最新刊期
期 6 ， 2019
- 摘要：As for the conductive plate in magnetic field generated by current-carrying three parallel coaxial circular coils and spherical coils,based on the Kirchhoff plate theory,the magnetoelastic transverse vibration equation of the plate in magnetic field was given. According to electromagnetic theory,the expressions of electromagnetic forces acting on circular plate in uniformly distributed region of the magnetic field generated by current-carrying coils were derived. By setting of a displacement function and using of Galerkin method,the magnetoelastic axisymmetric vibration differential equation of the plate and the expression of the natural frequency were obtained. By calculation examples,the curves of magnetoelastic natural vibration characteristics of the circular plate with clamped boundary condition and simply supported boundary condition were drawn. The analysis on laws of the natural frequency,damping ratio and electromagnetic moment varying with current intensity,turns of coils and plate thickness is presented finally.关键词：Circular plate;Magnetoelasticity;Natural vibration;Current-carrying coils;Electromagnetic forces
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发布时间：2022-09-22 - 摘要：Based on the reciprocating compressor,the dynamic response laws of the small end bushing abrasion on the basis of the dynamics simulation model were analyzed. According to the method of non-linear contact collision modeling,the dynamic model of small end bushing-crosshead pin joint was established. By changing the clearance between small end bushing and crosshead pin,the contact-impact parameters under different wear states were simulated and calculated,and features of the contact impact force between small head bushing and crosshead pin were analyzed,also between crosshead and middle body. The response which provides guidance for extracting sensitive characteristics under the wear fault was obtained. The correctness of the simulation results are verified through experiments,which provide an advanced warning and diagnosis method for the wear failure of small end bushing.关键词：Small end bushing wear;Dynamic simulation;Reciprocating compressor;Fault warning
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发布时间：2022-09-22 - 摘要：Conventional fast Fourier transform（ FFT） has been the most popular method of processing non-stationary and nonlinear signals. However,FFT has been known to be less efficient because of aliasing. In view of such constraints,this paper proposes a new method based on Hilbert-Huang transform-FFT of intrinsic mode functions（ IMFs）. In the present work,FFT of IMFs from HHT process has been incorporated to utilize efficiency of FFT in frequency domain. Take transmission system of mining machine cutting department for example,nonlinear vibration signals has been measured by experiment. Conventional FFT and FFT of intrinsic mode functions（ IMFs） are used for analyzing the nonlinear modulation characteristics of the experimental signals respectively. The comparative analysis presented in this paper indicates the effectiveness of using FFT of IMFs for recognizing the frequency components which participate in nonlinear frequency modulation. The method proposed can avoid the phenomenon of aliasing.关键词：Hilbert-Huang transform;Intrinsic mode function;Fourier transform;Frequency modulation
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发布时间：2022-09-22 - 摘要：Tools are the key parts in the process of NC milling machine. They are in high-speed processing for a long time and are prone to failure. Aiming at the problems of less tool wear state data,low diagnostic efficiency,high maintenance cost and lack of effective diagnostic methods during CNC machine tool processing,A method of extracting features by wavelet packet analysis and kernel principal component analysis,and using BP Ada Boost algorithm to diagnose tool wear state is proposed.The tool vibration signal and the cutting force signal are collected by installing an acceleration sensor on the machined workpiece of the numerical control machine tool and a force gauge on the workbench; Then the wavelet packet decomposition is performed on the signal to pass the signal through the low-pass filter and the high-pass filter of different dimensions,so that the conditional selection can be performed to form the energy value corresponding to the different frequency bands. The data after the dimension reduction of the kernel principal component analysis is taken as the characteristic parameter of the tool wear state; Finally,the eigenvectors are used to train and validate the BP AdaBoost classification model. The experimental result shows that the BP Ada Boost algorithm can effectively diagnose the wear state of the tool in CNC machine tools compared with the SVM algorithm.关键词：Tool wear state;Cutting force signal;Acceleration signal;Wavelet packet analysis;Kernel principal component analysis（KPCA） dimension reduction;BPAda Boost
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发布时间：2022-09-22 - 摘要：Aiming at the problem that accuracy of orthogonal locality preserving projections（ LPP） for fault diagnosis is not high enough,a fault diagnosis method based on none parameter supervised kernel locality preserving projections（ NPSKLPP） for dimension reduction is proposed. In NPSKLPP,firstly,by changing the Euclidean distance to the Cosine distance which is more robust to outline,and constructing a none parameter nearest-neighbor graph which combined sample label information. And then use the nonlinear mapping to map the high dimension fault feature into an implicit feature space to dimension reduction. Thus a linear transformation is performed to preserve locality geometric structures of the fault feature,which solves the difficulty of parameter selection in computing affinity matrix,as a result,better fault diagnosis accuracy can achieved. The experiment results of gear fault diagnosis verified the effectiveness of the method.关键词：Fault diagnosis;Locality preserving projections;None parameter;Supervised;Gear
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发布时间：2022-09-22 - 摘要：Regarding the vibration signal characteristics of gear with broken teeth,the fault characteristic frequency can be extracted by means of calculating IHPS（ Improved Harmonic Product Spectrum） and SPS（ Sideband Product Spectrum） after FFT when the vibration shock is not obvious. Verified by simulation analysis and experiment,the method is proved effective and can be a feasible path to early detection for such faults.关键词：Fault signal processing;IHPS;SPS;Gear teeth broken;Vibration fault
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发布时间：2022-09-22 - 摘要：The matching of crack tip constraints is a difficult problem in the current structure integrity assessment method.Due to the restriction of current constraint parameters,the matching of crack tip constraints between different laboratory specimens,between laboratory specimens and actual structures have not been established. In this paper,based on the unified constraint parameter Ap,the constraints of different SENB,CT,SENT and CCT specimens were studied,the J/Jref-（Ap）1/2 correlation lines and the matching of crack tip constraints between different laboratory specimens were established. This study will provide scientific support for building an accurate structure integrity assessment method which considers constraint.关键词：Constraint;Matching;Laboratory specimen;Structure integrity assessment
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发布时间：2022-09-22 - 摘要：As a kind of natural biological material,compared with common metal materials,spruce wood has lighter specific gravity and has the advantages of green,environment-friendly and recyclable. This study took spruce wood as research object,explored the dynamic responses of spruce wood sandwich structures under low velocity impact loadings,compared energy absorption capability of spruce wood sandwich structures with traditional metal sandwich structures,and analyzed the effect of different impact energy and material thickness on its structural deformation process and energy absorption characteristics. The microstructure of spruce wood core was observed with high magnification microscope to analyze how the failure form of core material affect energy absorption characteristics and the relationship between microstructure and macro damage further. The study aims to promote the application of green and environment-friendly materials in body and multi-fields.关键词：Low-velocity impact;Spruce wood;Sandwich structures;Energy-absorption;Microstructures
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发布时间：2022-09-22 - 摘要：The stress-strain curves and fracture characteristics of 7003 aluminum alloy under different stress triaxiality and strain rates were obtained by dynamic and static tests,and the constitutive model of Johnson-Cook material with sensitive strain rate was fitted by the experimental results. The experimental results show that the fracture process of 7003 aluminum alloy has strain rate sensitivity,and the fracture strain decreases with the increase of stress triaxiality. The whole fracture process of 7003 aluminum alloy was simulated by LS-DYNA software,and the simulation results were in good agreement with the experiment.关键词：7003 aluminum alloy;Johnson-cook constitutive model;Stress triaxiality;Strain rate
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发布时间：2022-09-22 - 摘要：The development of virtual prototype technology makes the vehicle multi-bod dynamics simulation and virtual fatigue durability calculation become the necessary means of engineering research,and obtaining reliable and effective road spectrum is the premise of the two means. This paper build road spectrum solution joint simulation platform based on FEMFAT LAB-ADAMS,and the response channel is established on the multi-body dynamics model according to the installation position of the actual vehicle sensor. The road spectrum is calculated based on the virtual iteration theory and the real road spectrum of the engine connection point and the shock absorber mounting point. The reliability of the road spectrum solution is verified by comparing the monitoring signal and the measured signal from three aspects of time domain characteristics,frequency domain characteristics and damage calculation. The results show that the reliable road spectrum can be used for vehicle multi-body dynamics simulation and virtual fatigue durability calculation.关键词：Damage;Transfer function;Joint simulation;Virtual iteration;Femfat LAB-ADAMS
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发布时间：2022-09-22 - 摘要：In order to improve cold roll-beating forming spline surface roughness and surface quality,cold roll-beating experiment is carried out. According to cold roll-beating spline forming principle,the main influencing factors（ rolling wheel speed,workpiece feed rate,beating ways,beating depth） of the surface roughness of cold roll forming spline are analyzed. The relationship between the rotational speed of the rolling wheel,workpiece feed rate and the surface roughness is quantitatively analyzed. Research shows: The surface roughness with the increase in the rotation speed of the wheel shows a downward trend.And the surface roughness increases with the increase of workpiece feed rate. When the rotational speed of the rolling wheel is in the range of 1581 r/min ～ 2032 r/min and the workpiece feed rate is in the range of 21 mm/min ～ 35 mm/min,the suitable cold roll-beating spline surface roughness and considerable surface quality is obtained.关键词：Cold roll-beating forming spline;Processing parameters;Surface roughness
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发布时间：2022-09-22 - 摘要：Ti-6 Al-4 V titanium alloy specimens were built using selective laser melting. Some specimens were heat treated and some were hot-isostatically pressed. Half of these specimens in three conditions were polished. Tensile test was conducted to research into the effect of heat treatment/hot-isostatic pressing and polish on the mechanical properties. The microstructure and fractography were observed using optical microscope and scanning electron microscope to find the reason for mechanical property modifications. The test results demonstrate that,after heat treatment or hot-isostatic pressing,the ultimate tensile strength of SLM Ti-6 Al-4 V is reduced significantly while the elongation is improved by around 50%. Polish results in the increase of yield and ultimate strength by about 30 MPa for hot-isostatic pressed specimens,but leads to no apparent improvement in mechanical properties for as-built and heat treated specimens.关键词：Selective laser melting;Heat treatment;Hot-isostatic press;Surface roughness
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发布时间：2022-09-22 - 摘要：Automobile 6061 aluminum alloy materials has been taken as the research object,the samples have been obtained by the metallurgical technology by adding reinforcing phase fly ash,the cutting theory model under different process parameters have been established based on the grey multi response optimization theory,at the same time the cutting experiments under different process parameters have been conducted,the effects of different process parameters on the cutting of the automobile 6061 aluminum alloy materials have been studied by the theory and experimental methods. The research shows that with the increase of strengthening phase fly ash,the automobile 6061 aluminum alloy material hardness increases,its density showed a trend of opposite; with the increase of cutting speed,fillers,the surface roughness of composite automotive materials gradually reduce,the surface roughness increases with the increased of the feed; PCD cutting tool machining of complex automotive materials surface roughness significantly below K10 hard alloy cutting tools; the relative error value of theoretical calculation value and experimental is small to verify the correctness of the theory and test methods,and the engineering feasibility for improving the application of the new automotive aluminum alloy composite material preparation and cutting technology.关键词：Automobile 6061 aluminum alloy materials;Cutting processing;Grey multi response optimization theory;Processing parameters
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发布时间：2022-09-22 - 摘要：In order to increase the burst pressure of copper pipe,save the copper material under the premise of guaranteeing safety,overpressure enhancement of TP2 copper tube was tested at room temperature,the relationship between the burst pressure of copper tube and the pretreatment pressures was studied,the changes of TP2 material tensile strength was analyzed. Based on28 groups burst test of TP2 copper tubes under different pretreatment pressure at room temperature,studies have shown that: 1)If the enhancement pretreatment pressure of TP2 copper tube is equal to the yield pressure,the thermal effect of copper tubes brazing should be improved,copper tube burst pressure and TP2 material tensile strength should be strengthened to a certain extent. 2) Compared with non overpressure enhancement at room temperature,for the burst pressure and the tensile strength of TP2 copper tube used appropriate pressure pretreatment,the means of copper tube burst pressure and the TP2 material tensile strength are increased significantly,the standard deviation and coefficient of variation are decreased significantly,and the precision is improved obvious. For the burst pressure and the tensile strength of TP2 copper tube,the fluctuation range of the average,standard deviation and coefficient of variation are smaller,and the stability is become well.关键词：TP2 copper tube;Overpressure enhancement;Burst pressure;Tensile strength;Precision;Stability
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发布时间：2022-09-22 - 摘要：In view of the problems that the traditional variance-based Sobol’method had a low solving efficiency,lacked of enough robustness,and it cannot further effectively decompose and reasonably distribute the influences of the high-order cross subterms,a practical and effective structural global sensitivity method was proposed in this paper based on partial derivative whole domain integral and optimal polynomial surrogate model. Firstly,optimal surrogate model was constructed through polynomial structure-selection,which had good fitting and predictive ability,and it was convenient for direct integral operations. Then,local sensitivity method based on partial derivative was extended to a global sensitivity method by integrating partial derivatives of model variables in variable sapces. In addition,the paper redefined a more conveniently calculated sensitivity indice that can achieve effective decomposition for the high-order sensitivity indices,and the sensitivity results directly corresponded to model variables without the high-order indices,which had more practical engineering significance. Numerical example 1 shows the deficiency of Sobol’total sensitivity indices in application. Numerical example 2 illustrates the validity of the proposed method for complex high-dimensional model. Engineering example demonstrates the applicability and effectiveness of the present method for complex engineering structure problems.关键词：Structural global sensitivity;Partial derivative whole domain integral;Polynomial structure-selection;The optimal polynomial;Sobol’method
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发布时间：2022-09-22 - 摘要：Aiming at mechanical parts for multi-failure modes,the advantages of using Copula functions to describe correlations,a reliability modeling method for multi-failure mode related mechanical parts is proposed. Based on the Vine Copula function,the reliability problem of mechanical parts related to complex and multi-failure is transformed into the analysis of multiple two-dimensional Copula functions,optimal two-dimensional Copula function is identified by using maximum likelihood estimation and AIC information criterion. Mechanical parts failure mode is relatively small,access to less failure samples. To avoid the variability of AIC values,based on improved parameters is proposed to identify the optimal two-dimensional Copula function when the failure sample size is small. The feasibility of the improved parameter Bootstrap method is verified by Matlab simulation,then the reliability of the multi-failure mode related mechanical parts is solved by using the Vine Copula model.Finally,through the comparison between the calculation example of drive shaft and other methods,the method is rationality and validity.关键词：Mechanical parts reliability;Correlated failure mode;Vine Copula function;AIC;Improvement parametric Bootstrap
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发布时间：2022-09-22 - 摘要：In order to reduce the weight of the frame and improve the static and dynamic performance of frame structure,the structure parameters of frame beam,crossbeam were served as the design variables,sampling points were obtained by using optimal Latin squares design of experimental method. The Kriging method was adopted for the multi-objective system of the frame NVH,torsional stiffness,bending stiffness and frame quality,an approximate model was optimized by using NSGA,and then the Pareto optimal solution set was obtained.关键词：Frame;Approximate model;Optimal Latin squares design;Kriging method;NSGA;Lightweight
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发布时间：2022-09-22 - 摘要：In order to reduce the flow pulsation of the inner meshing gear pump,taking PGH type involute internal gear pump as the research object,the mathematical model of flow pulsation rate and tooth profile parameters was established,and the instantaneous flow rate of gear pump outer gear ring and internal gear in different meshing relations was analyzed. Based on these,a mathematical model of gear pump optimization was established. The improved particle swarm optimization was obtained by introducing the genetic operation and mutation operation of the genetic algorithm into the particle swarm optimization algorithm,through this algorithm、the parameters of gear indexing circle pressure angle、modification coefficient、addendum coefficient and tooth number were optimized,and the gear parameters of gear pump with minimum flow pulsation rate were obtained. The simulation verification was carried out by MATLAB,and the results showed that the flow pulsation rate and the tooth shape parameters of the gear pump are nonlinear; Under the condition of satisfying the structural requirements and reasonable transmission,the flow pulsation rate of the gear pump is reduced by 7. 27%,and the flow pulsation of the internal gear pump is reduced.关键词：PGH internal gear pump;Improved particle swarm optimization;Optimization of tooth profile parameters;Flow pulsation
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发布时间：2022-09-22 - 摘要：The extended finite element method（ XFEM） is one of the most widely used numerical methods to deal with cracks,holes and inclusions. Based on the partition of unity method（ PUM）,the additional function terms are introduced to the displacement approximation function of the standard finite element method（ FEM） to reflect the discontinuous characteristics and singular characteristics of the displacement field in XFEM. The introduce of the additional function terms leads to the uncertainty of the element stiffness matrix（ ESM） of XFEM. Hence,the assembly algorithm of standard FEM global stiffness matrix（ GSM）is no longer applicable to XFEM. A new assembly algorithm based on the‘Generalized adjacent node pairs’ is proposed. In this algorithm,we use the one-to-one corresponding relationship between‘Generalized adjacent node pairs’ and the non-zero terms in GSM,And with the compressed sparse row storage format（ CSR） of large sparse matrix,the GSM of compressed storage is formed directly from the ESM. In this paper,the implementation process of the algorithm is detailed,and the program is successfully implemented in the XFEM program developed by Fortran,and the effectiveness of the algorithm is verified.关键词：XFEM;Global stiffness matrix;Compressed sparse row（CSR） storage;Assembly algorithm of stiffness matrix
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发布时间：2022-09-22 - 摘要：A novel parallel hybrid powertrain was proposed. The PX type single-loop system was adopted. It could effectively avoid the CVT’s torque and power capacity. By serially connection to 2-speed gearbox,The PX type single-loop system ratio spread was enlarged. For regenerative braking mode,the power flow reversibility of the PX single loop system was verified.The electric motor was used to realize pure electric drive and recovery braking energy. At high speed and heavy load,the vehicle was driven simultaneously by the engine and the motor. The bond graph model of the powertrain was established,and the state equation of the system was given. Based on MATLAB/Simulink,the vehicle simulation model was established,and the highway portion of the US06 drive cycle was selected to simulate the powertrain. The simulation results show that: through mode switch,engine operates in high efficiency areas,and the actual speed of the vehicle can well follow the driving cycle. At the same time,the battery state of charge is ensured in the expected range before and after the simulation.关键词：Parallel hybrid powertrain;PX type single-loop system;Mode switch;Bond graph
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发布时间：2022-09-22 - 摘要：To solve the problem of stubborn balance,improve the efficiency of tunneling,the design of advanced support equipment of arch. In order to study the structural stability of the device,the multi-point distributed static model of the advanced support roof is established based on the actual working conditions. The stress and displacement equations of the roof beam are listed according to the principle of force method and singular function method. The simulation results show that there is stress concentration in the supporting roof beam with maximum stress of 192. 71 MPa and safety factor of 1. 22. Finally,the design of the top beam structure is optimized by using the Design Explorer module in ANSYS Workbench. The simulation results show that the quality of the single roof beam is reduced by 7. 6%,the overall stress is reduced by 28. 3%,the safety factor is increased to1. 70,Indicating that the optimized support structure has good structural stability. The conclusion can provide a reference for the structure,size design and optimization of the advanced support equipment and similar support equipment.关键词：Stubborn balance;Advanced support;Roof collapse;Size optimization
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发布时间：2022-09-22 - 摘要：Based on the force model of the ball in the cage type constant velocity universal joint,the expressions of the circumferential force of the groove on the steel ball,the normal contact force of the channel to the steel ball and the normal contact force of the cage window to the steel ball are deduced when the steel ball moves in the inner groove and the bell shaped outer channel of the star sleeve. On this basis,based on the Herzt contact theory,the above force is verified by Adams dynamics.The results show that the simulation results are basically consistent with the theoretical calculation. The circumferential force,the normal contact force,the friction force of the steel ball and the star sleeve and the friction force of the seven channel cage type constant velocity universal joint are less than that of the six channel,and they change with the change of the swinging angle.关键词：Seven channel Rezzpa universal joint;Outer raceway;Circumferential force;Normal contact force
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发布时间：2022-09-22 - 摘要：Before the production of products,it is the mainstream mode of equipment research and development to use the digital design or simulation technologies to comprehensively evaluate and optimize their performance. As complex structures,it is inevitable that there are some differences between the simulation model and the real model due to the simplification of model and other reasons. In this condition,Model confidence is an important factor to evaluate whether a simulation model can effectively guide the structural design. The paper analyzed the equivalent modeling method of dynamics model of complex structure and the influence factors in the simulation model. A bottom-up model updating method was proposed which is combined with the characteristics of electronic equipment structure. A typical case was given to verify the feasibility of the method. The simulation model satisfying the requirement of engineering precision is obtained by using the bottom-up model updating strategy,which lays a foundation for the subsequent design and simulation of similar products.关键词：Complex electronic equipment;Dynamic Analysis;Modal test;Model confidence;Model updating
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发布时间：2022-09-22 - 摘要：Micro-machining can produce size effect under mesoscopic scale,by using the strain gradient plasticity theory of dislocation mechanism,considering the microstructure characteristics of the material,the material constitutive model under mesoscopic scale is established,which can be used to explain the size effect of micro-machining. The material constitutive model under the mesoscopic scale derived from the theory is analyzed and studied,and the stress-strain curves and simulation results under different conditions are obtained in this article. The research shows that with the increase of cutting thickness,the stressstrain curve of the material will tend to the stress-strain curve of macro cutting. As the rake angle of the tool increases,the internal stress of the material increases accordingly,and the scale effect of the material becomes more obvious. The rake angle of the tool also has a great influence on the formation of the chip,and the smaller tool rake angle is more conducive to accumulating material and thus forming chips. The cutting edge radius of the tool is the root cause of the phenomenon of minimum cutting thickness. With the decrease of the cutting edge radius,the scale effect of the material becomes more prominent.关键词：Mesoscopic scale;Size effect;Strain gradient;Minimum cutting thickness
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发布时间：2022-09-22 - 摘要：Autonomous vehicles should have the ability that could independently complete steering operations, but traditional electric power steering systems cannot satisfy this function. In order to achieve the purpose of automatic steering of autonomous vehicles,the vehicle steering system is designed to meet both the driver’s driving and the vehicle’s automatic driving conditions,key parts of the system are selected and designed; The mathematical model of the steering system is established according to different driving conditions,and simulated in Matlab/Simulink environment. The simulation results show that this steering system can satisfy the automatic driving conditions,and can guarantee the stability of the vehicle,but due to the error between the output value and the input value of the steering system,there is a certain deviation in the trajectory.关键词：Autonomous vehicle;Driving rights;Automatic driving;Steering system
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发布时间：2022-09-22 - 摘要：As a parameter characterizes the ability to resist crack propagation,fracture toughness plays an important role in evaluation of pipeline integrity. It is of both scientific and engineering significance to carry out a thorough study on its size effect.At present,the research on size effect of fracture toughness of metal materials is mainly focused on the linear elastic fracture parameter stress intensity factor K,and mostly only the influence of specimen thickness is considered. In order to establish a systematic law of size effect on high strength and high toughness pipe steel,a three-dimensional finite element model of standard single-edge notched beam（ SENB） specimens based on GTN model was set up. The ductile fracture process of this specimens under displacement load was simulated. The Crack-tip Opening Displacement（ CTOD） and Crack-tip Opening Angle（ CTOA）were selected to characterize the fracture behavior. The distribution law of them along the specimen thickness direction was analyzed,and the effects of crack depth and specimen thickness were also studied. At the same time,the stress triaxiality was selected to evaluate the constraint level,so as to explain the cause of the size effect. The results show that the fracture toughness along the thickness direction remains unchanged within a certain range and reaches peak value at the free surface. The crack depth has little effect on fracture toughness and it decrease with the increase of specimen thickness.关键词：CTOD;CTOA;Stress triaxiality;Size effect;Constraint
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发布时间：2022-09-22 - 摘要：Based on three dimensional continuum damage mechanics,an improved progressive damage analysis method was proposed for bi-modulus fiber-reinforced polymer（ BFRP） composites laminated structure. Firstly,according to the bi-linear model of bi-modulus materials and constitutive theory of orthotropic material,the stress-strain relation for BFRP composites lamina was described. Secondly,in-situ strength of lamina was calculated using Dvorak model. Plus,damage initiation and its evolution inside laminates were described by three-dimensional Hashin strength criterion and the exponential damage evolution criterion,and the cohesive element was used to describe the interlaminar mechanical behavior. Then,the progressive damage analysis code for BFRP composites laminated structure was realized through ABAQUS material subroutine UMAT. The new method was verified by comparing to the experimental results in literatures. Finally,this method is used to examine the load limit of a BFRP arm structure which is a part of space station and obtain the prediction results.关键词：Bi-modulus;Continuum damage mechanics;In-situ strength;Progressive damage analysis;Hashin failure criterion
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发布时间：2022-09-22 - 摘要：During the process of combined rotor modularization amplification or reduction,due to the size effect,the law of the influence of microcrack expansion on the dynamic performance of the combined rotor with different sizes is not clear.Dimensional analysis method of similarity theory was used to introduce the "size effect"existing in the process of microcrack expansion. And taking the prototype,2. 3-fold scale model and 1. 3-fold scale-up model of a heavy duty gas turbine combined rotor as the research objects,the combined rotor natural frequency drift were analyzed in the case of initial microcracks varying with combined rotor size. The results show that there is comparatively large deviation when using the ordinary Paris formula to analyze the natural frequency drift of the different size combined rotors caused by microcrack expansion. There is a certain correlation between the change of dynamic performance and the size of combined rotor considering microcracks.关键词：Combined rotor;Similarity theory;Microcrack;Dynamic performance;Serial design;Size effect
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发布时间：2022-09-22 - 摘要：The Nahshon-Hutchinson shear modified GTN damage model was used to simulate the mechanical and damage behavior of small punch test（ SPT）,where the study material is silicon steel. Based on finite element simulation and factorial experimental design method,the influence degree of the damage evolution parameters on the SPT load-displacement curve were evaluated,and three key impact damage evolution parameters（ fN,εN,ks） were identified,the response surface method（ RSM）was then used to determinate the three key damage parameters. The facture parameters（ fc,fF） was determined by comparing the SPT load-displacement curve obtained by simulation and experimental results. Finally the effective of the identified parameters were verified by SPT experiments with different specimen thickness.关键词：Small punch test;GTN damage model;Finite element method simulation;Response surface method
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发布时间：2022-09-22 - 摘要：In order to predict fatigue life of frame,the MBS model of full vehicle has been built,based on the road load data,by applying virtual iteration technique,the dynamic load of interface point of frame has been obtained. In order to solver the time-consuming problem of dynamic load simulation caused by off-road in durability procedure,the road has been reduced by applying time correlated fatigue analysis with damage editing method,the value and distribution of damage are same as the original one,the mileage of single loop has been reduced to 1. 6 Km from original 3 Km,the dynamic load simulation has been accelerated. The fatigue life of frame has been predicted by applying Miner Counting Algorithm for Acuminated Fatigue Analysis,the analysis result has shown that the fatigue life can satisfy the target,and the vehicle has ultimately passed the durability validation of proving ground,which has shown that the analysis result is accorded with the test.关键词：Multi-body system dynamics;Virtual iteration;Reduction;Dynamic load;Fatigue analysis
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发布时间：2022-09-22 - 摘要：A six-point bending test that characterized the failure of the stiffener-skin interface of a stiffened composite panel at the post-buckling stage is studied. A FEM model for a stiffened panel subjected to compression and a six-point bending test model were created in Abaqus. The initial failure location,the failure model,and the stress distribution of the stiffener-skin interface of the six-point bending test were analyzed compared with a stiffened panel by using the cohesive element and the submodel method. Based on the results of the FEM model,running loads transferred through the bond layer were derived,failure criteria and failure envelops were developed for the stiffener/skin interface. The results indicate that the six-point bending test can characterize the interface failure of a composite stiffened panel at the post-buckling stage availably.关键词：Composite;Stiffened panel;Post-buckling;Six-point bending test;Failure characterization
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发布时间：2022-09-22 - 摘要：Based on the minimum rank damage identification method,a minimum rank update method is proposed to study the damage identification of space truss structures. The propose combines the residual force equation with the minimum rank update method by introducing the eigenvalue matrix,effectively dealing with the problem about the number of taken modes must be equal to the rank of the stiffness perturbation matrix,and ultimately solving the space truss structure damage location and damage degree by the minimum rank update method. A space truss structure is taken as an example to verify the minimum rank update method,and the influence of measurement noise is analyzed and discussed. The results show that the minimum rank update method is accurate and reliable,and has strong robustness.关键词：Damage identification;Residual force;Minimum rank update method;Eigenvalue matrix
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发布时间：2022-09-22 - 摘要：Precision speed reducer is one of the key parts of industrial robot. For a long time,its Core Technology has been monopolized by the several foreign developed countries,which seriously restricting the development of China robot industry.Technology development and its status of RV reducer at home and abroad were described in paper. Then,the main causes of restricting the development of our countries’ RV reducer have been detailed analyzed. Relevant documents and policies were sketched,which play an active role in promoting the RV reducer. Finally,some personal opinions and suggestions on how to improve the situation of our countries’ precision speed reducer were submitted.关键词：Industrial robot;RV reducer;Development status;Restrict
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- 2163
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发布时间：2022-09-22 - 摘要：To obtain the stress information of the spiral drum of the thin coal seam shearer under the complicated condition,and then guide the design of its parameters or the matching of kinematic parameters. The models of drum and coal rock were established by PRO/E,and imported to ANSYS through a dedicated interface. According to the actual situation,the operation of adding elements,material,meshing grid,restriction and contact were done. Finally,the coupling model of the spiral drum cutting gangue coal rock was established in LS-DYNA. Set the hauling speed was 4 m/min,the drum speed was 80 r/min,and the dynamic simulation was carried out. The contact force information and the stress contours of the corresponding parts were obtained. The results show that: the maximum stress of cutting alloy heads,picks,holders and blades are 1209. 26 MPa,812. 5 MPa,371. 79 MPa and 103. 56 MPa,respectively,which are less than the allowable stress of each material,and can work reliably. This method can find the weak link of the drum,and can provide important theoretical reference for the design of the spiral drum and the matching of its kinematic parameters.关键词：Spiral drum;Shearer;Coal rock coupling;Stress;Strength
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- 327
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发布时间：2022-09-22 - 摘要：In order to avoid the time-domain signal is too long to be loaded,the stress power spectral density simulation and experimental verification are carried out by using the transfer function theory. The Dirlik’s life prediction method is determined according to the bandwidth coefficient. Combined with the S-N curve,the fatigue life based on power spectral density is predicted.Verify the results of life through the time domain method. The results show that the relative error of Dirlik method’s life and time domain method is small,and the life prediction method is accurate,which can provide references for improving the fatigue life precision of automotive components.关键词：Transfer function;Fatigue life;Stress power spectral density;Dirlik method
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- 416
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发布时间：2022-09-22 - 摘要：The gap can result in the characteristics of the main drive system of the mill become bad,the influence of the gap size on the system is the concern of enterprises. This paper is based on numerical simulation and finite element analysis,to study the main drive system of the initial mill with multiple gaps,its dynamic characteristics are changed due to the difference of gap size. a The difference of dynamic response and stress change of the system is obtained by using MATLAB numerical simulation and ANSYS finite element calculation. This two methods verify and supplement each other to provide theoretical reference for mill production practice.关键词：Rolling mill;Clearance;The numerical simulation;Finite element analysis
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- 117
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发布时间：2022-09-22 - 摘要：Aiming at solving the cracking problem of a light card fuel filter bracket in the vehicle road test. Firstly,each road vibration acceleration were collected,the test results show that the washboard road vibration acceleration is the largest.Secondly,the frame end was taken an exciting point and the measured frequency domain signal were load,the bracket was vibration analyzed based frequency response method,the analysis results show that the bracket Z direction maximum von Mises stress value exceed the yield strength of the material. It is located at the circular tube bend and it was consistent with the actual failure position. Lastly,the fuel filter bracket was multi-objective optimization analyzed based on Isight platform integrated CATIA,HYPERMESH and NASTRAN by adopting non-dominated sorting genetic algorithm. So the circular tube optimal parameters are obtained and the bracket maximum stress value are lower than the allowable stress after optimization. The optimization effects are obvious and it could meet fatigue strength performance requirements. The optimization scheme had passee the road test,so the cracking problem was successfully solved. The analysis method wad integrated with road test,finite element technology,frequency response method and vehicle reliability road test,the advanced reference and practical engineering application for the similar brackets vibration analysis and optimization design were provided.关键词：Fuel filter bracket;Vibration acceleration;Frequency response analysis;Optimization
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发布时间：2022-09-22 -
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