最新刊期
期 3 ， 2018
- 摘要：Based on the high attitude platform of building slabstone-installing robot with independent development,research was carried out about multi-DIM vibration. The paper firstly constructs the system with two degrees of freedom parallel mechanism as the main body and rotating MR damper as actuator. The dynamics equation of the vibration system is established by using Lagrange equation. The paper analyzes the vibration characteristics and designs a kind of rotary MR damper based on a shear mode of magneto rheological fluid. The mechanical characteristics of MR damper is analyzed. The kinematics and kinetic analysis of parallel mechanism is done. The multi-DIM vibration suppression works quickly based on the position of platform according to the kinematics equation. Finally the simulation experiment of this system of multi-DIM vibration suppression is introduced with the aid of to calculate and analysis whether the model is effective and feasible.关键词：High altitude operation platform;Magnetic flow;Parallel mechanism;Vibration suppression
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发布时间：2022-09-22 - 摘要：Combining a negative stiffness mechanism composed of tension spring with a linear positive stiffness spring in parallel,a novel quasi-zero stiffness vibration isolation systemwas designed which can be used to isolate low or ultra-low vibration. The static model of the system was established and the condition of quasi-zero stiffness characteristics was obtained.The fore-displacement curves of the tension-type isolator and a compression-type isolator were compared. The effect of adjustment of vertical spring in the system was analyzed. The dynamic equation was established when the system was excited by a harmonic amplitude on the displacement and the equation was solved by using Harmonic Balance method. The displacement transmissibility curves of the tension-type and the compression-type isolators were also compared. The effect of the main parameters on response of the system was explored. ADAMS model was established and the static model was proved to be correct. The vibration simulation results prove that the quasi-zero stiffness system has greater advantage than linear system in low or ultra-low vibration isolation.关键词：Tension-type quasi-zero stiffnesssystem;Low vibration isolation;Transmissibility;Adams Simulation
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发布时间：2022-09-22 - 摘要：Adaptive time frequency analysis based on local mean decomposition and nonlinear quantization ability of sample entropy,combined with radial basis function（ RBF） neural network. A method of structural damage identification based on local mean decomposition（ LMD） sample entropy and radial basis function neural network is proposed. Firstly,the original signal is decomposed into a number of product function components（ PF component） by LMD to the original signal of structure vibration.Then extract the sample entropy of the first 3 PF components to realize the feature quantization of the PF component. Finally,the sample entropy of the component is used as the damage characteristic vector. The radial basis function neural network is used to identify the bottom plate of scaled carbody for high-speed train. The experimental results show that while this method is used to identify structural damage,the damage identification errors of location and degree are 96. 97% and 96. 25% respectively. The validity and accuracy of this method in structural damage diagnosis are proved.关键词：Damage identification;Local mean decomposition;Sample entropy;Radial basis function neural network
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发布时间：2022-09-22 - 摘要：It is a new method of sound signal testing and analysis,but the SNR is too low,so we raise a feature extraction method of sound signal to rolling bearing based on blind source separation and adaptive Morlet wavelet. Firstly,the wavelet packet is used to change the single channel of the voice signal separated into two virtual channels,then using BSS to extract the source of signal. Minimum Shannon entropy is used to optimize the Morlet wavelet shape factor,in order to match with the impact component. Then,an abrupt information detection method based on the transitional stage of singular curve of wavelet coefficient matrix is used to choose the appropriate scale for the wavelet transformation. Finally,the fault feature of the signal can be extracted using this method. The experimental results shows that the method could extract sound signal fault feature more effectively.关键词：Sound signal;BSS;Wavelet transform;Shannon entropy;Fault diagnosis
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发布时间：2022-09-22 - 摘要：The rolling control of car focus usually on reducing the roll angle passively. This control has the limited performance for increasing handing stability,passing speed,ride comfort and preventing rollover when the car is turning. This project proposes a control methodology to control the automobile to roll toward the turning direction by using the active suspension. A 6-DOF vehicle model with a 2-DOF steering model and a 4-DOF roll model is established. The active roll sliding mode controller which makes the steady-state roll angle error be zero is established after the desired roll angle is established by dynamic analysis. The simulation results confirm the effectiveness of the control method. The controller makes the perceived lateral acceleration and the lateral load transfer rate be greatly reduced,which effectively improves the handling stability,ride comfort,and the vehicle speed when vehicle is turning,and makes the possibility of rollover be decreased extremely.关键词：Active roll;Active suspension;Sliding mode control;Perceived lateral acceleration;Lateral load transfer rate
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发布时间：2022-09-22 - 摘要：The oblique condition of study on mining machine drum load characteristics is the drum（ pick） squeeze coal judgment conditions,using the squeeze area and the coal and rock fracture theory,oblique roller axial additional load are obtained. Accurately understand the oblique cutting and feeding roller load changes,to avoid the proportion of the existing calculation method and power calculation method of defects and errors,for shearer initiative designed to provide theoretical basis.Using numerical simulation software MATLAB draw before and after coal mining machine oblique cutting and feeding roller force,and uses Adams multi-body dynamics simulation software response simulation of shearer beveling feeding coal mining process mobility. The vibration displacement and acceleration of each mass block are obtained under different traction speeds. It provides a theoretical basis for the stability,reliability design and dynamic analysis of the whole machine and its components,and it has a certain guiding role for the active design of the shearer.关键词：Shearer;Beveling feeding;Lateral force;Dynamic response;Roller
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发布时间：2022-09-22 - 摘要：Aiming at the problem that the influence of environmental factors and insensitive damage indicators make structural damage identification difficult,a new method of structural damage identification based on EEMD and normalized energy difference of IMF was proposed. First,a group of IMF components of original signal was obtained by EEMD. The energy of IMF components of each measured point was calculated and normalized,The difference between the normalized energy of IMF components before and after damage was obtained. The change curve of each state was constructed by using the difference as the structural damage indicator and conclude the damage location and degree through comparing before and after structural damage.Finally,a series of the experimental data from a three-story building structure and simply supported beam were analyzed to validate the viewpoints in this paper. Results indicate that the method is effective.关键词：EEMD;Energy of the IMF;Normalized difference of energy;Framework model;Damage identification
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发布时间：2022-09-22 - 摘要：This paper mainly investigated the nonlinear dynamic behavior of diaphragm coupling systems with angular misalignment. First of all, a dynamic model is built according to the characteristic of diaphragm coupling with angular misalignment,whose dynamic differential equation is deduced by the second Lagrange equation. Later,the differential equation is solved by the numerical method. And bifurcation diagram of the systems with the speed changing and the angular misalignment changing are drawn,also the diagrams of displacement response,rotor orbit and phase trajectories under different speeds. And then appropriate nonlinear dynamics are analyzed for these diagrams.关键词：Diaphragm coupling;Angular misalignment;Bifurcation;Nonlinear dynamic
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发布时间：2022-09-22 - 摘要：Aiming at the fact that the vibration signal of rolling bearing would exactly display non-stationary characteristics and fault features hard to extracted,a fault method of rolling bearing based on local characteristic-scale decomposition（ LCD）and multifractal detrended fluctuation analysis（ MF-DFA） was proposed. Firstly,the vibration signals was decomposed into several intrinsic scale components（ ISC）. Secondly,the intrinsic features hidden in each major ISC were extracted by using MFDFA,among which the generalized Hurst exponents are selected as fault feature. Thirdly,liner local tangent space alignment（ LLTSA） was applied to compress the high-dimension features into low-dimension features which insensitive to fault. Finally,the support vector machine（ SVM） was employed to diagnosis fault. Experiment results of rolling bearing show that the proposed method can classify typical fault of rolling bearing exactly and has certain superiority.关键词：Local characteristic-scale Decomposition;Multifractal detrended fluctuation analysis;Feature extraction;Rolling bearing;Fault diagnosis
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发布时间：2022-09-22 - 摘要：Aiming at the fact that the mechanical vibration signal would exactly display non-stationary characteristics,a new method named as multiscale base-scale entropy（ MBSE） is introduced for measuring the complexity of time series,while MBSE which is based on base-scale entropy（ BSE） is defined to measure the complexity and irregularity of time series in different scale factors,and contains more and deeper information of time series. The concepts of BSE and MBSE are introduced firstly in this paper,and then they are used to measure the complexity of rolling bearing fault vibration signals. Finally,a new rolling bearing fault diagnosis method based on multiscale base-scale entropy and relevance vector machine is put forward. The experiment results show that the proposed method can diagnosis different fault state of rolling bearing effectively.关键词：Multiscale;Base-scale entropy;Complexity;Fault diagnosis
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发布时间：2022-09-22 - 摘要：Whether the brittle fracture criterion of theory of critical distance is suitable for graphite plates with different shape notches was studied by means of analysis of finite element: including tensile specimens with U notches,blunted V-notch specimens of semi-circular bend,three-point bending specimens with single V-notch and compressed specimens of Brazilian disk.According to the theory of critical distance,the parameters of fracture toughness for two graphite materials were calculated by the calibrated characteristic distance and inherent strength and compared with the given values in the literature. The values of fracture loading for all notches under mode I were predicted and also compared with the experimental values. The theory of critical distance can not only predict the fracture loading and but also provide an engineering method to evaluate the fracture toughness by the fracture experiment of notched components. The theory of critical distance suitable for engineering just makes use of the numerical results,avoiding the complex analytical solutions of stress fields near the tip of notches,which is the best advantage.关键词：The theory of critical distance;Fracture toughness;Graphite;Notches
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发布时间：2022-09-22 - 摘要：In order to study the effect of coal properties on the plow planing cutter load characteristics in the process of coal plough testing by using the self-developed real-time sensor for testing on two planes load properties of coal or rock under,through the wireless acquisition module to collect the test data,get the planer load data curve and carries on the analysis and research on the fractal characteristics of the wavelet. The results show that with the increase of hardness of coal rock,planing force increases gradually,the plough vertical planer X direction,the maximum value of the curve is 35. 642 kN,in the Y direction perpendicular to coal wall,just contact the coal wall produces an instantaneous pulse,reached the minimum value of-19. 831 kN in this curve,in the Z direction along the planer operation,the maximum value is 20. 419 kN; the fractal dimension of load was about1. 5. The fractal dimension in three directions with a coal nature difference,coal load curve fluctuation with lower hardness is more obvious,to reduce the consumption of coal plow cutting coal seam in the process of energy,the smaller the shape factor is better. The results for the properties of coal and rock identification provide a new point of view,to provide data support for the design and optimization of coal plough parts.关键词：Coal and rock properties;Planer load;Wavelet analysis;Fractal characteristics
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发布时间：2022-09-22 - 摘要：In order to obtain the dynamic mechanical properties of FV520 B martensitic precipitation-hardening steel,quasistatic and dynamic compression test of cylinder samples with different temperatures（ 20 ℃,100 ℃,300 ℃,500 ℃,700 ℃respectively） and strain rates( 0. 001 s-1,1000 s-1,3000 s-1,6000 s-1 respectively) were performed by Instron hydraulic testing machine and Split Hopkinson Pressure Bar（ SHPB）. Based on the Jonson-Cook and Power-Law constitutive model,the constitutive relation of material was fitted by the experiment results. The experiment results show that the yield stress and flow stress of material increase with the decrease of temperature. As the strain and strain rates increased,the yield stress increase at a certain temperature. The strain hardening effect,strain rate hardening effect and temperature effect were analyzed in this paper.It also can obtain that Power-Law model is more suited for FV520 B than Jonson-Cook model. The Power-Law constitutive model agrees well with the experimental results.关键词：FV520B;Dynamic mechanical properties;Constitutive model;Temperature;Strain rate
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发布时间：2022-09-22 - 摘要：The experiment on vibration,acoustic noise and stress of gearbox housing in high-speed train under various work condition was determined and experimental test was carried out on test bench according to the characteristic of gearbox housing.The results revealed that amplitude of acceleration,value of air noise and stress increased with the rotating speed increased when rated load remained constant. The value of acceleration of gearbox reached the greatest when the rotating speed is 2 500 r/min or3 500 r/min. The vibration of gearbox housing was caused by engagement frequency and multiplication frequency according to the frequency domain analysis of acceleration and air noise under the rated rotating speed and load was constant,and there was sideband near to engagement frequency and multiplication frequency which frequency interval was the rotating frequency of the output shaft and input shaft. The maximum value of air noise is 89. 74 dB which occurred around the frequency of 2 400 Hz,it meets the engagement frequency of 2 391. 7 Hz. The experimental results can provide experimental data for the theoretical analysis of the gearbox housing.关键词：High-speed train;Gearbox housing;Vibration;Acoustic noise;Stress;Experiment
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发布时间：2022-09-22 - 摘要：The fatigue feature of LY12-CZ aluminum alloy under atmospheric corrosion environment is studied and the corrosion law is analyzed. Atmosphere data of the service place is collected and the accelerating environment spectrum is built through weighting analysis. The accelerating experiment of LY12-CZ aluminum alloy is carried out and the accelerating factor of spectrum is calculated by analyzing the effective theory of corrosion and declining rule of fatigue life.关键词：LY12-CZ aluminum alloy;Accelerating corrosion;Environment spectrum;Effective theory of corrosion;Declining rule of fatigue life;Accelerating factor
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发布时间：2022-09-22 - 摘要：When the thickness of aerostatic guide way gas film is in the scale of micron meters,the air flow inside is in the slip regime according to Kn. In this case,pressure distribution and bearing characteristics of the gas film will be influenced by rarefied effect. The most outstanding characteristics is shown as velocity slip and temperature jump. Based on LBM,velocity and temperature distribution in the radial direction can be achieved. Based on the study of a mathematical model and simulation analysis,with the increase of Kn,the degree of velocity slip increases. The result of velocity slip benefit cooling effectiveness,but the temperature jump is negative. This is because temperature jump acts as an additional thermal resistance between rail and air film,which is not beneficial to radiating of aerostatic guide way.关键词：Aerostatic guide way;Rarefied effect;Lattice boltzmann;Velocity slip
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发布时间：2022-09-22 - 摘要：Sleeve plate of clutch disk is studied in this paper,according to the fracture problems of sleeve plate by carbonitriding and phosphating treatment,the fractured sleeve plate was analyzed by means of fracture macroscopic analysis,fracture microscopic analysis,metallographic analysis,hardness testing and chemical composition analysis of material. The results show that the fracture of sleeve plate occurs before surface phosphating treatment,crack starts at left part of round window for sleeve plate,and it extends to run through the fracture in the process of production. In addition,due to cylindrical section is smaller and the surface area adopts hardening treatment,when the surface area is subjected to abnormal impact,it is very easy to cause the cracking of sleeve plate,especially the coarse structure leads to the increase of brittleness and it increases the probability of cracking of the parts.关键词：Sleeve plate;Fracture failure;Macroscopic analysis;Microscopic analysis
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发布时间：2022-09-22 - 摘要：The quasi-static model of angular contact ball bearing is established using no raceway control hypothesis to analyze the motion status of bearings. An improved Newton-Raphson algorithm is proposed to deal with the problems of determination of the initial value difficultly,the iterative process not easily to converge and the slow convergence rate which are arisen out while the quasi-static model solved by the traditional Newton-Raphson algorithm. Firstly,the intermediate variables are introducd to reduce the number of unknowns and the nonlinear equations are solved with step algorithm by which it’s ease to select the initial value. Secondly,the iterative correction factor optimized by bisection method is used to improve NewtonRaphson algorithm by which the convergence time is shortened. Finally,the solution process of the Jacobi matrix is simplified through the matrix transformation. The calculation results of the B7008 C bearing shows that the proposed algorithm is superior to the traditional algorithm and can effectively decrease the difficulty to solve the quasi-static model of the angular contact ball bearing with higher convergence.关键词：Angular contact ball bearing;Quasi-statics;Numerical solution;Iterative correction factor;Matrix transformation
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发布时间：2022-09-22 - 摘要：Increase the loading capacity of coal is an important part in the development of thin seam shearer. Optimization method based on the combination of genetic algorithm（ GA） and BP neural network was proposed for the problems that traditional method can`t solve about the multi Factor impact shearer coal capacity. Established mathematical model of thin seam shearer,we use genetic algorithm to optimize the weighted values and threshold values of the BP neural network,using the simulation data for training and testing samples,and then use the BP algorithm to train the neural network,thus avoiding the local minimum values when the training is done with the BP neural network alone. The result shows that method not only speeding up the convergence speed but also improve the training accuracy,also obviously valuable for the performance prediction of thin seam shearer.关键词：Genetic algorithm;BP neural network;Loading performance;Prediction
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发布时间：2022-09-22 - 摘要：The rotating butt skirt is works in the deep water area of the ocean,In order to solve the safety problem of rotating butt skirt working in deep water,In this paper,fixed skirt,direction skirt,angle skirt was took as the research object.Multi-Objective Genetic Algorithm is used to optimize the key parameters of fixed skirt,direction skirt and angle skirt,and we get the optimal parameters of the three. The results show that the optimized fixed skirt reduces weight by 9. 76% after optimize,optimized direction skirt and angle skirt reduces weight by 13. 56% after optimize. And the fixed skirt,the direction skirt and angle skirt after optimized are meet the design requirements. Finally,the three-dimensional model of the rotating butt skirt was established by using the optimized data,and the test prototype was made,which laid the foundation for the subsequent sea test.关键词：Rotating butt skirt;Sensitivity analysis;Multi-objective optimization design;Strength checking;Finite element analysis
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发布时间：2022-09-22 - 摘要：Aiming at the fact that the 3-parameter Weibull distribution model is complex and traditional methods have a low accuracy rate in the case of small samples,a new parameter estimation method based on GM-SVM was proposed. Grey model（ GM） and support vector machine（ SVM） were combined in this method. Firstly,to take advantages of location parameter estimation based on GM method. Secondly,making full use of the accurate estimated results based on SVM in small samples.This method is applied to the establishment of a Weibull distribution parameter estimation model based on GM and SVM,and to the reliability life distribution parameter estimation of certain engine blade. The simulation test results show that this model has preferable parameter estimation accuracy,has obvious advantages in small samples. This model can accurately obtain the three parameters of Weibull distribution.关键词：3-Parameter Weibull distribution;Small samples;Grey model;Support vector machine
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发布时间：2022-09-22 -
MUITI-OBJECTIVE OPTIMAZATION IN THE ELECTRICAL DISCHARGE MACHINING OF THE TA7 BASED ON BSO ALGORITHM
摘要：For the existing EDM machine,there is no specification of titanium alloy processing standard,the design center combination experiment,comprehensive consideration of no-load voltage,peak current,pulse width and pulse interval on TA7 EDM material removal rate,surface roughness and electrode Loss rate. The prediction model of material removal rate,surface roughness and electrode loss rate was established. In order to take into account the three conflicting process objectives of material removal rate,surface roughness and electrode loss rate,a process objective optimization model was established,and the brainstorm algorithm was designed to solve the optimization model. The results show that the average relative error between the measured value of material removal rate,surface roughness and electrode loss is 5%,4. 7% and 5. 5%,respectively. The results show that the brainstorm algorithm can effectively obtain the best process parameters of TA7 titanium alloy EDM.关键词：Electrical discharge machining;TA7;Material removal rate;Brain storm optimization algorithm- 4
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发布时间：2022-09-22 - 摘要：Using ANSYS/ls-dyna software to establish the complex coal seam under the condition of the spiral drum coupling model of coal and rock,different position of a cut and dirt band containing inclusions spiral drum impact load distribution and the shape of coal and rock deformation; the time history curves of the stress and strain of the alloy head and the tooth body are obtained by the dynamic analysis of the cutting teeth,and the stress distribution law of the cutting teeth in the working process was found out. The research shows that: when the spiral drum cutting the coal seam with the inclusion,its working load appears larger fluctuation,The maximum stress of the cutting teeth are mainly concentrated in the contact area of the teeth tip of the alloy head and the shaft shoulder of the head of the handle; under the same traction speed,the stress of the pick is decreased with the increase of the rotating speed of the drum. If the rotation speed of the roller is constant,the stress increases with the increase of the traction speed. The analysis results provide an important reference for improving the structural design of thin coal seam shearer drum and cutting performance.关键词：Spiral drum;Cut teeth;Rock breaking process;Load
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发布时间：2022-09-22 - 摘要：The factors,which influence the stability of thin-wall perforated steel components are complex. Take the columns as an example,in the existing research,much attention has been paid to the continuous section,but little paper on noncontinuous one. According to the characteristics of the non continuous cross section,based on performance testing and finite element analysis of columns,with the method of BP neural network intelligent stability prediction,the stability prediction model of the columns is established. The predict results are compared with the test data,and the error is less than 2%,which is more accurate than the finite element analysis results. It is very promising that the intelligent prediction method has applied in the structure engineering.关键词：Ultimate bearing capacity;Non continuous section;Back propagation;Section properties;Stability design
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发布时间：2022-09-22 - 摘要：Based on Wilson incompatible element technique and Reddy ’s layerwise theory（ LWM）,an incompatible layerwise method（ ILWM） is presented to deal with the bending problems of laminated shells in this study. Derivation of the equilibrium equations of the ILWM is performed. Several examples are studied to validate the capabilities of proposed method.The numerical results indicate that The ILWM achieves better convergence rate and computational accuracy compared with LWM for bending models.关键词：Wilson incompatible element;Layerwise;Bending problem
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发布时间：2022-09-22 - 摘要：According to the load characteristics of the new metal belt continuously variable transmission,the force balance equation of the tight side is established,taking p811 CVT as the research object,the stress change law of the wire rope is simulated by ABAQUS software. The results show that the bearing characteristics of interactive twist wire are better than the same twisted wire band under the torque load. When the metal band enters the cone pulley,the axial stress fluctuation amplitude of the interaction kudu wire reaches 37. 07% of the average stress,and there is obvious dislocation; In the process of transmission,the stress wave and the dislocation change of shengnei wire are more obvious in the xiangqiechu of metal belt and cone pulley,and uneven phenomenon exists in radial and axial load.关键词：The new type of metal V-belt;CVT;Steel wire belt;Mechanics modeling;Bearing characteristics
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发布时间：2022-09-22 - 摘要：Based on Electromagnetic thermoelastic constitutive equations,its increased dimensions constitutive relationship on the basis of relevant literature was established,and the electromagnetic thermo-elastic material generic shell homogeneous state equations were derived. Then,by Laplace transform onthe homogeneous state equation,complex high-order terms form of the polynomial coefficient matrix can be got. Considering the convenience and efficiency to solve the problem of inverse transform,the article made a fractional separation process on complex high-order coefficient matrix after Laplace transform which had complex high-order polynomial terms. Finally,numerical examples show that the method is correctness,and the computational efficiencyis almost the same as the precise integration method.关键词：Electro-magneto-thermoelastic;Homogeneous state equation;Orthogonalhyperbolic shell;Laplace transformation
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发布时间：2022-09-22 - 摘要：As the rapid development of steel smelting industry,the casting cranes are developed tend to high speed and large-scale. The reliability and safety of a crane was largely affected by the dynamic property of the bridge. The 200/60t casting crane was studied to investigate the dynamic property of the bridge in the lifting process. In this scheme,the iron melt ladle lifting process dynamic model is established to analysis steel rope tension under different conditions. And then,the iron melt was taken as the heat source and taking heat radiation and conduction as heat transfer mode to analysis the temperature field of the bridge in the iron melt ladle lifting process. After that,loading the node temperature of the bridge model and applying structural load which is the sum of the steel wire rope tension and the weight of the main trolley,and the corresponding transient dynamic analysis is implemented by using thermo-elastic coupling method. Analysis results show that,the lifting position and speed of the iron melt ladle have great influence on the dynamic property of the steel wire rope. The temperature field of the bridge presents nonlinear variation with the iron melt ladle lifting,that the temperature field of the bridge changes more significantly while the lifting speed faster. It’s indicated that,the thermo-elastic coupling method can analysis the dynamic tress and property of bridge structure in the iron melt ladle lifting process more effectively. This study provides the theory basis for the structure reliability design of casting crane’s bridge.关键词：Casting crane;Load-lifting dynamic;Dynamic stress;Structural vibration;Thermo-elastic coupling
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发布时间：2022-09-22 - 摘要：J-integral is an important fracture parameter which quantitatively describes the stress and strain fields near a crack tip. Accurate and efficient measurement of J-integral is of great significance for the evaluation of crack stability and propagation in mechanical equipment. This paper proposes a new method for J-integral measurement by using digital image correlation technique. The displacement and strain fields on the surface of a pre-cracked compact tension specimen were firstly measured and calculated by digital image correlation technique under different loads. A MATLAB program was then developed to calculate the J-integral by selecting a rectangular integral path around the crack tip. The calculated results were compared with those obtained from the US Electric Power Research Institute（ EPRI） estimation method and finite element method. The proposed method can produce similar results compared with other methods. It also has advantages of non-contact,high-precision,simple optical path,and less sensitive to the environment. The proposed method for J-integral measurement has potential to be applied to the crack evaluation for large in service mechanical equipment.关键词：J-integral;Digital image correlation;EPRI;Finite element method
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发布时间：2022-09-22 - 摘要：The effect of thermo-mechanical coupling was considered in order to obtain the fatigue life of spilt torque transmission row angular contact ball bearings in helicopter. Based on the L-P fatigue life and Hertz contact theory,an mathematical model was established with the combination of Goodman formula,material P-S-N curves and EM modify rule. The friction calorific effect was calculated and the convective heat tranfer coefficient was determined. Then the steady thermal analysis was conducted and the steady maximum temperature under different radial forces and rotate speeds was discussed. Finally the bearing fatigue life was investigated under the effect of thermo-mechanical coupling. The results show that the fatigue life decrease obviously with the operationg temperature raising,so the effect of frictional heating on fatigue life can’t be neglected.关键词：Row angular contact ball bearings;Fatigue life;Temperature distribution;Thermo-mechanical coupling;Loading distribution
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发布时间：2022-09-22 - 摘要：Based on the measured load of the 5 t loader working device,the method of solving the load with the attitude change to the local coordinate system of the boom has been studied and the MATLAB software to write the corresponding data processing program has been sued to obtain the loader arm under the fixed attitude of the load time course. The dangerous position of the boom is determined by the static analysis,and the equivalent external load of the boom is obtained by the stress equivalent principle of dangerous cross section position. On this basis,the boom load spectrum is compiled. The results provide a reference for the fatigue test and anti-fatigue design of the boom.关键词：Loader;Boom;Equivalent load;Load spectrum
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发布时间：2022-09-22 - 摘要：To explore the issue of easy breakage of the scraper conveyor dumbbell pin, through a combination of experimental research and fatigue analysis of dumbbell analysis. First,the force model of dumbbell pin was established,in which the pin used ANSYS dumbbell finite element was analyzed then the stress distribution results were obtained. By using the load testing system for the dumbbell pin,the loading data of dumbbell pin in the actual work were obtained; the n-Code Design Life was used to extract the maximum loading data of the dangerous area. And the rain flow counting and fatigue life analysis were carried out. The results show that: Dumbbell pin damage is from the dumbbell pin neck stress concentration of the largest region of the formation of fatigue,when the crack propagation area to a certain extent after the arrival of fatigue fracture zone,so that the entire dumbbell pin fracture. According to the working conditions of the scraper conveyor,the time of crack of the dumbbell pin is 92 days. The paper provides a design basis for the structure improvement of dumbbell pin.关键词：Dumbbell pin;Mechanical model;Experimental study;Load spectrum;Fatigue life
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发布时间：2022-09-22 - 摘要：Aiming at typical connection structure of the bolt holes errors on edge strip of front spar of central wing,this paper analyzes the fatigue property of the structure. The fatigue life of the structure is analyzed by means of structure durability analysis theory. The detail fatigue rating is worked out by finite element analysis and through experimental verification; this paper studies the changes of fatigue life and detail fatigue rating between structure with manufacturing errors and the original structure.Through theoretical and experimental analysis,this paper judges the validity of repair methods for the fastening holes error in the current aviation industry and provides theoretical and experiment data support for repairing methods.关键词：Edge strip of front spar of central wing;Manufacturing errors;Manufacturing errors repair;Fatigue property;Detail fatigue rating（DFR）
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发布时间：2022-09-22 - 摘要：In view of the controversial problem of damage zone in stress field intensity method,a method was proposed to determine damage zone by stress contour. Stress contour calculating steps were given. The example was given to demonstrate the calculating process. The result of the example analysis shows that the damage zone is not a regular and spherical zone,but is irregular. The method can reflect the real damage zone and is accord with the fatigue mechanism. The damage zone size and the load applied show a quadratic curve relationship and monotone increase. This method considers the changing load’s effect on the damage zone and even large load is applied it still can accurately predict the fatigue life of components. In order to prove the universality of the method,two examples with different notch shapes and load forms were given to verify. The result shows that the method can accurately predict the fatigue life of components with any notch shape and any load form and good predicted results have been achieved.关键词：Stress field intensity method;Damage zone;Stress contour;Fatigue life prediction
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发布时间：2022-09-22 - 摘要：Gasoline hydrogenation is an important processing technology in petrochemical production. The majority of supporting platforms of production equipment in the form of steel structure,which the strength and stiffness are very important to the production safety. The finite element model is established by ANSYS Workbench software. The static load and ground motion load response analysis are carried out according to the actual force of the support platform,and optimize the design of supporting platform. Regarding both the lower weight of the 2th and 3th layers of H type steel and lower value of the deformation which under static load as the objectives of optimizing design,and the section size of the 2th and 3th layers of H type steel as the design variable. Total amount of steel for supporting platform is reduced by 16. 8% than before,and the production cost reduced obviously. The stress value of the optimized frame steel structure which under the ground motion load is reduced by 4. 2%.关键词：Supporting platform;Static load;Seismic dynamic load;Optimum design;Amount of steel;Deformation
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发布时间：2022-09-22 - 摘要：In the process of dynamic loading,the loading plate temperature is one of the main problems about non-contact electromagnetic loading device. The nature of the electromagnetic load is that using electromagnetic force to simulate the working load,while,the loading plate will generate eddy currents in the process of dynamic loading which can make the loading plate hot. This paper mainly analyzes the temperature rise of loading plate at different speeds. By testing the loading plate temperature in real time with infrared thermometer,analyzing and calculating the thermal power as basis,and utilizing Transient Thermal Circuit to solve the loading plate temperature according to the actual size,we can obtain the temperature variation curve of loading plate at different speeds and temperature rise performance, which can provide an important basis for improving this electromagnetic loading device.关键词：High speed motorized spindle;Electromagnetic loading;Thermal power;Thermal analysis
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发布时间：2022-09-22 - 摘要：In the aerospace sector,foreign object damage（ FOD） is a serious threat to the normal operation of aircraft and aviation security and bird strike damage is the most common. Based on AUTODYN finite element software,a bird bullet SPH model and a Lagrange model of 2024 aerospace aluminum alloy target are built to study the dynamic response and damage characteristic of aircraft envelope when subjected by bird strike. By comparing the simulation result with the experimental data,the validity of bird bullet SPH model is verified. Exploring the influences of largest drum kits,stresses and energies of target impacted by bird strike at different target laminates and bird strike velocities,the best target stack mode would be selected.关键词：Bird strike;Target;Layering order;Dynamic response;Numerical simulation
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发布时间：2022-09-22 - 摘要：The stepped shaft of ball screw was breakaway after loading test of transmission mechanism. To solve this problem,analysis and calculations were carried out from higher hardness,material defect,machining process and experimental loading. The results show that electro discharge machining（ EDM） causes tensile stress and microcosmic cracks on the surface microstructure. Meanwhile,thread corrosion of stepped shaft reduces the loaded area. As a result,torsional fracture of the stepped shaft happened. According to the result,improvement measures including process criterion of EDM control,grinding and polishing are proposed.关键词：Ball Screw;Stepped shaft;Fracture
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发布时间：2022-09-22 - 摘要：Taking the new type of protuberant foil hydrodynamic thrust gas bearing as the research object,the finite element method and the Newton-Raphson iterative method are used to solve the numerical model of fluid-solid coupling by MATLAB software. The film pressure distribution,the thickness distribution and the carrying capacity of the bearing under different temperature of the same lubricating gas and the same lubricating gas at different temperatures were obtained. And the influence of the physical properties of the lubricating gas on the static characteristics of the foil dynamic pressure thrust bearing in the aircraft turbo cooler is studied. The results show that the lubricating gas with large dynamic viscosity has a large gas film pressure and thickness distribution,and the higher carrying capacity. With the high temperature of the bearing running at high speed for a long time,the change of the physical parameters of the lubricating gas is conducive to improving the carrying capacity.关键词：Lubricating gas;Aerodynamic thrust bearing;Carrying capacity
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发布时间：2022-09-22 - 摘要：According to customers’ needs,Based on ergonomics principle,a Boss Chair footrest was designed. Using Adams software to take kinematics simulation,which has verified the movement characteristics of the organization. Based on finite element analysis AWE environment on the organization,To check the strength and stiffness of the structure. On the basis of the physical prototype,to take mechanical properties test. It turned out that the footrest meet requirements of ergonomics size and movement stability,static strength,fatigue strength and stiffness of the structure conform to the BIFMA test standard. The testing results coincided with the finite element analysis.关键词：Ergonomics;Footrest;Kinematics simulation;Finite element analysis;Prototype test
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发布时间：2022-09-22 - 摘要：This article is focus on the crack problem of bench test in the development of twist beam,FEA and stress data collection are applied to comprehensive comparison,seek for the reason of crack,improved project is introduced with the manufacturing technique. CAE and sample bench test are applied to verify the feasibility of the project,the crack problem of bench test was solved by repeated optimization finally.（ In Chinese）关键词：Twist beam;Bench test;Finite element analysis
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发布时间：2022-09-22
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