最新刊期
期 1 ， 2020
- 摘要：According to the working characteristics of varying speed and varying load of wind turbines in the random wind field,and based on the combined wind speed model,the time-varying load caused by random wind speed is studied. Considering internal and external excitations of the gear transmission system of wind turbine,the dynamic equation of the system is derived by Lagrange-theory. The numerical method is used to simulate the dynamics performance of the gear transmission system of wind turbine,the vibration displacement and the meshing force in system which are influenced by time-varying input torque are got.The results can provide a theoretical reference for vibration characteristic analysis and structural optimization design of main drive train of wind turbine.关键词：Wind turbine;Main drive system;Random wind speed;Stiffness excitation;Dynamic response
- 4
- |
- 334
- |
- 3
发布时间：2022-09-22 - 摘要：In order to investigate the transient nonlinear dynamic behavior in connection to the contract between the auxiliary bearing and magnetic rotor under high-speed rotation,bifurcation diagrams,time responses,Poincaré sections and phrase diagrams are synthetically employed in the present article based on the numerical integration method. Firstly,the respective effect of geometric coupling parameter α,proportional feedback gain P and derivative feedback gain D on the system is explored. Then,the impact of stiffness ratio K and Coulomb sliding friction coefficient μ on unbalanced parameter U are also discussed respectively. The results show that when the value of geometric coupling parameter α is large,it can lead to the offset of the rotor from the equilibrium position,corresponding to the rub-impact phenomenon of the rotating rotor and auxiliary bearing so that the equipment is disturbed by the abnormal vibration,however,either the large value of proportional feedback gain P or derivative feedback gain D can be in connection with the stable state of the system. In addition,the softly mounted auxiliary bearing is beneficial to the stability of the system,and the choice of unbalanced parameter U has a significant effect on the state of the system.关键词：Magnetic rotor;Auxiliary bearing;Rub-impact;Vibration;Chaos
- 3
- |
- 362
- |
- 4
发布时间：2022-09-22 - 摘要：Emergency diesel engine is the last safety barrier for nuclear power plants. Nuclear safety criteria require that it can start up to rated speed（ such as 1 500 r/min） within 10 seconds in an emergency and have loading conditions,so its startup performance is particularly important. During the start-up process,the power of high-pressure air is a key factor for success.In this paper,a vibration-based method by analyzing high-pressure air（ domestic units are generally 40 bar·g） power to evaluate starting performance is presented. The large amount of monitoring data obtained indicates that high-pressure air is rapidly charged into the cylinder to generate high-frequency（ approximately 11 kHz） gas exciting impact,and the impact phase will continue to shift backward with increasing speed. Firstly,the Teager energy operator and an adaptive threshold impact location method were used to automatically capture the high pressure gas impact area of each cylinder in each cycle of the start-up phase. Secondly,the energy of the local impact envelope was extracted to characterize the function of the high-pressure air. Finally,the gray evaluation method carried out a comprehensive assessment. The actual test result verifies the effectiveness of this method and has the value of popularization and application.关键词：Emergency diesel engine;Starting performance;Monitoring and evaluation;Vibration and shock
- 5
- |
- 84
- |
- 1
发布时间：2022-09-22 - 摘要：The probability of collisions between offshore wind turbines and ships increases with the development of offshore wind farm. Based on nonlinear dynamic analysis method,through LS-DYNA to simulate the 5000 t ship impact a 4 MW offshore wind turbine tripod at different speed,study rubber-foam aluminum-steel crashworthy devices influence on structure dynamic response characteristics of tower in the process of collision. Comparison and analysis of energy conversion,maximum collision force and stress distribution at the collision between offshore wind turbine and ship collision system with or without guard. The results show that the top of the tower of wind turbine response inhibition effect is obvious after the installation of crashworthy devices; The biggest displacement,velocity and acceleration of top tower than the absence of protective device decreased by 56. 4%,27. 2% and 44. 2% respectively; Tower bottom structure deformation can be dramatically reduced,deep of tower less than the uncrashworthy devices; Crashworthy devices to avoid the collision force focused on tower,to a certain extent,reduce the concentration of stress.关键词：Tripod;Offshore wind turbine;Collision;Dynamic response;Crashworthy devices
- 4
- |
- 122
- |
- 6
发布时间：2022-09-22 - 摘要：In order to improve fault diagnosis accuracy of gear,a fault extraction method of gear based on symbol entropy of LCD was proposed. The vibration signal was decomposed adaptively with local characteristic-scale decomposition（ LCD） to obtain the components in different scales of the original signal. Considering the ability of the symbol entropy in distinguishing the complexity of different signals effectively,the symbol entropy of intrinsic scale components（ ISCs） by LCD was calculated. Thus the complexity metric in different scales of the original signal was gained,which was consequently taken as the feature parameter to describe different gear states. The feature parameters were then put into ANNC for diagnosing the gear faults. Experiment results of gear show that the proposed method can classify typical fault of gear exactly and has certain superiority when compared with some other methods.关键词：Intrinsic scale component;Symbolic entropy;Feature extraction;Gear
- 2
- |
- 95
- |
- 1
发布时间：2022-09-22 - 摘要：Compressive mechanical properties of thin-walled hollow spheres structure were researched by experiment and finite element method. Ping-Pong balls were selected and bonded together with a linking neck to comprise the ideal model of thinwalled hollow spheres structure. The experimental result validated the effectiveness of the finite element model. The effects of the material and geometry parameters of the hollow spheres and the linking neck were then investigated by finite element method. The results reveal that:（ 1） the deformation process of the structure includes four stages: elastic deformation,axisymmetric buckling,forming non-axisymmetric polygon and transforming to axisymmetric mode;（ 2） the elastic modulus and yield stress basically increase with the hollow sphere wall thickness,linking neck radius and center thickness as well as the Young’s modulus and yield stress of spheres material;（ 3） the strain of structural self-contact behavior increases with the linking neck center thickness and radius.关键词：Thin-walled hollow spheres;Cellular materials;Compression experiment;Large deformation
- 5
- |
- 131
- |
- 0
发布时间：2022-09-22 - 摘要：In order to validate the durability attribution of leaf-spring rubber bushing fast and effectively,with the inputs of six-component force from proving ground,and taking rear suspension multi-body model as a carrier,based on the road load data,by applying virtual iteration technique,the dynamic load of bushing has been extracted. In order to keep the connection between the test-rig and the road of proving ground,according to equivalent damage theory,the fatigue test procedure of test-rig has been draw up by using multi-block fatigue load method,and the time consuming of test-rig has been shortened,and acceleration factor of 5. 03 was achieved by comparing the test time of test-rig and proving ground,the bushing has ultimately passed the durability validation of test-rig.关键词：Leaf-spring bushing;Virtual iteration;Dynamic load;Multi-block fatigue load;Test-rig fatigue test
- 4
- |
- 170
- |
- 2
发布时间：2022-09-22 - 摘要：In this paper,the crack propagation test was carried out under the real-time measured load spectrum for eight years. A metabolic model is constructed to predict crack length and the errors between the experimental results and the predicted results under different conditions is compared. The analysis results show that the model,combining with nondestructive testing techniques,could effectively predict crack length without fitting the material constants using a large number of tests. This model can also reduce the influence of load dispersion and material dispersion to prediction results,so that it greatly improves the reliability of prediction results. Moreover,this model can be applied to predict crack length in corrosion environment.关键词：Real-time measured spectrum;Crack length prediction;Information updating
- 5
- |
- 133
- |
- 1
发布时间：2022-09-22 - 摘要：Rehabilitation technique of pipelines plays a very important role in ensuring the safe operation of oil and gas pipelines. Based on the internal pressure test of repaired pipelines by enwinding glass fiber composites,the finite element model of the repaired pipe is established by considering the anisotropy of the composite material. The finite element calculation results are in good agreement with the experimental results,and the accuracy of the finite element model is verified. The results show that the circumferential strain of the defect center presents a nonlinear three stage trend with the change of internal pressure after repaired. The second aggravation of circumferential strain growth trend in defect center is the characteristic of pipeline failure,this moment,the expansion of the tube wall is no longer uniform,and the elastic retention zone on both sides of the defect will cause the dent in the defect area. The research results provide reference for the design of pipeline enwinding layer.关键词：Glass fiber composites;Oil and gas pipelines;Strain analysis;Finite element analysis;Repair
- 4
- |
- 189
- |
- 1
发布时间：2022-09-22 - 摘要：In order to enhance the practicability of hydraulic mechanical continuously variable transmission（ HMCVT） in the field of vehicle,a new method based on improved simulated annealing algorithm and genetic algorithm for optimal design of transmission parameters of automobile HMCVT is presented in this paper. In this paper,a light cargo vehicle is taken as an example. The new method takes into account three aspects: maximum transmission efficiency, matching vehicle design requirements with transmission characteristics and lightweight. The two-stage method is used to optimize the transmission parameters of a three-stage HMCVT. Specifically,10 first stage parameters of planetary characteristic and gear pair transmission ratio are optimized by using genetic algorithm to optimize transmission efficiency and transmission characteristics; 33 secondary parameters of gear tooth number,modulus,helical angle and tooth width with the aim of lightening are optimized by using improved simulated annealing algorithm. The results of optimization design show that the new design method proposed in this paper has better optimization effect and can improve the design efficiency of HMCVT to a great extent; average transmission efficiency increased by 5%; the transmission performance can match vehicle driving requirements,and the design error is 0. 62%; the light weight effect of transmission is obvious.关键词：Hydraulic mechanical continuously variable transmission;Improved simulated annealing algorithm;Genetic algorithm;Transmission efficiency;Lightweighting;Optimum design
- 3
- |
- 167
- |
- 1
发布时间：2022-09-22 - 摘要：In order to realize high efficiency and energy saving in surface milling,this paper takes surface milling as an example to study the optimization method milling path of ball milling cutter based on hybrid algorithm. First of all,considering the spindle speed,feed,surface quality and the actual constraints of no repeat tool,a tool path optimization model with the goal of high efficiency and energy saving was established. According to the workpiece processing requirements,the surface is discretized to obtain a reasonable number of knife contact points. The crossover,mutation and reversal operations of genetic algorithm are introduced to improve the particle swarm optimization algorithm. Finally,the effectiveness of the proposed method is verified by two semi-finishing experiments.
- 3
- |
- 111
- |
- 1
发布时间：2022-09-22 - 摘要：Taking single stage double suction centrifugal pump ASP150-355R as the research object,the rotor structure and accessory parts were modeled by Pro/Engineer. Through the static analysis and fatigue life analysis of the rotor structure by the finite element software ANSYS Workbench,the maximum damage location and the minimum number of fatigue life cycles are obtained,which correspond to the results of static analysis and verify the correctness of fatigue analysis. The ANSYS APDL command flow is used to parameterize the modeling of the rotating shaft and generate the probability analysis file. The reliability of the rotating shaft is analyzed by ANSYS PDS module. The result shows that the reliability of the pump shaft under certain confidence is 0. 936 when the confidence is 95%,the reliability of the rotating shaft structure is 0. 936. The pump group is stable under the design condition,and the working performance of the rotor meets the design requirements. The research results have certain reference value for the performance of similar pumps under design conditions.关键词：Workbench;Rotor;Pump shaft;Fatigue life;Reliability
- 4
- |
- 253
- |
- 1
发布时间：2022-09-22 - 摘要：In order to study the processing method of spring fatigue data,a cylindrical helical compression spring with high service stress was designed and fatigue test was carried out. A new process of spring fatigue data processing is proposed. We developed a Weibull distribution parameter determination program with visual interface using C # and MATLAB mixed programming method based on the traditional Weibull reliability analysis and the graph estimation method based SVM. Using the developed software program analysis of Weibull reliability with different sample sizes spring fatigue data. The methods of graph estimation based SVM and traditional Weibull distribution parameters are compared. The results show that the graph estimation method based SVM has better fitting precision in the case of large sample or small sample. Therefore,the method of graph estimation based on SVM can be used as a method of reliability analysis of Weibull fatigue life of cylindrical helical compression springs. At the same time verify the validity and accuracy of the developed program.关键词：Weibull analysis;Spring fatigue;SVM;Visual interface
- 4
- |
- 411
- |
- 4
发布时间：2022-09-22 - 摘要：In order to improve the reliability of the atmospheric probes of the B737 fleet,this paper takes the fault data of the probes as research object to analyze their reliability. Due to the incompleteness of fault data,this paper first employs the distribution fitting evaluation method to determine that the fault data is in accordance with the right censoring three-parameter Weibull distribution,and then proposes the maximum likelihood method to estimate the parameter of right censoring threeparameter Weibull distribution. According to the definitions of Weibull distribution and maximum likelihood,this paper converts the problem into a two-parameter equation to work out the optimal solution to the problem. Moreover,in light of genetic algorithm,this paper manages to work out the shape parameter β = 2. 2614,the size parameter δ = 5317. 186 and the location parameter θ =13253. 36. Finally,with the aid of KS test,this paper tries to verify the degree of model fitting,proving that it is appropriate to employ the right censoring three-parameter Weibull distribution model. On the basis of the above analyses,this paper predicts the lifespan and the maintenance interval of the probes and offers corresponding suggestions for maintenance. For the airspeed heads with complete maintenance records and limited use,their maintenance and management should be carried out within 10216 flight hours.关键词：Airspeed head;Genetic algorithm;Weibull distribution;Reliability analysis
- 2
- |
- 204
- |
- 1
发布时间：2022-09-22 - 摘要：In order to give full play to the lightweight potential of the tread braking unit（ TBU） overhaul tooling support seat and improve the reliability and robustness of the optimization design,an optimization strategy composed of topology optimization and 6σrobustness optimization was proposed. Support seat’s topology structures was extracted based on topology optimization with variable density method. The response surface model was established based on the central composite design method and the finite element numerical simulation technique. The support seat’s 6σ robustness optimization design model was established based on this model. The sequential quadratic programming method was adopted to solve this optimization problem.The reliabilities of the optimization results were obtained with the mean value first order and second moment method,and were transformed into corresponding σlevels. The results show that reliability of the design variables,strength and stiffness are all 1,reaching eight sigma level,the support seat’s weight is reduced by 67. 0% and the lightweight effect is remarkable; compared with the support seat’s traditional deterministic optimization design after topology optimization,this method enhances the strength and stiffness of the support seat,meanwhile,improves the reliability of the optimization design,the robustness of the strength,the robustness of the stiffness and the consistency of the weight. So the proposed optimization strategy is proved to be efficient.关键词：TBU overhaul tooling support seat;Lightweight design;Topology optimization;6σ robustness optimization;Response surface mode
- 3
- |
- 180
- |
- 3
发布时间：2022-09-22 - 摘要：In order to improve the crashworthiness of the crash cushion energy-absorbing box,firstly,this paper established the"vehicle-crash cushion"FE models of frontal impact,offset impact,oblique impact and frontal side impact in accordance with the regulations,and then a crashworthiness topology optimization method of cellular automata was used for the energyabsorbing box topology optimization in the transverse and longitudinal extrusion constraint respectively,the optimized results show that the obtained beam configuration in the longitudinal extrusion constraint is different from the barrel configuration in the transverse extrusion constraint and it performs better in the crashworthiness. Secondly,taking into account the effects of the design variable uncertainties on the crashworthiness target responses,a multiobjective robust optimization combined with Taguchi method and satisfaction function was carried out for the optimization design of the new beam energy-absorbing box. The results show that the acceleration of the optimized energy-absorbing box is 106. 6 m/s~2,less than 200 m/s~2,it is in good safety performance; SEA is 2. 54 kJ/kg,it improves 32. 8% than before optimization; the total satisfaction increases 30. 4%,it greatly enhances the robustness of the energy-absorbing box.关键词：Crash cushion energy absorbing box;Crashworthiness;Topology optimization;Longitudinal extrusion;Multiobjective robust optimization
- 5
- |
- 305
- |
- 3
发布时间：2022-09-22 - 摘要：In order to solve the problem that temperature drift of silicon piezoresistive pressure sensor affects the accuracy of engineering measurement,proposed a temperature compensation strategy for BP neural network based on glowworm swarm optimization. The generalized BP neural network is used to optimize the weights and thresholds by using the firefly algorithm,thus improving the generalization performance and searching speed of the neural network,carried out temperature compensation of pressure sensor by optimized BP neural network. The temperature compensation performance of optimized BP neural network compares to that of conventional neural network and particle swarm optimization neural network. The results showed that compared with the conventional neural network and PSO optimization BP neural network,the optimized GSO optimization BP neural network is effective.The compensation error of GSO-BP neural network is 52% less than that of BP and 23% less than that of PSO-BP.Considering the time of compensation,the comprehensive performance of the BP neural network optimized by GSO is better.The compensated sensor data meet the experimental requirements of the subject.The compensation algorithm is feasible.关键词：Glowworm swarm optimization;BP neural network;Sensor;Temperature compensation
- 3
- |
- 402
- |
- 2
发布时间：2022-09-22 - 摘要：On the basis of analyzing the transmission principle and structure characteristics of the RV reducer,from the point of view of the system,considering the coupling deformation of the two stage transmission system of the RV reducer,the structure of the cycloidal gear spoke and the bearing stiffness,the analysis model of the meshing characteristic of the RV reducer is established. The meshing characteristics of the pin-cycloidal gear transmission of the RV reducer are simulated and analyzed,and the influences of the thickness of the cycloidal gear,the amount of modification and the load on the meshing characteristics are discussed in detail. At the same time,the torsional stiffness of the RV reducer is analyzed according to the analysis model established. Finally,the test of the pressure stress of the tooth root of pin wheel housing of the RV reducer and the test of the torsional stiffness are carried out. The correctness of the simulation analysis is verified.关键词：RV reducer;Pin-cycloid transmission;Meshing characteristic;Finite element method;Experiment
- 7
- |
- 397
- |
- 1
发布时间：2022-09-22 - 摘要：According to the structure orthogonal anisotropic periodic raised structure plate,the equivalent stiffness of the arc periodic raised structure plate is investigated. Based on the classical theory of elastic thin plate and the homogeneous distribution characteristics of the plate,the analytic equation of the equivalent stiffness of the arc periodic raised structure plate is derived.The finite element method is used to simulate the numerical results of arc periodic raised structure plate with simply supported on Four Sides under the concentrated load. The rationality and accuracy of equivalent stiffness is verified. Then the natural frequency of the arc periodic raised structure plate under simply supported on four sides is calculated by using the analytic method. The calculation results are in agreement with the finite element simulation results,and the correctness of the analytical equation of the equivalent stiffness is verified again. The present new method can be used to calculate the equivalent stiffness of the periodic raised structure plate accurately. Moreover,the calculation is directly performed with the geometric parameters of the typical unit.This method is intuitive and concise,and improves the efficiency of solution. The results have important guiding significance for studying the static and dynamic characteristics of the periodic raised structure plate and engineering applications.关键词：Periodic raised structure plate;Structure orthogonal anisotropic;Equivalent stiffness;Finite element method;Natural frequency
- 4
- |
- 138
- |
- 1
发布时间：2022-09-22 - 摘要：First,the lifting mechanism of neutron spectrometer sample table was designed. Then,the part flexible models and flexible multibody model were built by using ANSYS and ADAMS. Finally,the part flexible models and flexible multibody model were analyzed when lifting mechanism lifts at the highest point and sliding table center moves along the X or Y axis. The results indicate that Z direction’s average deformation is maximum among all direction deformations of sliding table center,which is 30. 12μm. Outer cylinder take up the largest proportion of the deformation in X direction,which is 75. 8%,middle cylinder take up the largest proportion of the deformation in Y direction,which is 91. 32%,inner cylinder take up the largest proportion of the deformation in Z direction,which is 89. 36%. Of eight guide rails of lifting mechanism,four guide rails between inner and middle cylinder are under uniform load,other four guide rails between middle and outer cylinder are under non-uniform load. The findings of the research could guide the design of the neutron spectrometer sample table. In order to develop a high precision neutron stress spectrometer sample platform,the stability and reliability of the sample table is achieved.关键词：Neutron spectrometer sample table;Lifting mechanism;Flexible multi-body model;Finite element analysis
- 3
- |
- 80
- |
- 1
发布时间：2022-09-22 - 摘要：Finite element contact analysis of a planetary drive with small teeth difference in a beveloid gear RV drive was carried out. The results show that the meshing performance differs from that of the traditional gear design theory result. The effect of elastic meshing under different loads on the axial force,contact force,number of actual contact teeth,load distribution among the teeth,contact stress of the tooth surface and tooth root stress. The results of the analysis provide the basis for improving the bearing capacity,gear parameter optimization,tooth profile modification and the strength calculation of parts with small teeth difference.关键词：Beveloid gear;Planetary drive with small teeth difference;Contact analysis;Elastic meshing effect;Finite element method
- 3
- |
- 135
- |
- 1
发布时间：2022-09-22 - 摘要：In order to study the micro-vibration characteristics of satellite platform and the effect of micro-vibration on the payload in space,a six-dimensional disturbance force simulator is designed to simulate the micro-vibration in space. First,the theoretical modeling analysis of the six-dimensional disturbance force simulator was performed. Secondly,the structure design of the uniaxial actuator and simulator model were performed and the finite element simulation analysis was applied on the models.Finally,the uniaxial actuator modal test was carried out and the simulator perturbation force experiment was performed. The results show that the error between the modal test results and finite element simulation analysis results of the single axis actuator does not exceed 2. 46 %; the error between the experimental results of the six-dimensional disturbance force simulator and the results of the disturbance force theoretical analysis is within 5%. Therefore,the six-dimensional disturbance force simulator meets the design requirements.关键词：Spatial micro-vibration;Single-axis exciter;Structural design;Finite element simulation analysis
- 2
- |
- 93
- |
- 1
发布时间：2022-09-22 - 摘要：A parameters optimization of a hydraulic support column remanufacturing method was studied in this paper. The mathematical model of the radial shrinkage of the coating was established by using the constitutive equation,the geometric equation and the relation between the linear expansion coefficient and the temperature variation. The effect of material,coating thickness and assembly temperature on the radial shrinkage of the coated layer and the range of research parameters were analyzed by MATLAB software.The RAMP interpolation model was used to interpolate the material parameters. The optimization model was set up and the optimization solution process was designed. The post column was taken as an example.The thickness of the coating is reduced by 0. 5 mm.The assembly temperature is reduced by 80 degree Celsius and the radial shrinkage force is increased by 0. 0195 N/mm~2. The optimized remanufactured column can reduce the 0. 13 mm and 0. 11 mm,respectively,under the working condition of the conveyer and the moving frame.关键词：Remanufacture;Hydraulic support;Parameter optimization;RAMP interpolation
- 3
- |
- 133
- |
- 1
发布时间：2022-09-22 - 摘要：Rotating sleeve distributing-flow system is a new-type distributing-flow system,overcoming the shortcomings of traditional valve-type flow distribution systems such as large volume,loose structure,and low volumetric efficiency. The cam groove profile of the rotating sleeve directly affects the kinematics characteristics of rotating sleeve distributing-flow system. In this paper,by analyzing the self-locking characteristics of the sinusoidal cam groove profile,four new types of cam groove profiles are proposed,the kinematics analysis of rotating sleeve and drive pins under the four cam groove is performed. The results showed that: the amplitude of the angular velocity and angular acceleration of the line cam groove profile rotating sleeve is the smallest,which is 203. 1 rad/s and 4. 961 × 10~4 rad/s~2,respectively,and there are two impacts in one cycle; The radial speed and acceleration of drive pin under line cam groove profile is the smallest,which is -0. 387 m/s and 115. 0 m/s~2,respectively,and there is no impact during cycles. So,the line cam groove profile is the best choice.关键词：Cam groove profile;Self-locking;Rotating-sleeve;Distributing-flow system
- 3
- |
- 55
- |
- 2
发布时间：2022-09-22 - 摘要：With the increasing requirements of the high-speed CNC machine tools for the motion accuracy of the spindle,it is necessary to study the accuracy of the permanent magnet synchronous（ PMS） grinding motorized spindle. Based on the spindle vibration error and thermal analysis,mathematical models of radial error motion,tilt error motion and axial error motion are established. The least squares approximation algorithm is applied to fit the radial trajectory of the spindle,and then the inclination error is modeled to obtain the tilt angle of the spindle’s axis of rotation. Combined with the time domain and frequency domain signal analysis methods,the axial motion error trajectory is analyzed. To achieve a radial and axial error displacement of the spindle and obtain the spindle thermal error,a typical double standard ball 5-DOF measuring spindle error device is used.Experiments were carried out on the spindle rotation error during the test run by the PMS motorized spindle developed by a domestic machine tool factory. The results show that when the speed increases to the maximum speed,the radial error and the axial error increase,the centrifugal force has a more obvious effect on the spindle accuracy; when there is the spindle eccentricity,the radial error motion trajectory gradually transitions from the approximate circle to the petal state. The double standard ball five-point test method can not only judge the manufacturing,assembly and other problems of the electric spindle manufacturing,and the experimental method can be applied to the experiment of the electric spindle error motion,while satisfying the inclination error,the axial error motion and the spindle temperature deformation test.关键词：Motorized spindle;Spindle accuracy;Motion error;The least squares approximation;Algorithm double standard ball 5-DOF method
- 4
- |
- 153
- |
- 1
发布时间：2022-09-22 - 摘要：According to the influence of glass fiber embedded in flexible photoelectric printed circuit board received the thermal stress. The three-dimensional model of flexible photovoltaic substrate was established. Using the finite element thermodynamic analysis method,the comsol software was used to obtain the thermal stress value of the optical fiber in three kinds of groove structures including rectangular,U-shaped and trapezoidal under the SnAgCu lead-free solder reflow soldering process conditions. The results show that the maximum stress occurs at both ends of the optical fiber. When burying a glass fiber without coating layer,the U-shaped groove structure is suitable and the maximum thermal stress is 116. 8 MPa,which is the smallest one in the three kinds of structures. For coated glass fiber,the rectangular groove one is acceptable,and its maximum thermal stress is 100. 99 MPa; In three kinds of groove structures,the maximum position offset in three directions of XYZ is less than 1 μm.The research conclusion has certain reference value and guiding significance for designing the embedded structure of flexible optoelectronic printed circuit boards.关键词：Flexible photoelectric printed board;Reflow soldering;Optical fiber embedded structure;Thermal stress
- 4
- |
- 131
- |
- 1
发布时间：2022-09-22 - 摘要：The thermal transient load of the primary loop nuclear pipeline will cause fatigue damage at sensitive locations.And cumulative fatigue damage factors of these sensitive locations need to be monitored during the life extension of the nuclear power plant,and thermal transient stresses need to be calculated rapidly during online monitoring. Taking the thermal shock of the spray nozzle of pressurizer as an example,the double temperature boundary Green’s function method is discussed. By the volume integration of Green’s function,the transient thermal stress under the heat-up condition is calculated. The accuracy of the two temperature boundary Green’s function is verified by comparing with the direct calculation results of finite element method.Studies have shown that the Green’s function should be established separately for subdivisions which are divided according to the differences of the flow heat transfer boundary（ such as the convection heat transfer coefficient） and the width of the temperature range. While in a certain temperature range,it is feasible to establish the Green’s function based on the average temperature of the temperature range with large enough step temperature.关键词：Green’s function;Thermal stress;Nuclear pipe;Thermal transient
- 3
- |
- 90
- |
- 1
发布时间：2022-09-22 - 摘要：The performance degradation of combined rotor with crack of the disk is one of the significant reasons which cause malfunctions and accidents of gas turbine,while rules of performance degradation are still unclear. By using the finite element ANSYS platform to establish the combined rotor model,the dynamic analysis of the combined rotor with the crack in disk was conducted. The rules of performance degradation of combined rotor were obtained through defining degradation degree parameters. The rules of the performance degradation of combined rotor with crack in disk were verified experimentally. The results show that the performance degradation of combined rotor is extremely slow in the stable degradation stage,the significant transition point which leads to accidents occurs when the degradation reaches a certain extent. The different temperatures,rotation rate,ratios of crack depth to length and positions of the crack in disk have great influence on the degradation of combined rotor.关键词：Combined rotor;Crack;Operating condition;Degradation degree
- 3
- |
- 105
- |
- 0
发布时间：2022-09-22 - 摘要：Experimental and simulation methods were used to predict the fatigue life of the connecting part of the aircraft beam structure. First of all,based on the statistical analysis,the marker load was chosen. The experimental results show that the marker load method can quantitatively record the initiation and propagation of cracks. Meanwhile this paper established a finite element model of the three-dimensional connection part of aircraft beam structure,with soft-soft contact and pre-stressing force modal. The errors between the results of the finite element model and the static experimental results are within 10%. Finally,with the help of the local stress-strain method and the software FEMFAT,the fatigue life of the test specimens was successfully predicted. The two results were compared to each other. It is find out that the crack formation time generated by the local stressstrain method is radical,while the FEMFAT software can obtain a conservative crack formation time which is consistent with the test results.关键词：The marker load;Pre-stressing force;Finite element analysis;Local stress-strain method;Fatigue life
- 9
- |
- 455
- |
- 3
发布时间：2022-09-22 - 摘要：Based on Reynolds equation and finite element method,the pressure distribution of fluid penetrating into the rail surface crack was calculated by the two-dimensional wheel/rail rolling contact model. Then the stress intensity factor of the crack tip was analyzed,and the effect of fluid viscosity on the rolling contact fatigue crack growth was studied. The results show that the crack propagation mode transforms from type Ⅱ to typeⅠ in the presence of liquid on the surface of the rail,and the liquid that penetrates into the crack is more likely to cause material peeling. The greater the viscosity,the larger the average crack propagation angle,and the propagation path changes from smooth to tortuousthe. When the viscosity is constant,the larger the initial angle of crack,the lower the crack growth rate. And with the increase of viscosity,the crack growth rate decreases.关键词：Rail;Fluid viscosity;Stress intensity factor;Rolling contact fatigue crack;Numerical calculation
- 3
- |
- 190
- |
- 3
发布时间：2022-09-22 - 摘要：As an important fracture parameter,the stress intensity factor plays a crucial role in the fracture analysis of engineering components. Based on the theory of J2 integral and the bending theory in material mechanics,this paper analyzes the stress intensity factors of 60 degree thin-walled equiangular steel corner cracks and edge cracks under tensile and bending loads,and gives a simple and practical method to determine the stress. The method of the intensity factor,the method given can obtain a closed solution,and the calculation is simple. The results are compared with the finite element solution,and the effectiveness of the calculation method is further pointed out.关键词：J2-integration method;Stress intensity factor;60 degree thin-walled angle steel;Angular crack;Fracture
- 4
- |
- 87
- |
- 0
发布时间：2022-09-22 - 摘要：For bolts on the pitch bearing of the connection between the blade and the hub of the 1. 5 MW wind turbine unit,a method to calculate the fatigue damage value of connecting bolts was proposed. First,a reasonable finite element model was established by ABAQUS and moment load to the center of the blade root was added. Then the bending moment time history spectrum was transformed into the stress time history spectrum by MATLAB. And the stress time history spectrum was processed by the rain flow counting method. Finally,the fatigue analysis of the bolt was calculated by the Miner linear cumulative damage theory and S-N curve. The results showed that the fatigue damage value of the bolt was within the safety range,and the fatigue damage of the bolt before the wind turbine reached the service life was very small. The research work can guide the optimal design of the connecting bolts on the entire wind turbine generator and provide reference for fatigue design and life analysis of bolts.关键词：Pitch bearing connecting bolt;Fatigue damage;Finite element calculation;Miner linear cumulative damage theory
- 4
- |
- 308
- |
- 1
发布时间：2022-09-22 - 摘要：In view of the fact that the gearbox body has excess strength and the mass is too heavy,it needs to be optimized.In the current research on optimization constraints,most scholars use static strength as the strength constraint but lack the consideration of fatigue strength. Therefore,based on the fatigue theory,combined with the rain flow cycle count,according to the transmission box specifications to linearly extrapolate the number of cycles to obtain the number of cycles and then as its life,compare the number of extrapolation cycles with the number of test load spectrum cycles,combined with S-N curve of 90%reliability,to obtain the theoretical stress amplitude. According to the dynamic load coefficient,the maximum stress is calculated.Compare it with tensile strength to get individual component strength constraints. It can provide more accurate constraints for optimization,save the subsequent verification process,and improve the optimization efficiency.关键词：Fatigue strength;Rain flow cycle count;Dynamic load factor;Linear extrapolation
- 3
- |
- 180
- |
- 1
发布时间：2022-09-22 - 摘要：Focus on fatigue fracture of shearer cutting gearbox housing（ SCGH）,the fatigue failure mechanism of（ SCGH）is investigated considering both high frequency internal excitation caused by gear meshing and low frequency external excitation caused by coal cutting. Force analysis is proposed to obtain the region of stress concentration and stress values are calculated by finite element analysis. Torque caused by gear meshing Mp and eccentric L0 is firstly considered in mechanical model and the influence of them on strain amplitude is analyzed. Local resonance characteristics are analyzed based on vibration signals of shearer cutting experiment. Power spectral density（ PSD） analysis is used to obtain local resonance frequencies and they were checked to be natural frequencies of SCGH. Based on strain modal analysis,the region of strain concentration of modal shape and stress concentration are compared. The results show that: Region of local resonance modal shape strain concentration is similar to that of stress concentration. 15th 23 th and 27th vibration modes are excited by gear meshing excitation and cause local resonance of SCGH. Beat phenomenon which accelerates fatigue fracture of SCGH is caused by close space of 23th and 27th vibration modes.Fatigue fracture failure of SCGH was caused by both stress concentration and local resonance.关键词：Fatigue fracture;Mechanical model;Local resonance;Vibration experiment;Beat phenomenon
- 3
- |
- 126
- |
- 0
发布时间：2022-09-22 - 摘要：Considering the dispersion of the material properties and load,the collaborative analysis of the air-cooled turbine blade low-cycle fatigue reliability was done using the distributed collaborative response surface method. The deterministic analysis of the turbine blade was completed by the finite elements software. The total strain amplitude and mean stress response surface was established using the artificial neural network and the material life response surface using the linear hetero-variance regression method. The blade life response surface was established by collaborating with the two response surfaces. The low-cycle fatigue reliability analysis of the blade was completed using the Monte-Carlo method. Comparing with the traditional response surface method,the distributed collaborative response surface method is more accurate.关键词：Air-cooled turbine blade;Low-cycle fatigue life;Reliability;Distributed collaborative response surface method;Artificial neural network
- 5
- |
- 253
- |
- 2
发布时间：2022-09-22 - 摘要：In order to solve the problem of multiple failures of the oil collecting box connecting pin of the arc gear toothed when the 1580 mm hot strip mill F2 rolling mill was rolling the thin plate,several field tests were performed on the F2 rolling mill drive system and roll system,and the test signal was processed in time domain and frequency domain. The three-dimensional finite element model of rolling mill was built to simulate the natural frequency of the vibration,including main drive system,roller system and frame. The calculated results are basically consistent with the test results. It can be determined that the mill unit has a resonance and the dominant frequency corresponds to the maximum vibration displacements are found at the side of the gear box,providing an effective reference for further analysis of the mill vibration characteristics and causes.关键词：1 580 mm hot strip mill;Modal analysis;Resonant;Oil collecting box connection pin
- 4
- |
- 78
- |
- 1
发布时间：2022-09-22 - 摘要：Gear transmission system is one of the core components of tracked vehicles. In order to grasp the load characteristics of gears during system operation,this paper built a joint modeling method based on Creo,HyperMesh and RecurDyn software platform based on rigid-flexible coupling dynamics. Based on the time-varying contact force and the flexibility of the gear,the system rigid-flexible coupling simulation model was established and its accuracy was verified by the test bench.Taking a practical working condition as an example,the simulation results of the rigid-flexible coupling model and the rigid body model are compared and analyzed. The results show that the rigid-flexible coupling model can more accurately describe the bearing motion of the gear. According to the variation law of gear stress obtained by simulation,the causes of the interruption of the tooth failure during the system operation are analyzed. The simulation process and results provide a reference and basis for gear fatigue life prediction and system fault diagnosis.关键词：Gear transmission system;Rigid and flexible coupling;Load characteristics;RecurDyn
- 4
- |
- 378
- |
- 2
发布时间：2022-09-22 - 摘要：The methods of consistency evaluation are introduced for the finite element simulation and test of the aircraft structure. First,the strain interpolation method is studied based on the element shape functions,and the transformation method is given for the consistency between simulation and test strain gauges; Second,linearization correction for the test strain gauges was obtained by using the least squares principle. The consistency evaluation methods are investigated based on graph partition and probability respectively. Finally consistency evaluation is carried out for the computation and test of the civil aircraft structure. It is shown that the evaluation results can provide support for the modification of the model.关键词：Structural test;Structural analysis;Aircraft structure;Strain;Consistency evaluation
- 5
- |
- 127
- |
- 1
发布时间：2022-09-22 - 摘要：The hydraulic jacking machine is widely used in mining,construction and other engineering fields. In order to prevent the hydraulic jacking machine from accidents during the jacking process and the equipment failure during the jacking process,it is necessary to add the spacer as the safety device with the jacking up. The height of the work to be carried out is constantly adjusted,which is inconvenient and unsafe. A hydraulic jacking machine with automatic following safety device is designed for this purpose. And the impact stability analysis is carried out with ANSYS LS-DYNA,and the screw combination deflection of the fuse is obtained. The variation law of equivalent stress and the dynamic buckling shape produced by thescrew combination show that the screw combination can withstand the impact of the weight within a certain distance. The maximum distance that can exist between the load-bearing roof and the weight during the jacking process is obtained. It provides a theoretical basis for the design of the jacking machine following control.关键词：Jacking machine;Shock;Stability;Deflection;Equivalent stress;Dynamic buckling
- 3
- |
- 77
- |
- 0
发布时间：2022-09-22
- Technical support is provided by Beijing Founder electronics co., LTD 豫ICP备05013835号-4
京公网安备11010802024621 - It is recommended to read the content of this site in Chrome&IE9+. Please switch to extreme mode in browser 360.
- Cookies We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies.
0