最新刊期
期 4 ， 2018
- 摘要：According to shearer vibration problems in the practical work,using multi-body dynamics theory,considering shearer support characteristics of guide boots and flat boots,and the stiffness of rocker arm and adjustment height oil vat,6 degrees of freedom dynamic model in the vertical direction of shearer was established.The vertical direction of shearer drum load was used as an external excitation,and the effect of different lift angle on vertical direction vibration characteristics of shearer were solved by using numerical analysis method.The results show that the lift angle has great influence on vibration displacement of drum and ranging arm when the range is 17° 37°,and the displacement range is 21.5521 15.424 mm,9.4005 ~3.306 4 mm.Because of the low frequency vibration of shearer under actual operating conditions,the vibration acceleration under different lift angle is insensitive.关键词：Shearer;Lifting angle;Vibration;Numerical analysis
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发布时间：2022-09-22 - 摘要：To simulate the micro-vibration of the space platform such as satellites,space stations and so on,a multidimensional micro-vibration simulator based on the Gough-Stewart configuration was designed.Firstly,the structural design of the multi-dimensional micro-vibration simulator was introduced.The theoretical model of the simulator is established by NewtonEuler’s method.In this model,the situation of misalignment between the origin of the relative reference frame and the barycenter of upper platform and load was considered.Combining with the principle of virtual work,the equations of the natural frequencies and mode shapes could be gained.Secondly,the modal of the simulator was analyzed by the finite element method and the analytical method.The first six natural frequencies and the modal shapes were obtained.The maximum error of FEA simulation is4.17% compared with the mathematical analytical solution.Finally,a prototype of the micro-vibration simulator was manufactured and its performance was testing.The test results indicate that the effective operating frequency of the simulator is up to 100 Hz,meeting the need of the vibration test.关键词：Space optical payloads;Micro-vibration;Gough-stewart configuration;Modal test
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发布时间：2022-09-22 - 摘要：A novel DNC（distributed numerical control） system,which is used to remotely monitor CNC machine tools of FANUC NC system as well as inspection equipment or devices,has been developed based on Socket communication and multithread technology by using SQL Server database and.NET platform.This DNC system can collect the real time information of CNC machines and inspection equipment or devices,and has the functions like the machine state monitoring,data integration and management,performance analysis,fault remote diagnosis,workshop production management,and product quality management and control.In this way,the data integrity and integration has been realized.The architecture of the system is presented and the approaches to the realization of the function modules are elaborated.The data flow,data interpretation and alarm monitoring mechanism are also discussed.This system has been applied in manufacturing plants and performs well.关键词：FANUC NC system;DNC（distributed numerical control） system;Remote diagnosis;Data analysis
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发布时间：2022-09-22 - 摘要：Aiming at the problem that accuracy of orthogonal locality preserving projections（OLPP） for fault diagnosis is not high enough,a fault diagnosis method based on semi-supervised neighborhood adaptive orthogonal locality preserving projections（SSNA-OLPP） for dimension reduction is proposed.In this method,fault features that can represent the fault state is firstly constructed based on local characteristic-scale decomposition（LCD） and time-frequency domain feature.And then,the SSNA-OLPP is used to compress the high-dimension feature into low-dimension feature which has better discrimination.Finally,the low-dimension feature are input support vector machine（SVM） to identification fault.SSNA-OLPP can adaptive adjust the neighborhood with the guidance of local cluster coefficient,at the same time,information of some labeled samples are also used to adjust the weight matrix among all samples in the original characteristic space,as a result,better fault diagnosis accuracy can achieved.The experiment results of rolling bearing fault diagnosis verified the effectiveness of the method.关键词：Fault diagnosis;Dimension reduction;Orthogonal locality preserving projections;Rolling bearing
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发布时间：2022-09-22 - 摘要：Aiming at the problem that the Local mean decomposition（LMD） method is difficult to draw early weak fault,a fault diagnosis method for the roller bearing based on maximum correlated kurtosis deconvolution（MCKD） and LMD was proposed.Firstly,the fault signal was de-noised and meantime periodic impact components were enhanced by MCKD method,Then,that result is decomposed by LMD to get PF,the correlation coefficient between the PF and the signal is used as the standard of judgment,so that the redundant low-frequency PF can be rejected.Finally,the effective PF is selected to analyze the spectrum and extract the fault feature.The experiment of the simulation data and the actual roller bearing fault diagnosis data show that the method can effectively extract the feature frequency information of incipient fault and has a certain reliability.关键词：Rolling bearing;Fault diagnosis;LMD;MCKD
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发布时间：2022-09-22 - 摘要：Deep learning can make the computing model that contains a number of processing layers to learn the data that contains many levels of abstract representation.This kind of learning way in the most advanced speech recognition,visual object recognition,object detection and many other areas,such as biology,genetics and medicine brought significant improvement.Deep learning can find the complex structure of large data,and the convolution neural network as one of the important models of the depth study in the processing of voice,image,video and text,and other aspects of a new breakthrough.It is the use of BP algorithm to guide the machine how to get the error before the layer to adjust the parameters of this layer,so that these parameters are more conducive to the calculation of the model.In view of the shortcomings of traditional BP algorithm,a fast BP algorithm is proposed,which has the disadvantages of slow convergence speed and often falls into local minimum points.The improved convolutional neural network is used to validate the data set MNIST,English character recognition and medical image.The simulation results show the effectiveness of the proposed algorithm.关键词：Deep learning;Convolutional neural network;Improved BP algorithm
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发布时间：2022-09-22 - 摘要：The dynamic mechanical properties of aluminum honeycomb sandwich panels were investigated under low velocity drop weight impact test.The failure behaviors,destruction process and typical force-displacement curves were analyzed.The impact velocities and panel thickness have influence on ultimate impact force and energy absorption was analyzed respectively.The mechanical properties of sandwich panels with corresponding panel thickness under quasi-static test were compared.The tests result show that typical impact load-displacement curve of aluminum honeycomb sandwich panels presents five stages.The ultimate impact force and energy absorption of sandwich panels under different impact velocities are basically identical.With the panel thickness increasing,ultimate impact force and energy absorption of sandwich panels increase.Compared with quasi-static experiment,the ultimate impact force and energy absorption of sandwich panels with three kinds surface thickness under low velocity drop weight impact tests are improved.关键词：Aluminum honeycomb;Sandwich panel;Impact velocity;Panel thickness;Ultimate impact force;Energy absorption
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发布时间：2022-09-22 - 摘要：Aiming at analyzing the reason of damage of safety hanger on metro vehicle,the finite element model and modal test was conducted for modal analysis.Finally,the natural modes near 340 Hz and 990 Hz were obtained.At the same time,in order to obtain the acceleration and dynamic stress level of the safety hanger in the operation process,a line tracking test was performed on the vehicle.According to the test data,it was found that due to the presence of rail corrugation excitation,the energy of the dynamic stress and acceleration at 340 Hz increased sharply,which indicates that the first-order mode was excited to generate resonance.According to the dynamic stress data before and after the rail corrugation,the fatigue life of the safety hanger was evaluated and compared.It is found that the fatigue damage caused by the rail corrugation greatly shortens the service life of the safety hanger.关键词：Safety hanger;Vibration fatigue;Modal analysis;Rail corrugation;Fatigue life
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发布时间：2022-09-22 - 摘要：To obtain the dynamic fracture toughness of 20 Cr Mn Ti,an impact loading test was conducted on three-point bending specimens with the improved Hopkinson pressure bar.Dynamic stress intensity factor was determined by the spring mass model.The onset time of crack initiation is experimentally detected using the strain gauge method.Dynamic fracture toughness of20 Cr Mn Ti with type I crack was obtained through the above experimental procedure.The geometrical dispersion distortion caused by lateral inertia effect is effectively inhibited by the wave shaping technique,to ensure the consistency of stress wave signal in measuring point and loading point is guaranteed.At the same time,the high-speed camera system was used to collect the image and the change of the surface strain field during the loading process was analyzed with GOM Correlate.The results show that samples before crack initiation has reached the dynamic strain balance,ensure the validity of the experiment.关键词：20CrMnTi;Hopkinson pressure bar;Lumped mass-spring models;High-speed camera system;GOM Correlate;Dynamic fracture toughness
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发布时间：2022-09-22 - 摘要：The aluminum honeycomb sandwich plates were impacted by the hemispherical-nosed projectiles and the bluntnosed projectiles launched by a one-stage gas gun,and the influence of the nose shape of projectiles on the ballistic limits,the failure mechanisms of the targets and energy absorption efficiency was analyzed.The results show that the ballistic limit of bluntnosed projectile is higher than hemispherical-nosed projectile,and the nose shape of projectile has a significant effect on the failure mode of aluminum honeycomb sandwich plates.The energy absorption efficiency of sandwich target against blunt-nosed projectile impact is significantly higher than hemispherical-nosed projectile,but the difference between the energy absorption efficiency decreases with the increase of the initial kinetic energy.关键词：Nose shape of projectiles;Aluminum honeycomb sandwich plates;Ballistic limit;Failure mode;Energy absorption efficiency
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发布时间：2022-09-22 - 摘要：Low cycle fatigue test（0.1 Hz 0.3 Hz,10~3 10~5 cycles） and conventional high cycle fatigue test（150 Hz.10~4 10~7 cycles） and ultra-high cycle fatigue test（20 k Hz,10~5 10~9 cycles） were carried on Ni-Cr Alloy at room temperature.The results of the three forms fatigue test were compared,and the energy-life curve reduced by 3-parameters power function were fitted.The fractograph of specimens were investigated and analyzed with scanning electron microscope.The results show that the fatigue crack initiation sites change from multiple surface cracks to single surface crack,then to subsurface of specimen with decreasing the load amplitude.关键词：Ni-based material;Low cycle fatigue;High cycle fatigue;Ultra-high cycle fatigue;Subsurface crack initiation;3-parameters power function energy model;Frequency effect;Twin structure
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发布时间：2022-09-22 - 摘要：In view of the problems such as low efficiency and surface cracks in optical glass processing,the experiment studied the influence of cutting parameters and acoustic parameters on milling forces and established a milling force model of optical glass ultrasonic vibration that based on the high frequency impact effect of ultrasonic vibration,through which on ultrasonic vibration milling of optical glass.The effects of factors such as milling speed,feed per tooth and milling depth on milling force were discussed through comparative experiments on ultrasonic vibration milling and conventional milling of optical glass.The experimental results show that under ultrasonic milling,the milling force is significantly lower than the conventional milling force.关键词：Ultrasonic vibration milling;Optical glass;Milling force;Multi-factor orthogonal experiment method
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发布时间：2022-09-22 - 摘要：Cohesive zone model was used to simulate polycrystalline intergranular fracture at the grain level model,the finite element model build-ing reflected the actual situation is a difficult point.In this paper,Mixed Programming of Matlab,Python and Abaqus,An algorithm was presented which can easily and quickly generated Voronoi geometric model and the grain sizes distribution agrees with lognormal distribution.Realized the automatically insert the zero-thickness cohesive interface element by writing nodes and elements at crystal boundary,firstly solved the void zone at the intersection of the three zerothickness cohesive element,which is the triple junction,And to make up the defect of cohesive zone model.The whole process of the finite element analysis was performed automatically by secondary development,including the assignation material properties,material orientation,load application,model solution.Finally,polycrystalline aluminum was used as an example to simulate the intergranular fracture process without the initial damage.The results show that the method is more effectively and practically,which can be used to simulate polycrystalline intergranular crack initiation and propagation in random microscopic grains.关键词：Intergranular fracture;Triple junction;Voronoi diagram;Zero thickness cohesive element;Secondary development;Mixed programming
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发布时间：2022-09-22 - 摘要：The theory of macro-micro two scale model obtains the micro plastic strains by using the macro-micro connecting factor,which is an effective theory to investigate the damage accumulation of the high fatigue and its failure mechanism.Based on the macro-micro theory,the evolution rule of the micro stresses and strains with plastic hardening was studied,and it solved the micro stresses and strains of the three-dimensional models by making programs,which considered the linear mixed plastic hardening.It established the 3 D finite element models,and calculated the micro stresses and strains and obtains the equivalent stress-strain hysteresis loops with linear mixed hardening.Compared with the finite element results,the effectiveness of the algorithm results is verified.关键词：Macro-micro two scale model;Linear mixed plastic hardening;Finite element model;Algorithm program;Hysteresis curve
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发布时间：2022-09-22 - 摘要：Based on the micro-electro-mechanical systems（MEMS） technology,the chip structure of a two-axis force sensor with comb structure was designed.Silicon force sensitive structure converted the faint mechanical signals into measurable electrical signals.After finite element model was established,the structure and electrical properties of the sensor were analyzed.The corresponding relation between the mechanical signals and the electrical signal was obtained.The mode analysis and harmonic response analysis were performed for the model.The natural frequency of the structure and the harmonic response frequency both are verified that far away from the operating frequency of the system.The work stability and measurement accuracy of the chip are guaranteed.The resolutions of force and moment of the sensor chip are 2.85 μm and 0.0382 μN·m,respectively.The linearity of the signal conversion reached 0.999 6 and 0.999 9.The first and second order modal natural frequency is783.28 Hz and 1 294.3 Hz and harmonic response frequency is 770 Hz.Simulation results meet the requirement of performance specification.关键词：Micro-electromechanical systems（MEMS）;Force sensor;Two-axis;Comb structure;Physical design
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发布时间：2022-09-22 - 摘要：With the problems of complicated calculation process and lower computational efficiency in topology optimization using the traditional level set method（LSM） of heat conduction structures,parametric level set method（PLSM） is introduced into topology optimization for heat conduction structures.The compactly supported radial basis functions（CS-RBFs） are used to interpolate the initial level set function.The interpolation coefficients of CS-RBFs are proposed as the design variables,dissipation of heat transport potential capacity is adopted as the objective function,and the volume of material is used as the constraint.The topology optimization model for heat conduction structures is thus built.Because the method of moving asymptotes（MMA） is used to update the interpolation coefficients of CS-RBFs,the process of topology optimization for structures is transformed into that of updating interpolation coefficients and the optimal topology is finally obtained.Numerical examples show that the optimal results using PLSM are essentially in agreement with those of LSM optimal results,which illustrates the feasibility and validity of the proposed method.关键词：Parametric level set method;Topology optimization;Heat conduction structures
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发布时间：2022-09-22 - 摘要：Roller is an important task of the coal winning machine cutting coal institutions,its structure and motion parameters will directly affect the working efficiency and working reliability of coal winning machine.Based on virtual prototype technology coal winning machine the coupled model is established,through dynamic simulation of coal winning machine equivalent stress values of key parts;Simulation different drum rotating speed,drawing speed,cylinder helix Angle,and the cutting line spacing they cut the shell and the equivalent stress value of planet carrier,the roller structure and motion parameters on reliability of key parts of coal winning machine cutting part influence trend;Combined with neural network technology,with different roller structure and motion parameters of the equivalent stress of key parts of coal winning machine values as the neural network training sample,the helix Angle of optimization design,stress value of key parts in the hour of cylinder helix Angle.The research for the drum more accurate theoretical foundation for the selection of structure and motion parameters,has certain engineering application value.关键词：Shearer;Drum;Reliability;Neural network;Optimization design
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发布时间：2022-09-22 - 摘要：Random fiber distribution may lead to randomness of longitudinal compressive behavior of fiber reinforced plastics（FRP）.To mimic random fiber distribution over the cross-section,a new algorithm named Latin Hypercube Sampling based on Random Sequential Expansion（LHS-RSE） is proposed,which can simulate the random fiber distribution of FRP with fiber volume ratio as high as 70%.Then,3 D FE model with random fiber distribution of unidirectional fiber reinforced plastic T300/914 is developed in Abaqus/Standard to investigate the influence of random fiber distribution on the compressive behavior.It is shown that random fiber distribution over cross section greatly compromises the longitudinal compressive strength of FRP.Random distribution of longitudinal compressive strength resulted by random fiber distribution tends to follow normal or lognormal distribution.关键词：FRP;Finite element;Random fiber distribution;Compressive strength;Latin hypercube sampling
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发布时间：2022-09-22 - 摘要：A lightweight design method based on the idea of secondary optimization was proposed for a certain commercial vehicle front axle.The finite element model of the front axle was established and simulated.Combined with the fatigue endurance test,the true load of the front axle was investigated to verify the accuracy of the finite element model.The static tensile load and bending fatigue test of the real material of the front axle are taken as the light weight reference for obtaining the mechanical performance index of the front axle material after heat treatment.The overall model of the front axle is optimized and secondary optimization based on the mechanical model to ensure that the structure of the front axle meets the requirements of strength,stiffness and service life while achieving a lightweight design.The final total mass reduced 5.7 kg,to achieve the purpose of lightweight design.关键词：Front axle;Material properties;Secondary optimization;Lightweight;Structural optimization
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发布时间：2022-09-22 - 摘要：The mathematical models of many engineering problems can often come down to two-dimensional optimization problems,it has been one of the hot issues of seeking the high effective and precision optimizing method.The characteristics of harmonic function and Green theory were used to study the relations between the values of harmonic function and its boundary values,and demonstrate the non-locality of its extreme value.When the objective function of the optimization is harmonic function,the two-dimensional optimization can be simplified as a one-dimensional optimization on the boundary of its feasible region.At last,three examples were given to show the feasibility of the method here.The research ideas and the conclusions can be generalized to the solution of the three-dimensional optimization problems.关键词：Two-dimension optimization problem;Harmonic function;Feasible region boundary;Maximum;One-dimensional search
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发布时间：2022-09-22 - 摘要：Main failure parts of wind turbine gear-box were determined by Failure Modes and Effects Analysis（FMEA）.Gear,rolling bearing and gear transmission system for the wind turbine reliability evaluation models were built based on dynamics.Four order moment method was adopted in contact fatigue and bend fatigue reliability sensitivity analysis of planetary gear,Gear reliability sensitivity is discussed.The results of influence of parameters on reliability of planetary gear are illustrated by a specific example.关键词：Dynamics;Wind turbine-box;Reliability sensitivity
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发布时间：2022-09-22 - 摘要：Split Hopkinson pressure bar（SHPB） tests are widely used for testing material mechanism behavior under high strain rates,A series of SHPB numerical tests were done based on K＆C local concrete damage model,The stress-strain curves of the concrete specimens were reconstructed with the two-wave theory,and the damage of the concrete was analyzed.According to the comparison between the numerical and the test results,Proving K＆C model can simulate concrete in concrete under high strain rate compressive mechanical behavior.Proving the increase of dynamic strength of concrete under the influence of structural effects.关键词：Concrete;Dynamic increasing factor（DIF）;Strain rate;Split Hopkinson pressure bar（SHPB）
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发布时间：2022-09-22 - 摘要：The mating state between a flange bore and a shaft and the position error for a flange shaft in a bore has an important influence on the assembly accuracy of precision products.In view of the fact that three-dimensional cylindricity was usually ignored in existing researches,a contact method was developed,which was based on equal vector judgment criterion and measured profile data of the parts.It can effectively determine the actual fitting clearance between bore and shaft taking threedimensional cylindricity errors into account.The effects of the cylindricity error and the number of lobes on the fitting clearance were analyzed in detail.The results indicate that the cylindricity error has significant influence on the actual fitting clearance.By the principal of error composition and neutralization,the actual fitting clearance between a flange bore and shaft was obtained considering the coupling of dimension errors,three-dimensional cylindricity errors and perpendicular errors.It is effective to preanalyze the position accuracy for a flange shaft in a flange bore.Then it can provide guidance for subsequent assembly processes to increase assembly efficiency and improve assembly accuracy of precision products before they are assembled.关键词：Contact method;Cylindricity error;Fitting clearance;Error coupling;Assembly accuracy
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发布时间：2022-09-22 - 摘要：To satisfied the requirement of the laser angle adjustment,this paper proposed a micro 3-PSP parallel robot with a special structure with the diameter of the static platform is 50 mm,the height of the system is about 74 mm-80 mm;Using the‘closed-loop vector method’to set up the inverse kinematics model of the parallel robot.Then get the solution of the inverse kinematics.On the basis of the inverse kinematics solution,the constraint of the shaft movement and the parameters of the mechanism,we get the 3 D working space of the parallel robot via MATLAB.Finally,we simulated the kinematics of the parallel robot by Solid Works and Adams,and the results show that the 3-PSP parallel robot could accomplish three dimensions moving with smooth.
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发布时间：2022-09-22 - 摘要：Complex eigenvalue analysis using ABAQUS has been carried out,based on a simplified finite element model of high-speed disc brake system.The critical factors generating brake squeal have been computationally studied and verified by experiments.Simulation results show that,brake squeal more likely to occur under the conditions of low-speed,high pressure,negative μ-υ slope,and high coefficient of friction.The effects of sliding speed and normal contact pressure on the generation of brake squeal have been verified.This study will provide effective guidance in the prevention and control of brake squeal.关键词：High-speed brake;Natural frequency;Complex eigenvalue analysis;Brake squeal;Braking parameters;ABAQUS
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发布时间：2022-09-22 - 摘要：Based on the basic theory of heat transfer and tribology,the calculation formulas of the friction heat flux density of meshing pair,the meshing tooth surface and the end face convective heat transfer coefficient with two-tooth difference swing-rod movable tooth drive are derived under the slip condition.A finite element model of the thermal analysis of the gear meshing pair is established,and the steady-state temperature field of the meshing pair under thermal balance state is calculated and analyzed by using the ANSYS finite element software.Combined with numerical simulation results,the influence of tooth profile design parameters on the temperature field is revealed.The result shows that:the steady-state temperature field of the meshing pair is determined collectively by the heat flux of the contact zone and the convection heat transfer coefficient of each surface.Because the temperature rise of sliding friction is larger,the maximum temperature appears in the center of the gear meshing face width of the center,the radius of the base circle radius has a great influence on the body temperature of the meshing surface,and the swing rod length is less affected.The research results lay the foundation for the study of the thermal deformation and thermal mechanical coupling characteristics of the meshing pair,so as to guide the dynamic design of the two-tooth difference swing-rod movable tooth drive.关键词：Two-tooth difference swing-rod movable tooth drive;Heat flux;Steady-state temperature field;Design parameters of tooth profile
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发布时间：2022-09-22 - 摘要：Based on ANSYS software established board level optical interconnect module finite element model,by means of the analysis of the model of the thermal-structure random vibration coupling,obtained the data of stress and strain under the coupling condition,analyzed the influence of the change of the shape parameters of three kinds of solder joints,the height of the solder joints,the diameter of the pad and the volume of the solder balls.The results show that the stress and strain value of the solder joint is gradually reduced from the center position to the solder joint at both ends;the maximum stress and strain point appeared in the solder joint at the corner of the array.With the increase of the solder joint height,the maximum stress and strain of the solder joint increased gradually.With the increase of the diameter of the pad and the volume of the solder ball,the maximum stress and strain decreased gradually.关键词：Optical interconnection;Thermal vibration coupling analysis;Solder joint array;Stress and strain;Finite element analysis
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发布时间：2022-09-22 - 摘要：2022 alloy has some characteristics of high strength,resistance to damage,can strengthen aging,When used in the next generation of supersonic aircraft skin and armored fighting vehicles and other fields,hot rolled and cold rolled are distinguish due to the different incoming member shapes.After aging treatment,hot-rolled plates tensile and yield strength higher than cold rolled sheet,but its elongation decreased.Under the same kind of rolling state,the perpendicular to the rolling direction of tensile higher than the yield in the rolling direction,but,elongation is reduced.By optical and transmission electron microscopy find hot rolled sheet grain relatively small and recrystallized grains increase than cold rolled sheet.The precipitation of hot-rolled plate small,densely distributed in the aluminum matrix compared to sheet cold-rolled,in macro the reaction to the higher tensile strength and hardness.关键词：2022 aluminum alloy;Hot-rolled;Cold-rolled;Microstructure;TEM
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发布时间：2022-09-22 - 摘要：The determination of structural dynamic stress spectrum is of great significance in the structural fatigue strength evaluation as well as reliability design.To evaluate structure of fatigue strength accurately,stress history on fatigue key parts of motor bogie framework was obtained through dynamic stress test of high-speed EMU on actual operation line.Fatigue damage values per kilometer of stress spectra with different grouping numbers were calculated using equidistant grouping method and Palmgren-Miner linear cumulative damage theory.Then,the effect of different group number on fatigue damage was analyzed.The results show that when the grouping number is small,it can lead to deviation of fatigue damage.As the grouping number increasing,damage decreasing,and tends to the theoretical value.This phenomenon can be interpreted by the EMU framework dynamic stress characteristic of small stress cycles high concentration.Meanwhile,an unequal distance grouping method was presented which is applicable to framework structure stress spectrum.The study can provide the basis for framework structure design.关键词：Bogie framework;Stress spectrum;Grouping method;Fatigue damage
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发布时间：2022-09-22 - 摘要：Perdynamic（PD） is used for analyzing crack propagation in engineering material fracture,the bonds constitute to the constitutive relation of the peridynamic,and the broken bonds represent to material fracture,but it can’t be used for the fatigue analysis.Based on the Miner’s linear cumulative damage theory,the bond fatigue break criterion was proposed instead of the old break criterion,the PD fatigue fracture model for high cycle fatigue was constructed.Finally,a bending fatigue fracture analysis was carried out on a standard involute gear,the results show that the fatigue fracture process for gear by PD fatigue fracture model is consistent with experiment,the PD fatigue fracture model provides a method which consists of life prediction and fatigue crack propagation.关键词：Peridynamic;High cycle fatigue;Bond;Fatigue fracture criterion;Life prediction;Fatigue crack
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发布时间：2022-09-22 - 摘要：In order to reduce the cost of fatigue crack growth test and shorten the research period of welding process on new aircraft siding structure,this paper uses Abaqus finite element software to simulate welding residual stress field by using predefined temperature field method.The stress intensity factor values of crack tip are obtained by finite element simulation.Based on the structural characteristics of large welded plate,the Pairs formula was used to predict the crack propagation rate of welded plate.Based on this model,the fatigue crack growth rate of specimens with different stress ratio and welding process was studied.It is found that the effective stress ratio increases with the residual stress,but the effect decreases with the increase of the stress ratio.The trend of the effective stress ratio is similar to that of the residual stress distribution.The welding residual stress increases the crack growth rate of the welded structure.The feasibility of the proposed method is verified by comparison with the experimental results.关键词：Crack growth;Welding residual stress;Finite element analysis
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发布时间：2022-09-22 - 摘要：The established nonlinear fatigue damage model based on the theory of damage mechanics has been widely applied to multiaxial fatigue life prediction,however,this method does not consider the physical significance in the damage plane.This problem can be solved by combining with the critical plane method.Taking the thin-walled cylindrical specimen as the study object,a new damage parameter applicable to proportional and nonproportional multiaxial fatigue damage is proposed by means of von Mises rule based on the critical plane method with consideration of the influences of phase delay on the fatigue life are analyzed as well.The new defined damage parameter not only considers the maximum shear stain and normal strain on the critical plane,but also considers the effect of the additional cyclic hardening caused by the nonproportional loading on the fatigue life.The fatigue life predicted by the proposed damage model of three types of materials are proved to be in good agreement with experimental results.It is convenient for engineering application because the uniaxial fatigue data and material constants are considered only in this model.关键词：Damage mechanics;Critical plane method;Fatigue damage model;Maximum shear strain;Multiaxial fatigue life
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发布时间：2022-09-22 - 摘要：This paper proposed an analysis scheme for the multiple fracture failure of the gear rotor of the melt pump used in the key equipment of a chemical plant.Through the analysis of damage fracture analysis,material property analysis,microstructure analysis and strength checking,the root causes of failure were found,the conclusion of failure was concluded and the improvement scheme was proposed.The analysis results show that the gear rotor of molten pump has some defects in the process of design and machining under complicated conditions,which leads to its frequent failure during operation.By changing its structure,reducing stress concentration,the selection of good materials,improve production processes and other ways to effectively improve the performance of the shaft to meet their functional needs.The results of this research could provide certain reference value in improving the service performance of key transmission parts,especially gear type transmission shafts.关键词：Gear rotor;Crack;Stress concentration;Invalid
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发布时间：2022-09-22 - 摘要：In order to investigate torsion pendulum dynamic characteristics of scraper chain system,dynamic model of scraper chain system was established by using finite element method.Numerical simulation was analyzed for dynamic characteristics of scraper chain system by applying pulse load,step load and slope load.Torsion pendulum dynamic characteristics of scraper chain system,dynamic response of chain and dynamic tension transfer characteristic of scraper were researched.The results show that scraper has a big angular displacement at bearing section,and has a big torsion moment.Angular displacement amplitude and torsion moment amplitude gradually reduce from bearing section to the sides.The results provide theoretical basis for dynamic design of scraper conveyor.关键词：Scraper conveyor;Scraper chain system;Torsion pendulum
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发布时间：2022-09-22 - 摘要：The wing is designed by specific flight conditions,and its aerodynamic efficiency under various conditions needs to be optimized.This paper studies the trailing edge of the morphing wing to make it meet the aerodynamic optimal deformation range under the premise of continuous smooth deformation.By using the method of topology optimization with variable density method,the minimum square error between the actual displacement of the airfoil and the target displacement is taken as the optimization objective function,and the position of the trailing edge multi-point driving load is optimized by genetic algorithm to establish the compliant trailing edge comprehensive optimization model.Using the moving asymptotic method to solve.Finally,the result was simulated by ANSYS,the effectiveness of trailing edge deformation is discussed and verified.关键词：Multi-points Driving compliant mechanism;Morphing wing;Genetic algorithm;Topology optimization
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发布时间：2022-09-22 - 摘要：The manufacturing processing of blade,which has complicated structure and irregular surface shape,become increasingly high-speed.Thus,high acceleration is required to ensure the rapid movement of each axis.At the same time,the machining accuracy should be confirmed under the acceleration impact.The finite element model of a domestic blade machining center is established to take the transient response analysis by using ANSYS Workbench.Moreover,a new method of composite unit is presented to bolted joints and guide joints.And,the load solutions are given to linear and rotational acceleration impact.The transient responses of machining center under different accelerations are obtained,and the vibration attenuation time is analyzed to meet the machining accuracy.Thus,the impact of machine vibration on machining accuracy is minimized under high acceleration.The results provides theoretical basis for rational allocation of acceleration,optimization of the blade processing and improvement of dynamic characteristics of machining center.关键词：Blade machining center;Acceleration;Transient response;Composite unit
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发布时间：2022-09-22 - 摘要：In this paper,the influence of the spiral angle of shearer drum on the cutting performance is studied in this paper.The calculating formula of the drum helical blade coal throwing force and loading quantity theory.According to the theoretical analysis,it is known that the axial force of the blade is inversely proportional to the helix angle and the rotation speed of the roller,which is proportional to the speed of the traction.The theory of the loading quantity and the roller speed is proportional to,and with the increase of spiral angle of parabola increased first and then decreased.Using ADAMS software to simulate the variation of axial force and cutting power of shearer drum in different spiral angle,and the results are consistent with the theoretical analysis.In the design of the shearer drum,the influence of the spiral blade on the cutting performance of the shearer should be considered,so that the utility and economic benefit of the shearer can be optimized.关键词：Shearer;Spiral blade;Cutting performance;Coal;Coal throwing axial force
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发布时间：2022-09-22 - 摘要：Local resonance is a key reason for fatigue damage of gear housings.Local modals could be excited by vibration caused by gear meshing.Considering the shearer rocker arm for example,the local resonance characteristics of gear housing are analyzed in this paper.Finite element method is used to obtain the natural characteristics of housing and field testing with 0 load is employed to get the vibration acceleration values at the ratings.Local resonance characteristics are obtained by comparing frequency spectrum and natural frequencies.Housing wall thicknesses are selected as design variables to get the influence to natural frequencies.The results show that new frequencies which consist of meshing frequencies of different transmission stages occur and some of them can cause local resonance.Housing wall thicknesses should be changed to avoid local resonance.Excessive strain stress could be caused by local resonance and incur fatigue damage.This research could be a reference for resonance analysis and optimum design.关键词：Cantilever gear box;Local resonance;Vibration experiment;Fatigue failure
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发布时间：2022-09-22 - 摘要：Cage is one of the key components of constant velocity joint.The cage is in the dangerous situation when the CV joint in the limit Angle,thus the strength of the cage under the limit Angle plays an important role in meeting the requirements for the design and manufacturing.The strength of cage was studied by experiment and the finite element simulation.First of all,stress state and dangerous area were obtained through simulation under the condition of the limit Angle and torque.The fracture torque of the cage was studied by torsion test.Finally,the hardness of the cage was measured by the micro hardness tester,and the distribution regulation that the strength of the cage was obtained by the transformation of the hardness and strength.The results show that the cage strength meets the requirements.This study can provide technical basis for design and manufacturing.关键词：Cage;Strength;Limit angle;Finite element simulation;Strength test
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发布时间：2022-09-22 -
OUTSIDE REARVIEW MIRROR PANORAMIC CAMERA POSITION ON THE AERODYNAMIC CHARACTERISTICS OF IMPACT STUDY
摘要：In order to reduce the influence of the panorama camera on the aerodynamic noise of the vehicle,the exterior flow field and sound field analysis are carried out on the rearview mirror of three different lens placement positions.The calculated results are in good agreement with the experimental data,which verifies the reliability of the numerical simulation.At the same time,it is found that the different position of the panoramic lens has an influence on the air flow which through the exterior mirrors,thus changing the rear flow field and the front window noise radiation intensity.Scheme Ⅲ is compared with other schemes,the tail vortex,the turbulence kinetic energy and the noise emission of the front window are relatively weaker,which can reduce the aerodynamic noise.Finally,by comparing the noise test of three kinds of schemes,it is found that the noise of scheme Ⅲ is lower than that of other schemes,which verifies the correctness of the analysis method.The analysis results provides the guidance for the reasonable arrangement of the rearview mirror panorama image lens,and is favorable for improving the comfort of the driver.关键词：Exterior Mirrors;Panoramic Camera lens;Flow Field;Aerodynamic Noise;Test- 3
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发布时间：2022-09-22 -
DURABILITY FATIGUE PREDICTION AND STRUCTURE OPTIMIZATION OF LOAD-BEARING KEY PART OF TRACKED VEHICLE
摘要：Strat from the structure of torsion shaft to more reasonably use durability and design life,realize the various optimization of mechanical construction.A parameterized model of torsion shaft was developed based on Solidworks and imported into ANSYS Workbench by data interface.Transient stress and durability fatigue of parameterized model were analyzed in ANSYS Workbench.The multi objective optimization of torsion shaft was designed in Design Exploration module and the optimized structure of torsion shaft was reanalyzed in ANSYS Workbench.The result of optimization design shows that optimization model meets durability life of torsion shaft and weight decreased 9.9 percent.The result demonstrates the correctness of the optimization.关键词：Torsion shaft;ANSYS;Durability;Optimization;Parameterization- 4
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发布时间：2022-09-22
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