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It was shown in previous reports by authors that friction coefficients of the level of 0.0001 were achieved when ZrO2 (Y-PSZ: yttria partially stabilized zirconia) pins were slid against diamond-like carbon (DLC) films in H2-gas environment under heavy applied load of 63.7 N (friction fade-out, FFO). It was also shown that FFO continued long when the main H2-gas flow was mixed with a small amount of aqueous-alcohol vapor. A tribofilm was formed at the contact area of ZrO2 surface, and it was considered that the aqueous-alcohol vapor made the tribofilm strong. In the present research, the run-in process for achieving more stable FFO is investigated by varying the run-in pattern consisting of load step-up and aqueous-alcohol vapor addition, and the stable FFO continuing several hours is realized reproducibly. Then, before and after the FFO onset, the contact area on ZrO2 surface is observed by SEM, and nano-indentation hardness of tribofilm is measured. It will be shown that a substance made of hydrocarbons with low melting temperature, low electrical conductivity and low nano-indentation hardness such as hydrocarbon polymers is formed on the tribofilm, suggesting the evolution of hydrocarbon gas at the sliding surface.

Abstract The present paper is devoted to a theoretical analysis of sliding friction under the influence of oscillations perpendicular to the sliding plane. In contrast to previous works we analyze the influence of the stiffness of the tribological contact in detail and also consider the case of large oscillation amplitudes at which the contact is lost during a part of the oscillation period, so that the sample starts to “jump”. It is shown that the macroscopic coefficient of friction is a function of only two dimensionless parameters—a dimensionless sliding velocity and dimensionless oscillation amplitude. This function in turn depends on the shape of the contacting bodies. In the present paper, analysis is carried out for two shapes: a flat cylindrical punch and a parabolic shape. Here we consider “stiff systems”, where the contact stiffness is small compared with the stiffness of the system. The role of the system stiffness will be studied in more detail in a separate paper.

In the present work, we analyze a device for measuring the dynamic response of rubber in sliding contact. The principle of the device is to measure excited oscillations of a mechanical system with a sliding contact between a rubber roller and a rigid surface. Depending on the contact properties, varying oscillation amplitudes are measured. The goal is to determine dynamic response properties of rubber from oscillating tests. For this sake, an analytical model is introduced in which the contact problem and system dynamics are considered in detail. Analytical and numerical results obtained for this model are compared with some experimental data and discussed both on a qualitative and quantitative level.

This paper develops a method for calculating the contact and bending stiffness of a Curvic coupling, and investigates stiffness changes according to the coupling shape and surface roughness characteristics. The surface of the on-site Curvic coupling is chosen as reference for a most accurate simulation. The three parameters representing the surface roughness characteristics—the standard deviation of the asperity height distribution, the average radius of asperities, and the density of asperity on the nominal contact area—are calculated with a profile of the coupling surface through a random process: the contact problem between rough surfaces is tackled using the Greenwood-Williamson model, the Curvic coupling is modeled assuming that it has as many teeth as possible within the machining limits depending on the contact angle, and the tangential stiffness resulting from the contact angle is calculated by dividing into the stick and slip regions, and is taken into account in terms of total stiffness. With this, results showed that using Curvic couplings reduces stiffness than using flat disc couplings because of the contact angle, and that the standard deviation of rough surface height is the most crucial surface parameter affecting stiffness. [ABSTRACT FROM AUTHOR]

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One of the most important grinding parameters is the real depth of cut which is always lower than its programmed value. This is because in reality abrasive grains of the grinding wheel are not fixed but attached to a bonding material which is deformed during the process. In this study we investigate the effect of the contact stiffness between a single abrasive grain and the workpiece on the depth of cut and the grinding process characteristics via three-dimensional Molecular Dynamics (MD) simulations. Contact stiffness has been modelled by attaching a single trapezoid abrasive grain to a spring in the normal grinding direction. MD experiments have been repeated due to the stochastic nature of the grinding process in favour of statistical accuracy. Various grinding speeds have been considered while the case of a rough abrasive-workpiece interface has been investigated as well using fractal models. Our results indicate that the trajectory followed by the abrasive grain is not a straight line, as in the case of a rigid abrasive, but a curved one, asymptotically converging towards the equilibrium point which corresponds to the selected value of the spring stiffness. This behaviour alongside the grinding velocity and rough abrasive-workpiece interface have been found to affect the grinding forces, friction coefficient, morphology of the ground surface and subsurface temperature. The present MD model has also been proven to be capable of capturing the thermal softening phenomenon at the abrasive-workpiece interface. Unlabelled Image • Workpiece subsurface temperature increases with grinding speed and grain stiffness. • Grinding forces increase with the grain stiffness due to the higher depth of cut. • Quality of the ground surface depends on the grain stiffness and grinding speed. • The workpiece exhibits viscoplastic behaviour/thermal softening. • Interfacial fractal roughness affects grinding forces and subsurface temperature. [ABSTRACT FROM AUTHOR]

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper presents a method for testing the dynamic parameters of the contact system. The method is based on the single-degree-of-freedom forced non-resonance method, the vibration test system is used for harmonic excitation, the acceleration sensor is used to collect the excitation signal and the response signal, and the correlation analysis method is used to process the signal, so that the equivalent contact stiffness of the two objects can be obtained, as well a s the equivalent contact damping coefficient. In order to illustrate the application of this method in the analysis of actual mechanical system dynamics, two application cases are given. They are to test dynamic parameters of the 0-ring rubber flexible support system and the "spindle-package-roller" system. This method provides a new way for experimental testing of complex rigid-flexible coupling contact systems. [ABSTRACT FROM AUTHOR]

This paper investigates the effects of fretting wear on frictional contacts. A high frequency friction rig is used to measure the evolution of hysteresis loops, friction coefficient and tangential contact stiffness over time. This evolution of the contact parameters is linked to significant changes in natural frequencies and damping of the rig. Hysteresis loops are replicated by using a Bouc-Wen modified formulation, which includes wear to simulate the evolution of contact parameters and to model the evolving dynamic behaviour of the rig. A comparison of the measured and predicted dynamic behaviour demonstrates the feasibility of the proposed approach and highlights the need to consider wear to accurately capture the dynamic response of a system with frictional joints over its lifetime. • The impact of wear on the dynamics of structures has been experimentally quantified. • Wear leads to shifts in natural frequency and damping of structure vibration modes. • Wear needs to be included in models to capture the dynamics of jointed structures. • A Bouc-Wen formulation is presented to account for wear in dynamic simulations. [ABSTRACT FROM AUTHOR]

• The paper proposed a simple method to calibrate the LFM system by determining the PSPD signal dependency on the lateral tip displacement, which is analogous to the constant-compliance region in normal force calibration. • To suppress the error owing to low contact stiffness, an amorphous surface (silica or glass) ensuring sufficiently high contact stiffness between the Si AFM tip and sample is used. • The lateral tip displacement during the stick-slip on stiff, amorphous surfaces is determined by using the feedback loop control of AFM system. We calibrate the lateral mode AFM (LFM) by determining the position-sensitive photodetector (PSPD) signal dependency on the lateral tip displacement, which is analogous to the constant-compliance region in normal-force calibration. By stick-slip on stiff, amorphous surfaces (silica or glass), the lateral tip displacement is determined accurately using the feedback loop control of AFM system. The sufficiently high contact stiffness between the Si AFM tip and stiff, amorphous surfaces substantially reduces the error of PSPD signal dependency on the lateral tip displacement. No damage or modification of the AFM probe is involved and only a clean silicon or glass wafer is needed. [ABSTRACT FROM AUTHOR]

Taking an HSR15 A rolling linear guide as a research object, its elastic deformation under the conditions of pre-loading and thermal deformation is analyzed on the basis of Hertz contact theory. The geometric relationship of the deformation of the rolling linear guide’s joint surfaces is established, and the theoretical model for the influence of thermal deformation of joint surfaces on contact stiffness is derived. The temperature distribution of the rolling linear guide under different vertical loads and the influence of thermal deformation on the guides’ s stiffness are analyzed by using the finite element software. The results showthat with the increase of vertical load, the stiffness of the upper raceway increases gradually, while the stiffness of the lower raceway decreases and the equivalent stiffness decreases also; the stiffness of the rolling linear guide can be reduced by thermal deformation, and the influence of the thermal deformation on the stiffness becomes more and more significant with the increase of vertical load. [ABSTRACT FROM AUTHOR]

Abstract One key relationship in the depth-sensing indentation technique is the proportionality between the contact stiffness and the contact size, as can be proved from the Sneddon's solution of axisymmetric frictionless contact. However, Sneddon's solution is only accurate when the indenter approaches a half-space (e.g., for conical indenter, the half-apex angle approaches 90º) and the interface is frictionless. As Hay et al. (J. Mater. Res., 1999) pointed out, sharp indenters lead to a radial inward displacement on the sample surface, thus leading to extra indentation force needed to push the surface back to conform with the conical indenter. In this paper, we argue that the physical origin arises from the incorrect use of reference and deformed coordinates in the boundary conditions that define Sneddon's problem. This yields two correction factors for both load and depth solutions, which are needed for sharp pyramidal indenters and frictional contact. Approximate solutions are derived which compare favorably well with the finite element simulations. We also find that the stiffness correction factor of three-sided indenter is about 11∼15% times higher than that of conical indenter, and this multiplicative factor is only a weak function of the indenter angle but does not depend on the friction coefficient and Poisson's ratio. [ABSTRACT FROM AUTHOR]

Highlights • The interface behavior of recycled concrete aggregate is examined experimentally. • A micromechanical custom-built apparatus is used in the study. • The grains show soft behavior with low Young's modulus values. • High friction angles are observed from the grain-scale shearing tests. • Surface damage is inspected through SEM images and interferometry analyses. Abstract Recycled concrete aggregate (RCA) is an excellent substitute of natural aggregates and its use in civil engineering projects has received great attention in recent years. One of the important factors that control the behavior of RCA when used as granular construction material or ballast in geotechnical and infrastructure engineering projects is the mechanical behavior at the contacts of the grains. In the present study, an experimental work is presented investigating the micromechanical behavior of RCA with a focus on the normal and shearing contact response of pairs of grains. Based on these tests, normal and tangential contact stiffness as well as the interface friction coefficient are quantified and thoroughly compared with studies presented in the literature on a broad range of geological and engineered materials. Microscopic image and white light interferometry were applied to inspect changes of grain surface characteristics before and after shearing, while, the basic characterization of the grains was conducted performing SEM analysis, roughness and micro-hardness measurements. The results from the study provide some basic understanding of the contact behavior of RCA interfaces and can be useful in DEM simulations of aggregate assemblies. [ABSTRACT FROM AUTHOR]

The purpose of this study is to establish a calibration approach for connecting the macro elastic properties and micro contact properties of the DEM model based on Voronoi tessellation method. Analytical solutions were formulated to predict macro elastic properties for the DEM model with regular contact sets. Based on the combination of the analytical solutions and numerical calculations, a simple calibration approach has been established to predict the elastic modulus and Poisson's ratio of the DEM model with Voronoi tessellation. The influences from contact stiffnesses, block size and the spatial distribution of contacts can be comprehensively considered. Variations of the proposed approach were studied, which is size effected, and the uncertainties related to the approach were shown graphically. [ABSTRACT FROM AUTHOR]

A transversely isotropic half space with surface effects subjected to axisymmetric loadings is investigated in terms of the Lekhnitskii formulism. Surface effects including residual surface stress and surface elasticity are introduced by using the Gurtin–Murdoch continuum model. With the aid of the Hankel transforms, solutions corresponding to several different axisymmetic loadings are derived and used to determine the influence of surface effects on contact stiffness in nanoindentations. Numerical results are provided to show the influence of surface effects and material anisotropy on the material behaviours. Meanwhile, the obtained analytical Green's functions for two special cases can be used as building blocks for further mixed boundary value problems. [ABSTRACT FROM AUTHOR]

In recent years, the method of dimensionality reduction (MDR) has started to figure as a very convenient tool for dealing with a wide class of elastic contact problems. The MDR modeling framework introduces an equivalent punch profile and a one-dimensional Winkler-type elastic foundation, called henceforth Popov's foundation. While the former mainly accounts for the geometry of contact configuration, the Popov foundation inherits the main characteristics of both the contact interface (like friction and adhesion) and the contacting elastic bodies (e.g., anisotropy, viscoelasticity or inhomogeneity). The discussion is illustrated with an example of the Kendall-type adhesive contact for an isotropic elastic half-space. [ABSTRACT FROM AUTHOR]

The 3-2-1 fixture design principle is the most used method to locate prismatic workpieces. To further increase location accuracy, the influence of friction and contact stiffness between workpiece and fixture parts should be minimized. This can be achieved by decreasing the structural stiffness of the locators in the tangential direction to the contact. Hence, based on flexure hinges, locators with two different stiffness values are investigated. To analyze the influence of locator stiffness, a special experimental setup is developed to study two locators positioned in the secondary plane of the 3-2-1 fixture. Experiments are carried out to compare the locators with flexure hinges to a rigid one. The displacement and rotation of the workpiece are investigated as a function of the clamping force. The experimental results show that the reduction in the tangential stiffness can improve the position and orientation accuracy of workpieces. [ABSTRACT FROM AUTHOR]

Highlights • A method to predict contact stiffness of spindle/tool holder interface was proposed. • The modeling method of contact stiffness took the micro morphology into consideration. • The surface contact coefficient was introduced to correct the contact stiffness. • The modeling model was useful for fast identification of contact stiffness. Abstract The contact stiffness of the spindle/tool holder is essential for the cutting stability of the spindle system because the elastic connection of the spindle/tool holder interface determines the dynamic characteristics of the spindle system. To predict the dynamic characteristics of the spindle system at the design stage, an analytical model of the contact stiffness of the spindle/tool holder interface was proposed based on the fractal theory and the multi-scale contact mechanics model to consider the combined effect of the cutting force and drawbar force on the contact stiffness. The fractal theory was used to characterize the micro-morphology of rough surfaces and the fractal parameters were identified by the power spectrum method. For the contact of two rough curved surfaces, the surface contact coefficient was introduced into the multi-scale contact mechanics model to correct the contact stiffness, the actual contact area and the contact stress. To verify the validity of the method, the experiments were conducted and the results showed that the modeling error of the contact stiffness was reduced from 25.13% to 4.72% by the proposed method. Finally, the effect of such factors as the cutting force, the mean roughness, the material properties, the preload and the temperature variation on the contact stiffness was discussed. The contact stiffness of spindle/tool holder interface increased with the cutting force and the drawbar force and that the contact stiffness decreased with the mean roughness. Moreover, the shear contact stiffness increased with the equivalent elastic modulus, the interference fit and the temperature. The conclusion was drawn that the model can be used to predict the contact stiffness of the spindle/tool holder interface at the design stage. [ABSTRACT FROM AUTHOR]

Highlights • A discrete dynamic model is proposed to evaluate the bending vibration of FSSBs. • The FSSB tension is determined indirectly by the measured natural frequency of the exposed section. • A frequency correction equation is proposed to correct tension test errors. • The tests show that the proposed test method is feasible and practical. • A rapid non-destructive testing is developed to determine the FSSB tension after tensioning. Abstract This paper presents a new non-destructive dynamic tensile test for fine-rolled screw-threaded steel bars (FSSBs) in prestressed concrete box-girder bridges. In this study, the anchorage nut and anchor plate are connected by a coupling spring, so are the steel bar and nut threads. A discrete dynamic model of a spring–mass system was therefore established to evaluate the bending vibration of the anchorage system. The tensile force in prestressing FSSBs can be determined indirectly using the measured natural frequency of the exposed section. Based on the force transmission characteristics of threads, a frequency correction equation is proposed to correct the test error in the tensile force. The laboratory model and field tests of multiple bridges show that the proposed test method for tensile force is feasible and practical. The proposed tension test method is rapid, non-destructive, and can be used repeatedly. It has no impact on the construction and offers potential wide applications. The study results are significant in terms of the testing and analysis of the induced tensions in mechanical components and similar structures of civil engineering. [ABSTRACT FROM AUTHOR]

Highlights • A boundary element method was developed to examine the frictionless, adhesive contact between a rigid spherical indenter and an elastic quarter-space. • The adhesive coupling was modeled as a Maugis interaction with continuous transition between the DMT and JKR adhesive limits. • The model provides solutions for the load dependencies of the indentation depth and contact stiffness for various values of the adhesion parameter and position from the edge of the quarter-space. • The developed methodology can be used for contact mechanics analysis on a sample with edge geometries to correctly separate the material and geometrical contributions to the measured indentation response of the sample. Abstract In this work, the effect of the edge compliance on the adhesive, frictionless contacts near the edge of a quarter-space is analyzed in terms of stress, deformation, and contact stiffness. The study relies on the numerical implementation of the conjugate gradient method (CGM) to adhesive contacts near the edge of a quarter-space. It extends the previous CGM developed for contact analysis of non-adhesive and adhesive contacts on half-space to the matrix formulation of the quarter-space problem. The considered adhesive contact interaction is in terms of the Maugis–Dugdale model to provide insight into the transitional behavior from non-adhesive to various type of contact adhesive regimes. It is found that the edge compliance affects the contact mechanics of adhesive contacts as a function of position, applied force, and adhesive parameter. The analysis provides calculations for quantities like depth indentation and contact stiffness that can be found directly in indentation-type experiments performed on samples with edge geometries. Such understanding and characterization of edge contacts can be used to unambiguously account for the mechanical response of nanoscale structures near their edges and detect possible mechanical variability introduced by fabrication and processing. Graphical abstract Image, graphical abstract [ABSTRACT FROM AUTHOR]

The present paper is devoted to a theoretical analysis of sliding friction under the influence of in-plane oscillations perpendicular to the sliding direction. Contrary to previous studies of this mode of active control of friction, we consider the influence of the stiffness of the tribological contact in detail and show that the contact stiffness plays a central role for small oscillation amplitudes. In the present paper we consider the case of a displacement-controlled system, where the contact stiffness is small compared to the stiffness of the measuring system. It is shown that in this case the macroscopic coefficient of friction is a function of two dimensionless parameters—a dimensionless sliding velocity and dimensionless oscillation amplitude. In the limit of very large oscillation amplitudes, known solutions previously reported in the literature are reproduced. The region of small amplitudes is described for the first time in this paper. [ABSTRACT FROM AUTHOR]

Highlights • A rough surface contact model which is suitable for ultrasonic-assisted surfaces is proposed. • The correlation between the parameters of grinding and the contact performance is obtained. • The interference motion of abrasive particles is good for contact performance of surface. Abstract The contact performance of ultrasonic-assisted grinding surface is studied in this paper. An improved simplified model of rough surface profile is proposed to find the microscopic feature parameters, such as the curvature radius of the asperity, which are suitable for contact analysis and calculation. Then a more accurate rough surface contact analysis model is obtained by combining the classical ZMC contact model. Based on the contact analysis model, the contact mechanism of ultrasonic-assisted grinding surface is studied. The contact stiffness and local maximum contact pressure of the surfaces under different cutting depths and ultrasonic amplitudes are calculated, and the correlation rule between the parameters of ultrasonic-assisted grinding and the contact performance of the machined surface is obtained: (1) With the increase of the cutting depth, the surface roughness of the workpiece increases; under the same load, the contact stiffness decreases and the maximum local contact pressure increases. (2) With the increase of the ultrasonic amplitude, the surface roughness of the workpiece first decreases and then increases. Under the same load, the contact stiffness increases first and then decreases, while the maximum local contact pressure resents an opposite variation trend. Under the experimental conditions, the surface contact performance of the workpiece is the best when the ultrasonic amplitude is 4 μm. Additionally, the contact performance of the ultrasonic-assisted grinding surface and the conventional grinding surface is compared: (1) When the ultrasonic amplitude is 4 μm, the surface roughness of the workpiece is at least 24% lower than that of the conventional grinding surface. (2) Under the same load, the surface contact stiffness of the ultrasonic-assisted grinding surface is increased by at least 68%, and the maximum local contact pressure is reduced by at least 17%. It is found that the interference motion of abrasive particles in the ultrasonic-assisted grinding process makes the surface height distribution more concentrated and the density of asperity increased, which results in a better contact performance compared with the conventional grinding surface. [ABSTRACT FROM AUTHOR]

Highlights • Determination of silicon nanomechanical properties by instrumented nanoindentation • Top-down fabrication of silicon pillar structures by nanoimprint lithography • Precise control of inductively coupled plasma cryogenic reactive ion etching • Qualitative and quantitative analysis of indentation modulus and hardness on monocrystalline silicon with different crystal orientation • Comparison of elastic-plastic response of bulk and micro-structured silicon materials Abstract Nanomechanical properties of bulk and micro-pillared monocrystalline silicon are experimentally investigated using nanoscale depth-sensing indentation technique. Silicon pillar arrays with different crystal orientations, i.e., Si<100>, Si<110>, and Si<111>, are prepared by means of a top-down approach consisting of nanoimprint lithography and cryogenic dry etching. A three-sided Berkovich tip used during the experiments has provided highly resolved load-depth-curves and imprinted hardness impressions on the silicon materials. Depending on the aspect ratio of the pillars, the axial stiffness of the objects under measurement has to be considered. Corrected values of the elastic modulus are determined revealing direct nanomechanical comparison between silicon bulk and pillar structures. In summary, enhanced comprehension of elastic-plastic-response occurred within micro-structured silicon materials is shown, providing the potential to use silicon pillar arrays as fundamental material for accurate force measurements. [ABSTRACT FROM AUTHOR]

Accurately predicting the nonlinear dynamic response of aero-engine components is critical, as excessive vibration amplitudes can considerably reduce the operational lifespan. This paper compares experimental and numerical nonlinear dynamic responses of an industrial aero-engine, specifically focusing on the first stage turbine bladed disk with under-platform dampers (UPDs). The friction forces between UPDs and blades result in a strongly nonlinear dynamic response, influenced by stick, slip and separation contact states at the interfaces. These contact states, and the resulting global dynamic responses, are predicted with an advanced industrial modelling approach for nonlinear dynamics. The predictions are compared, updated and validated against measurement data from an operational engine test. Results highlight the importance to validate models against industrial data and show that realistic contact pressure distributions are required for increased prediction reliability. The novelty of this work includes (1) the use of unique industrial experimental data from a fully operational aero-engine, (2) the observation, at the end of engine testing, of real contact conditions in blade/UPD interfaces, (3) detailed modelling of these contact conditions with high-fidelity finite element representations in nonlinear dynamic solvers. Based on this unique industrial validation work, guidelines are proposed to improve the state-of-the-art modelling of nonlinear dynamics in structures with friction contacts. [Display omitted] • Using Harmonic balance method to predict dynamics of turbine blades with friction. • Unique experimental benchmark from fully operational industrial aero-engine is used. • State-of-the-art approaches for nonlinear dynamics validated with industrial dataset. • Using real wear contact locations is required to accurately capture blade dynamics. • Guidelines provided to enhance existing approaches for nonlinear dynamics modelling. [ABSTRACT FROM AUTHOR]

• Contact stiffness and damping of a tenon connection structure are identified. • A test bench for studying contact characteristics of the structure is built. • Dynamic characteristics are analyzed based on the thin layer element method. • The average relative error of identifying the contact stiffness is 0.48%. • Contact damping decreases to zero when the mean contact stress increases. A tenon connection structure is widely used for the blade-disk connection in turbomachinery, and its contact stiffness and contact damping have caused nonlinear dynamic characteristics. The nonlinear dynamic characteristics of a blade-disk structure are mainly affected by its contact stiffness and damping characteristics, which are difficult to accurately predict and affected by many factors such as the operating speed and the centrifugal force caused by the rotation speed. Based on a single blade and tenon groove structure and the use of the dynamic characteristics experiments and simulations, the influence law of the contact stiffness and damping of the tenon connection structure with the change of the blade root compression force on the dynamic characteristics of the structure is obtained. The average relative error of identifying the contact stiffness is 0.48%; thus, identification of the nonlinear contact stiffness and damping of multiple pairs of contact curved surfaces is realized. [ABSTRACT FROM AUTHOR]

The present study considers finite element analysis of an elastic and elastic-plastic contact between a rigid flat and a real rough surface taking into account the asperities interaction. Numerical modeling and measurement of the normal interfacial stiffness were conducted. Surfaces with different rms roughness values were investigated in the elastic and power-law hardening models to highlight the combined effect of the topography and the strain hardening on the contact characteristics. The influence of the surface roughness on the interaction between neighboring micro-contacts, the residual stress and deformation for the power-law hardening material was analyzed. The obtained results have shown the importance of considering the strain hardening in the modeling of a rough contact especially for rougher surface.

This paper presents the effect of grinding wheel contact stiffness on the plunge grinding cycle. First, it proposes a novel model of the generalized plunge grinding system. The model is applicable to all plunge grinding operations including cylindrical, centerless, shoe-centerless, internal, and shoe-internal grinding. The analysis of the model explicitly describes transient behaviors during the ramp infeed and the spark-out in the plunge grinding cycle. Clarification is provided regarding the premise that the system stiffness is composed of machine stiffness and wheel contact stiffness, and these stiffnesses significantly affect productivity and grinding accuracy. The elastic deflection of the grinding wheel is accurately measured and formulas for representing the deflection nature under various contact loads are derived. The deflection model allows us to find the non-linear contact stiffness with respect to the normal load. The contact stiffnesses of four kinds of grinding wheels with different grades and bond materials are presented. Both cylindrical grinding and centerless grinding tests are carried out, and it is experimentally revealed that the time constant at ramp infeed and spark-out is significantly prolonged by reducing the grinding force. It is verified that a simulation of the grinding tests using the proposed model can accurately predict critical parameters like forces and machine deflection during plunge grinding operations. Finally, this paper provides a guideline for grinding cycle design in order to achieve the required productivity and grinding accuracy.