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To clarify the unconscious response actions to a friction stimulus applied to a finger, ten participants performed a friction test using their right index finger and a specimen on which a self-assembled monolayer was striped to intentionally change the shear strength. Drastic changes were observed in both normal load and shear strength when a finger slid across the striped surface. Because the rate of change under normal load was negligible as the sliding speed increased, the response action to the friction stimulus appeared to depend on sliding speed. • A self-assembled monolayer was striped to change the shear strength. • A negative correlation between the differences in normal load and shear strength. • The shear strength remained constant as the sliding speed increased. • The change rate of the normal load approached zero as the sliding speed increased. • The response to the stimulus depended on the speed at which the finger slid. [ABSTRACT FROM AUTHOR]

The paper deals with the plane problem of normal and tangential load for microperiodic composite with slant lamination. The boundary condition was considered as a normal and tangential load given on the surface of the composite half-plane. Microperiodic composite consisted of two components, differing in their Young's modules. The homogenized model with microlocal parameters, which is presented by Woźniak (Int J Eng Sci 25:483–498, 1987. 10.1016/0020-7225(87)90102-9), Jędrysiak (Compos Struct 202:1253–1262, 2018. 10.1016/J.COMPSTRUCT.2018.05.155) was used to solve the considered problem. The problem was formulated and solved using the averaged boundary condition given by Perkowski et al. (Compos Sci Technol 67:2683–2690, 2007. 10.1016/J.COMPSCITECH.2007.02.013). The considered boundary value problem will be solved using the Fourier transform method. An analytical solution was obtained in a general form for any form of the function describing normal and tangential loads on the surface of a half-plane. An analytical solution was determined for the special cases of an elliptical, normal and tangential loads and for the special case of the concentrated force. The results are shown in the form of figures. [ABSTRACT FROM AUTHOR]

The rail transit system is a large electric vehicle system that is strongly dependent on the energy technologies of the power system. The use of new energy-saving amorphous alloy transformers can not only reduce the loss of rail transit power, but also help alleviate the power shortage situation and electromagnetic emissions. The application of the transformer in the field of rail transit is limited by the problem that amorphous alloy is prone to debris. this paper studied the stress conditions of amorphous alloy transformer cores under different working conditions and determined that the location where the core is prone to fragmentation, which is the key problem of smoothly integrating amorphous alloy distribution transformers on rail transit power supply systems. In this study, we investigate the changes in the electromagnetic field and stress of the amorphous alloy transformer core under different operating conditions. The finite element model of an amorphous alloy transformer is established and verified. The simulation results of the magnetic field and stress of the core under different working conditions are given. The no-load current and no-load loss are simulated and compared with the actual experimental data to verify practicability of amorphous alloy transformers. The biggest influence on the iron core is the overload state and the maximum value is higher than the core stress during short circuit. The core strain caused by the side-phase short circuit is larger than the middle-phase short circuit.

Amorphous carbon–containing CrAlCN coating was deposited on Cr12MoV steel by cathodic arc ion plating. The effect of amorphous carbon on the tribological performance of obtained coating under the different normal loads was investigated using a ball–on–disc tester, and the lubrication and wear mechanisms of amorphous carbon were discussed in detail. The results show that the CrAlCN coating is composed of AlN, CrN and CrC phases with the amorphous carbon. The average coefficient of friction of CrAlCN coatings under the normal loads of 2, 4 and 6 N are 0.458, 0.586, and 0.666, respectively, where the amorphous carbon plays a self–lubrication role in the friction process. The wear degree is deteriorated with the increase of normal load, and the wear mechanism is changed from abrasive wear to adhesive wear. • The amorphous carbon–containing CrAlCN coating presents the high nanohardness and elastic modulus • The CrAlCN coating improves the friction reduction and wear resistance performances. • The amorphous C in the CrAlCN coating plays the roles of friction reduction and wear resistance. • The wear mechanism of CrAlCN coating is changed with the increase of normal load. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Relationship between material removal mode and scratching direction is investigated. • A theoretical model is developed to relate machining depth with normal load. • An optimal machining direction is selected based on the quality of the grooves. Abstract The material removal state, which is closely related to machining quality, is an important factor in any machining process. During the machining using a non-rotational symmetric cutting tool, scratching direction manifests significant influence on the material removal state. In the present study, the relationship between material removal mode and scratching direction was investigated during the nanoscratching process on single crystal copper using an atomic force microscopy (AFM) tip. Considering the installation angle of the cantilever and the height of pile-up, a theoretical model was developed to relate machining depth with normal load for the machining of a single groove. Experimental results revealed that the theoretical normal load model was more suitable when materials were expelled in constant chip formation with small pile-ups. In addition, based on the scratching tests in different directions, the critical included cutting angle determined whether materials were expelled in chip formation or not. The height of pile-up was also influenced by the included cutting angle during the scratching in face-forward direction; however, during the machining in edge-forward direction, the distance between the cutting swept faces formed by the lateral and front edges determined the height of pile-up. Finally, an optimal machining direction is selected based on the quality of the machined grooves, which can be used in the potential application. [ABSTRACT FROM AUTHOR]

Composite materials are wildly applied in the engineering and a lot of them behave as orthotropic. An accurate and efficient method for the orthotropic plate will contribute to the accurate design and quality promotion of this kind of structure. In this paper, the 2D Green's function for the orthotropic plate loaded by a normal line force is derived at first. By virtue of the 2D general solution of orthotropic material, a series of new harmonic functions which contain undetermined constants are constructed. Inserting the harmonic function into the general solution, the corresponding elastic fields in the orthotropic plate are obtained. These undetermined constants can be determined by the boundary conditions and the equilibrium equations. Then, based on the superposition principle and the obtained Green's function, the solutions for the arbitrary distributed normal loads can be obtained. At last, numerical analysis is presented to discuss the accuracy and efficiency of this method and the stress distribution in an orthotropic plate loaded by the normal loads are studied. [ABSTRACT FROM AUTHOR]

Electrostatic charging resulted by sliding contacts of particles and wall is ubiquitous in gas-solid systems. However, the mechanism of sliding electrification involved the initial charge is still unclear. In the current paper, to accurately obtain triboelectric charge, the initial charge and the final charge were measured. A quantitative comparison of the experimental results and the value of theoretical model based on the condenser model is provided. And the results suggest the final charge of the grain is linear with the initial charge for a short sliding distance, whereas the experimental data become scattered for a long sliding length. The longer sliding length generation was found to generate more triboelectric charge, and the influences of the normal load on the triboelectric charge density were analyzed by considering the contact area. It provides a comprehensive perspective that the triboelectrification is fundamentally described as a synergistic effect of the sliding contact area and the real contact area. [ABSTRACT FROM AUTHOR]

The present study consists in analyzing the friction coefficient as a variable of the normal load and slip speed for 5 % Cr steel, by applying the Block-on-Disk method according to ASTM D2714. The friction coefficient increases linearly 23,25 % from 0,214 to 0,266 when the load is increased from 196 N to 392 N; the same phenomenon is observed when the friction coefficient increases 47,82 % from 0,23 to 0,34 when the slip speed increases from 0,18 m/sec to 0,54 m/sec. The friction coefficient increased by 23,25 % for an increase in the load from 196 N to 392 N, which corresponds to 100 %, while an increase of the friction coefficient of 47,82 % occurred by increasing the speed from 0,18 m/sec to 0,54 m/sec which corresponds to 200 %. [ABSTRACT FROM AUTHOR]

In this study, an in-situ Single Wheel Tester (iSWT) was used to investigate the effect of the most important independent variables on the lateral force of a high lug agricultural tire. The variables include some soil parameters and tire characteristics. Response Surface Methodology (RSM) also was used to construct a design of experiment and propose the lateral force model as a function of seven variables (various combination treatments of soil characteristics and tire parameters). A total of 152 experimental tests were conducted to find the appropriate model. Reduced form of a quadratic model was selected to predict the tire lateral force (R2>0.9). The results showed that the side slip angle and the moisture content had major and minimal effect on tire lateral force respectively. When all other variables were in their middle points, the 95% increase of the normal load would cause the 112% increment in the lateral force. Also, the difference between the lateral force when the moisture content is at minimum and maximum levels, is about 4%. Noteworthily, increasing the tire normal load, not only increases the maximum value of tire lateral force attainment, but also pushes the peak value of the lateral force to higher slip angles. [ABSTRACT FROM AUTHOR]