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As railway transportation advances towards higher speeds and increased axle loads, the fatigue damage between wheels and rails has become more severe, significantly limiting the service life and safety of trains. Therefore, developing upgrade wheel-rail materials with enhanced contact fatigue properties has been considered an effective approach to avoid damage. This study reports a newly developed heavy-haul wheel steel with a superior rolling contact fatigue performance and the fatigue damage of wheel was studied by a novel RCF tester with a vision system. The results indicate that the newly developed heavy-haul wheel steel (NW) consists of smaller pearlite layer spacing and reduced proeutectoid ferrite. The NW steel demonstrates outstanding fatigue resistance in both oil and dry conditions, with a fatigue life 2.7 times longer than CL65 wheel steel and superior performance compared to most typical wheel steels. With increasing in pearlite content and decreasing in pearlitic interlamellar spacing, the fatigue damage degree of wheels under oil or dry contact conditions decreases obviously, leading to a significant enhancement in fatigue life. Properly controlling the pearlite content and the interlamellar spacing can optimize the fatigue properties of wheel materials. The vision system observed that the average area and perimeter of the defects gradually increased on the sample surface. The shape of the defect became more rounded under oil contact conditions but showed the opposite result in dry contact. When subjected to cyclic loading, surface cracks propagated along various paths after initiation, eventually forming different morphologies of peeling. The results will not only help optimize wheel materials for heavy-haul railways, but also offer an effective means for analyzing damage evolution in wheel-rail contact. [ABSTRACT FROM AUTHOR]

The overtopping-inundation process of a tsunami results in the collisions of drifting objects on the coast, which damage structures, thereby increasing the risk of collapse. This study conducted laboratory experiments on the collision between a drifting container caused by the overtopping-inundation process of a solitary wave and a fixed port crane's leg. The movement trajectory and velocity of the container as well as the collision velocity by solitary wave inundation, were analyzed using motion analysis software. Overall, increasing solitary wave scale, collision velocity, and drifting object weight and decreased distance between the two objects tended to increase the collision force. However, different experiment results were also obtained due to pitching in objects that fully floated without bottom friction owing to the solitary wave bore. This resulted in line-to-surface collisions. Thus, surface-to-surface contact occurred under the incomplete floating condition owing to the difficulty because of interference with the bottom; however, the collision force decreased under complete floating conditions owing to line-to-surface contact. Therefore, the contact condition according to the floating behavior must be considered a parameter while predicting the collision forces of drifting objects. Thus, surface-to-surface contact occurred under the incomplete floating condition owing to the difficulty because of interference with the bottom; however, the collision force decreased under complete floating conditions owing to line-to-surface contact. Therefore, the contact condition according to the floating behavior must be considered a parameter while predicting the collision forces of drifting objects. [ABSTRACT FROM AUTHOR]

The divergence of a thin elastic plate reinforced by stiff ribs (stringers) with cyclic symmetry is considered, with some approximations. The incoming air flow is assumed to be supersonic, and so the aerodynamic load is described by means of approximate piston theory, for a steady temperature field. In taking account of the composite structure, attention is paid to the configuration of the stiffening ribs; a contact formulation is adopted. The lower critical velocity of the incoming air flow is determined by the first approximation, and its dependence on the number of stiffening ribs is investigated. It is shown numerically that, with increase in the distance between the ribs, the critical rate of divergence approaches its value for a smooth plate. [ABSTRACT FROM AUTHOR]

We consider a frictionless contact model whose constitutive law and contact condition are described by means of subdifferential inclusions. For this model, we deliver a variational formulation based on two bipotentials. Our formulation envisages the computation of a three-field unknown consisting of the displacement vector, the stress tensor and the normal stress on the contact zone, the contact being described by a generalized Winkler condition. Subsequently, we obtain existence and uniqueness results. Some properties of the solution are also discussed, focusing on the data dependence. [ABSTRACT FROM AUTHOR]

We consider a frictionless contact model whose constitutive law and contact condition are described by means of subdifferential inclusions. For this model, we deliver a variational formulation based on two bipotentials. Our formulation envisages the computation of a three-field unknown consisting of the displacement vector, the stress tensor and the normal stress on the contact zone, the contact being described by a generalized Winkler condition. Subsequently, we obtain existence and uniqueness results. Some properties of the solution are also discussed, focusing on the data dependence.

We characterize the passage from nonlinear to linearized Griffith-fracture theories under non-interpenetration constraints. In particular, sequences of deformations satisfying a Ciarlet-Nečas condition in S B V 2 and for which a convergence of the energies is ensured, are shown to admit asymptotic representations in G S B D 2 satisfying a suitable contact condition. With an explicit counterexample, we prove that this result fails if convergence of the energies does not hold. We further prove that each limiting displacement satisfying the contact condition can be approximated by an energy-convergent sequence of deformations fulfilling a Ciarlet-Nečas condition. The proof relies on a piecewise Korn-Poincaré inequality in G S B D 2 , on a careful blow-up analysis around jump points, as well as on a refined G S B D 2 -density result guaranteeing enhanced contact conditions for the approximants. [ABSTRACT FROM AUTHOR]

Ball screws and ball bearings are important mechanical elements in automobiles and machine tools due to their high mechanical transmission efficiency. However, with the spread of electric vehicles, the designs that ensure low noise and high durability are required. Currently, numerical analysis is mainly used to clarify the inner balls motion, but it is necessary to tune simulation models based on knowledge obtained from experiments in order to reproduce the behavior of experimental systems. Moreover, while there are the quantification methods of contact states and rolling motion of steel balls inside the ball screw using mathematical methods, the contact state and the ball motion are only considered in limited circumstances. Therefore, this study aims to extend mathematical methods to clarify the contact state and rolling motion of steel balls and guide grooves inside ball screws in order to contribute to noise reduction and longevity of ball screws. Four arc shapes of a Gothic arc, considering the helix orbit of steel balls and the position and dimensional errors of the steel balls in the contact plane under non-driven and non-loaded conditions of the ball screw, are given as geometric shapes, and the balance and rolling motion of steel balls during ball screw drive are calculated. Next, numerical examples are presented to examine the effects of changes in the arc shape on the revolution and rotation of steel balls and the impact on noise, wear, and lost motion inside the ball screw. Finally, the validity of the mathematical model is demonstrated by comparing the measured values with the theoretical values using a device composed of intersecting straight grooves with a crossing angle.

A structure consisting of three identical perfectly rigid plane or spatial square frames is considered. The article proves the existence of a certain angle between the planes of the frames at which the structure can be implemented and has rigidity. [ABSTRACT FROM AUTHOR]

When a circular tube is under axial compression, it can be developed into specific forming technologies (e.g., tube inversion). However buckling failure is prone to occurring and seriously restricts the successful realization of the forming process or service performance. In this paper the conical convex or concave dies with different semi-cone angles were adopted to change tube end contact conditions and the buckling process, critical buckling force and the buckling waves of AA6061 tube under axial compression were investigated by using finite element simulation combined with experiments. The results show that the buckling deformation, the position where initial buckling wave appears, and the distribution of axial stress in tube blank are quite different when axially compressed on a flat die or a conical convex die (semi-cone angle β = 60°). For the conical convex dies as semi-cone angle increases from 75° to 87.5°, or for concave dies as semi-cone angle decreases from 110° to 92.5°, the axial compressive stress, critical buckling force and critical reduction increase, while the peak of the buckled wave decreases, i.e., occurrence of buckling delays and the buckling becomes more difficult to occur. When β is 90° (flat die), the critical buckling force and reduction reach the peak values.

Serious wheel polygonal wear usually causes drastic wheel/rail interactions, which threats the running safety of railway vehicles. This paper presents an investigation into the effect of polygonal wear of heavy-haul locomotive wheels on the dynamic performance and wheel/rail interactions through extensive on-site tests and numerical simulations, in which a special attention is paid to locomotive vibrations and dynamic wheel/rail tangential forces. The measured results conducted on two objective locomotives were firstly compared, including the characteristics of wheel polygonal wear and locomotive vibrations in vertical, longitudinal and lateral directions. A 3D heavy-haul train-track coupled dynamic model was then formulated to investigate wheel/rail dynamic interaction induced by polygonal wear of locomotive wheels. A low adhesion zone (LAZ) and a PI-based anti-slip control algorithm were embedded into the dynamic model to analyse the effects of wheel polygonal wear on wheel/rail longitudinal and lateral interactions under normal and low adhesion conditions. The results show that the severe wheel polygonal wear affects not only the vertical but also the longitudinal performance of the wheel/rail system notably. The wheel high-order polygonal wear has a conspicuous effect on longitudinal, lateral and vertical vibrations of locomotive system components. [ABSTRACT FROM AUTHOR]

Rolling ceramic thermal insulation balls have advantages of low cost, large output and easy control of particle size, so it is likely to become the main raw material for 3D printing in the future, but there is little research on its thermal insulation. In this study, we used three kinds of rolling aluminum oxide balls as raw materials to obtain single-granularity-level and multi-granularity-level bulk materials. And the effects of temperature, particle size, and thermal fatigue times on the thermal conductivity of the samples were analyzed. Additionally, the experimental results were verified by FloEFD heat conduction simulation software using finite analysis method to analyze their heat conduction characteristics. With the increase of temperature from 400 °C to 1500 °C, the thermal conductivity of single-granularity-level and multi-granularity-level bulk materials increased linearly. The thermal conductivity of single-granularity-level bulk materials have no direct relationship with the particle size, and the thermal conductivity of multi-granularity-level materials with small particle size difference was a bit lower than that of materials with large particle size difference, and a bit higher than that of materials with single-granularity-level. The simulation results showed that the main reason for the above phenomenon was that the point contact between particles played a dominating role in the heat transfer process. When the contact area increased, the thermal conductivity increased obviously, and the thermal conductivity with the increasing of temperature decreased in a quadratic curve. The improved model considering the shrinkage could improve accuracy of simulation results. Heat flux at the surface contact area was 10.19 times higher than that of the point contact and 15.10 times higher than that of the solid-gas contact at 400 °C. Therefore, reducing the surface contact area and increasing the porosity could significantly reduce the thermal conductivity of the materials. [ABSTRACT FROM AUTHOR]

Material removal in the cutting process is regarded as a friction system with multiple input and output variables. The complexity of the cutting friction system is caused by the extreme conditions existing on the tool–chip and tool–workpiece interfaces. The critical issue is significant to use knowledge of cutting friction behaviors to guide researchers and industrial manufacturing engineers in designing rational cutting processes to reduce tool wear and improve surface quality. This review focuses on the state of the art of research on friction behaviors in cutting procedures as well as future perspectives. First, the cutting friction phenomena under extreme conditions, such as high temperature, large strain/strain rates, sticking–sliding contact states, and diverse cutting conditions are analyzed. Second, the theoretical models of cutting friction behaviors and the application of simulation technology are discussed. Third, the factors that affect friction behaviors are analyzed, including material matching, cutting parameters, lubrication/cooling conditions, micro/nano surface textures, and tool coatings. Then, the consequences of the cutting friction phenomena, including tool wear patterns, tool life, chip formation, and the machined surface are analyzed. Finally, the research limitations and future work for cutting friction behaviors are discussed. This review contributes to the understanding of cutting friction behaviors and the development of high-quality cutting technology.

• The effect of stack and contact model on macro-properties is analyzed in pore scale. • Re K for flow state transition in single layer and staggered stacked mesh is found. • Neglecting inertia force cause 50 % error of permeability for Forchheimer flow. • Applicability of various thermal conduct models to local contact k eff is discussed. • Permeability predictive correlations and k eff theoretical model is proposed. Metallic woven mesh screens are representative porous media with periodic structures, which have great application prospects in emerging technology and industrial equipment. However, the effect of their pore structure on macroscopic properties is not clear, which limits their large-scale engineering application. In this paper, to investigate the influence mechanism of stacking patterns and wire contact conditions on flow and heat conduction from the pore scale, a representative elementary volume model of the square-shaped plain copper micromesh was reconstructed according to the geometric parameters obtained by the optical microscope and porosity test experiment. Furthermore, based on the understanding of microscopic mechanism, the theoretical calculation model for macroscopic characteristics was proposed. The results show that the flow characteristics in meshes are mainly affected by stacked patterns. When Re K is 0.08 and 0.28, the flow in single layer and staggered stacked woven meshes transitions from Darcy flow to Forchheimer flow. In Forchheimer flow regime, neglecting the inertia force causes a maximum 50 % error for permeability calculation. The permeability empirical correlations for Darcy and Forchheimer flow are proposed according to Kozeny-Carman and Kozeny-like model. The z -direction effective thermal conductivity of copper woven meshes is significantly affected by wire contact conditions, the maximum value is from 2.5 to 13.5 W/(m·K). The z -direction effective thermal conductivity of tangent and gap contact conditions can be described by the ZBS model, while the random model is suitable for that of overlapped contact conditions. The x -direction thermal conductivity is little affected by contact conditions, the maximum value is 50.3 W/(m·K), but the tortuosity effect of copper wires should be considered for calculation. The calculation model of anisotropic thermal conductivity for single-layer woven meshes is established according to Kirchhoff's law, which is also extended to the staggered stacked woven meshes by introducing a compactness factor. [ABSTRACT FROM AUTHOR]

In the material designing process of footwear outer-soles, the rubber grip property under lubricated conditions is important. Generally, friction behaviors of rubber under such conditions are influenced by contact states, which can be changed by various factors, i.e. viscosity, sliding velocity, normal force, surface roughness and wettability between two substrates. To discuss the influences of each parameter, the contact conditions are investigated. The purpose of this study is to establish a new method to measure the distributions of real contact area and film thickness between two substrates based on the decay behavior of an evanescent field in a total reflection method. In conclusion, film thickness was measured with an accuracy of 1 nm in a range of clearance of less than 800 nm.

With the development of powder metallurgy technology in recent years,the applications of powder metallurgy gear becoming more and more widely. But the porosity structure of material may results in larger gear tooth bending deformation of powder metallurgy gear compared with the traditional material gear. The larger gear tooth bending deformation will influence on the transmission efficiency of powder metallurgy gear and even dynamics. By using gear tooth contact conditions of traditional material gears as reference,the influence of the porosity structure of powder metallurgy material on gear contact conditions is studied. At the meantime,the contact fatigue life of surface densified powder metallurgy gear is analyzed. The reference for further research of powder metallurgical gear is provided.

Deformation of acetabular cups when press-fitted into an undersized cavity is inevitable due to the inhomogeneous stiffness of acetabular bone. Thinner cups or screw holes might increase the risk of high cup deformation. The aim of this study was to examine the influence of cup design and liner assembly on the deformation response during cup implantation. Acetabular cups with different designs were implanted into polyurethane foam models simulating the anatomical situation with nominal press-fits of 1mm and without nominal press-fits (line-to-line). Deformations were determined using a tactile coordinate measuring machine. A 3D laser scanner was used to determine the contact conditions at the cup-cavity interface. Polyethylene and ceramic liners were assembled to the implanted cups and the influence of the insertion on the deformation response evaluated. Fixation strength of the cups was determined by push-out testing. Cup deformation increased with smaller wall thickness (P < 0.037) and screw holes (P < 0.001). Insertion of ceramic liners reduced the deformation (P < 0.001), whereas polyethylene liners adapted to the deformation of the implanted cups (P > 0.999). Thin-walled cups exhibited a higher fixation strength for similar implantation forces (P = 0.011). Thin-walled cups achieved higher fixation strengths and might be more bone-preserving. However, in combination with screw holes and high press-fit levels, wall thickness should be considered carefully to avoid excessive cup deformations leading to potential complications during liner assembly. Line-to-line insertion of thin-walled cups should be accompanied with a rough surface coating to minimize the loss of fixation strength due to the low press-fit fixation. • Reduced cup wall thickness and screw holes increased cup deformation. • Thin-walled cups achieved higher fixation due to increased cup deformation. • Polyethylene liner adapted to the cup deformation after assembly. • Insertion of ceramic liner reduced the cup deformation. [ABSTRACT FROM AUTHOR]

Dynamic contact resistance measurement (DRM) is an effective technique to evaluate the contact condition in substations without dismantling circuit breakers. However, performing DRM tests with unsuitable test parameters will cause low repeatability of the test results, and even lead to the misdiagnosis of contact condition. Performing the DRM tests at high DC injected current can improve the repeatability. This paper studies the mechanism of the DC injected current on the repeatability of the DRM test results, and it also promotes a new determination method of the DC injected current amplitude. The impact of the DC injected current on DRM test results is reviewed. The mechanism of the DC injected current on DRM test results is investigated by analysing the chemical composition of the contact surface, the force exerted on the contacts, and the temperatures of a‐spots on the contacts' surface. Results indicate that not the Lorentz force, but the temperature of a‐spots is the primary influencing factor. The amplitude of the DC injected current can be determined by calculating the temperatures of the a‐spot on the contacts' surface. And this method can also be used for other SF6 circuit breakers. [ABSTRACT FROM AUTHOR]

This paper mainly focused on the establishment of the moisture diffusion models of two-component foods under different contact conditions in an impermeable package. Two-component foods were simulated by cookies (low water activity component) and agar gels (high water activity component). The different contact conditions were achieved by full contact, non-contact, and partly contact of the two components. Optimized moisture diffusion models that considered the air resistance of these contact conditions were deduced and established based on the Fick's second law and the solution of partial differential equations. Model verification was carried out by comparing the measured data and the predicted ones, results showed the models of all contact conditions had high accuracies, where the Af values were all closed to 1. [ABSTRACT FROM AUTHOR]

Abstract Background Reaming of the acetabular cavity and cup implantation directly influence the hip rotation center and contact area between implant and bone. Previous studies have reported on an altered rotation center after total hip arthroplasty, but have not studied the influence of reaming and cup implantation separately. Aim of this study was therefore to analyze the individual influence of acetabular reaming and subsequent cup implantation on the rotation center and how this influences the contact conditions at the bone-implant interface. Methods Acetabular press-fit cups were implanted into the left and right hips of three full cadavers (n = 6). CT scans were performed to calculate the change in hip rotation center after reaming and prior to liner insertion. 3D models of the cups were used to determine the polar gap, the contact conditions and the effective press-fit. Findings Reaming the acetabular cavity shifted the rotation center medially (median 5.8 mm, range 4.8–9.1), superiorly (5.3 mm, 3.0–7.0) and posteriorly (2.9 mm, 1.0–5.3). With cup implantation, the rotation center shifted back towards the native position, but no full restoration was observed. The degree of shift increased with the size of polar gap (r s = 0.829, P =.042), which inversely reduced the contact area (r s = 0.886, P =.019). Interpretation This study reveals that the dominant factor in hip rotation center restoration is the reaming process, while the cup implantation for a given nominal press-fit has only a small influence. Increasing the press-fit would improve the restoration but bares the danger of insufficient bone coverage and periprosthetic fractures due to the high forces needed. Highlights • Acetabular reaming is the dominant factor to restore the hip rotation center. • Acetabular reaming shifts the hip rotation center away from its native position. • No full restoration of the altered rotation center achieved with cup implantation. • Restoration of the hip rotation center is dependent on cup seating and press-fit. • Medialization during acetabular reaming tended to increase implant bone coverage. [ABSTRACT FROM AUTHOR]

Analytical solutions can quickly and simply evaluate stresses and displacements in tunnels and are widely adopted in the preliminary design phase of tunnels. Tunnels must be able to withstand static loading and seismic loading. This paper proposes new analytical solutions for the stresses and displacements of tunnels under static and seismic loading. The tunnel lining is treated as a thick-walled cylinder. Moreover, the contact stiffness coefficient k 0 and the stress release coefficient η 0 are introduced to consider the arbitrary contact conditions at the ground–lining interface and the amount of excavation unloading. The new analytical solutions are verified by comparison with finite element analysis results. The results demonstrate the accuracy and applicability of the proposed analytical solutions. In addition, parametric analyses are conducted to explore the effects of the stress release coefficient η 0 and stiffness coefficient k 0 at the ground–lining interface, as well as the incident angle α of shear waves. The analysis results indicate that the proposed analytical solutions offer satisfactory performance and can be applied as an effective tool for preliminary tunnel design. [ABSTRACT FROM AUTHOR]

To investigate and understand conditions of mutual contact and collision impact between a wheel-flat and a roller rig, we first did a bench test of a bogie with the wheel flat on the roller rig. In the bench test, the effect of the rotational speed of the wheel and the sprung mass on the vertical acceleration of an axlebox was observed. Based on the results of the bench test, we built a dynamic simulation model of the bogie composed of the rigid bodies. By comparing the vertical accelerations of the axlebox calculated by the model with those by the bench test, we could verify that the calculation results of the simulation model provided good agreement with the experimental ones. The model calculation made clear that the wheel rotated contacting the roller rig continuously up to the speed of 10 km/h, and at higher speed had a short period during which the wheel did not contact with the roller rig at the beginning of the flat. When there were any contactless periods, the maximum value of the vertical contact force occurred at the moment of the collision impact just after the contactless state. Particularly at 25 km/h, the impact spot was located around the area from the center to the end of the wheel-flat, and it was revealed by the result of the simulation that differences in the potential energy stored in a compressed axle spring result in differences in the collision velocity of the wheel to the roller rig in a higher speed range than 25 km/h according to the load on the bogie.

The integrity of flange joints is critical in all pipe systems. To test this integrity, an ultrasonic method characterizing the condition of the flange joint would be a vital tool. In this study, we analyzed the contact conditions on a metal/gasket/metal connection. The instantaneous frequency profile, i.e., the phase change of the wave with time for longitudinal waves transmitted in an Al alloy/gasket/Al alloy system, was evaluated under various contact pressures. The instantaneous frequency (IF) was calculated with a complex continuous wavelet transform with a modified Morlet function as a mother wavelet. The maximum IF of the waves monotonically increased with contact pressure, showing similar properties as the amplitude of the waves. A one-dimensional numerical calculation with a finite difference time domain method with a spring condition for expressing various contact conditions or contact stiffness revealed that a large phase delay of the transmission wave was generated at a low contact stiffness interface, and the amount of delay was correlated with the contact stiffness. On the other hand, the delay in the reflected wave was very small.

Abstract A passive support with a pivot mechanism was previously designed for increasing damping of the vibration modes of a flexible structure. Here, to investigate the influence of the contact conditions between the pivot support and a flexible plate, the contact area is discretised into line contacts using metal rollers. The effect of contact stiffness is also investigated using additional plastic rings. Impact hammering tests are conducted and measured dynamic compliances are compared. Machining tests are subsequently performed to confirm vibration suppression. The line contacts are found to exhibit good vibration suppression capability in both the vibration and machining tests. [ABSTRACT FROM AUTHOR]

A new analytical model for forming force prediction in the whole process of incremental sheet forming (ISF) is presented in this work. The modelling of contact region, thickness distribution and strain components are carried out as the basis for the prediction of vertical and horizontal forces. The effect of local contact behaviour and material deformation, as well as the behaviours of global bending, changes of deformation mode and contact condition are taken into account in the modelling of ISF force history. The force prediction model at both plane strain and biaxial tension condition areas is developed based on the differences in contact region and thickness distribution between these two different deformation states. Validated by ISF tests for a truncated cone and pyramid part with varying drawing angles, the prediction of force history captures well the fluctuation of different force components due to the change of deformation conditions and provides an insight into the material deformation mechanisms and the direct correlation to forming force characteristics of the whole ISF process. In a practical case, the model is successfully applied to the force prediction in ISF-based cranial plate manufacture. The model is also validated by a series of ISF tests with accurate force predictions of both the peak and stabilised forces. [Display omitted] • A new force prediction model with consideration of complicated deformation in ISF. • Forming force history of the whole ISF process. • Demonstration of a direct correlation between ISF forces and deformation states. • ISF force dependency on local contact, deformation, and global bending. • Comprehensive and accurate force prediction in ISF. [ABSTRACT FROM AUTHOR]

The stress distribution and failure process in the Brazilian test disk are numerically studied using the continuum-based discrete element method. The stress distribution in the immediate contact vicinity between disk and jaws with two types of contact conditions are compared, and the position of failure initiation is determined based on the generalised Griffith criteria. Moreover, the whole process of the Brazilian test is modelled for disks with various material properties under two contact conditions and the modelled Brazilian tensile strengths of the disks are obtained. Numerical simulations show that the distribution of stress components in the vicinity of the contact have remarkable differences between the two contact conditions, and the difference increase with the increasing of loading level and disk's elastic modulus. However, the stress distributions exhibit almost no difference on the disk's centre area. The disk's elastic modulus and the ratio of compressive strength to tensile strength are the main factors that influence the distribution of stresses in the vicinity of the contact, thereby affecting the failure initiation and tensile strength, especially under no-cushion contact conditions. The thin plastic cushion can alleviate the stress concentration in the vicinity of the contact between the disk and jaws, and cracks initiating from the vicinity of the contact can be avoided for almost all of the rock-like materials. However, the enlarging contact ranges will result in a larger deviation between the test results and the real tensile strength. An improved Brazilian test method considering two contact conditions of with and without cushions for rock and rock-like material is proposed. [ABSTRACT FROM AUTHOR]