最新刊期
期 4 ， 2017
- 摘要：Taking into account the operational principle of forepoling equipment,and as the target to improving support efficiency and reducing the disturbance on the roof in the process of supporting,a kind of speed and pressure composition control method was presented.The control method adopts the constant pump driven directly by servo motor to replace the traditional electro-hydraulic proportional valve,and the variable structure algorithm based on the fuzzy sliding mode was used as control strategy.Theoretical analysis and experimental results show that,compared with the traditional speed and pressure control method,the control method presented in the paper can reduce concussion on the roof in the process of switching from speed control to pressure control,and can improve support efficiency.Research findings can provide a theoretical basis for the development and control strategy of forepoling equipment.关键词：Forepoling equipment;Composite control of speed and pressure;Fuzzy control;Sliding mode variable structure;Servo drive
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发布时间：2022-09-22 - 摘要：In order to study the distribution of sound field and quantitative estimates of the cutting noise,a multiphysics coupling model was constructed.Firstly,the vibration response of the fluid structure interaction system was extracted under multibody dynamic contact by using method of center difference.Moreover,a co-simulation method for the acoustic radiation model based on the boundary element method and acoustic coupling theory was presented.On this basis,a structure acoustic coupling model was established to calculate the sound pressure according to the results of the vibration response previously calculated.Then,the sound radiation in time domain characteristics and domain characteristics with the coupled system in half the space is studied.On the basis of the FSI theory,the computing results of the one-way coupling method and two-way coupling method are compared.Finally,the effects of radiating area influence on the sound power is discussed,makes clear the primarily radiation area.As compared with the experimentation results,the multi-field coupling model established in this paper about cutting noise of the saw blade is correct and feasible.关键词：FEM;BEM;Multi field coupling;Central difference method;Noise
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发布时间：2022-09-22 - 摘要：In order to avoid the design of the rotor of the dry gas seal high speed test stand occur resonance phenomenon during high speed running,the transfer matrix method was applicated to calculate the natural frequency.Then it obtains that its natural frequency is 14044.586r/min when the dry gas seal static and ring `s quality is 33.78 kg in rotor system,and using the finite element method analysis the modes of the rotor system when it is operating in the vicinity of its natural frequency,then it will get the modal figure with four modal value.Comparative and analysis the results of the two methods,though simplified model are not the same,the results are similar.And the design of speed can meet the requirements,so it can describe the design of the rotor system is reasonable.关键词：Dry gas seal;High speed;Natural frequency;Transfer matrix;Finite element method
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发布时间：2022-09-22 - 摘要：As one of the key components of mechanical drive system,gear fault holds a large proportion in the transmission system fault,its working status directly affect the performance of the equipment.Aiming at the characteristics of the gear fault signal mostly for the non-stationary modulation signal,proposed based on spline and an improved algorithm of LMD continuation boundary characteristics,through the adoption of cubic spline interpolation,the signal of extreme value point interpolation to get the upper and lower envelope,and local characteristic scale boundary continuation method is adopted to reduce the endpoint effect,improve the precision and computational efficiency of decomposition.The simulation study of simulated signals and experimental platform of fault data show that improved LMD algorithm is proposed in this paper that decomposition PF components is smaller error compared with the ideal value,shorter time decomposition,accurately analyzing the fault characteristics of the gear.关键词：Gear;LMD;Cubic spline interpolation;Characteristic scale extension;Fault diagnosis
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发布时间：2022-09-22 - 摘要：Considering the early fault feature information of rolling bearings is difficult to identify,and form the frequency bands after wavelet packet decomposition can not be effectively determined and adaptive to extract the resonance band,the concept of amplitude entropy of frequency band is proposed.On this basis,the wavelet packet transform and Teager energy spectrum was combined,a rolling bearing early fault feature extraction method is proposed based on wavelet packet transform adaptive Teager energy spectrum.Firstly,the vibration signal was decomposed by wavelet packet,and the frequency amplitude entropy of each subband was calculated.Then,on the basis of kurtosis index to determine the best entropy and the optimal decomposition level of wavelet packet,thus,the resonance band was extracted adaptively and effectively.Finally,the Teager energy spectrum analysis was performed to identify the frequency of the bearing fault.Through the signal simulation and experimental data analysis it verifies the effectiveness of the proposed method.关键词：Rolling bearing;Amplitude entropy of frequency band;Wavelet packet transform;Teager energy spectrum;The adaptive resonance frequency band extraction;Early fault
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发布时间：2022-09-22 - 摘要：Blow pressure is the key factor to influence the dynamic characteristics of liquid-air hammer,in order to improving control accuracy of the forging equipment,liquid-air hammer was regard as research object,established liquid-air hammer blow process stages of non-plastic deformation and plastic deformation of Lagrange dynamics model,using the Matlab/Simulink numerical simulation to analyze movement regularity of liquid-air hammer blow process,researched for blow pressure impact on the dynamic characteristics of liquid-air hammer,provided the theoretical basis for the equipment later debugging in order to achieve the purpose of precise control.The field experiment results show that the control system can meet the requirements of liquid-air hammer precision blow process.关键词：Liquid-air hammer;Blow pressure;Dynamic characteristics;Control accuracy;Movement regularity
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发布时间：2022-09-22 - 摘要：U-bimetallic finned tube is a new widely used heat exchange component.In order to predict and control the flowinduced vibration damage of U-bimetallic finned heat exchange tubes,their natural frequencies must be calculated accurately.Inplane and out-of-plane vibration modal of U-bimetallic finned tubes were investigated by means of the hammering method and finite element method.The influence of arc bending radius R of U-bimetallic finned tubes on their natural frequencies was analyzed.The finite element simulation results of natural frequencies of U-bimetallic finned tubes were compared with the measured values for free-free boundary condition,the maximum error of the first 18 order frequencies is 7.3%.The natural frequencies of U-bimetallic finned tubes decrease with increasing the arc radius R for clamped-hinged case.关键词：U-bimetallic finned tubes;Vibration modal;Hammering method;Finite element method
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发布时间：2022-09-22 - 摘要：For a more complete extraction of the rotor fault feature,a new rotor fault feature extraction methods-Full vector local characteristic decomposition（FVLCD） was proposed.FLVCD Combined local characteristic decomposition（LCD） with full vector spectrum（FVS）.Mutually perpendicular channel vibration signals were decomposed into intrinsic mode components of the series based on LCD and corresponding envelope signals were obtained by Hilbert transform.Then the corresponding vector spectrum was obtained by fusion of the envelope signal FVS.Rotor rubbing fault analysis results show that this method is effective fusion of the two co-channel vibration signal information,fault characteristics are more comprehensive and accurate.关键词：Full vector;Local characteristic decomposition;Rotor fault;Full vector spectrum;Hilbert transform
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发布时间：2022-09-22 - 摘要：To efficiently design damping system of MEMS Strapdown Inertial Navigation System（SINS） which performs well on vibration attenuation,a method to design vibration damping system of MEMS SINS according to transfer function and performance demand were present.First the design of supporter and the assign of vibration damping devices were finished.Then through sine scanning vibration experiment,the amplitude-frequency characteristic curves of the each inertial device in MEMS SINS were obtained,and the vibration damping goal for each inertial device in MEMS SINS were got through the study these curves.At last the amplitude-frequency characteristic curves of the accelerator that sensitive the vibration direction were simulated under logarithmic coordinates,and the design were finished according to outputs requirement.Simulation through MATLAB indicate,after vibration attenuate,designed system perform well in meeting the requirements for outputs of MEMS SINS,meanwhile it decreased the output deviations of three MEMS gyroscope.Simulation indicate,for the vibration damping problem of MEMS SINS,well performed vibration attenuation system can be quickly designed under the output requirement for MEMS SINS through this way.关键词：MEMS Sins;Vibration attenuation;Sine scanning vibration experiment;Amplitude-frequency characteristic
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发布时间：2022-09-22 - 摘要：At the thin steel plates running a period,cracks may occur at the material or weld,and traditional repair methods aren’t suitable for cracks repair of the thin steel plates.But the method of drilling hole at the crack tip and pasting CFRP on the steel plates is a choice for crack repair.Firstly,through five groups of fatigue test,it analyzed the effect of the crack fatigue life of the hole joint CFRP reinforcement and the other methods.Then,based on the cohesive force theory,it established the finite element model of notch steel plate reinforced with CFRP.With the finite element model,it studied the repair parameters of the stiffness,length and width of CFRP.The results demonstrate that the remaining fatigue life of the hole joint CFRP reinforcement is better than drilling holes or pasting CFRP,and even more than the steel plate with no crack.So it is especially suitable for the thin-wall steel plate with short cracks.关键词：Composite materials;Crack repair;Cohesive;CFRP
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发布时间：2022-09-22 - 摘要：Variable helix cutter can reduce the location error of the finished surface,leading to a more accurate machining operation.Considering the geometries of variable pitch and helix angle,and the piecewise continuous regions of the cutting,an analytical model for predicting the cutting force for milling process with variable helix angle cutter is presented.The validation of the proposed model is conducted via some cutting tests.Based on proposed model,the influence of variable helix character on cutting force is studied.Analyses show that cutting force coefficients obtained from the traditional cutting tool could be used to accurately predict the cutting forces of the variable helix cutting tool.The bigger helix angle corresponds to the smaller cutting force and bigger width of phase.The character of variable-helix angle has more significant influence on cutting force when axial depth of cut is larger.关键词：Milling;Cutting force;Variable helix;Variable pitch
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发布时间：2022-09-22 - 摘要：Transverse residual stress of tooth root has significant influence on bending fatigue strength of gears.But given the geometry of gears,using the method of exposing teeth root to complete determination of transverse residual stress at present,it not only destroys the original stress state of material surface,but conflicts with the concept of residual stress measurement by Xray nondestructive.so in order to do not cut gears,which can also more accurately measure transverse residual stress of the gear tooth root,in this paper,through combining with the theoretical analysis and experimental verification method,the relationship of transverse and longitudinal residual stress of the gear tooth root is derived.With the known of Bragg Angle of free stress— θ0,the transverse residual stress of Gear tooth root can be calculated by the size of the longitudinal residual stress through the X-ray method measured,so it is convenient to measure the transverse residual stress of gear tooth root.关键词：The gear bending strength;Residual stress;Measurement of X-ray
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发布时间：2022-09-22 - 摘要：Considering the installation error and tooth flank clearance of modified involute cylindrical gears influencing on load density,oil film thickness,and local friction coefficient.an optimum design method based on the minimum flash temperature was proposed.Applied TCA and LTCA to modification technology,the friction coefficient was determined according to the film thickness ratio under different lubricating condition,oil film thickness and loads on contact line were discretized,so discrete temperature according to the Blok flash temperature formula were got.used genetic algorithm to optimize the parameter of curve,and got the best deviation surface.the results shows that there are more uniform loads and flash temperature with modified gears,while the smallest is at engaging-in area due to the effect of curvature radius,besides the flash temperature has little changes in the single tooth meshing zone of spur gear.关键词：Spur gear;Loaded tooth contact analysis;Flash temperature;Optimization
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发布时间：2022-09-22 - 摘要：Finite element modeling of polycrystalline micro-structure is one of the important contents of polycrystalline metal material research.In view of the problem of the limited application of traditional methods and the difficulty of precisely modeling for Polycrystalline,Polycrystalline modeling method was proposed in this paper.This method generated weight circles according to the specified grain size distribution first.Normal circles generation method and generating new circle based on the interference types were analyzed and then divided weight circles boundaries.At last,combining with ANSYS,modeling and mesh experiments were carried out according to four specified functions.This method can model according to all kinds of grain size distributions within a small error range,which is helpful to improve the accuracy and reliability of the simulation and its operation is simple.关键词：Polycrystal modeling;Material micro-structure;Grain size distribution;FEM
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发布时间：2022-09-22 - 摘要：In order to study the influence of Carbon nanotubes on the mechanical properties for multi-layer materials material,in this paper,the mathematical model between the content of carbon nanotubes and mechanical properties of multi-layer material was proposed to predict the mechanical performance of multi-layer material.First,introduced the functional relationship between reinforcing material content and the Young ’s modulus of composites materials,and then deduced the relationship between reinforcing material content and the Young’s modulus of multi-layer materials based on multi-layer beam theory transform section method.Finally,we can get the basic parameters of the mathematical model on carbon nanotube multi-layer material by bending experiments to reveal the impact of carbon nanotubes on the mechanical properties of multi-layer material.This method of establishing a mathematical model is also applicable to other reinforcing material and the application of new multi-layer material has a positive significance.关键词：Carbon nanotubes;Multi-layer materials;Mathematical models;Mechanical properties
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发布时间：2022-09-22 - 摘要：For the gear sets of wheel side reduction systems used in electric vehicles,a new lightweight design method based on road load spectrum is put forward.According to the standard road driving cycle,the computational load spectrum of gears generated by extrapolation methods generate gears and the gear fatigue strength characteristics,the reliability and durability of the gear sets can be analysed.Controlling variable method is used to have a good understanding of how the change of module of gear or the gear parameter influence reliability and durability of gear sets.Meeting the demands of driving mileage required,the lightweight optimization design of gear sets has been made.关键词：Load spectrum;Wheel driving;Deceleration system;Gear;Light weight design
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发布时间：2022-09-22 - 摘要：In fault tree analysis of aircraft hydraulic brake system,the probability statistical information of failure rate for bottom event is usually not sufficient.To solve this problem,a fault tree analysis method based on hyper-ellipsoidal model was given.Firstly,according to hydraulic brake system principle and the failure mechanism,the system fault tree model was established.Then the hyper-ellipsoidal model was introduced to describe the uncertainty of bottom event.Finally,the simulation process of system top event failure probability as well as the importance of bottom events was deduced based on double Monte Carlo method,and comparison was made with fault tree analysis under interval model.Results show that the fault tree analysis method under hyper-ellipsoidal model just needs the value range of bottom event failure probability,without requiring the detailed probability statistical information of bottom event.Compared with the interval model,the hyper-ellipsoidal model exhibits stronger robustness,and its results meet the engineering practice better.At the same time,the importance measurement analysis of bottom events was conducted to identify key failure events,which provides guidance for the brake system in design and maintenance.关键词：Hydraulic brake system;Hyper-ellipsoidal model;Fault tree;Failure probability;Monte-Carlo method
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发布时间：2022-09-22 - 摘要：Numerical method for reliability sensitivity design is presented based on fourth moment technique,track-laying vehicle drive shaft mechanical model is set to discuss and analyze only know the mechanical components under random distribution parameters before four moments of the mechanical components of the sensitivity of the analysis and design problems,reliable transmission shaft the degree of sensitivity variation with its various structural parameters when changes are given,the effects of changes in the structural parameters of the drive shaft of the reliability and provide a theoretical basis for the reliability optimization of the drive shaft,and then based on the results of the sensitivity analysis of structural improvements to the drive shaft research,the production can be very useful if it extended to correlated area of machine sensitivity design.关键词：Drive shaft;Fourth-moment technique;Reliability sensitivity design;Arbitrary distribution parameters;Structure optimization
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发布时间：2022-09-22 - 摘要：The drum ’s load calculation program of the staggered and sequential arrangement has been developed by MATLAB based on the shearer cutting mechanics model,which can get drum load spectrum,cutting performance parameters and the rate of lump coal under 5 typical working conditions;Shearer loading performance of two picks arrangement were analyzed by three-dimensional discrete element software PFC;The reliability of the key parts of the coal machine under different conditions has been analyzed Based on the PRO/E,MATLAB,ANSYS and ADAMS.The results show that:When the coal is cutting coal gangue,the pick should be used in sequential order,the load fluctuation is small and the reliability is high;Under normal conditions,the sequential pick arrangement of shearer can improve the lump coal rate,the cutting area will increased 1.99 times and the founder rate will increased 21% compared with the sequential type.关键词：Picks arrangement;Cutting performance;Coal lump rate;Loading rate;Reliability
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发布时间：2022-09-22 - 摘要：Using the mechanism of the tooth climbing of the belt,the mathematical model of the transmission error is established,reveals the transmission error of the synchronous belt is a function of the pulley pitch angle.Establish the virtual prototype dynamic transmission simulation model of synchronous belt based on Recur Dyn,through collect data and numerical analysis that mesh point with climbing tooth trace-Archimedes spiral,simulation results are consistent with the experimental results,to verify the accuracy of the simulation analysis.And compare the transmission accuracy of the new profile and L type trapezoidal tooth synchronous belt.The results showed that the transmission error of the new profile synchronous belt（Δθ =0.932mrad） less than L type trapezoidal toothed（Δθ = 1.615mrad）,shows that the capacity anti climbing tooth of the new profile synchronous belt is stronger than L type trapezoidal tooth,the tooth design of new profile synchronous belt is more reasonable.关键词：Synchronous belt drive;Transmission Error;Virtual Prototyping;Transmission accuracy
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发布时间：2022-09-22 - 摘要：The automobile crash box is an important buffering and absorbing energy structure.Due to the advantages of light weight,high stiffness,high strength and good crashworthiness for hydroforming tubular,the hydroforming crash box is designed instead of the stamping and welding structure.By numerical simulation,analysis the crash box key energy absorption properties,comparison of tube hydroforming crash box and stamping one absorbing performance.Design the load-curves for Tube Hydroforming automobile crash box,which is influence the crash box thickness distribution after forming.In this paper,maximizing of the minimum wall thickness of crash box after hydroforming is used as the research object,select the pressure control parameter on the load-curves as design variables,using fractional factorial designed experiment,then use of Kriging spatial interpolation method to build approximation model,Finally,the use of genetic algorithm to obtain the optimized loadcurves,increasing the minimum wall thickness of crash box after hydroforming.关键词：Crash box;Tube hydroforming;Fractional factorial;Kriging;Genetic algorithm
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发布时间：2022-09-22 - 摘要：As it is difficult to check water pumps and fuel boiler pipes,design and study a telescopic boom used in narrow space.Adopt steel tape to design telescopic arm,and the tapes’ edges are welded to form mechanical arm.Motor drive the divided wheel by gears,divided wheel drive steel tape to stretch,and telescopic boom has curly storage function.The arm’s section parameters include thickness,central angle,arc length;By the thin shell theory,analyze and calculate the central angle.Based on the Workbench software,analyze the central angle and thickness’ s infiuences to X and Y direction deformation.Results show that with the increase of central angle,the Y direction deformation decreases gradually,and the X direction deformation increases gradually.Deformation rate changes quickly before 40 °,and changes slowly after 40 °.With the increasement of thickness,the X and Y direction’s deformation rate are smaller.Based on theory and simulation,the final thickness is 0.1 mm and the central angle is 45 °.Finaly through experiments,verify the arm’s section parameters and bearing capacity.关键词：Telescopic boom in narrow space;Section parameters;Straight ability;Thin shell theory;Finite element analysis
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发布时间：2022-09-22 - 摘要：The present paper presents a numerical approach to investigate the surface layer residual stress after ultrasonic surface rolling process（USRP）,which is a severe plastic deformation process involving complex static extrusion and dynamic impact.According to the technological principle of USRP developed finite element model,assessment of meshing accuracy as well as definition of loading condition.As supplied 304 Austenitic Stainless Steel disc was subjected to ultrasonic surface rolling for validation of FEM,then simulates the processing of ultrasonic surface rolling,analysis of the residual stress field distribution characteristics and the influence of processing parameters on the rule.From the simulation results it can be seen that the surface of the material has a uniform distribution of residual compressive stress,with the increase of depth,the residual stress has a compressive stress peak and a smaller peak of the tensile stress and finally reduced to 0.The influence of machining parameters on the magnitude and depth of residual stress is different,the static pressure,the coverage rate and the number of processing have great influence on the amplitude and the amplitude is small.关键词：Ultrasonic surface rolling;Finite element analysis;Residual stress
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发布时间：2022-09-22 - 摘要：According to the problems that loose structure,large throttling loss and Efficiency is affected by the operating frequency,when reciprocating plunger pump uses valve type orifice structure.Rotating-sleeve distributing-flow system for reciprocating plunger pump was put forward,which has the advantages of simple and compact structure,small throttling loss,stable work and assignment without delay.Described the working principle of rotary sleeve type flow system,established the kinematics model of three different cam groove liner,analyzed kinematics characteristics influence of distributing-flow system that three cam groove type rotating-sleeve effect on,and analyzed the shear strength of the drive pin.The numerical results showed that compared with the other two linear cam grooves,the angular velocity and angular acceleration of sinusoidal cam groove rotating-sleeve has smallest size and magnitude,and has no inflection point and step,and the rotating-sleeve can rotates relatively stable,the impact force of each parts of distributing-flow system is smallest.关键词：Cam groove;Rotating-sleeve;Distributing-flow system;Linear
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发布时间：2022-09-22 - 摘要：As key component of the roadheader,gyration platform has a significant impact on the performance of the work efficiency and dynamic reliability of the oadheader,Based on the coupled multi-body system dynamics theory,roadheader’s flexible virtual prototype coupling model of gyration platformwas established;combined with the actual working condition,cutting head’s load files were obtained based on the "roadheader design system software",equivalent stress and strain contours of the gyration platform were obtained by ADAMS;gyration platform’s fatigue life analysis was researched by NSOFT and reliability theory,and then to do optimize design in 10 areas of the low fatigue life reliability,after the optimize,gyration platform ’s maximum equivalent stress was reduced by 35.027%,Concept areas achieves reliable working conditions,which meet the design requirements.关键词：Roadheader;Gyration platform;Fatigue life;Dynamic reliability;Optimization
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发布时间：2022-09-22 - 摘要：The strength problems of large-aircraft wingbox is complex.Studying the bearing characteristics of wingbox,plays an important role in wing structure refined design,weight optimization and development cost saving.Based on the explicit time integration,this paper simulated the static loading process of typical wingbox section until failure in quasi-static limits,while taking the material nonlinearity and damage characteristics into consideration.Both the strain distribution and the strength prediction agree well with the experimental results.The study provides a reference for evaluating the ultimate strength of aircraft assembly.关键词：Wingbox;Qusi-static;Post-buckling;Stiffened panels;Nonliner FEM;Ultimate strength
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发布时间：2022-09-22 - 摘要：The transmission shaft is a critical component of the automobile transmission system,it’s static and dynamic characteristics good or bad is directly related to the safety and NVH problems of vehicle.To solve these problems,using Abaqus software establish the finite element model of the transmission shaft assembly strength and modal analysis,and through the modal experiment verifies the correctness of the finite element simulation analysis model,point out that the reliability of the analytical method,and through the theoretical calculation verify it,results show that the strength and modal of the transmission shaft assembly are meet the requirements of the vehicle matching design,the method provides a theoretical basis for the transmission shaft static and dynamic design.关键词：Transmission shaft;Static and dynamic character;Modal analysis;Modal experiment
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发布时间：2022-09-22 - 摘要：The influence of thermal cycle loading on optoelectronic PCB（Printed Circuit Board） reliability was presented.In product conceptual design stage,the three-dimensional finite element model of photoelectric PCB was established.The finite element analysis was carried out under thermal cycle loading which defined by GJB 150.5-86.The influence includes solder joints reliability of optoelectronic PCB,optical coupling efficiency and optical fiber reliability.The following results are obtained.First,the maximum stress of solder joint and optical fiber ribbon is in the security range and the structure is not destroyed.Second,photoelectric coupling efficiency is not changed significantly,which guarantees the stability of the optical transmission.It proves the feasibility of the design scheme and promotes the engineering applications of photoelectric interconnection technology.关键词：Photoelectric PCB;Thermal cycle;Finite element analysis;Reliability
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发布时间：2022-09-22 - 摘要：According to the effect of welding residual stress on fatigue fracture in crawler frame drive department when roadheader cross sectional,mechanical model of roadheader cross sectional was established,using MATLAB language calculate the different cross sectional angles of lateral force on the crawler frame;distribution law of welding residual stress of crawler frame drive department was analyzed by using finite element method.Based on the above analysis,and equivalent stresses under different cross-sectional angles on driver fatigue life analysis.The results show that the minimum lateral loads on the crawler frame and drive department weld fatigue life the greatest when the cross sectional angles of 5°.关键词：Residual stress;Roadheader;Fatigue life;FE-SAFE
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发布时间：2022-09-22 - 摘要：Based on the tailor-welded blanks with the radius of 180 mm arc-weld-line,and use Dynaform numerical simulation techniques to study TWBs with the transverse arc-weld-line a under the variable blank holder force changing with travel distance or position,The research shows that a certain range of blank-holder force can control the weld-line movement of TWBs and the springback angle of TWBs under the condition of VBHF changing with position.But beyond the change of the blank holder force,it is beneficial to sheet metal forming,not to the control of springback angle.Compared with other methods,V loading method benefits for the control of the weld-line movement and springback control,it has great effect on the forming of welding plate under the condition of VBHF changing with travel distance.Variable blank-holder force control methods,including changing with position and changing with travel distance,allow more thin side in sheet metal forming into the die,and reduce the welding plate deformation of the thin side material,due to easing the tailor-welded plate thickness caused by uneven deformation.Finally,the weld-line movement and the springback angle controlled to improve the forming quality of welding plate.关键词：Numerical simulation;VBHF;Arc-weld-line;Movement weld-line;Spring-back
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发布时间：2022-09-22 - 摘要：During the drilling operation,the drill pipe near the surface usually stands the largest tension and torsion.Stress concentration is relatively serious in the upset transitional section of the drill pipe,where initiation of fatigue cracks,washouts and even fracture accidents are prone to happening.Based on the actual operating loads of G105 drill pipe,which is near the well head of an ultra-deep vertical well,finite element model of the inner upset transitional section containing a circumferential semielliptical surface crack was established.The fracture characters of the cracked model were simulated under the combination of tension and torsion.For different loading ratios and crack depths,the transition aspect ratios are determined and variation laws of the dimensionless stress intensity factor are fitted along with the crack propagating.This paper provides a basis for study on the fatigue life of drill pipe which is subjected to combined loads.关键词：Drill pipe;Inner upset transitional section;Semi-elliptical surface crack;Fracture character;Stress intensity factor
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发布时间：2022-09-22 - 摘要：According to studying Angle cutting conditions of shearer drum cutting teeth distribution on the influence law of load spectrum,which provides reference for the design of the cutter tooth,in which equivalent test tooth holder to roll the same spiral blades cut line cut tooth load the real-time online monitoring,synchronous export analysis after storage.Experimental results show that the system is reliable,stable performance,can real-time dynamic testing of cutter tooth cutting force changes,through different cut line cut tooth time-cutting force change curves available:cutting force curve variation rule has the similarity,oblique cutting coal and rock,drum cutting tooth load whole curve peaks and troughs alternating form,cutting teeth with different cutting depth change of cutting force changing process;Same cutting resistance of greater than its feeding resistance,but its fluctuations are similar,have many irregular fluctuations;Single pick on the cutting resistance and traction resistance of instantaneous value obey the symmetry good Gamma distribution,the distribution parameters with pick in the cutting line spacing end plate distance relationship is a Fourier series,for the research on the rules of cutter tooth load spectrum provides a new method.关键词：Cutting pick;The test pick;Gamma distribution;Fourier series
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发布时间：2022-09-22 - 摘要：It has established that a crack has an important effect on the dynamic behavior of a structure.To identify the location and depth of a crack on a structure,a method is presented which uses hybrid neuro-genetic technique.This method combines genetic algorithm（GA） with neural network,and uses genetic algorithm to optimize the BP network.Though the finite element analysis,acquire the first three natural frequencies of the beam,which used as inputs into neural network models for damage assessment.Genetic algorithm（GA） optimizes the weights and thresholds of the network,and using the optimization results as the initial value of the three layer BP neural network.Though the training of the sample data,then establish the suitable network.Finally,using the theoretical natural frequencies as the test values,obtain the predicted results of crack parameters.Comparing the theoretical value with the predicted value,the results show that this algorithm can identify the damage structure accurately.关键词：Crack identification;Inverse problem;Neural network;Genetic algorithm
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发布时间：2022-09-22 - 摘要：With high precision grinding technology development,the requirement for machine tool reliability is higher and higher.The load spectrum of grinding is key scientific basis of building the grinding machine spindle reliability experiment platform.Based on bearing ring machine tool grinding process,the load spectrum signal characteristic and processing method is studied through long time grinding spindle load measurement,recoding and analysis.Then,the compilation method is provided to get load spectrum.At last,the programmed load spectrum for "idle-grinding-idle"is drawn,which is consistent with real field load.It provide the loading condition and theory basis for grinding machine tool spindle reliability experiment,and also is very important to improve machine tool spindle design.关键词：Bearing ring;Grinding machine;Load spectrum;Experiment study
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发布时间：2022-09-22 - 摘要：Currently,the damage constitutive model based on D-P（Drucker-Prager） criterion of rock has occupied dominant position in the field of damage constitutive model of rock.its advantages have become increasingly prominent.This paper mainly analyzes the results of the experimental data based on Drucker-Prager Criterion and finds some fatal errors.Poisson’ratio is key factor in it.Poisson’ratio of rock is variable value from the experimental observation.Since the Poisson’s ratio is used in the full damage constitutive model,We propose a new conception of"quasi-poisson’ratio",derived the formula of quasiPoisson’s ratio and introduce it to the constitutive model of rock based on Drucker-Prager Criterion in order to revise it.The new modified model is a new breakthrough for numerical analysis and software application.We believe the conception of "QuasiPoisson’Ratio"will lead to many aspects of the improvements in rock mechanics and has long-term meanings.关键词：Rock;Damage constitutive model;Quasi-poisson’ratio;Revise
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发布时间：2022-09-22 - 摘要：For the research on the method of building the load spectrum of ZLK50 type loader hydraulic system under the actual working conditions,a measurement scheme of multiple working conditions of the hydraulic cylinder is proposed based on the signal wireless acquisition mode.Statistic calculation of the time history of the bucket hydraulic cylinder load is carried out.Based on the statistical method of the rain flow matrix data in the shape of "from-to",a non-parametric frequency extrapolation method of the amplitude rain flow matrix based on kernel function estimation is introduced.According to the method,the eight stages’ program load spectrum of the bucket hydraulic cylinder in digging stage is established,and the program loading spectrum compilation on full operation stage of the hydraulic cylinder is finished.The data support for the fatigue life estimation of the loader hydraulic cylinder is provided.关键词：Engineering machinery;Load spectrum;Rain flow frequency extrapolation;Kernel density estimation
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发布时间：2022-09-22 - 摘要：For the gear transmission mechanism of a slat,based on S-N curve and linear cumulative damage theory,the reliability fatigue life caculation formula of gear contact can be obtained.In order to realize the global influence of the basic random variables on the distribution of the response performance function completely,the global sensitivities are proposed,which can provide effective theoretical guidance for optimazation and reliability design of gear.关键词：Gear;Linear cumulative damage;Reliability;Fatigue;Global sensitivity
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发布时间：2022-09-22 - 摘要：It has already been proved that the Neuber method overestimates the notch root stresses and strains and the equivalent strain energy density（ESED） method underestimates those,that is,the upper limit and lower limit can be obtained by the above two methods.On the basis of the analysis of results of notch root subjected to biaxial loading,a modified calculation method is proposed based on Neuber method in order to make up it’s shortage.Meanwhile,in the case of plastic stage,the effect of the material constants of elastic modulus,yield stress and poisson’s ratio on the stresses and strains should be considered and the results calculated by modified method should locate between those by Neuber method and the equivalent strain energy density method.Taking the LD5 notch sample as an example,the notch root stresses and strains are calculated.Finally the calculation results using modified method are validated with those by the finite element method.关键词：Biaxial loading;The notch root stresses and strains;Neuber method;Equivalent strain energy density method;Finite element method
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发布时间：2022-09-22 - 摘要：The determination of the dynamics parameters for the steel cord rubber conveyor belt is the key problem to research the dynamic characteristics and the operation energy consumption of the belt conveyor.Firstly,the transition state and the stable state for the dynamics parameters are defined according to the relaxation and the time-variant characteristics of the rubber conveyor belt.Secondly,the stress analytic solution of the conveyor belt under the dynamic strain is derived by taking the standard solid model as the viscoelastic constitutive model,the transition state and the stable state are analyzed according to the attenuation term in the analytic solution,and the general identification model and the simplified identification model for the standard solid model parameters of the conveyor belt are established.Finally,the dynamic strain loading experiment using st1600 steel cord rubber conveyor belt is performed,and the Matlab cftool tool box is employed to identify the experiment result.The result shows that under the experimental parameters,the difference between the general model identifying result and the simplified model identifying result decreases with the increase of loading cycling times,and the general model identifying result and the simplified model identifying result are the same and maintain stable when the loading cycling times is greater than 67.The loading cycling times or the loading cycling time that the general model identifying result and the simplified model identifying result are the same first can be taken as the criterion to distinguish the transition state and the stable state for the dynamics parameters of the conveyor belt.关键词：Conveyor belt;Dynamics parameters;Viscoelastic constitutive model;Identification model
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发布时间：2022-09-22 - 摘要：The static stiffness of the spindle is an important index to evaluate the static characteristics of the motorized spindle,which is essential to ensure the machining accuracy of precision CNC machine tools.Based on the calculation formulas of cutting force under typical conditions and those of radial stiffness of angular contact ball bearing,the axial deformation in front of the spindle,as well as the static stiffness in the specified condition,were obtained through the 3D finite element model of rotor-bearing system.The static stiffness test was performed on the experimental platform.By comparing the simulation results and the experimental results,the validity of the finite element model was indirectly verified.Based on the reliable finite element model,the variations of the static stiffness of the spindle with the preloads of the front and rear bearing groups were gained.关键词：Static stiffness;Motorized spindle;Finite element;Preload
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- 306
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- 2
发布时间：2022-09-22 - 摘要：In order to improve the impact mechanism of the impacting and breaking rock roadheader dynamic characteristics under the cycle impact load,the first six natural frequency and mode shape as well as the displacement-frequency curves were obtained by using stress wave synthesis theory and finite element method in the paper,the modal and harmonic response of the mechanism were analyzed,the main deformation portion and main vibration direction and three axial weakest points of the mechanism were confirmed,structure size optimization of the rocker arm were adopted with multiple objective genetic algorithm,The maximum displacement response of the mechanism was reduced,and the dynamic characteristics of the mechanism were improved,which provides a method and basis for researching and improving the dynamic performance of the mechanism.关键词：Roadheader;Impacting mechanism;Modal;Harmonic response;Optimization design
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发布时间：2022-09-22 - 摘要：Analysis of oscillating rod of rigid structure horizontal log-periodic antenna under wrap ice was performed,due to winter weather oscillating rod is bent,somewhere in the north in February 2014.In the finite element software ANSYS platform,to wrap the ice thickness,wrap ice when wind speed is known conditions,a detailed analysis of wrapped ice of bending oscillating rod was performed.The results show that the actual thickness beyond the design wrapped ice thickness.So cause the wrap ice load and wind load area increases,beyond the oscillating rod and its cable carrying capacity,resulting in instability of the oscillating rod bent.According to the oscillating rod bent reason,in order to meet the requirements of heavy ice wrapped,the improved design of the oscillating rod was proposed.关键词：Horizontal log-periodic antenna;Oscillating rod;Bending;Wrap ice analysis;ANSYS
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发布时间：2022-09-22 - 摘要：Chain drive is a convenient mechanical transmission for use,which has such characteristics as compact structure and high reliability.Chain is a flexible body.In the course of transmission,the polygon effect and the meshing impact are the fundamental reason to produce dynamic loadand vibration,meanwhile,this process is abstract and difficult to be understood.With chain drive kinematic theory and multi-rigid-body dynamics as the theoretical basis,the polygon effect and the meshing impact were simulatedby using Recur Dyn software,which visually showedthe inhomogeneity of the chain speedand the beating effect of the chain drive.It provides the right virtual prototyping model for the whole machine simulation and mechanism optimization analysis about chain transmission,and it has some guidance and reference value for the development and improvement of products about chain drive.关键词：Chain drive;Recur Dyn;Polygoneffect;Multi-body dynamics
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- 220
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发布时间：2022-09-22 - 摘要：In this paper,the input shaft of the agitator 34-M-2001 in a polypropylene device is studied.For the fracture problem of the input shaft in the same key groove,the strength of the shaft,force distribution of the key grooves and its factors such as the processing technology are analyzed synthetically to determine the causes of the failure and propose the optimized improvement program.In the case of the impossibility to change the shaft diameter,the performance of the shaft can be improved by changing the chemical composition of the material or choosing a better material.Simultaneously,the optimization for reducing the stress concentration at the tail of the key grooves is proposed by changing the processing technology.The studies indicate that the improved shaft has an excellent performance.The above researches have a great reference value for improving the mechanical performance,service lift of the transmission parts,especially for the shaft.关键词：Input shaft;Fracture;Processing technology;Mechanical properties of materials;Performance optimization
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发布时间：2022-09-22 - 摘要：The marking mechanism,as an important part of one steel plate marking machine that before heat treatment,its dynamic characteristic could influence marking effect.First,estiblished 3D model of marking mechanism by Pro/E,using the condition of marking typical character "N " as example,kinematics analysis have been done,obtain the law of speed and acceleration varies with time when marking character;on the basis of it,build the finite element model of marking mechanism according to actual condition and transient dynamics analysis has been completed based on Ansys Workbench,solved the curve of maximium stress and deformation varies with time,the result shows that the intensity and stiffness of marking mechanism could satisfy the requirement,and provide theory foundation for the structure design and optimization.关键词：Writing mechanism;Dynamic characteristics;Kinematics analysis;Transient dynamics analysis
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发布时间：2022-09-22
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