最新刊期
期 4 ， 2016
- 摘要：Translational-rotational coupling dynamic model of the cylinder gear transmission system was established using the lumped-parameter method,which considered the time-varying mesh stiffness,mesh damping,friction of tooth surface.According to the design parameters,Runge-Kutta was used to get the vibration displacements of each gear and the mesh force of the gear pair. The multi-body contact dynamics model of the gear transmission system was built based on ADAMS,and dynamic mesh forces and vibration displacement and vibration velocity were obtained by the simulation. With the test plan,the vibration acceleration of the gear transmission system was measured,and then the velocity and displacement could get by numerical integration to analyze the vibration characteristics. The results show that in terms of gear velocity and displacement,the test data and theoretical analysis results have good consistency,which verify the feasibility of comparative rearch of the two method.关键词：Gear dynamics;Lumped-parameter;Dynamic response;Multi-body dynamics
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发布时间：2022-09-22 - 摘要：This paper presents an investigation of the nonlinear problem of electrically actuated single-walled carbon nanotube. A clamped-clamped carbon nanotube connected to the fixed electrode plate,forming a capacitor under the external excitation voltage. According to the beam theory,the nonlinear dynamic equation of carbon nanotube system is established,it is a nonlinear partial differential equation. By means of the method of multiple scales,nonlinear vibration equation of the system is acquired and the numerical calculation is carried out. Numerical analysis of the influence of different parameters is analyzed.With the increase of carbon nanotube length and AC voltage,the amplitude and the unstable interval become larger. With the increase of carbon nanotube radius and plate distance,the amplitude and the unstable interval become smaller. Whenσis close to zero,the amplitude of the response curves hardly changes with the other system parameters.关键词：Single-walled carbon nanotube;The method of multiple scales;Weak nonlinear;Harmonic excitation
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发布时间：2022-09-22 - 摘要：Supposing the oil film at the laminar state,an approximate analytical method is proposed for calculating nonlinear oil film forces of finite length journal bearing. The dynamic ‘π’oil film assumption is usually taken to determine nonlinear oil film forces in the dynamic analysis of hydrodynamic journal bearing-rotor system. However oil film field is not‘π’zone. In this paper,the assumption is taken that the start position of the oil film is 0,and the termination position needed to be calculated.Based on the variational principle,the separation of variables is employed to obtain the pressure distribution in this paper. The results calculated by the proposed method are in good agreement with the oil film forces by the finite element method. Meanwhile,the influence of the parameters on the oil film forces is analyzed.关键词：Oil film forces;Finite length journal bearing;Separation of variables;Variational principle
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发布时间：2022-09-22 - 摘要：There are no rules and standards relating to the calculation of pinned connection because of its partial structure and internal stress state are very complex. In the design of pinned connection,great strength reserves are chosen to compensate for the lack of calculation accuracy. The typical pinned connection in the crawler crane luffing tension plates was took as the research object,based on similarity theory,the distorted model photoelastic experiment was conducted to study the mechanical behavior of pinned connection and the stress state of tension plates. Based on the results of pinned connection in the tension plate,Setting algorithm parameters of finite element,the results can be used as a reference in the designing and checking of pinned connection.关键词：Pinned connection;Digital photoelastic experiment;Similarity theory;ANSYS
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发布时间：2022-09-22 - 摘要：Cutting chatter is one of the major problems which constraints the high-performance and high-precision of the machining products. A damping lathe tool based on intelligent material — magnetorheological fluid was developed in order to effectively suppress cutting chatter by using excellent mechanical-electrical coupling characteristics of smart material. The investigations show that hysteresis nonlinearity is a characteristic of magnetorheological vibration damping device. So,an accurate mechanics model of damping lathe tool is essential to implement cutting chatter control effectively. A steady-state vibration testing platform was established in the paper. Through steady-state vibration experiment,force—displacement hysteresis curves have been explored under different excitation current and vibration frequency. Based on the theory of nonlinear hysteresis and combined with the data decomposition and parameter identification,the nonlinear elastic force、damping parameter、the hysteresis stiffness and hysteretic restoration force are calculated. It lays a theoretical foundation for chatter control with the damping lathe tool later.关键词：Magnetorheological;Nonlinear hysteresis;Steady-state vibration;Stiffness;Damping
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发布时间：2022-09-22 - 摘要：In order to study the turnabout roller coal slime freezing adhesion problem in the process of open-pit mine during winter,experimental apparatus was designed by ourselves,simulated the production site,studied the change of freezing adhesive characteristics of different material in different temperature and different freezing time condition. The results show that different materials and dry basis moisture content 40% of the coal slime have different freezing adhesive strength,among them PTFE material in normal and tangential freezing adhesive strength is lower than other materials,2. 5hours at- 25℃,normal freezing adhesive coefficient is 0. 037 MPa,tangential freezing adhesive coefficient is 0. 076 MPa,it is about 1 /3 of UHMW-PE material ’s normal freezing adhesive coefficient,and about 1 /6 of it’s tangential freezing adhesive coefficient; it is about 1 /44 of Q235 material’s normal freezing adhesive coefficient,and about 1 /19 of it’s tangential freezing adhesive coefficient,It illustrates PTFE has good antifreezing adhesive ability. Tests also show that temperature of freezing adhesive strength has a certain influence,but is not a linear relation; After 3 hours freezing adhesive strength change is small; Material of tangential freezing adhesive coefficient is usually larger than normal freezing adhesive coefficient; Surface freezing adhesive strength is independent of how much coal sample.关键词：Roller;Freezing adhesion;PTFE;Freezing adhesive coefficient;Coal slime
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发布时间：2022-09-22 - 摘要：Butt-weld specimen has been made for coke drum material 15 Cr MoR. For both parent and weld materials,uniaxial tensile tests and uniaxial ratcheting tests have been conducted under different temperatures. The OW-II kinematic hardening constitutive model has been used to predict the material ratcheting effect using the experimental data obtained. Test results show that the OW-II model can well predict ratcheting strain rates for the stable period. Based on the obtained uniaxial tensile test data,basic parameters for predicting low cycle fatigue life have been obtained. The MSRS model has been used to predict the fatigue lives of the parent material and weld metal. The predicted results are within the 2 times error band and are uniformly distributed on both sides of 45 ° line accurately. Furthermore,the ratcheting strain rate and the strain amplitude for the stable period are obtained for the parent metal and the weld metal respectively by the OW-II kinematic hardening constitutive model under the same conditions. The MSRS model predicts that the fatigue life of the parent material is significantly lower than that of the weld metal and during the stable period the ratcheting strain rate of parent material is significantly higher than that of the weld metal.关键词：15CrMoR;Ratcheting;Low-cycle fatigue;Life prediction
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发布时间：2022-09-22 - 摘要：Use of a color code to identify fringe orders has been in use in conventional photoelasticity. Phase shifting technology is the most widely used for isochromatic evaluation due to its simplicity and accuracy. The phase shifting method obtain isochromatic only in a wrapped form. On the one hand the colors tend to merge beyond fringe order three in white light photoelasticity,and on the other phase unwrapping is a challenging issue. Due to the fact that the isochromatic fringes are continuously varying in fringe patterns,the white light photoelasticity and the phase shifting technique are adapted to determine the isochromatic fringe orders. The advantage of new approach allows for determination of isochromatic fringe orders regardless whether the zero-order fringe is present or not. Experimental demonstration was performed on a disc under compressive loading.关键词：White light photoelasticity;Isochromatic;Phase shifting;Unwrapping
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发布时间：2022-09-22 -
THEORETICAL ANALYSIS AND EXPERIMENTAL STUDY USED FOR SOUND QUALITY OF INVERTER AIR CONDITIONER NOISE
摘要：The A-weight sound level is difficult to evaluate the annoyed noise of the inverter air conditioner,so it is necessary to establish the sound quality and give objective evaluate parameters,such as loudness,sharpness,roughness,psychoacoustic annoyance etc. The sound quality software is developed to analyze outdoor noise of MIDEA inverter air conditioner and the competitive product; the main difference is low-frequency noise. Then,the"rock"noise and periodic"buzz"noise are analyzed in detail,and system dynamic balance and beat are main reasons. Some methods are obtained to eliminate the lowfrequency noise and can improve the sound quality. These methods can potentially become a powerful air conditioner sound evaluation tool in inverter air conditioner field.关键词：Inverter air conditioner;Low-frequency noise;Sound quality- 4
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发布时间：2022-09-22 - 摘要：In order to evaluate the safety of the derrick,taking a tower drilling rig derrick as the prototype,scaling factor and steel products style was confirmed,and laboratory model derrick was established. Static and modal finite element simulation analysis and test was done and got the stress distribution rule,the first ten natural frequency and modal modes. Comparing the results of simulation and test,the test results agree well with the simulation results,the error in the limitation,which verify that the finite element simulation means are correct. At last,the safety evaluation was undertaken on the model derrick,the evaluation results of modal derrick was extrapolated to the actual derrick according to the similarity relation,and then the safety assessment of the prototype derrick was done. These provide the methods to study the safe bearing capacity,structure optimization design and using of the real derrick.关键词：Model derrick;Finite element simulation;Test;Safety evaluation;Results extrapolated
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发布时间：2022-09-22 - 摘要：As for the mechanical strength of permanent magnet components,the researchers used the pressure testing machine to test the load limit of the products and observed the samples of the fracture surface with the scanning electron microscope. Then the researchers conducted comparative experiments on the permanent magnet components in the process of the pre-sintering,fine grinding and sintering,etc. The results show that Zr O2 should be added at 0. 10% 0. 20% with oxygen content at 9% 10% and pre-sintering temperature at 1 290 ℃ 1 310 ℃ for 2-hour preservation. Besides,the particle size of the slurry should be well distributed at the fine-grinding stage. In particular,the temperatures of permanent magnet components should increase slowly within the most-shrinkage temperature range（ i. e. 1 050 1 200 ℃） and be stably and effectively controlled at the highest sintering temperature area. All these requirements are conducive to the improvement of permanent magnet components in the respect of their microscopic structures,magnetic properties and load limit.关键词：Permanent magnet;Mechanical strength;Load limit
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发布时间：2022-09-22 - 摘要：Polymethyl Mechacry（ PMMA） has been widely used in aircraft structures such as windscreen and cockpit canopy because of its excellent performance of strength and transparence. The capacity of its resistance to crack growth is important to the service life and safety of the aircraft. The crack growth rate of three different PMMA has been tested using the CCT specimens. The tested data was dealt with seven point incremental polynomial method to compute the relationship between crack growth rate and range of stress intensity factor under various test conditions. The influence of stress ratio and residual stress has been analyzed. The experimental results provides the basis and reference to the selection,utilization and maintenance of PMMA for the aircraft.关键词：PMMA;Fracture crack growth;Seven point incremental polynomial method;Stress intensity factor;Stress ratio
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发布时间：2022-09-22 - 摘要：When lubricating gas film of aerostatic guide way worked in micron level,internal airflow was affected by rarefied gas,the pressure and flow rate along flow direction was different to the result of calculating. In the gas film height direction,due to the characteristic scale decreased,the effect of gas molecule was intensified,traditional assumption of ignored vertical pressure gradient no longer founded,not only interior air film present obvious stratified trend,but velocity slip phenomenon was more significant. Simulating flow patterns and calculating its velocity and pressure in gas film by LAMMPS（ Large-scale Molecular Massively Parallel Simulator）,LBM（ Lattice Boltzmann Method） and Fluent in this paper,came to the relevant conclusion: the gas film in the longitudinal direction was divided into pressure-driven area and Newton friction area,and it also was divided into near wall layer,thin layer,continuous flow layer along its height direction,velocity slip mainly occurred in the near wall layer and thin layer of pressure-driven area. Gas stratification and velocity slip present in pressure-driven and Newton friction areas;Gas Stratification and velocity slip was enhanced with increasing gas flow rate,gas film stratification in Newton friction zone was gradually weakening,slippage speed gradually degenerated into near-wall boundary layer.关键词：Rarefied effect;Velocity slip;Knudsen number;Molecular collision;Newton friction
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发布时间：2022-09-22 - 摘要：The miniature ball grid array（ BGA） solder joint three point bending stress and strain finite element analysis models were set up,and the influences of ball diameter,ball height,pad diameter and bending load speed on the stress and strain of miniature BGA solder joints were analyzed under the three point bending load. The results show that both of the maximum stress and strain of miniature BGA solder joints increase with the increase of the ball diameter,ball height and bending load speed respectively,whereas reduce with the increase of the pad diameter. With 90% confidence,the ball diameter has a certain effect on the maximum bending stress,the ball height and the pad diameter have no significant effect on the maximum stress of miniature BAG solder joint. The ball diameter,pad diameter,ball height affect the maximum stress of miniature BGA solder joints in a descending order.关键词：Microelectronic package;Ball grid array solder joint;Three point bending load;Finite element analysis;Stress and strain
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发布时间：2022-09-22 - 摘要：The traditional servo system has the advantages of simple structure and reliability,but it is easy to change with the parameters of the motor,so the anti load disturbance performance is poor,and the robustness is weak. In order to solve this problem,an adaptive fuzzy sliding mode controller is added to the system. As a kind of non continuity control,the biggest advantage is that the sliding mode is completely adaptive to the interference of the system. The integral sliding mode surface is used to design the switching function and the fuzzy method is used to realize the high precision control of linear systems and nonlinear systems. The simulation results show that the adaptive fuzzy sliding mode control is not only robust and fast response speed,but also can greatly weaken the chattering phenomenon of sliding mode control under the similar control effect.关键词：Servo system;Self-adaptation control;Fuzzy approximation control;Sliding mode control
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发布时间：2022-09-22 - 摘要：The integrated topology optimization design with respect to the structural topology configuration,the placements and the numbers of actuators as well as the control system weight parameters of a cantilever piezoelectric intelligent plate is studied in this paper,. The simultaneous optimization and topology extraction are realized by combining with design of linear quadratic optimal control system in coupled modal space,and strategies based on micro-genetic algorithm and wavelet analysis for noise reduction. Results of numerical examples show that the presented new method is rational and effective,with small computational cost and high efficiency. Meanwhile,clear structural topology and high control performances are obtained.关键词：Integrated topology optimization design of structure / control;Micro-genetic algorithm;Wavelet analysis for noise reduction;Topology extraction
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发布时间：2022-09-22 -
THE STRUCTURE OPTIMIZATION AND ANALYSIS OF THE SEMI-AUTOMATIC RAIL-MOUNTED BILATERAL CASTING MACHINE
摘要：With new semi-automatic rail-mounted bilateral casting machine as the research object,the study is mainly about the light-weight design and mode analysis after the optimization of the concave frame in main bearing parts of the casting machine.At the same time,static analysis of casting machine support system was made. Based on optimization design function of ANSYS Workbench,with total weight of concave frame as target function,total deformation volume as constrain function,section size of each part structure as optimization variable,the study made optimization design for concave frame by modal analysis. The study has reduced vibration and improved work stability. Its working security was determined through stress and deformation analysis of casting ladle support system. The study has also strengthened processing and optimization of its weak part. The casting machine performance has significantly improved after optimization. The process provides a reference for optimal design of casting machinery and other devices.关键词：Bilateral casting machine;Concave frame;Light-weight design;Modal analysis;Ansys workbench- 4
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发布时间：2022-09-22 - 摘要：According to the characteristics of waste PCB（ Printed Circuit Board）,an energy-efficient disassembly device was designed in this paper. PCB was heated by high temperature and high speed gas. And then the THD（ Through Hole Device）and SMD（ Surface Mount Devices） on PCB were removed by spiral hob. The cutter parameters were optimized for the optimization goal the minimum damage of THD. The research results showed that: When the diameter of the knife roller is 30 mm,the helix angle is 26°,the blade pressure angle of 0°,spiral line number is 4,the dismantling effect of THD is the best.New methods and technologies are provided for the efficient,green waste PCB recycling processing.关键词：PCB;Disassembly device;Cutter parameter optimization
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发布时间：2022-09-22 - 摘要：In order to obtain the positions of load spectrum measuring points of the loader working device,the structural strength and fatigue strength of the working device were evaluated. The bucket force model was set up and the working device finite element model was builted. The method with typical operating conditions was used in simulation and experimental research on the structure strength analysis. The results showed that the simulation results agree well with the measured values,and the error of them between the 1. 6% 7. 3%,so as to effectively determine the load measuring point location area. Goodman fatigue limit diagram method was used to evaluate the fatigue strength of the measuring point. The results showed that the structure satisfied the requirements of fatigue strength. The static strength and fatigue strength evaluation were combined to obtain a more complete structural strength analysis method. Structural strength analysis and test results provide bases for the load spectrum test and fatigue life analysis of the loader working device.关键词：Loader;Working device;Structural strength;Fatigue strength
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发布时间：2022-09-22 - 摘要：Sheet metal thickness of single point incremental forming deforming deformation zone is one of the important factors affecting parts strength and quality,it is believed that thickness follows the law of cosines and only depends on the size of the forming angle. This paper mainly research on deformation zone of conical parts from theoretical calculation and finite element simulation and experiment of these three kinds of aspects. It is research deformation thickness that is divided into several quarters,and analyzes the impact of tool head diameter,spacing of layers,the pressure plate’s inner diameter and the trajectory of forming on thickness of each region. The results show that a large tool diameter and small inner diameter of the plate can help to reduce to the thickness thinning rate,and improve the degree of uniformity of thickness; the large layer spacing can be increasing to thickness reach a stable value of speed; pressing point uniformly distributed trajectory can increase the minimum thickness and the average thickness,and has no effect on the degree of uniformity of thickness.关键词：Incremental forming;Deformation zone thickness;Experimental research;Finite element simulation
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发布时间：2022-09-22 - 摘要：when the material interface received strong impact,the large gradient zone or mutations of the pressure and velocity will appear on both sides,and in this case,the numerical simulation has become extremely difficult. Effect of strong impact on gas-gas and gas-liquid interface is studied numerically by Runge- Kutta discontinuous Galerkin method. Ghost fluid Method is r GFM and limiter is TVB limiter with M = 150,and the results showed that the impact is very easy to transfer to gas gas interface,and the impact of transmission is very difficult to through the gas-liquid interface; Error is very small when the impact of strong impact on the gas-liquid interface is on the numerical simulation,and the effect is good; The simulation of gas gas interface can capture the shock wave,but there are some error on the simulation of high density area,and it still need to continue to improve.关键词：Runge-Kutta discontinuous galerkin method;Strong impact;High resolution;Interface tracking
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发布时间：2022-09-22 - 摘要：Even a small axial vibration or an axis deflection vibration of the aerostatic bearing of DFC tool can be quite significant for ultra-precision machining. It is of great importance to obtain the accurate axial bearing characteristic（ bearing capacity and thrust stiffness） during its design,parameter optimization,machining and using process. However,there exists many error terms in the engineering practice to test the axial bearing capacity（ thrust bearing capacity） of T aerostatic bearing,such as, the machining error, effect of environment factors（ temperature, humidity, etc.） on the micro-displacement measurement device,deformation and deflection of the structure itself during the loading process,etc. All these lead to a large error between the measurement stiffness value and the actual value. Based on these problems,this article studied the axial bearing capacity（ thrust bearing capacity） of T aerostatic bearing by means of finite element simulation. Meanwhile,the influence of orifice number and air supply pressure on the axial bearing capacity（ thrust bearing capacity） of T aerostatic bearing is also studied and the accuracy of the simulation results has been validated by the carried out experiment.关键词：Aerostatic bearing;Axial bearing capacity;Orifice number;Inlet pressure
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发布时间：2022-09-22 - 摘要：Based on the horizontal two-cylinder diesel engine,the main bearing elastohydrodynamic lubrication model was constructed in AVL EXCITE PU software,some results were acquired at the maximum torque working condition（ 1600 r / min）under the consideration of the roughness of bearing bush and journal. The results showed that three main bearings’ minimum film thickness and maximum film pressure satisfy the design criterion. The 2nd main bearing ’s maximum film pressure is about150 MPa which is the oil pressure limits. The 2nd main bearing orbit was obvious centripetal movement,which showed that the2 nd main bearing had obvious bending moment. The bending moment was considered to analysis object,and the parameters influence to bending moment is width of main bearing,bearing clearance,oil groove width and oil port position with the orthogonal experimental design.关键词：Internal combustion engine;Horizontal diesel fngine;Main bearing;Elastohydrodynamic lubrication;Influence relationship
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发布时间：2022-09-22 - 摘要：Objective Analysis of torque screwing performance and four kinds of ultimate failure stress distribution of the J55 high strength no shoulder tubing premium connection,the inner wall of the tubing connection is smooth and alignment in favor of the eccentric wear of pumping rod. Methods Establish theoretical model for the specifications of 73. 02 × 5. 51 mm J55 high strength special thread joint pipe,stress analysis、four kinds of limit load failure（ stretched to failure、compressed to failure、internal pressure to failure、external pressure to failure） stress distribution and the theoretical limit failure load analysis,stress distribution and rationality analysis of threaded joints under various conditions of the whole stress,the stress analysis of sealing ring contact. Results The finite element analysis shows that the stress distribution of the oil pipe torque screwing was reasonable,sealing rings were kept in high contact stress,and joints on the top end of the face as a assisting seal has been maintained at high pressure,the main seal and end assisting seal of Teflon seal ring were work together,the joints shows good sealing ability. The failure of four kinds of limit load（ respectively as 408. 9 k N、584. 1 k N、84. 0 MPa、87. 0 MPa） are better than the strength requirements of the round thread in the API standard. The stress distribution of the threaded joint is reasonable. Conclusion The middle diameter of the threaded joint during the torque screwing can be reduced appropriately,in order to improve the performance of anti adhesion; in four kinds of limit load failure mode,the performance of high strength and special screw thread joint is good,accord with strength requirement of the specification of round thread in the API standard; the main seal and auxiliary seal effect of sealing ring is good.关键词：J55 tubing;Premium connection;Finite element analysis;Stress;Sealing ring
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发布时间：2022-09-22 - 摘要：For the planet transmission device whose sun gear shaft is connected with tooth coupling,floating displacement of the sun gear directly determines tilt angle compensating of the tooth coupling,However,because of the sun gear ’s floating displacement multiply affects by comprehensive errors of planetary gear train parts,Its real value is difficult to calculate and measure accurately. This paper proposed a method,which is based on the dynamics analysis principle,to solve the sun gear’s floating displacement. It applies the means of equivalent meshing error to consider the manufacture and installation error of planetary gear train key components,a dynamic model of planetary gear train has been built,and according to the geometric relations between drum shaped spline and sun gear shaft,the tooth profile of drum gear has been modified to reduce the misalignment of the two connecting shafts. Finally,the experiment of certain planetary-gear transmission demonstrates that theoretical model is correct and possesses significant value of engineering applications.关键词：Planetary transmission;Dynamic analysis;Floating displacement of the sun gear;Gear coupling;Profile modification
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发布时间：2022-09-22 - 摘要：Some external pressurized thin walled cylindrical shells could only be stiffened by small stiffening rings due to structural limitations. Such stiffening rings can only partially stiffen the cylinder which is less effective than big stiffening rings.Eigenvalue buckling analysis was done for a series of external pressurized thin walled cylindrical shells with various stiffening rings,which demonstrates two different types of buckling mode according to stiffening ring dimensions. When the stiffening ring is strong enough,buckling occurs only in the cylindrical shell with wave number bigger than 3,and the critical external pressure is irrelevant to the dimension of the stiffening ring,which should be defined as strong stiffening structure,and the ring as strong stiffening ring. However,when the stiffening ring is small,buckling occurs in both the cylindrical shell and the stiffening ring with wave number changing from 3 to 2 as the stiffening ring gets stronger,and the critical external pressure increases with the dimension of the stiffening ring,which should be defined as weak stiffening structure,and the ring as small stiffening ring. By parametric study,the design boundary curve was worked out for the weak and strong stiffening structures. For the weak stiffening structure,the design boundary curves have been also worked out to separate the 2 waves and 3 waves buckling. Empirical formulae were given out for the weak stiffening structures. Compared with the allowable external pressure given by the approximate calculation of HG / T20582-2011,the result by the suggested method is about 100% 450% higher,which is in favor of light weight design of structures.关键词：External pressure;Thin walled cylindrical shell;Stiffening ring;Weak stiffening;Buckling pressure
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发布时间：2022-09-22 - 摘要：According to the demand of outdoor rubbish advertisement cleaning,the design idea of a portable garbage advertisement cleaning machine is put forward. Its structure and function are designed and analyzed. The cleaning machine is mainly composed of a floating brush,a guide rod and a box. Driven by electricity,the brush rotates at the speed of 3000 r / min.The static method is used to analyze the stress of the brush and the guide rod,the mathematical model of brush is established,and the optimum solution of brush size and motor power is obtained by using MATLAB. the three-dimensional solid model of the cleaning machine is established by pro / E,static and modal analysis of brush are completed using ANSYS. The results showed that the stress is less than the allowable stress,And the stiffness was preferably,it is satisfied to design requirements. It provided a new method and idea for the research of this kind of cleaning machine.关键词：Rubbish advertisement;Cleaning machine;Finite element analysis;Floating broom;Portable type
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发布时间：2022-09-22 - 摘要：According to the requirements of the CBM special rotary control head lubrication and cooling system and combined with the existing mature rotary control head lubrication cooling technology,this paper designed a structure without cooling and lubricating pump station plugins. In order to ensure the structure satisfies the lubrication and cooling requirements of the rotary control head sealing system and bearing group,this paper applied the finite element analysis software and indoor experiment to carry out the thermodynamic analysis on the rotary control head lubrication and cooling system. The results show that the lubrication and cooling system meets the design requirements. The upper stabilizing bearing temperature is highest which is 71. 9 ℃ while the highest temperature of the dynamic seal assembly is 60℃. In addition,eccentricity,sealing pressure and rotating speed have greater impact on the lubrication and cooling system,the system temperature changes with the above three factors similarly to a linear change.关键词：Coalbed methane;Rotary control head;Lubricating and cooling;Thermodynamic analysis
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发布时间：2022-09-22 - 摘要：The chip component no-fillet solder joints finite element analysis models were set up. The influences of pad length,pad width,solder joint volume and solder joint material on the stress and strain distribution on no-fillet solder joints were analyzed under the thermal cyclic loading. The results show that the maximum strain and strain distribution in the chip component no-fillet solder joint are larger than that of the chip component solder joint with the fillet. On the condition of only changing the pad length,pad width,solder joint volume respectively,the maximum stress and strain in the chip component no-fillet solder joint increase with the increase of the pad length and the solder joint volume respectively,whereas reduce with the increase of the pad width. For the solder joint material of Sn63Pb37,Sn62Pb36Ag2,SAC305 and SAC387,the lead free SAC305 no-fillet solder joint has the minimum stress and strain under the same condition.关键词：Chip component;High-density assembly;No-fillet solder joint;Finite element model;Thermal cycle load
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发布时间：2022-09-22 - 摘要：In order to enhance heat transfer performance of plate-fin radiator,multi-objective optimization was carried out to the structural parameters of the serrated fin based on the genetic algorithm. According to the result of optimization,threedimensional physical model of the channel was built. The temperature field was investigated by the method of CFD. The heat transfer factor,friction factor and comprehensive performance evaluation factor of fin were obtained. The simulation results show that the heat transfer performance of the optimized fin was improved. Heat transfer performance of copper fin is better than that of aluminum fin. The validity of the simulation result is verified by wind tunnel test.关键词：Genetic algorithm;Thermal performance;Fluid-solid coupled;Heat transfer coefficient
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发布时间：2022-09-22 - 摘要：The pressurized thermal shock（ PTS） event poses a potentially significant challenge to the structural integrity of the reactor pressure vessel（ RPV） during the long time operation. In most countries（ with exception of the USA）,proving RPV integrity under the PTS load is based on the deterministic fracture mechanics（ DFM）. In the USA,the "screening criteria"for maximum allowable embrittlement of RPV material,which form part of the USA regulations,are based on the probabilistic fracture mechanics（ PFM）. In this paper,the FAVOR software of Oka Ridge National Laboratory is used to compare the difference between PFM and DFM analysis of the PTS even. The analysis method of FAVOR is shown through case study of the benchmark transient in the IAEA-TECDOC-1627 report. Finally,the limit of the current FAVOR（ Version6. 1） is shown.关键词：Reactor pressure vessel;Pressure thermal shock;Probabilistic fracture mechanical;FAVOR;Long time operation
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发布时间：2022-09-22 - 摘要：Diesel engine connecting rod bolt withstands pre-tightening force and tensile load in working process,its strength and stiffness have great effect on the performance. An assembly model of the connecting rod which had considered the detail of threaded portion was built,and the strength of those bolts were analyzed with the finite element method. On this basis,the result post-processing program was complied,and the fatigue strength of the bolts was assessed by drawing the bolt material Goodman fatigue curve. The results indicate the rigidity and static strength and the fatigue strength are all within the allowable range; the maximum stress is located in the first level thread,and the most dangerous place of fatigue damage is located in the bolt head.While the static strength and rigidity meet the requirement,using fatigue strength analysis method can find the failure position correctly. Such analysis provides reference for design of bolt.关键词：Connecting rod bolt design;Strength analysis;Finite element method;Fatigue strength analysis
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- 416
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发布时间：2022-09-22 - 摘要：Based on the Grey theory and Markov Chain theory,two prediction models were built,they are Grey Markov Chain prediction model based on absolute distribution（ GMCAD） and Grey Markov Chain prediction model based on probability summation（ GMCPS）. These two models were used to predict the corrosion life of the oil-gas pipeline. Firstly,the calculation method of pit depth was built by the Grey theory. Secondly,test of Markov property was done to verify its feasibility. At last,GMCAD and GMCPS were used,respectively,to predict the corrosion state of the pipeline and results were compared. It indicates that both two models can give a correct prediction and the result from GMCPS is more accurate.关键词：Pipeline;Corrosion;Grey Markov chain model;Life prediction
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- 339
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发布时间：2022-09-22 - 摘要：In order to investigate the failure of composite multi-bolt joints,a continuum damage model for composites which achieved good agreements with experiments,and the Johnson-Cook plasticity model for bolts,were employed to model the singlelap multi-bolt composite joints in this paper. The effects on the composite bolted joints with variable clearances have been studied. It has been found that the clearance has slightly effects on the failure modes and loading responses of the joints,but exacerbates the secondary bending of single-lap joints,and the models proposed in the article have achieved relatively accurate load-displacement responses and ultimate failure loads of the whole joints in simulation.关键词：Composite material;Bolted joint;Continuum damage;Secondary bending;By-pass load
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- 166
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发布时间：2022-09-22 - 摘要：Load spectrum obtained from automobile proving ground contains a large number of high frequency low amplitude loads,so the key step of establishing four-column bench test of a vehicle is to conduct the acceleration processing of measured load spectrum. Based on the measured load spectrum of a certain car ’s proving ground,combined with fatigue cumulative damage rule and low-load strengthening theory,a new principle that named low-load deletion was put forward. With the application of this principle in editing measured load spectrum, the accelerated test spectrum could be generated. The effectiveness of accelerated spectrum was theoretically verified from amplitude domain,pseudo damage and frequency domain.The results showed that,on the basis of retaining damage,together with ensuring the damage of load features and domain features,this method had achieved the acceleration. Finally,in the process of establishing vehicle bench test,the failure mode was consistent with that existed in automobile proving ground,so the rationality of load spectrum’s speedup method was verified.The method could provide a reference for accelerating the draw up of other models’ four-column bench test load spectrum.关键词：Vehicle four-column bench test;Development of spectrum;Low amplitude load;Low-load deletion principle
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- 322
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发布时间：2022-09-22 - 摘要：From the perspective of engineering practice,analysis of stiffened composite wall slab with a Delaminatong at the stringer interface in this paper,and typical structure / typical Delaminatong type is simulated using finite element method. In view of reasons of Delaminatong,feasible proposals of damage control and repair have been raised. Full-scale static test of structures with Delaminatong has indicated that the integer load-carrying capability is determined by the stability of the wall slab. Going with the increase of the working stress due to the Delaminatong between the stringer and the skin,local sustain stiffness of the skin is reduced,resulting in descending of initial bucking load and integer capability of load-carrying. Correctness of the finite element analysis method has been preferably verified by the results of test.关键词：Aircraft design;Composite;FE model;Delaminatong;Stability;Repair
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- 84
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发布时间：2022-09-22 - 摘要：Nonlinear finite element method（ FEM） was adopted to calculate the compressive stability of stiffened panel numerically. Simple support and clamped support of loaded ends as well as common used unloaded edge support fixtures,such as blade,bolt and rigid strip,for stability experiment were simulated by defining node constraint conditions of 4 edges of stiffened panel finite element model. The influences of boundary conditions of loaded ends and unloaded edges on compressive stability of stiffened panel were analyzed according to the FEM calculational results. Calculational results show that,buckling load and carrying capability of panel with loaded ends clamped are bigger than those of panel with loaded ends simply supported. When loaded ends are simply supported,both buckling pattern and failure pattern vary with different unloaded edge boundary conditions,and buckling loads of panel with unloaded edges supported are bigger than that of panel with unloaded edge free.When loaded ends are clamped,both buckling pattern and buckling load are almost the same despite different unloaded edge boundary conditions,whereas carrying capabilities of panel with unloaded edges supported are bigger than that of panel with unloaded edge free.关键词：Boundary condition;Stiffened panel;Compressive stability;Support fixture;FEM
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- 164
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- 3
发布时间：2022-09-22 - 摘要：Gantry crane girder structure testing systems can be measured with the deflection of main beam with different structures in the same test environment. At first,through the finite element analysis,the four-pillar tester couldn’t meet the requirements of the large span bending test,Thus,through the finite element simulation,two pillar tester can meet the test requirements,Besides,the use of reinforced concrete structures constitute a closed since the reaction force loading system with the load frame steel structure,instead of the traditional steel structure used in the large span bending test. Finally,compared with the selection of four column structure,the advantages of the two column structure with reinforced concrete structure are given in equipment costs,installation and debugging.关键词：The finite element analysis;The large span bending test;Two-column testing machine;Reinforced concrete structure
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发布时间：2022-09-22 - 摘要：Traditional method to calculate stress,concrete mixer truck mixing blades are usually of blade stirring power can be converted to uniformly distributed load,but due to the mixing blade in the process of acting force between concrete and is not evenly distributed,so that the calculation results have larger error. In order to accurately obtain the fluid load on the mixing blades. This study used the fluid-structure coupling analysis method,provided application of CFX and ANSYS Workbench numerical simulation analysis was carried out on the mixing blade,then it got the stress of mixing blade in the process of mixing and discharge,and compared with traditional stress analysis results. Analysis results show that the mixing blade root stress value,and the largest parts move biggest blade end,it offers the reliable basis for the intensity of the blade.关键词：Concrete mixer truck;Fluid-structure interaction;Mixing blade;Stress analysis;CFX
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- 245
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发布时间：2022-09-22 - 摘要：Local stiffness and performances of a beam structure will be changed by a crack,which causes changes in mode parameters. Focused on this problem,a simply supported beam is studied based on finite element method. A finite element model of the beam with a vertical embedded crack is presented. Effects of crack length and location on natural frequencies and mode shapes are investigated. Relationships between curvatures of mode shapes and crack length are discussed,as well as those between curvature and crack location. Numerical results show that natural frequencies decrease with crack length,and differences of mode shapes between normal and abnormal beam increase with crack length. Local stiffness of the beam around crack location is changed by the presence of crack,whose area increases with crack length. Curvature of mode shape can be used to detect location of a vertical embedded crack in a simply supported beam.关键词：Vertical embedded crack;Simply supported beam;Finite element analysis;Modal analysis;Curvature
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- 190
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- 1
发布时间：2022-09-22 - 摘要：By mechanical analysis to analyze the mechanism of wheel hub stud rotating and transtensional when taking strenuous test to forklift transmission,if pre-tightening force between rim and wheel hub is not enough because of the unqualified nut,Ground braking force is more than friction force when truck brakes,rim rotates to the brake drum and nut,wheel hub stud bears extra twisting force between rim and nut,causing wheel hub stud rotating and transtesional. Learning the mechanism of wheel hub stud rotating and transtensional is helpful to know further the wheel hub stud working force condition,and it can give theoretical basis to the failure analysis of wheel hub stud and nut关键词：Wheel hub stud;Nut;Transtensional;Ground braking force;Pretightening force;Friction force
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- 91
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发布时间：2022-09-22 - 摘要：This article is intended for proposing a solution to improvement,optimization and lightweight design of the heavy truck’s single-deck frame based on the causes to the fractured traditional double-deck frame assembly produced by SINOTRUCK WANGPAI MOTOR through the optimal design and improvement on the heavy truck‘s frame by finite element analysis of the structural stress and strain,which indicates that the optimized single-deck frame significantly improves in strength and rigidity and is lighter in weight that could satisfy the design requirements. The technology has been successfully applied to mass production of the current product line with good market response and favorable socioeconomic performance brought to the business.关键词：Heavy truck;Frame;Optimization;Lightweight design;Finite element analysis
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发布时间：2022-09-22
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