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The peak identification scheme based method (three-point definition) and the spectral moments based method (spectral moment approach) are both widely used for asperity peak modeling in tribology. To discover the differences between the two methods, a great number of rough surface profile samples with various statistical distributions are first randomly generated using FFT. Then the distribution parameters of asperity peaks are calculated for the generated samples with both methods. The obtained results are compared and verified by experiment. The variation rules of the differences between the two methods with statistical characteristics of rough surfaces are investigated. To explain for the discovered differences, the assumptions by spectral moment approach that the joint distribution of surface height, slope and curvature is normal and that the height distribution of asperities is Gaussian, are examined. The results show that it is unreasonable to assume a joint normal distribution without inspecting the correlation pattern of [z], [z′] and [z′′], and that the height distribution of asperities is not exactly Gaussian before correlation length of rough surface increases to a certain extent, 20 for instance.

Tungsten carbide tipped pointed attack picks is widely used in mechanical machinerysuch as roadheaders, continuous miners and longwall shearers. Great efforts have been made toinvestigate the interaction between point attack pick and rock. However, the research on theinvestigation of pick profile on the cutting performance is still a subject little investigated by thescientific community. In this study, the rock fragmentation process is simulated using a 2D discreteelement code, PFC2D. In the simulations, four types of pick tip geometries (mushroom insert, bulletinsert, conical insert, and cap) were employed to investigate the effect of pick profile on the cuttingperformance of point attack picks. The forces acting on the pick and crack propagation process werecontinuously monitored during the simulations. The preliminary results of cutting performance ofthe picks under different cutting scenarios were analyzed.

Purpose This paper aims to study the contact between rough cylindrical surfaces considering the elastic-plastic deformation of asperities. Design/methodology/approach The elastic deformation of the nominal surface of the curved surface is considered, the contact area is discretized by the calculus thought and then the nominal distance between two surfaces is obtained by iteration after the pressure distribution is assumed. On the basis of the Zhao, Maietta and Chang elastic-plastic model, the contact area and the contact pressure of the rough cylindrical surfaces are calculated by the integral method, and then the solution for the contact between rough cylindrical surfaces is obtained. Findings The contact characteristic parameters of smooth surface Hertz contact, elastic contact and elastic-plastic contact between rough cylindrical surfaces are calculated under different plastic indexes and loads, and the calculation results are compared and analyzed. The analysis shows that the solution considering the elastic-plastic deformation of asperities for the contact between rough cylindrical surfaces is scientific and rational. Originality/value This paper provides a new effective method for the calculation of the contact between rough cylindrical surfaces.

The ground workpiece surface is generated simulating the trajectory of all the abrasive grains and trimming these trajectories by the appropriate method. A realistic simulation requires the traject...

Solving gear meshing impact force problems by using ADAMS software is studied.A pair of tooth meshing model is established based on UG, modal neutral file is generated by using ANSYS software, calculating gear meshing impact after Importing ADAMS. The relationship between the impact velocity and the impact force by taking reasonable key parameter about penetration depth in ADAMS simulation.A new approach for studying gear meshing impact is proposed here, and the simulation results show that ADAMS software is a very useful tool for solving gear corner contact shock problems outside the normal path of action line.

A nonlinear dynamic contrastive analysis of face-gear drive with and without pinion tip relief is studied. Firstly, a 2-DOF lumped parameter dynamic model of face-gear drive, considering contact characteristics, backlash, time-varying mesh stiffness, is developed and the dynamic equations are deduced. Secondly, the mesh characteristics along the line of action are obtained by applying tooth contact analysis, and the time-varying mesh stiffness is calculated by using the FEA method. Finally, the dynamic equations are solved by using Runge-Kutta numerical integral method. By comparison of three cases of pinion tip relief on dynamic response, it is found that under the condition of pinion tip relief, the vibration amplitude is reduced.

A valid mathematic model is introduced to study the calculation of gear meshing transmission error, which is based on the manufacturing error and gear teeth deformation. Subsequently, take a pair of specific gear for example;The transmission error curves are obtained by the calculation model. The results show great consistency with the curves from Romax software, which indicates the validity and high accuracy of the mathematic model presented above. And it can be found that the shape change of transmission error curves affected mainly by the pitch error under the same conditions as the precision.

A measuring device for gear dynamic transmission error test is developed based on NI Labview software, and a new type eccentric bushing structure that can simulate a variety of installation errors is presented. The hardware and software design of the gear dynamic transmission error measuring device is given, and the gear dynamic transmission errors for low-speed and high-speed in different loads are gotten based on the device and the measured data. Experimental dynamic transmission error results show that the gear dynamic transmission error measuring device is a stable and friendly interface with easy operation and high accuracy, able to do real-time detection and data acquisition for gearing.

A lecture on the method to compute the the stress of V-tooth coupling under the actual operating conditions. the finite element analysis model of V-tooth coupling under the preload, axial load and torsion was established by used of the software ABAQUS,and the distribution of the bending stress at the root was obtained. The analytical method to compute the bending stress of V-tooth disk is deduced based on the basic principle of material mechanics, and the relative error within 10% compared with the results of finite element analysis.The paper work provide the reference for the precision design of V-tooth coupling.

The 3D geometric model was established based on working principle of a new keyway broaching machine. The horizontal deformation of drawing knife blade in working stroke is analyzed by the finite element software ABAQUS. The research which effect law of the feed, structural sizes of cutter rod and sizes of cutter guiding rod on position deformation of broaching blade in working stroke given quantitative relationship between parameters of processing craft and structure and cutting precision. The selection method and way of processing parameters and structural parameters to improve broaching precision of keyway broaching machine are obtained. The research work provides relevant technological basis for the design of high precision keyway broaching machine.

The periodic and chaotic dynamic responses of face gear transmission system considering time-varying mesh stiffness and backlash nonlinearity are studied. Firstly, a nonlinear time-varying dynamic model of face gear pair is developed and the motion equations are presented, the real accurate mesh stiffness is obtained by applying Finite element approach. Then, the dynamic equations are solved using Runge-Kutta numerical integral method and bifurcation diagrams are presented and analyzed. The stability properties of steady state responses are illustrated with Floquet multipliers and Lyapunov exponents. The results show that a process of periodic-chaotic-periodic motion exists with the dimensionless pinion rotational frequency as control parameters. The analysis can be a reference to avoid the chaotic motion and unstable periodic motion through choosing suitable rotational frequency.

Based on the Lagranges equations, a new nonlinear dynamic gear model is established by introducing two variables of relative rotation angleand mean rotation angle. The motion equations derived with Lagranges equation exhibit nonlinear terms which are absent in the equations derived on Newtons equations. Combining with the numerical simulation, the dynamic responses in time domain and frequency domain are deduced, and it can be concluded that the responses at low speed of three different models are different. However, they are similar at the designed speed without the consideration of dissipation energy. On the contrary, the dynamic responses are similar at low speed and the simplified Newtons equation differs at the designed speed including dissipation energy.

The analytical method based on “Hertz theory on normal contact of elastic solids” and the numerical method based on finite element method (FEM) calculating the contact stress of face-gear drive with spur involute pinion were introduced, and their relative errors are below 10%, except edge contact, which turns out that these two methods can compute contact stress of face-gear drive correctly and effectively. An agreement of the localized bearing contact stress is gotten for these two methods, making sure that the calculation results of FEM are reliable. The loaded meshing simulations of multi-tooth FEM model were developed, and the determination of the transmission error and the maximal load distribution factor of face-gear drive under torques were given. A formula for the maximal load distribution factor was proposed. By introducing the maximal load distribution factor in multi-tooth contact zone, a method for calculating the maximal contact stress in multi-tooth contact can be given. Compared to FEM, the results of these formulae are proved to be reliable, and the relative errors are below 10%.

The 3D model of a horizontal broaching machine is built in inventor, and the first ten natural frequencies and mode of vibration are obtained by the software of ANSYS. Dynamic response of the whole machine is also calculated in ANSYS, the weak link of the dynamic performance of the whole machine is found combined with the result of modal analyses, consequently, settings of the cutting speed and the improvement for the structure are provided.

Considering the meshing gear system as an impact-contact model, the nonlinear viscoelastic contact force model is introduced to establish the impact dynamic equations. With the application of numerical integration, the bifurcation characteristics and energy dissipation are analyzed. Numeric results show that the system has complex dynamic behaviors: ①during the excitation frequency zone[0.1,1.2], many forms of periodic collisional vibration and chaotic vibration appear alternately, ②excitation frequency being ω>ω7(ω7=1.147), there are significant differences on the value of energy dissipation between the forward bifurcation diagram and backward bifurcation diagram, which indicate that the initial state has great influence on the steady responses, ③the energy dissipation reaches its peaks at ω=0.45 and ω=0.8, corresponding to multiple collisions and large relative deformation.

A nonlinear dynamics bond graph model of gear pair is established including the time-varying stiffness, transmission error and tooth surface friction. A capacitive component C is introduced to represent the loads and tooth elastic deformation while introducing the concept of switched power junctions (SPJ) to describe time-varying gear mesh stiffness with clearance, and flow Sf represents the influences of the gear transmission error on the system dynamic equations. The tooth surface friction bond graph model involving the relationship of the relative velocity and the direction of friction are developed. According to the causal relations and the power flow, the state-space equations of the gear bond graph model are obtained. Research results show that bond graph modeling method can solve the modeling problem of the gear nonlinear dynamics.

The effect of surface friction on the dynamic response of spur gear pair is investigated in this paper. Firstly, surface friction during the mesh is described briefly, and realistic time-varying tooth stiffness and realistic static transmission error are introduced. Subsequently, the differential equation of the torsional vibration of gear transmission is developed in which the realistic time-varying stiffness and realistic static transmission error are incorporated. Finally, using the numerical simulation method, the solutions in time domain and spectrum graphs of the nonlinear system are obtained. Results show that surface friction has great influences on the dynamic responses nearby the pitch point but less influences far away the pitch point. Surface friction may also bring sudden change to the dynamic responses at pitch point when the rotational speed is low.

The effects of tooth modification on the nonlinear dynamic behaviors are studied in this paper. Firstly, the static transmission error under load combined with misalignment error and modification are deduced. These effects can be introduced directly in the meshing stiffness and static transmission error models. Then the effect of two different type of tooth modification combined with misalignment error on the dynamic responses are investigated by using numerical simulation method. The numerical results show that the misalignment error has a significant effect on the static transmission error. The tooth crowning modification is generally preferred for absorbing the misalignment error by comparing with the tip and root relief. The tip and root relief can not resolve the vibration problem induced by misalignment error but the crowning modification can reduce the vibration significantly.

Asperity radius of curvature and asperity density, which are generally obtained from rough surface simulation with fast Fourier transform (FFT), are the two essential parameters for statistical contact model. In simulation, however, the value of a parameter (defined as “autocorrelation function (ACF) truncation length” in this paper), which is arbitrarily chosen and has been paid little attention to in most relevant literature, is found to have a great effect on topography parameters, regardless of the methods chosen to calculate them. Improper determination of the ACF truncation length may induce erroneous results. This paper points out how to make the proper determination of the ACF truncation length to guarantee a certain degree of precision and explains why improper determination of the ACF truncation length may cause serious errors when calculating the topography parameters. Besides, the asperity radius of curvature and the asperity density of the generated rough surfaces are calculated using the eight-summit identification method, and their formulae in terms of correlation length are obtained through numerical fitting.

The dynamic characteristics of high-speed face geared rotor system coupled translation-rotation vibration are analyzed. Taking time-varying mesh characteristics into account, the periodic and chaotic behaviors of system are studied. Doubling bifurcation, periodic window and nonlinear jump phenomenon are observed.