces and frequencies. • Variations in total material loss with frequency with a maximum occurring at 5 Hz. • Mechanical part of total material loss was more sensitive to changes in frequency. • Complex interactions between normal force and frequency determined the total loss. [ABSTRACT FROM AUTHOR]

In this paper, complex Poynting theorem is used to calculate the power transmitted from primary to other areas of single-sided linear induction motor. By the help of Poynting theorem and boundary conditions, the longitudinal end effect is completely included into the analysis. Having comprehensive information about power flow and using the coenergy method, it is possible to calculate traction and normal forces due to each existing wave. So, it is shown that each of the traction and normal forces consists of five components. Then, the effect of some important design parameters on the calculated components of forces is analyzed. Results by the proposed model have been compared with those evaluated by finite-element method and with experimental measurements. [ABSTRACT FROM PUBLISHER]