最新刊期
期 6 ， 2018
- 摘要：According to working features of plough system,three sections of visco-elastic dynamic model were established based on wave theory. The boundary conditions,joining conditions and initial condition of wave equation under stable running were determined. Dynamic model of plough system including three partial differential equations were solved with separation variables method. The dynamic displacement, velocity, and tension of plough system under stable running were obtained. The tension change of plow systems at different locations were analyzed. The results show that the tension change of plow systems at different locations increase with cutting depth,and the cutting speed has little influence on tension. Compared with the experimental results,the distribution law of characteristics is uniform, and deviation meets accuracy requirements,Feasibility and correctness of the suggested method is verified.关键词：Plough;Semi-analytical solution;Continuous model;Separation of variables
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发布时间：2022-09-22 - 摘要：Accurate prediction of the remaining useful life（RUL） of the roller with double toothed roll crusher is an important basis for maintenance personnel to make scientific maintenance decision. In engineering practice, some state information is often observed. In order to solve the problem of the remaining useful life of the roller sleeve is difficult to predict accurately in the non-linear and non-stationary state, a new method of remaining useful life prediction based on wavelet transform and SVR fusion is proposed. Firstly, the correlation analysis is used to select the characteristic value of the vibration signal of the roller. Secondly, wavelet technology is used to eliminate the noise of the collected vibration signals. Then, the relationship between the residual life and the characteristic value is established, and the nonlinear dynamic change of the roll sleeve is described. Finally through the SVR model to predict the remaining useful life of the crusher roller. Prediction results show that the method can effectively solve the remaining useful life prediction of partially observable state, thereby reducing the maintenance cost, and has strong engineering applicability and popularization value.关键词：Partially observable state;Correlation analysis;Wavelet analysis;RUL Prediction;Support vector regression
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发布时间：2022-09-22 - 摘要：According to shearer vibration problems in the practical work,using multi-body dynamics theory,considering the connection characteristics between walking unit of shearer and scraper conveyor,the support characteristics of adjustment height oil vat,the stiffness of rocker arm of shearer,the connection characteristics between the parts of shearer,vibration angle of shearer,6 degrees of freedom dynamic model in the vertical direction of shearer was established.The vertical direction of shearer drum load was used as an external excitation,and the effect of different haulage speed on vertical direction vibration characteristics of shearer were solved by using numerical analysis method.The results show that the haulage speed has great influence on vibration displacement of front and rear cutting unit when the range is 2 m/min～5 m/min,the displacement range of front and rear drum is 12.3325 mm～38.9104 mm、7.5240 mm～23.7396 mm,and the displacement range of front and rear rocker arm is 4.8826 mm～15.4052 mm、3.0548 mm～9.6384 mm.Finally,the results of model is verified by experiment.关键词：Shearer;Haulage speed;Vibration;Numerical analysis;Experimental study
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发布时间：2022-09-22 - 摘要：If the fault is found in planetary gear of cutting unit in the shearer, the shearer will not be successful mining. In this paper, first, a variety of failure signal of reducer is collected and the parameters of support vector machine are optimized using PSO and the optimal classifier is obtained. second the collected various signals are processed using classifier of Support Vector Machines. The results show that this method can diagnose the various fault of reducer quickly and accurately. The proposed method is contribute to achieve fault diagnosis of planetary gear real-time and automatically.
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发布时间：2022-09-22 - 摘要：Aiming at the fault diagnosis problem of rolling bearing, a fault diagnosis method of rolling bearing based on variational modal decomposition（VMD）, improved fruit fly optimize algorithm（LFOA） and relevance vector machine（RVM） was proposed. Firstly, the bearing vibration signals was decomposed into several intrinsic mode components（IMF） and root mean square value and frequency of the center of gravity was calculated as fault feature vectors that could represent the operating conditions of bearings. In order to improve the classification accuracy, the LFOA was used to optimize the parameter of RVM and a LFOA-RVM model was built. And then, the fault feature were extracted for training and testing, so that it might recognize different fault type and different fault degree. The actual signals were analyzed and diagnosed, and compared with some other methods, it proves the validity of the method.关键词：Variational modal decomposition;Improved fruit fly optimization algorithm;Relevance vector machine;Fault diagnosis;Bearing
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发布时间：2022-09-22 - 摘要：Aiming at the key steps of hydraulic pump fault diagnosis such as feature extraction and pattern recognition, a fault diagnosis method of hydraulic pump based on symmetrized dot pattern（SDP） image feature and adaptive nearest neighbor classifier（ANNC） is introduced in this paper. Firstly, the time waveform was transformed to snowflake image in polar coordinate space by symmetrized dot pattern（SDP） method. And then, image shape feature which used as fault feature was extracted on the basis of analyzing the characteristic of the image. Finally, the ANNC was employed to classify and evaluate the fault feature. The experiment results of hydraulic pump fault diagnosis shown that the image shape feature can represent the fault states, and the ANNC increased the classification accuracy and validated the effectiveness of the proposed method.关键词：SDP;Image feature;ANNC;Hydraulic pump;Fault diagnosis
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发布时间：2022-09-22 - 摘要：The manufacturing requirements and research status of plastic forming pipe fittings in the industrial field are analyzed. The working principle of single point incremental forming metal bellows is introduced. In order to obtain the influence of process parameters on the forming process and forming quality, the finite element model of U-shaped metal bellows of single point incremental forming was established by the finite element analysis software ABAQUS/Explicit. The experimental platform was built and the experimental research was carried out. The T3 red copper was selected as material, through the experiments under different processing parameters, the corrugated forming height is used as the forming quality testing index, and the effect of the interlayer space, spindle speed and axial feed speed on the processing results in the process of single point incremental machining is obtained. The results show that the spindle speed has the greatest impact on the corrugated height of the metal bellows, followed by the interlayer space, and the axial feed speed has no significant influence on the forming quality. The single point incremental forming of metal bellows is of good quality and high precision when the spindle speed is 450 r/min and the interlayer space is 0.25 mm axial feed speed of 0.2 mm/r. The reliability of the optimization results is verified by simulation and experimental results. It provides a reference for the further application of the process.关键词：Single point incremental forming;U-shaped metal bellows;Wave height;Experimental study
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发布时间：2022-09-22 - 摘要：In order to analyze the fatigue fracture surface characteristics of composite insulator core rod, the fatigue damage process of insulators under different amplitude/torsion angle conditions was simulated by dynamic load fatigue test. The surface morphology of insulator fracture was observed by using an super deep scene 3 D microscope, and combined with fatigue loads and the number of stress cycles, the formation mechanism of the fracture surface was analyzed. The fractal geometry theory was used to describe the complexity of the fracture morphology in quantitatively and discussed the relationship between the fractal dimension and the fatigue loads. The results show that the fatigue fracture process of core rod is actually a stress corrosion process, which means that under the action of stress, the crack of the fiber gradually deepens until it breaks. The deformation and abrasion caused by the cyclic stress all determined the fracture surface morphology. The fractal dimension of the fracture surface is between 2 and 3, and the linear regression correlation coefficient is above 0.99, the strong correlation shows that the fracture surface of the insulator has obvious fractal characteristics. The formation of the fracture surface is not only related to the deformation, but also related to the number of stress cycles. The fractal dimension of the fracture surface is positively correlated with the loads and negatively correlated with the number of load cycles.关键词：Composite insulator;Fracture surface morphology;Fractal dimension;Stress cycle
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发布时间：2022-09-22 - 摘要：At present, the high lock bolt assembly standard of our country are come from abroad, lack of relevant theoretical and experimental research. Fatigue gain mechanism of high lock bolt interference on the base of different layer thickness is researched,through the method of combining the fatigue test and finite element simulation in a certain type of aircraft aluminum alloy structure. First, the fatigue test was designed and tested, and the results were analyzed by S-N curve, detail fatigue rating（DFR） and fracture location. Then, the finite element modeling and simulation are used to explain the experimental phenomena, and the mechanism of the interference fit to the fatigue gain is studied. Finally, the comprehensive detail fatigue rating results and the finite element simulation results are obtained, which are the standard recommended values of the high lock bolt assembly,and verified existing installation specifications, ensure the assembly quality of a certain type of aircraft.关键词：Interference fit;Hi-lock bolt;Fatigue strength;Finite element method;Detail fatigue rating
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发布时间：2022-09-22 - 摘要：Pore is one of the most common internal defects for a carbon fiber composite material, the size and distribution of the pore have a significant impact on the mechanical properties of carbon fiber composite material. Based on the extrusion molding of carbon fiber unidirectional reinforced composites as the test object, by using the ultrasonic attenuation and nonlinear ultrasonic testing methods for the comparing three different porosity of samples, extract the characteristics of the ultrasonic testing parameters, implementation of carbon fiber composite materials characterization of porosity size.关键词：Non-destructive testing;Nonlinear ultrasonic test;Carbon fiber reinforced plastic;Porosity;Attenuation coefficient
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发布时间：2022-09-22 - 摘要：The static pull-in instability of the electrostatically actuated cantilever micro-beams incorporating Casimir force was investigated based on the modified couple stress theory. The nonlinear governing equation and boundary conditions were derived using the principle of minimum total potential energy. The pull-in voltages and non-dimensional pull-in displacements of the electrostatically actuated cantilever micro-beams were calculated by applying the generalized differential quadrature method（GDQM）. The results show that the pull-in voltages of the electrostatically actuated cantilever micro-beams based on the modified couple stress theory are greater than the classical results and the size effects are obvious. The presence of the Casimir force can reduce the pull-in voltages and non-dimensional pull-in displacements of the cantilever micro-beams and the influence of the Casimir force can be neglected when the initial gap of the cantilever micro-beams g is far greater than the thickness of the beam h.关键词：The modified couple stress theory;Size effect;Pull-in effect;Casimir force;Generalized differential quadrature method
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发布时间：2022-09-22 - 摘要：In order to suppress gray-scale elements in Hybrid Cellular Automation method, distance factor and a new updating technique for state variables are proposed, combining the uncertainty of engineering structure, the optimization model of structural topology is established based on reliability. First, the modified random variables could be obtained through the reliability analysis, the reliability constraints are translated into deterministic constraints, and then the modified random variables are used for deterministic structural topology optimization. The optimization results under different updating techniques are contrasted. Results show that the proposed updating technique for state variables can effectively reduce the amount of gray-scale elements and reduce the strain energy of the structure.关键词：Hybrid cellular automation;Reliability based topology optimization;State variable;Distance factor
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发布时间：2022-09-22 - 摘要：In order to improve the dynamic reliability of the roadheader,the roadheader’s rigid-flexible coupled model was established based on virtual prototyp,dynamic reliability analysis was done on the rotary table of different structural parameters,evaluation function was established based on mechanical optimization design theory,the function’s design variables was half cone angle,helix Angle and cutting line spacing, the function’s objective function was the minimization of maximum equivalent stress as the objective function.The cutting head’s optimal structural parameters was obtained by genetic algorithm.Based on the cutting productivity and rotary table equivalent stress, the optimal yawing speed was obtained by optimized multi-objective.The results shows that after two optimizations,rotary table maximum stress is decreased 18.495 MPa,the fatigue life is improved from 3.067 E4 to 3.326 E6,productivity is improved 18.6 t/h,prediction error is less than 1.3%,meet the design requirement.This method provides data support for the structure and kinematic parameters of cutting head,provides a new method for the optimization design of heavy complicated mechanical equipment.关键词：Roadheader;Cutting head;Rotary table;Genetic algorithm;Optimization design
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发布时间：2022-09-22 - 摘要：The main purpose of the optimization design of Dump truck cab‘s ROPS system is to reduce the weight on the premise that cab’s strength, stiffness and dynamic performance are not significant changed; The cab is made up of many components and each component has different influence on the cab’s performance, so the design belongs to the multi-parameter and multi-objective optimization problems. Significant degree analysis method based on Orthogonal Experimental Design was raised. This method evaluated the significant degree of each parameter through calculating the design parameter’s variance to response. On the basis of these data, the design parameters which had more important influence were chosen as optimization variables, an approximate model between design variables and response was built by using TPS-HDMR, then get the optimized solutions by using NSGA-II genetic algorithm, The optimized results was verified. The experimental results agreed well with the simulation results, which can meet the requirements of the enterprise.
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发布时间：2022-09-22 - 摘要：To improve the problem that the conventional design results of planetary gear transmission could not guarantee all of objectives were the optimal, aiming at the shortcomings that adaptive particle swarm optimization algorithm easily produced infeasible solution and fell into local optimum, an adaptive particle swarm optimization algorithm based on multi-level penalty function with dynamic change penalty coefficient was proposed. The algorithm set the penalty function as a multi-level penalty function and the penalty coefficient could be adjusted with the iterative process. The reliability and others were taken as the constraint conditions, the volume, the contact ratio and the transmission efficiency as the objective functions. Combined with the ideal point method to construct the evaluation function for multi-objective optimization. The results show that the volume is decreased by 41.87%, the contact ratio is increased by 2.643%, and the transmission efficiency is increased by 0.1563%. The improved particle swarm optimization improves the defects of original algorithm, and each objective is reasonably optimized.关键词：Improved particle swarm algorithm;Planetary gear transmission;Multi-level penalty function;Reliability;Multi-objective optimization
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发布时间：2022-09-22 - 摘要：In virtue of Detail Fatigue Rating method（DFR）, an optimization design method of aircraft plate-web beam structure against fatigue buckling is proposed based on genetic algorithm. After finite element analysis and experimental verification, an optimized model of structure life on fatigue buckling is built by engineering method, and the structure design solution in the condition of minimum mass is achieved with maximum fatigue life. The theoretical results illustrated that the life can excessively increase than that of the original beam. This technology will provide the design strategy of reducing aircraft mass and cost production for general aircraft structure.关键词：Fatigue buckling;Critical buckling load;Genetic algorithm;Detail fatigue rating value
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发布时间：2022-09-22 - 摘要：The maximum likelihood method is used to estimate the unknown shape parameter in Lomax distribution under interval data, the expression of the shape parameter can not be obtained.The iterative formula of shape parameter can be obtained by using EM algorithm, it is easy to get the estimated value and the estimation has good convergence. Random simulation results show that EM algorithm has high accuracy, and the final estimation is independent of initial value.关键词：Lomax distribution;Interval data;EM algorithm;Parameter estimation
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发布时间：2022-09-22 - 摘要：In order to reduce sample points and make full use of information resources of sample points, an improvement of the response surface method for structural reliability analysis was developed, that structural reliability index was regarded as convergence condition. The method used mixed response surface method during iterations, at the first iteration a linear response surface function was used, at the following iteration a quadratic polynomial response surface without mixed terms was used. Then the sample points near the failure boundary from all sample points were selected after convergence, the limit state function was built by a quadratic polynomial response surface with mixed terms and square terms, and finally the structural reliability was calculated by the Monte Carlo method. Numerical examples show that the response function is able to approximate the real failure curve, and effectively improves the reliability calculation accuracy, using mixed response surface method during iterations sample points are reduced, in other words computing time in engineering are decreased.关键词：Structural reliability;Sample points reused;Mixed response function;Weighted response function;Monte Carlo
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发布时间：2022-09-22 - 摘要：In order to calculate the fatigue reliability of tower crane under random dynamic loads, this paper consider the distribution of the input parameters affect the tower crane reliability, such as distribution of maneuver load parameters, using stochastic finite element method to calculate stress-time history of tower crane fatigue check points, using rain flow counting method to get the load spectrum of the check points, the residual strength is calculated based on Miner linear fatigue cumulative damage theory. Considering the complexity of the structure of tower crane, it is unable to get the explicit expression of the reliability function. Based on stress-strength interference theory, this paper uses stochastic finite element method to calculate the tower crane reliability, and. the influence of overload on reliability is analyzed quantitatively. The results show that with the use of tower crane, its reliability decreased gradually and due to the cumulative fatigue damage there is a sharp decline of the reliability after a certain period of time, and overload has a great effect to the tower crane reliability. Due to the distribution of all input parameters influence the reliability of the tower crane were considered, and all possible conditions in the work of the tower crane were simulated, the results are more consistent with the actual than existing methods, which can provide reference for the evaluation of fatigue reliability of tower crane.关键词：Tower crane;Distributed parameter;Stress spectrum;Fatigue reliability;Stochastic finite element method
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发布时间：2022-09-22 - 摘要：Reliability and fuzzy theory was applied to analyze the contact fatigue reliability of cylindrical helical gear. Furthermore, the calculation method has been improved. The reliability for contact fatigue of cylindrical helical gear after working a period of time was obtained used Matlab as a tool for numerical simulation and it has been compared with the results based on general approaches. The result shows that the improved method is more comprehensive consideration than general methods. Moreover, it provides a reference for reliability calculation of the gear.关键词：Reliability;Random;Fuzzy;Cylindrical helical gear;Improve
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发布时间：2022-09-22 - 摘要：Based on the application of the honeycomb in the square guide rail,analyzed the tandem honeycomb deformation stability by experiments. Found tandem honeycomb is prone to instability in the impact process for the effect of uneven strength of simple honeycomb and impact load deflection. Analysis shows that the plate, with low intensity or its sectional dimension is smaller than guide rail section, is difficult to prevent honeycomb instability. To improve the effect of connection on keep tandem honeycomb deformation stability, studied the relationship among plate sectional dimension, guide rail sectional dimension and plate deflection degree from the theoretical level: when the guide rail sectional dimension unchanged, the longer the length of connection plate is, the smaller the deflection angle of plate is, the smaller the friction between plate and guide rail is, the better the guiding function of connection plate is. Based on the conclusion, designed a new guiding plate, it is not only improves tandem honeycomb deformation stability, but also solves the honeycomb peeling.关键词：Tandem honeycomb;Connection plate;Deformation stability;Guiding function;Anti-destabilization
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发布时间：2022-09-22 - 摘要：On the basis of mechanism structure and the flash temperature theory, the instantaneous contact temperature-rise principle of constantly no clearance precision steel ball equal-speed transmission is studied and the formulas of the spin speed on each contact point, maximum contact stress, and frictional power are derived. Meantime, the mathematical model of instantaneous contact temperature risen of engagement pairs is established. By the use of MATLAB programming, the change curves of maximum contact stress of engagement pairs in one motion cycle are drawn, the rated loads with different design parameters are calculated, and the instantaneous contact temperature-rise of engagement pairs in one motion cycle are drawn. Besides, the effects on instantaneous contact temperature-rise caused by design parameters like groove angle and eccentricity are analyzed. It is shown that the maximum value of the instantaneous contact temperature-rise appears when the steel ball position angle is π and the inner side bears the pressure. The research findings lay a theoretical foundation for the scuffing load capacity calculation of the contact engagement pairs and thermo-mechanical analysis of constantly no clearance precision steel ball transmission.关键词：No clearance precision steel ball transmission;Equal-speed mechanism;Maximum flash Temperature;Rated load;Spin angular velocity
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发布时间：2022-09-22 - 摘要：Circlip is an important fastener, its service performance at high speed directly affects the reliability of mechanical equipment. By analyzing the centrifugal force distribution of unequal diameter circlips, simulating and testing the initial contact between circlip and shaft, the results show that the maximum centrifugal force occurs in the thickest position of the circlip, the contact state can be simplified to be three point contact, then proposing the detaching point assumption and the radial failure criterion. By using German Seeger circlip models, simulating the circlip radial displacement in high speed,according to the German circlip standard DIN471, the results show that the relative error between circlip limit speed and the DIN471 standard is less than 8% based on the detaching point assumption, which verifies the validity of the radial failure criterion. This paper has reference significance for the development of the new national circlip standard GB/T 894-2017.关键词：Circlip;Radial failure;DIN471;Limit speed
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发布时间：2022-09-22 - 摘要：In order to analyze the stability of the thin-walled milling system, a continuous beam model of spindle tool workpiece system is established, from which, the equivalent mass and stiffness are obtained from the end of cutter and workpiece, respectively. The influences of workpiece sizes on milling stability of the system are researched consequently. The results show that the cross sectional width and height of thin walled workpiece has non-negligible influences on the milling stability. Among them, the height has greater impact, for a small height value pulls down the critical cutting depth severely. With the increase of the cross sectional height of workpiece, critical milling depth improves obviously. It is also noted that as the first natural frequency of the workpiece is close to or even greater than that of the spindle-cutter system, the workpiece’ shape has not significant influence on the milling stability. These above results can provide a theoretical basis for the stability machining for thin-walled parts.关键词：Critical milling depth;Continuous beam model;Spindle cutter system;Workpiece;Stability
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发布时间：2022-09-22 - 摘要：A semi-analytical solution theory is presented by combining the separable Hamilton canonical equation and finite element method. The problem of free-edge effect of orthotropic laminates is studied in symplectic system. First, the separable Hamilton canonical equations are established with modified Hellinger-Reissner variational principle. And the state equations are established with finite element method. Then, an example analysis of the distribution of interlaminar stresses in composite laminates is calculated. The numerical results show the efficiency of the proposed method.关键词：Free-edge effect;Hamilton canonical equation;State equations;Interlaminar stresses
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发布时间：2022-09-22 - 摘要：As enormous number of tubes in large fixed tubesheet heat exchangers, it is difficult to model all the tubes and tubesheet connections in detail for FEA. Therefore, it fails to yield an accurate stress field around the connecting region of tubes and tubesheet, which is essential for the effective stress intensity evaluation. Taking a large fixed tubesheet heat exchanger as example, the maximum stress intensity location is found for the tube layout region of the tubesheet according to the coarse model. Then the sub model is utilized in the predetermined maximum stress location. In the sub model, detailed connecting structure of the tube and the tubesheet are included, such as the weld metal and contact condition between the tube and tubesheet hole. Both stress classification and limit load analysis are preformed for the sub model structure. Although both the weld and the tube fail the evaluation based on stress classification, it is more reasonable to evaluate the connecting region with the direct route based on limit load analysis for the structure with non axisymmetric stress distribution. Limit analysis is carried out and limit load is determined by zero-curvature method. It is shown that the structure meets the strength requirement based on the relevant standards.关键词：Sub model;Fixed tubesheet heat exchanger;Finite element analysis;Limit load
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发布时间：2022-09-22 - 摘要：High-speed cold forming is a complex forming process coupling under multi factors, which has the rolling friction affecting the fluidity of the workpiece metal, and then affecting the quality and performance of the forming parts. In order to understand the variation of temperature field caused by thermal effect, then choose reasonable cold rolling forming parameters to improve product forming quality, the influence of rolling friction is analyzed on the basis of cold rolling forming spline principle. The finite element simulation model is established, which can obtain the variation law of temperature field produced by rolling friction and its influence on forming stress, strain, metal flow and rolling force. It can be the provide reference for cold roll-beating forming precision control.关键词：High speed cold roll beating;Rolling sliding friction;Thermo mechanical coupling;Thermal softening
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发布时间：2022-09-22 - 摘要：Taking the non-road turbocharged inter-cooled diesel engine for research objects, by means of coupled fluid-solid analysis method, established the coupled heat transfer model of Cylinder head-Cooling fluid-Cylinder liner-Cylinder block,did a temperature test of flame face of cylinder head and key points of cylinder liner, studied the deformation of cylinder liner under the mechanical loads、thermal loads and coupled loads. The result show that temperature distribution of cylinder liner is not uniform, the highest temperature located in the top of the first cylinder liner; The deformation is relatively small under mechanical loads and the maximum value appeared in the thrust side of the top of the forth cylinder liner; The deformation is heart-shaped under coupled loads, the maximum value appeared in the top of the forth cylinder liner and close to the direction of flywheel, the thermal loads are predominant.关键词：Turbocharged;Diesel engine;Cylinder liner deformation;Coupled fluid-solid
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发布时间：2022-09-22 - 摘要：The fatigue property data of 2 D plain-woven T300 carbon-fiber/SiC matrix composite material, which was published in literatures since 1990, was collected and categorized. The fitting of the total life S-N curve was conducted on the collected data. According to the shape parameter a of the S-N curve, T300 C/SiC material is classified into 3 categories. It is shown in the curve fitted results that the shape parameter a in the total life S-N curve represents the toughness of the material, in which case the larger parameter a is, the tougher the material is. Meanwhile the dimension parameter b represents the fatigue crack propagation rate, in which case the smaller parameter b is, the more sensitive to stress the fatigue damage is. On the basis of the fitted data, it is concluded that the endurance limit of 2 D plain-woven T300 carbon-fiber/SiC matrix composite material is approximately 70% of its strength.关键词：Plain woven;C/SiC composite material;S-N Curve;Endurance limit
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发布时间：2022-09-22 - 摘要：In order to reveal the damage mechanism in the working process of the traveling mechanism of shearer,establishing dynamic contact model of walking mechanism in LS-DYNA. By using the experimentally measured traction resistance and gravity of shearer as external load,transient dynamic simulation was executed.The rain flow count、load extrapolation and superposition of dangerous nodes maximum equivalent stress time history were conducted by using Rain-flow module in the n-code GlypWorks. Fatigue life of walking wheel and pin rows were calculated by using Stress Life module of n-code GlypWorks. The results show that: walking mechanism of shearer have good mechanical properties. Minimum fatigue life of walking wheel is 307 days, and minimum fatigue life of pin row is 323 days.The results provide theoretical basis for structure optimization of traveling mechanism.关键词：Shearer;Walking mechanism;Mesh stress;Fatigue life
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发布时间：2022-09-22 - 摘要：In the viewpoint of probability theory, An large-size structural part is a system consisting of many "elements", i.e. high stress zones, since all the high stress zones have their related individual probabilities to cause the structural part failure. Such a part should be taken as a serial system if any high stress zone failure means to part failure. As a random variable, the fatigue life of a complex structural part with many high stress zones does not equal to the fatigue life of any one high stress zone of the part. A probabilistic fatigue life prediction model for large-size structural part is developed by means of system reliability analysis principle, the concept of extreme statistics of the lives of all the high stress zones, as well as the Tailor expansion of Weibull reliability function. By this model, the fatigue life of a large-size structural part can be predicted according to the material’s P-S-N curve of the part, and the effect of the dependent failures of the high stress zones can be intrinsically reflected.关键词：Large size structural part;Fatigue;Reliable life;Common cause failure;Extreme statistics
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发布时间：2022-09-22 - 摘要：Crack propagation is a typical discontinuous problem, which is difficult to be simulated with traditional finite element method. In order to solve the defects of traditional methods, extended finite element method introduced level set function method to describe crack shape so as to realize initiation and development of crack in the inner element. The problem of crack propagation simulation in traditional method replying on the life and death of element was then solved. This paper used Python langrage to develop a crack automatically propagation program package in ABAQUS platform. I mode edge crack of a finite flat and the crack propagation in three point bending beam were simulated. Compared to the exact results, this method can effectively simulate the process of crack propagation. The propagation of multiple cracks was simulated at the same time. The results showed that the method in this paper not only took advantage of ABAQUS software to simulate complex loading and boundary, but also reflected program package’s superiority on crack analysis. This method provided a convenient and effective way to solve real complex problems.关键词：Crack propagation;XFEM method;ABAQUS second-development;Python script interface;SIF
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发布时间：2022-09-22 - 摘要：The nuclear task in fracture mechanics is to determine the stress intensity factor. According to the crack mouth widening energy release rate based on the principle of virtual work and bending theory,respectively, i.e. J2 integral theory is proposed to solve the stress intensity factor expression of D-shape cross section cracked pipe under tension and bending loads. The results show application of this method not only can give closed-form solution, but also extremely simple.Comparing the proposed method with the finite element method to show the feasibility of the proposed method.关键词：Fracture mechanics;Stress intensity factor;D-shape cross section cracked pipe;Crack;Finite element method
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发布时间：2022-09-22 - 摘要：The interaction integral method（IIM） is used to calculate stress intensity factors（SIF） of finite thickness semi-elliptical surface cracks. Results are compared with that predicted by the empirical equation and equivalent domain integral（EDI） method. The comparison with EDI method verifies computational accuracy of IIM for calculating 3 D crack problem. The SIF distribution along the semi-elliptical crack of different crack shape ratio and different finite thickness ratio conditions are calculated with the IIM and empirical equation. Relative error of empirical equation is evaluated. The results show that empirical equation produces larger error when the finite thickness ratio is large. Based on the analysis, the applicable range of the empirical equation is presented.关键词：Semi-elliptical crack;Finite thickness;Stress intensity factors（SIF）;Interaction integral method（IIM）;Equivalent domain integral（EDI）;Empirical equation
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发布时间：2022-09-22 - 摘要：A finite element model of the dynamic fracture in a full size gas pipeline is established based on the cohesive zone model. The dynamic crack growth of X80 pipeline steel was simulated using this model and the quantitative relationship between the crack growth rate and the internal pressure predicted is in agreement with the existing semi-empirical formula. Based on this model, some key parameters which are difficult to be directly measured in pipe blasting test（such as the crack tip opening angle, the stress and strain field surrounding the crack tip, energy dissipation, etc） could be quantitatively studied especially when the crack speed is very high. Accordingly, the proposed model would be a supplementary mean for the full-scale test. Moreover, the crack arrest design of the full-scale pipeline is also discussed based on this model.关键词：Finite element model;X80 pipeline steel;Dynamic fracture;Crack arrest design
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发布时间：2022-09-22 - 摘要：Utilizing the finite element method, the mechanical behaviors of the silicon rubber foam frictional contact with the rigid surfaces under the quasi-static condition was studied in the present work. Based on the multi-scale method, the micro-scale model-the unit cell model was set up and its stress response was investigated, considering the friction between the cell walls. The obtained results in the micro-scale model were implanted into the macro-scale model by the data transferring mechanism. The quasi-static contact of the silicon rubber foam with the rigid surfaces was simulated to analyze the load and structure deformation, considering the friction between the specimen and the rigid surfaces. The simulation data reveal that the friction affects the results quit limited both in the micro-and macro-scale models, and the present results agree with test data well.关键词：Finite element method;Silicone rubber foam;Rigid surfaces;Frictional contact;Multi-scale
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发布时间：2022-09-22 - 摘要：In order to find out the cause of the fracture of the cutting spindle as one of the key components of a cantilever roadheader, and to solve this fracture problem, this paper analyzes it in multiple ways and proposes an improved scheme. Through the analysis of fracture surface macro-morphology, material chemical composition, mechanical properties, microstructure and finite element stress of the cutting spindle, the failure conclusion is drawn and the corresponding improvement scheme is put forward. The results show that the cutting spindle in the actual complex working conditions, due to machining and heat treatment in the process of shortcomings, as well as the use of abnormal operation, resulting in the operation of the stress concentration in the greater position of fracture failure. According to the failure reasons, the corresponding improvement schemes are put forward: by optimizing the structure and improving the processing, reducing the stress concentration, improving the heat treatment process, improving its mechanical properties and other methods to improve the performance of the shaft to meet its functional requirements. The results of this study can provide a good reference value in solving the problem of failure of shaft transmission parts and improving the performance of shaft transmission parts.关键词：Cutting spindle;Stress concentration;Crack
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发布时间：2022-09-22 - 摘要：Static analysis and fatigue analysis of the tripod sliding universal joint was conducted by Solidworks and ANSYS Workbench software. The equivalent stress distribution contour plots and fatigue life nephogram of the tripod joint was obtained, though which the fatigue damage points were found. Different sizes of fillet chamfer sizes have different lifetimes, fatigue analysis of the tripod joint with different transition arc radius indicated changing effective stress concentration size could avoid its unreasonable life distribution and improve its fatigue life.关键词：The tripod sliding universal joint;Finite element;Statics;Fatigue life
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发布时间：2022-09-22 - 摘要：The existence of hydrogen in steel can lead to the decline of its mechanical properties,and result in high hydrogen pressure within void in steel. In the past, the research on the void of steel parts mostly focused on the effect of external load. The study of the mechanical properties of void under external load and internal pressure is rarely involved. Based on the hydrogen pressure theory and the gas state equation, a finite element model of void under external load and internal pressure is established. The effects of hydrogen pressure and void shape on the stress field and deformation behavior of the voids were investigated. The results show the hydrogen pressure in the void has a strong hindrance to the deformation of the void. Spherical voids are the most prone to crack initiation. The ellipsoidal void with an angle of 30 ° from the loading direction is most likely to generate cracks at the tangent point of the inner surface and the plane in the vertical load-carrying direction. The stress concentration is due to the presence of hydrogen inside void in the steel parts.And it severely reduces the strength of the parts.关键词：Steel parts;Void;High hydrogen pressure;Stress field;Deformation behavior;Strength reduction
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发布时间：2022-09-22 - 摘要：Momentum wheel、CMG etc high speed rator-equipmentsareimportantnoiseoriginswhich haveabadinfluence on in-orbit satellite stability. As space resolution raisingandexposuretimeincreasing,disturbance influence become greater to image qulity,so reducing disturbance of high speed rotor is one of key design items for high-resolution optical remote sensing satellite on GEO robit. Currently multiple effective schemes have been presented to solve the problem by researchers,astrategy is discussed and proposed to reducing disturbance resulting from static unbalance base on rotor-equipment layout. With optimization and stimulation,theresults show that the method is valid to reducing disturbance from static unbalance by using layout optimization.关键词：Satellite;High speed rotor;Static unbalance;Disturbance;Layout optimization;Stimulation
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发布时间：2022-09-22 - 摘要：·振动·噪声·监测·诊断·旋转运动导电圆板磁气弹性横向振动分析胡宇达李文强（1-01）基于能量法的超前支护-立柱动态稳定性分析谢苗赵春晓白雅静（1-08）一端简支、任意位置支撑长轴转子系统优化设计与后屈曲分析肖世富陈红永牛红攀（1-15）刮板输送机链条多边形效应振动特性研究张东升于海洋赵西贝宋振铎（1-20）基于邻域自适应LLTSA维数约简的故障诊断方法研究徐琼燕吴印华（1-27）微
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发布时间：2022-09-22
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