最新刊期
期 3 ， 2017
- 摘要：Due to time periodic characteristic of unsteady response induced by blade vibration,using frequency domain harmonic balance computation technique,with structural dynamics analysis,the unsteady flow field around oscillating blades was numerically simulated in one-way fluid-structure coupled manner. The flutter characteristics of blades were predicted by estimating energy transfer between structure and fluid. For the first stage rotor of a transonic fan,the flutter boundary of blades was obtained by analyzing aeroelastic stability of blades with different rotational speeds and back pressure specified. Result shows that,an existence of instability risk under unstalled operation at 100%,95% and 90% rotational speed means a supersonic unstalled flutter for the blades. Comprehensive effect aerodynamic work in the downstream of shock wave and near leading edge of blade tip determines aerodynamic stability of blades under different working points.关键词：Blade flutter;Harmonic balance method;Unsteady flow;Energy method
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发布时间：2022-09-22 - 摘要：To research the dynamic character of plough under oblique cut conditions,the cutting coal wall depth of planing tool and the condition of participate in cutting were derived. The dynamic model of plough was established by finite elem ent method. The numerical simulation analysis of dynamic character of plough was executed. velocity and tension fluctuation curve of plow head and chains were obtained. Take feeding velocity and middle trough swing angle as design variables,and take minimal unit energy consumption and minimal load fluctuation rate as objective function. The Optimal design was executed by the method of multi-population genetic algorithm. The results are obtained that the optimal feeding velocity is 1. 2m/s,and middle trough optimal swing angle are 1°,1°,0. 7°. The results provide theoretical basis for coal plough in engineering.关键词：Oblique cut condition;Optimization design;Plough;Genetic algorithm
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发布时间：2022-09-22 - 摘要：Aiming at the adverse influence of penalty parameter and mode number on the VMD（ variational mode decomposition）,a newly MVMD（ modification variational mode decomposition） was proposed through the information entropy difference. The change of the amount of information in each mode extraction characteristic of information entropy difference was analyzed. The information entropy difference under the condition of different penalty parameters was got through making full use of the analysis result of extraction characteristic. The excellent penalty parameter was determined in the position of jumpy information entropy difference. The Fourier spectrum of MVMD was used to detect the unbalance of Cardan shaft in high-speed train. The method and model was verified through the unbalance experiment data. The experiment results show that this method could effectively seize the basic frequency,multi-frequency fault features. With comparison to VMD,the problem of Parameter selection has been solved. With comparison to the classic ensemble empirical model decomposition,the fault detection ability has been significantly improved.关键词：Cardan shaft;Dynamic unbalance;MVMD;Information entropy difference
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发布时间：2022-09-22 - 摘要：With the continuous improvement requirements of reliability and security for mechanical equipment,accurate extraction of equipment fault development trend of degradation characteristic information and establishment of effective fault prediction model is the key problem to improve reliability of equipment operation. HMM has double random process properties that could describe the hidden state and observed state,it is similar to the equipment degradation processes that become a hot research topic now. On various methods based on the fault identification and diagnosis technology, the equipment fault prognostics methods based on hidden Markov model and hidden semi-Markov model are summarized, advantages and disadvantages of each method are analyst and compared. Finally,its development trend on equipment degradation assessment and prognostics is pointed out.关键词：Fault diagnosis;Degradation assessment and prognostics;Hidden Markov model;Hidden semi-Markov model
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发布时间：2022-09-22 - 摘要：Quasi-static localized indentation tests were carried out to investigate the indentation mechanical properties of the aluminum honeycomb sandwich panels. The destruction process,failure behaviors and typical force-displacement curves were analyzed. The impact of surface plates thicknesses,aperture sizes,intender types and boundary conditions on the ultimate load and energy absorption capacity were studied. The results indicate that the aluminum honeycomb sandwich panels have two kinds of typical force-displacement curves,and six stages are presented: elastic stage,local destruction stage,intensify stage,entirely damage stage,compression density stage and bottom damage stage. Surface plates thickness and aperture size have certain influence on load bearing capability and energy absorption capacity. Indenter types have much influence on load bearing capability and rigidity,but little influence on the energy absorption capacity. Different boundary conditions and core thicknesses have less influence on strength and energy absorption capacity of aluminum honeycomb sandwich panels.关键词：Honeycomb;Sandwich panel;Quasi-static localized indentation tests;Ultimate load;Energy
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发布时间：2022-09-22 - 摘要：This article presents an experiment and simulation study on the effect of Z-pin reinforced on the pull-off and sheat carrying capacity of fiber placement composite T-joints,we used CMT5504 to conduct the pull-off test meanwhile we used MTS to conduct the shear test. we studied Z-pin reinforced And non-reinforced test-pieces,drawing Load-displacement curves.The pull-off test results donate that Z-pin can effectively improved the pull-off carrying capacity of T-joints and slow the decrease of the load significantly after pick loading compared to the non-reinforced T-joints. The failure location is between stiffener and interlayer. The shear test results donate that Z-pin can effectively improve the shear carrying capacity of T-joints. The failure location of Z-pin reinforced test is between skin and interlayer and the failure location of non-reinforced test is bwtween stiffener and interlayer. On this basis,we created pull-off and shear model of T-joint specimens. The interface failure was simulated with cohesive zone model,and the effect of Z-pin was simulated with nonlinear springs inserted into the interface. The numerical results agree well with the test data and shows that the model is effective.关键词：Fiber placement composite;T-joint;Z-pin;Numerical simulation
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发布时间：2022-09-22 - 摘要：In order to study the mechanical properties of scraper conveyor chain under complicated conditions,the scraper conveyor chain tension changes during the operation of on-line monitoring was realized,The wireless transceiver module and storage testing data signal,export to stay after the test data and analysis were carried out. Experimental results showed that the same round link chain of two straight tension appeared the obvious unequal phenomenon; Coal winning machine cutting coal,increased near the coal mining is bigger than the lateral side chain tension goaf side chain tension. Image shows that whenever the chain after a sprocket will produce a Zhang Lijie leap mutation,half the no-load operation cycle time interval of 51 s,scraper conveyor motion resistance of 16 kN no-load current end,chain tension value is 896 k N. The results of the study provides theory basis for design and optimization of the chain.关键词：Scraper conveyor;Round link chain;On-line monitoring;Tension
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发布时间：2022-09-22 - 摘要：The surface roughness of traditional grinding gear has the typical anisotropy characteristic in microcosmic direction. After the barrel finishing of the tooth surface,the micro-surface is isotropic. According to the Hertz theory and the theory of contact fractal strength of gears,the influence of microstructure contact stress calculation was discussed. The contact stress limit of the traditional grinding gear and the barrel finishing gear was obtained by gear contact fatigue strength comparison test. The results show that the isotropic finishing process can make the micro-texture of the tooth surface tend to be isotropic,and improve the contact fatigue strength of the gears,which provides a reference for the life design and reliability design of the gear.关键词：Isotropic barrel finishing;Fractal contact model;Contact fatigue strength;Contact fatigue test
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发布时间：2022-09-22 - 摘要：By modification and heat treatment,analyzed from all aspects of microstructure,hardness and impact toughness through three kinds of modifiers for low-alloy white cast iron. Experimental results showed that modification could change the morphology and distribution of low alloy white cast iron,it also could enhance that’s continuity of the matrix and the toughness of the material,and the Zn + Ca-Si + Nb modification have the best effect,normalizing treatment after modification can further improve performance.关键词：White cast iron;Modification;Normalizing
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发布时间：2022-09-22 - 摘要：Since the wing is the principle bearing structure of aircraft,wing skin is repaired by using mechanically fastened joints. In this paper,scheme design,experimental verification,finite element analysis and design improvement investigation of aircraft composite wing panel with discrete-source damage were carried out. Firstly,the specimen with discrete-source damage and the repaired which used fastened joint repair method were designed and manufactured. Experimental verification of scheme design was performed. Load-carrying capacity of the repaired specimen increases about 124%,compared to the unrepaired,which fully meet the design requirements. Then,for further analysis,two different specimens’ FEM models were established.The results showed that the initial repaired scheme was conservative,and the cost of structure weight was increased. Finally,three improved design configurations were proposed,and the load-carrying capacity of configuration II increased by 4. 7%,its structure weight decreased by 3. 9%. This repaired scheme provides reference for the repair design of aircraft composite wing panel with discrete-source damage.关键词：Composite wing;Stiffened panel;Discrete-source damage;Repair design;Scheme Improvement
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发布时间：2022-09-22 - 摘要：Based on the feasibility of the discharge machining of the semiconductor material,it analyze several major factors which influences the material removal rate,including the open circuit voltage,peak current,pulse width and pulse interval.Using central composite design experiments,it inspects the influence of the three factors peak current、pulse width and pulse interval to the material removal rate of the monocrystalline silicon in the course of the electrical discharge machining and establishes a response model of the material removal rate of the monocrystalline silicon in the course of the electrical discharge machining and makes analysis to the response surface. The result of the variance analysis indicate that the model has good fitting degree and adaptability. It uses satisfactory rate function（ DFA） to determine the optimum technology parameters of the monocrystalline silicon in the course of the electrical discharge When the value of the peak current is 18. 5 A,the value of the pulse width is 358. 62μs,the value of the pulse interval is 20μs and the degree of satisfaction is 0. 912,then the optimal value of the material removal rate is 76. 26 mm~3/min It has measured the average MRR of the P type monocrystalline silicon is 73. 86mm~3/min through repeated experiments many times on the electrical discharge shaping machine with the optimal processing parameters which are identified The average relative error of the model prediction results compare with experimental results under the optimum technological parameters is 3. 4%. The verification test indicates that this model can achieve the prediction of the material removal rate of the corresponding semiconductor material in the course of the discharge machining.关键词：EDM;Semiconductor;Material removal rate;Response surface method
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发布时间：2022-09-22 - 摘要：The ferrogel sample was prepared by carbonyl iron powder as conductive phase and vulcanized silicone rubber as matrix. The microstructure and mechanical properties of the sample are analyzed and tested by using X ray diffractometer（ XRD）and MTS testing machine. Based on the analysis of the microstructure and morphology features and the compression performance data,a stress-magnetization coupled model was established in accordance with the magnetic interaction between particles,and some factors influencing on magneto-induced effect and macroscopic response of ferrogel are analyzed theoretically,including the magnetic particle content,size ratio,magnetic field strength and compress strain etc. The results show that the roughness has little effect on the average peak shear stress when compress strain is low,while with the increase of the normal stress,the magneto-induced effect comes into play. And the magneto-induced compressive modulus of ferrogel tends to increase with the increment of the magnetic particle content,size ratio,magnetic field strength and compression strain. If the mass fraction of the magnetic granular in ferrogel is more than 70wt%,the ductility and fracture toughness of ferrogel composites would be notably reduced. In order to gain ferrogel composites with excellent magneto-induced effect,the the optimized combination of the selected factors would be employed were in the preparation of ferrogel materials. This provides theoretical help for material production and optimization of functions and behaviors for the device.关键词：Ferrogel composites;Stress-magnetization coupled;Magneto-induced effect;Micromechanics
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发布时间：2022-09-22 - 摘要：Orifice throttle is a common way of throttling in the air static pressure guide rail,In order to study the gas film pressure distribution of the air static pressure guide rail,a gas thrust bearing gas film pressure distribution test bench was developed. In this paper,the orifice throttling is an example,based on the law of the gas film pressure decline,the gas film is divided into the pressure driven area and the Newton friction area. The gas flow pattern in the gas film support area is simulated by Fluent and the flow rate and pressure are calculated. The experimental results are in good agreement with the numerical analysis of the gas pressure distribution. It is concluded that the gas film is divided into the pressure driven area and the Newton friction zone along the length of the gas film,which verifies the validity of the pressure partition theory.关键词：Gas lubrication;Pressure zone;Micro scale flow;Couette flow
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发布时间：2022-09-22 - 摘要：Aiming at the vulnerability poor quality and need prior knowledge of traditional mathematical programming theory on multi-objective optimization in practical engineering optimization problem. Put forward an improved particle swarm optimization conjugated the criterion with minimum Euclidean distance to a base value and then combined with grey decision to make multiobjective optimization. Applied the above multi-objective optimization method on roadheader shovel plate parameters and have done some simulation on shovel plate grubbing coal rock,has obtained a good optimization effect. By doing so,it verifies the feasibility of this method and provides convenience and reference to deal with multi-objective optimization problems in engineering practice.关键词：Minimum Euclidean distance;Improved particle swarm optimization;Grey decision;Multi-objective optimization;Roadheader shovel plate parameters
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发布时间：2022-09-22 - 摘要：As the protection of key component of the Shearer,torque shaft has a significant impact on the performance of the reliability and fatigue life of the shearer. Shearer’s flexible virtual prototype coupling model of torque shaft,rocker arm shell,planet shafts and carrier was established,combined with the actual working condition,pro-and post drums ’ load files were obtained. Based on the " shearer’s load simulation program ",shear stress and strain contours of the torque shaft were obtained by ADAMS. Based on neural network and reliability sensitivity theory,the torque shaft shear stress and strain ’s sensitivity of unloading groove structure parameters were obtained. To shearer traction speed and torque shaft shear stress and displacement as constraints,optimize the unloading groove. Results show that when the shearer traction speed is greater than 12. 2367m/min,the torque shaft fracture in time,could improve the reliability of coal winning machine and service life.关键词：Shearer;Torque shaft;Neural network;Reliability;Sensitivity;Optimization design
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发布时间：2022-09-22 - 摘要：According to the less effectiveness and difficulty in fault diagnosis of welding robots for its lots of uncertain faults phenomena and faults causes,this paper proposes the Fuzzy Fault Tree Analysis apply to welding robots fault diagnosis. Based on the analysis of welding machine structure and the T-S fuzzy fault tree analysis method,taking the torch’s gesture and suspension height setting of welding machine as an example,the fuzzy fault tree based on T-S model is established,and the reliability analysis for welding robots is discussed. The result shows that this method can find the weak link of the system without understanding the failure mechanism accurately,and can overcome the shortcomings of traditional fault tree analysis.关键词：Welding robots;Fuzzy fault tree;Fault diagnosis;T-S model;Reliability analysis
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发布时间：2022-09-22 - 摘要：In order to optimize the design of the pressure vessel,an optimization mathematical model was established. It takes the minimum quality of the pressure vessel shell as its optimization object,the inner diameter and wall thickness as its discrete design variables. The essay puts forward an improved firefly algorithm and it can improve the overall searching ability and the convergence performance of the algorithm by adopting the self-adaptive step size strategy,ignoring the local optimal strategy and the spatial domain constraint strategy. Simulation results show that compared with the normal one,improved firefly algorithm can converge to the optimal solution faster,and it can also effectively solve the problem of optimal design for the pressure vessel.关键词：Improved firefly algorithm;Pressure vessel;Discrete variables;Optimum design
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发布时间：2022-09-22 - 摘要：In order to enhance the competitiveness of the domestic hydraulic support. It is imperative to carry out reliability engineering. The reliability evaluation of the hydraulic support in service can effectively provide reference for the development and improvement of the product. It can also provide a reference for development of new type of reliability test. Based on support vector machine has great advantages in small sample data processing,Putting forward using support vector regression machine estimate weibull distribution parameter of hydraulic support failure time,when the failure date is small sample. The accuracy of the results obtained by different empirical formulas is compared. The reliability of the model is evaluated and predicted by the highest accuracy. Research shows that: support vector machine can be used to evaluate the reliability of hydraulic support under small sample maintenance data. Shape parameter of some commonly used hydraulic support reliability Weibull distribution is3. 0157,the scale parameter is 61728.关键词：Hydraulic support;Support vector machine;Weibull distribution;Small sample;Reliability assessment
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发布时间：2022-09-22 - 摘要：Aiming at flaws of scale-texture on the surface of cold-roll beating forming parts,according to the basic principles of cold-rolling beating forming,analyzes the main reasons and affecting factors of scale-texture flaws is carried out. The simulation model is built by using the simulation software of ABAQUS. The change law of scale-texture height and width were simulated under the way of forward beating and backward beating,and when rolling wheel speed change and the work-piece bottom surface along the positive direction. The height and width of scale-texture and section shape were simulated under the way of forward beating and backward beating. Forming experiment is conducted on the refitted cold roll-beating forming equipment,the height of scale-texture and 2D section shape is obtained by scale-texture measurement on the surface of cold roll-beating forming parts,the validity of finite element simulation model is verified by intercomparison of experimental results and 2D section shape,so as to provide reference for surface quality control and selection of parameters parameters
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发布时间：2022-09-22 - 摘要：In order to study the haulage speed of shearer drum load effect by Tikhonov regularization method,pick load reconstruction model was constructed,and the haulage speed and pick load was deduced. The roller and haulage unit of mutual coupling system dynamics model was established,the model solved by using numerical simulation method,and the results using statistical methods that different haulage speed shearer drum three-axis force the average value and the standard difference,validated by experiment. The results show that simulation results and experimental results in the mean and the standard deviation error range is less than 5%,to verify the correctness of the theoretical model.关键词：Shearer;Drum’s three-axis force;Coupling dynamics;Regularization
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发布时间：2022-09-22 - 摘要：The design and optimization of standard parts to the machine tool is always being the focus of domestic and foreign countries,which is helping for the machine tool inspection and assessment of the performance. In this study,according to the advantages and disadvantages of standard specimen of the universal five-axis NC machine tools,comparing the structural characteristics and machine features for the testing performance of ISO international standard specimen, NASA979 series specimen,"S"shape of the specimen and other specimens. The most characteristics of modern aviation parts are combined to design the "X"form of new aircraft thin-wall standard specimen. By analyzing the "X"shaped aviation thin-walled specimen with the finite element method,the open,close angles and curvature continuity curves are calculated and discussed. Based on the results of finite element analysis,it’s the first time to put forward the processing complexity coefficient concept,compares the cutting force and thermal load,the cutting force dominates in the residual stress generated,this paper only consider the effect of cutting force,to evaluate the characteristics of the"X"shape aviation thin-wall specimen in the geometric model and mechanical structure design in-depth. It proved that "X"shaped aviation thin-wall specimen is better than the other standard specimens in comprehensively reflecting the multi-axis linkage and dynamic stiffness characteristics of the CNC machine possess,showing more comprehensive and superiority in the aspect of detection. All above conclusions provide the scientific basis and effective approach for integrated precision detection characteristic of five-axis CNC machine based on the "X "shaped new aircraft thin-walled standard specimen.关键词：Thin-walled standard specimen;Machining characteristics;Processing complexity coefficient;Open and close Angle;The curve curvature
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发布时间：2022-09-22 - 摘要：Based on bond graph theory,considering the time-varying meshing stiffness,damping and tooth surface friction force of internal and external gear,using LuGre friction model,the bond graph model of NGW type planetary gear was established. And then,the bond graph analysis models of the XP type and PX type single loop planetary transmission system were set up. The speed and efficiency of XP type and PX type single loop planetary transmission system was computed and simulated in 20 sim software. The results show that the modeling theory and method of bond graph can be used to solve the nonlinear dynamic problems of single loop planetary transmission system.关键词：Bond graph;Single loop;Nonlinearity;20sim;Planetary transmission system
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发布时间：2022-09-22 - 摘要：The chain scraper conveyor is the most important material conveying equipment in the fully mechanized working face,and the sprocket and the chain ring is the core part of the conveyor system,the meshing problem of the sprocket and the chain ring is the most prominent problem of the transmission system. In order to research the rules of the sprocket contact force under the chain condition,first of all from the chain ring and sprocket meshing process carries on the theoretical analysis,and has carried on the analysis to his contact force changes. Then established the visual prototyping model based on the MSC. ADAMS and analyzed the touch dynamics quality between sprocket and chink hoop when the scraper conveyor starts and are operated for a long time. The change law of the contact resultant force tangential force and normal force when the sprocket and the chain ring are engaging,and the maximum engaging force and the corresponding position are analyzed. Finally we analyzed the engaging force when the sprocket and chain ring during the engaging progress based on software of workbench,and got the maximum engaging force and corresponding position,which provides the theoretical basis for the optimization design of the scraper conveyor sprocket and the chain ring.关键词：Chain jammed;Scraper conveyor;Sprocket;Chain ring;Contact dynamic;Mesh;ADAMS;LS-DYNA
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发布时间：2022-09-22 - 摘要：Bolted joints is one of the most widely used fixing joints in machine tool structure,which directly affects the performance of the whole machine tool. In order to ensure the accuracy,the fine mesh is needed,which will result in a large scale of calculation and time consuming,using finite element analysis software to analyze the structure and performance of the whole machine tool. And so the exploration of simple and effective approach combining of the finite element model of machine tool bolted joints is of great significance. According to the experimental results,this paper obtains the characteristic parameters of the joint surface and the six stiffness of each element in the bolted joints is obtained by means of the analytical methods. And then,bolted joints of each element are replaced with the four equivalent springs of symmetric distribution in pairs and the calculation method of the equivalent spring stiffness ＆position is given on the basis of the principle of equivalent stiffness. In the finite element analysis of the whole machine tool,the equivalent spring unit is substituted for unit bolted joints and the solution of finite element model uses the equivalent stiffness of bolted joints by finite element model,which can greatly simplify the calculation of finite element model. The experimental results show that this method is feasible.关键词：Bolt joint;Stiffness;Static characteristic;Finite element model
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发布时间：2022-09-22 - 摘要：The effects of load,speed and material parameters on the amplitude of central pressure and pressure spike were investigated under line contact EHL condition. Based on the analysis of mass numerical data and regression,the fitting formulas of amplitude of central pressure and pressure spike of line contact EHL state were proposed and the accuracy of fitting formulas was verified. The result shows that in a fairly wide range of the parameters,the accuracy of fitting formulas is satisfactory,which can completely meet the demands of engineering designs.关键词：Line contact;EHL（elastohydrodynamic lubrication）;Amplitude of central pressure;Amplitude of pressure spike;Fitting formula
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发布时间：2022-09-22 - 摘要：The virtual prototype model of transmission system of automotive trapezoidal toothed synchronous belt is built and the simulation analysis of movement process is carried out by using multibody dynamics software Recurdyn. Based on the characteristics of synchronous belt transmission,the effects of different initial tension,speed and transmission load on the equivalent stress of the synchronous belt is studied in the transmission process,a feasible method to study the design and optimization of automobile synchronous belt structure of trapezoidal toothed is provided.关键词：Synchronous belt;Dynamic characteristic;Virtual prototype;Rigid flexible coupling contact
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发布时间：2022-09-22 - 摘要：The study has been done with focus on the pneumatic power conversion efficiency by analyzing Perfect Meshing Profile（ PMP） correction of the scroll expander with the serious top profile invasion of the inlet port problem in application. The maximal invasion rate reaches 50%,which leads to the increase of inlet air flow friction coefficient. Therefore,on the basis of the circular arc plus line-shaped top profile correction,special correction method for the top profile was proposed. According to the feature of special top profile correction method,it comes to a conclusion that special top profile correction has low invasion rate（ the maximum only was 9%） and airflow friction coefficient of the inlet port decreases. In addition,in the intake process,at any time the actual inlet port can remain relatively smoothly,therefore reducing the airstream friction coefficient and the inlet port power loss. And what’s more,symmetric synchronous inflation of scroll expander has been accomplished,and consequently the results are smooth power delivery with reducing the mechanical vibration. Theoretically,the scroll expander pneumatic power conversion efficiency has been improved by reducing inlet port inflation power loss.关键词：Special top profile correction;Inlet port power loss;Invasion rate;Inlet port roundness
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发布时间：2022-09-22 - 摘要：Introduces the method of calculating equation and theory of spiral drum loading rate numerical discrete element method,and combined with the actual project,according to the shearer drum blade helix angle,thickness,coal and blade friction coefficient,roller speed and other related parameters to calculate the theoretical rate of coal mining machine. The establishment of the coal mining machine model and introduced into the general CAE software using EDEM Pro-e software,set according to the actual conditions of coal seam conditions and coal mining machine system simulation model and parameters such as material properties. The discrete element simulation of the loading rate of loading rate results and theoretical research and analysis,to verify the accuracy and feasibility analysis of the research on Simulation of shearer drum loading effect of discrete element method,provides an important reference for the research on Shearer loading performance of the discrete element method.关键词：Discrete element method;Shearer;Coal properties;Coal and rock particles;Simulation
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发布时间：2022-09-22 - 摘要：A finite element method of the hybrid（ bonded/bolted） joints is developed,and load transfer is analyzed. The three-dimensional cohesive zone model is used to simulate adhesive layer. Elasto-plastic deformation of metal structure is taken into account. Meanwhile,experimental data of the bonded joints,the bolted joints and the bonded/bolted hybrid joints are obtained and compared with the predictions. A good agreement between experimental results and numerical predictions is observed. In addition,single bolt and double bolts hybrid（ bonded/bolted） joints models are developed,and analysis shows that load-bearing capacity of single bolt hybrid isn’t improved,relative to bonded joint. Meanwhile,in the double bolts hybrid joints,adhesive layer outside of the bolts is destroyed soon,because of biggish peeling force. That inside of bolts is carried pure shear force due to normal constraint force of bolts,and it could enhance carrying capacity of the adhesive layer. So the parameters and forms of bonded-bolted hybrid joints are improved,as enhanced the joints strength.
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发布时间：2022-09-22 - 摘要：Cord reinforced rubber hose was widely used in automobile,aviation,aerospace and other fields. Meeting mechanical performance was the key to the safe use. In this paper,modeling of knitting cord was probed firstly. Then mechanical performance of aramid cord reinforced EPDM rubber hose was analyzed by ANSYS. Finally influence of cord’s needle number on mechanical properties of rubber hose was researched. The results show that maximum stress of cord is more than three hundred of times of maximum equivalent stress of rubber and maximum deformation of rubber is several times of maximum deformation of the cord when hose is imposed 0. 24 MPa inner pressure. And rubber and cord will not be destroyed. Experimental Bursting pressure of rubber hose is 2. 04 MPa,which is 97% of forecast bursting pressure 2. 10 MPa. With cord ’s needle number increasing,equivalent stress and deformation of cord and rubber all decrease sharply at first then tend to be gentle.关键词：Hose;Rubber;Cord;Aramid;ANSYS
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发布时间：2022-09-22 - 摘要：Object of study was the large Z shaped stiffened-welded plate,combined with theoretical analysis and finite element simulation of Abaqus researched the compression instability ultimate load,to provide theory and simulation for the application of large welded plate,save the test cost and improve efficiency. The theory studied the relationship between effective width and radius of inertia,calculation of the average load as skin with truss had different material. In the simulation of analysis,ultimate load was determined by extracting the extreme value of the load proportion factor（ LPF）. For improving the accuracy of the simulation,according to the strength of the welding seam with the cloud image judged the welding sequence,studied on the variation of ultimate load in welding,to determine the limit load range. Theoretical and the simulation value compared with the experiment. Influence of the elastic modulus of material on the overall ultimate load was analyzed,by the result of the analysis,the modulus of the long truss material is more conductive to improve the ultimate load.关键词：Stiffened-Welded Plate;Ultimate load;Finite element analysis;Open welding
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发布时间：2022-09-22 - 摘要：Excessive thinning rate of deformation zone thickness in metal sheet single point incremental forming process is an important factor that influence the forming limit. Prediction of deformation zone thickness is an important way to control the rate of thinning. The process of deformation zone thickness in single point incremental forming process were analyzed,the finite element model of single point incremental forming was established by the finite element analysis software ABAQUS and the 1060 Aluminum was selected as material of sheet. A relatively high accuracy formula to predict the deformation zone thickness is fitted by using the simulation results. the impact of process parameters such as tool diameter,layer step,feeding speed,sheet thickness,forming angle on thinning rate were analyzed respectively. The correctness of finite element simulation was verified by experiment and proposed a method to control thinning rate by changing forming trajectory. The results showed that the thinness value calculated by fitted formula to predict the deformation zone thickness is more close to the experimental data than by sine theorem. Thinning rate of deformation zone thickness increases with the increase of tool diameter,forming angle and sheet thickness and the decreases of step size,the feeding speed had no significant effect on the thinning rate. The most important factor of thinning rate is forming angle. The thinning rate is effectively reduced by using pressing point uniformly distributed forming trajectory.关键词：Single point incremental forming;Thinning rate;Finite element analysis
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发布时间：2022-09-22 - 摘要：Commercial pure titanium（ CP-Ti） TA2 was pressed 1 pass by equal channel angular pressing（ ECAP） with BC route at room temperature（ RT） and 300℃,respectively. The microstructure and mechanical properties of the samples were investigated to find the influence of ECAP temperature on the mechanical properties of CP-Ti. The experimental results suggested that grains of the samples after ECAP 1 pass were elongated and lath-like and crystal twinning was found,the microhardness and tensile strength of the samples pressed 1 pass at room temperature and 300℃ increased from 179. 5 kgf·mm-2,443 MPa to 234. 2 kgf·mm-2,560 MPa and 213. 5 kgf·mm-2、544 MPa,respectively,while the elongation at break reduced from 21. 5% to 11. 5% and 16. 5%,respectively.关键词：Equal channel angular pressing（ECAP）;CP-Ti;Temperature;Microstructure;Mechanical properties
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- 129
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发布时间：2022-09-22 - 摘要：Aiming at the problem of long time of vehicle engine reliability life test,the grey system forecasting theory is used to forecast vehicle engine reliability life test data,and the unbiased grey GM（ 1,1） power model for engine reliability life test data is proposed. By examining the overall distribution function equality of test data sequence and forecasted data sequence,it is confirmed that the proposed unbiased grey GM（ 1,1） power model can be effectively used for the prediction of engine reliability life test data. The example results show that the grey theory forecasting method for the prediction of engine reliability life test data has high precision,and distribution function parameters of test data sequence and forecasted data sequence are very close. Using the proposed method can shorten engine reliability life test time and save test cost.关键词：Engine;Reliability;Life test data;Grey forecast method
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- 223
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发布时间：2022-09-22 - 摘要：A direct solution procedure for structural damage identification based on stiffness change ratio was proposed.Utilized with Neumann series expansion,the damaged structural stiffness change ratio matrix was derived,in a form of matrix product. The stiffness loss of the damaged element was treated as accessional dummy stiffness,and then the extent of element damage obtained by transformations of stiffness change ratio matrix. The method contributes a concise expression and higher computational efficiency. Numerical simulation example of a 3D aircraft wing frame model was performed via the proposed method,and the influence of test noise and incomplete test modal was considered,the results show that the identified values are accurate and stable.关键词：Damage identification;Damage index;Modal flexibility;Neumann series expansion
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- 122
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发布时间：2022-09-22 - 摘要：The 3D contact finite element model of helical gear pair is built to generate mode neutral file by ANSYS,the flexible dynamics simulation anslysis is carried out by using ADAMS,and contact force of helical gear pair is obtained as load spectrum. The fatigue life of the helical gear pair is performed by using nCode based on load spectrum,stress-strain of helical gear pair under contact analysis in ANSYS and the S-N curve of helical gear pair. Meanwhile,the 3D model of helical gear pair with tooth profile deviation is established to study teh influence of tooth profile deviation to fatigue life of helical gear pair. The results show that the fatigue life decrease of helical gear pair with the increase of tooth profile deviation.关键词：Gear;Dynamics simulation;Load spectrum;Fatigue life anslysis;Tooth profile deviation
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- 291
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发布时间：2022-09-22 - 摘要：First of all,stress analysis of lug under different loading angles was carried out. For the fatigue life analysis of lug under tension-compression loads,the compression load was treated equivalently,and the effective equivalent load factor λ was obtained. The fatigue load spectrum was equivalent to Pmax λPmin,and then the fatigue life of lug structure was obtained by the Detail Fatigue Rating（ DFR） method. Finally,the method was proved by the fatigue test of lug in 45° angles load,which proves that the method is practical in engineering.关键词：Lug;Tension-compression load;Detail Fatigue Rating（DFR）;Effective equivalent load factor
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- 115
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发布时间：2022-09-22 - 摘要：Air film thickness for the air cushion belt conveyor relates to carrying capacity of conveying device,fan pressure and working efficiency. Gas film thickness was required to be kept in a reasonable range,and the target for article was stable and effective operation of the conveyor. With establishing gas film mathematical model,the theory of gap flow and experimental test,the gas film thickness of air cushion belt conveyor was analyzed. The gas film peak type distribution is obtained,which lays the theoretical foundation for the practical application and improvement of the air cushion conveyor.关键词：Air cushion belt conveyer;Film thickness;Analysis and research
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- 195
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发布时间：2022-09-22 - 摘要：The compression open hole packer was one of the core parts of horizontal well open hole staged fracturing completion technology. Due to working in an environment of high temperature,high pressure and complex and deep stratum,the packer setting often turned to low pressure and losed efficacy earlier. The main reason was that the sealing structures of the packer were unreasonable,which reducing the contact stress between rubber and well wall. Based on the elasticity theory,the maximum contact pressure of packer rubber setting was derived and a new sealing structure of compression open hole packer was constructed which consisted of four-rubbers. By using ABAQUS,the contact stress distribution between conventional and new combined rubbers were comparativelly analyzed in the same condition,and the head face bevel of new type combined rubbers was optimized.In the end,the effects on contact stress of new type combined rubber tube caused by friction factor were discussed. The analytical result shows that the new sealing structure could transfer the setting force to sealing rubbers more effectively,and the contact stress significantly increased and distributed more evenly,which ensuring the reliability of the sealing rubber.关键词：Staged fracturing;Compression;Open hole packer;Rubber;Sealing structure
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- 262
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发布时间：2022-09-22 - 摘要：Based on the design of the new type of humanoid foot shaped wheelchair and the usage of large-scale engineering software named ADMAS,to simplify the wheelchair model to establish a multi-body dynamics system,and analyzed a virtual prototype simulation. In order to apply the rotation pairs of the front and back wheels of the wheelchair of the ADAMS and IF function and AZ function,many simulation experiments are carried out to simulate the parameters of the driving motor and the mechanical parameters of the mechanical legs. The mechanical characteristics of the key parts of the robot are compared. The kinematics curves and the mechanical curves are analyzed. And the stability of the climbing process is analyzed. It provides an important basis for reasonable selection of the model and the length of the machine,and provided a theoretical basis for the optimization design of other mechanisms.关键词：Humanoid foot type stair climbing wheelchair;Multi-body dynamic;Motor selection;Structure parameter optimization
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- 330
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发布时间：2022-09-22 - 摘要：In order to ensure the safety of ship escalator,the force on metal truss were investigated when ship escalator running process is affected by the ship’s static,roll,pitch and heave. The truss stress and deformation are obtained by taking static analysis on metal truss with software ANSYS. The results shows weak part of metal and it is improved to meet standard requirements.关键词：Ship escalator;Metal truss;Load;ANSYS
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- 164
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发布时间：2022-09-22 - 摘要：Aiming at the people’s requests of comfort and functions,a rack of massage chair was designed. Numerical analysis was done based on the three-dimensional model. Kinematic simulation was run on the virtual prototype model based on the ADAMS software,the functions was verified and the theoretical basis was supported for the choose of the electric putter.Finite element analysis was done on the key components of the structure under the environment of ANSYS Workbench,the strength and stiffness were checked. Experimental study was done after the prototypes were made. The research results indicate that the rack can meet the function requests of zero gravity and zero against the wall. The strength and stiffness of the structure can meet the requests of the testing standard. The experimental results consistent with the numerical analysis results. That verifies the validity of numerical analysis. The research results also offer important basis for the later structure optimization.关键词：The rack;Numerical analysis;Zero gravity;Zero against the wall;Experimental study
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- 194
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发布时间：2022-09-22
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