最新刊期
期 5 ， 2019
- 摘要：Comparing with nonlinear ultrasonic nondestructive testing method using harmonic signals and modulation methods, the local defect resonance（LDR） inter-modulation effect can greatly enhance the nonlinear behavior between the damaged interfaces,also,it uses the modulation between input signal and LDR frequency thus the input signal is simplified. When the excitation signal satisfies the specific frequency condition, the local resonance is produced at the micro-defect or damage area under ultrasonic excitation, which leads to the high order harmonics, subharmonics and the inter-modulation between input frequency and local damage resonance frequency in the response signal. In this paper, a single degree of freedom nonlinear model for damage local resonance effect was constructed, considering both quadratic and cubic stiffness nonlinearity, and analyzed using multi-scale method to explain the mechanism of local resonance modulation effect. Experiment of a carbon fiber composite plate with impact damage was carried out to verify the results of theoretical model analysis and the feasibility of the damage local resonance internal modulation method applying to nonlinear damage detection. Result shows that using LDR inter-modulation effect can effectively detect the impact damage of composite plate.关键词：Local defect resonance;Damage detection;Multi-scale method;Impact damage;Modulation
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发布时间：2022-09-22 - 摘要：A method based on Weibull distribution and GG fuzzy clustering is studied and proposed in order to solve the issue of healthy condition recognition for quayside container crane（QCC） reducer. Using envelope method to denoise data which caused by the complexity conditions firstly. Then the scale parameters and shape parameters are created using Weibull distribution fitting, which could show change characteristics of collected samples quantitatively. In order to recognize the reducer condition further, the GG fuzzy clustering method is used to divide the different stages of the healthy condition, realizing recognition for reducer healthy. Test data from NetCMAS system is adopted in living analysis, FCM and GK clustering algorithm are analyzed for contrast. The results show that the method proposed in this paper is effective and has better clustering effect.关键词：Quayside container crane reducer;Weibull distribution;GG fuzzy clustering;Condition recognition
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发布时间：2022-09-22 - 摘要：This paper integrates Isomap that transforms data features from original high-dimensional space to projected low-dimensional space into DBN model for gear fault diagnosis. The run-to-failure experiment of gearbox was conducted for validation studies, through a series of comparison experiments with the original features without space transformation, PCA and LE, HMM and BPNN, the proposed method in this paper is proved more effective for gear fault diagnosis and state assessment.关键词：Feature extraction;Isomap;Feature transformation;DBN;Gear fault diagnosis
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发布时间：2022-09-22 - 摘要：The transverse free vibration model of the rubber conveyor belt with the steel rope core is established based the small deflection theory of the orthogonal anisotropy sheet model. By using the classical solution method, the analytical solutions of the SFSF boundary model of the lower branch conveyor belt, the SCSC boundary model of the upper branch slot shape bottom, and the SFSC boundary model of the side. The main stiffness of the conveyor belt with the steel rope core is derived by using the Khobar approximation. The previous-order natural frequencies of the lower branch conveyor belt and the upper branch conveyor belt, the vibration type and the variation law of natural frequency with the tension variation are obtained by employing the numerical analysis. The results show that the natural frequencies of the lower and the upper branch of the conveyor belt increase with the increasement of the belt tension, and the tension influences the frequency of the lower branch conveyor belt greatest and the frequency of the upper branch conveyor belt bottom smaller. The researching results provide the bending vibration response analysis and the resonance avoiding design of the conveyor belt with the basis.关键词：Conveyor belt;Orthotropic thin plate;Flexural vibration;Natural characteristics;Modal parameter
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发布时间：2022-09-22 - 摘要：Based on the Condition Assessment of Thin-walled Robot Bearing, developed an assessment method of multi-sensor data fusion. Firstly, acoustic emission（AE） and vibration acceleration signal were collected, and the characteristics of two kinds of signals were extracted separately in time domain and frequency domain. Secondly, the characteristics of AE and vibration signals were used as the characteristic parameters to identify the fault type of thin-wall robot bearing. Finally, self organizing maps（SOM） neural network was used to integrate the characteristics information of AE and vibration signals. The result shows that the method can effectively identify the fault type of thin-walled robot bearing after analysed of the measured data.关键词：Thin-walled robot bearing;Condition assessment;Vibration;Acoustic emission;Data fusion;Self organizing maps（SOM）
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发布时间：2022-09-22 - 摘要：In view of the problem of crack location in wind turbine blade, based on the relation between the difference ratio parameter of natural frequency of cracked blade and damage location, the crack location parameter of natural frequency difference ratio was put forward.The database of crack location parameters was established by numerical simulation calculation, the crack location parameters and crack location criteria were put forward to realize the crack location in the blade. Meanwhile, the variation law of crack location parameters in the crack zone was studied. The mapping relationship between the crack location parameters and the relative position of the crack region was established, and the accurate location of the blade crack interval was realized. The effectiveness of the method is verified by numerical simulation, and the positioning accuracy is high, which provides a powerful basis for practical application.关键词：Wind turbine blade;Crack location;Natural frequency;Numerical simulation calculation
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发布时间：2022-09-22 -
FAULT DIAGNOSIS BASED ON MIXED LABEL INFORMATION LOCALITY PRESERVING PROJECTIONS DIMENSION REDUCTION
摘要：In order to preserve the local structure of high dimension fault feature better, locality preserving projections（LPP） are improved and a fault diagnosis method based mixed label information locality preserving projections（MLILPP） for dimension reduction is proposed. MLILPP constructed similarity matrix and divergence matrix based on label information. The similarity matrix is used to preserve the local structure of the same-label samples before and after dimension reduction, whereas the divergence matrix is used to enlarge the distance between the different-label samples after dimension reduction. As a result, data structure is retained effectively, better low dimension structure can be obtained, and higher fault diagnosis accuracy can achieved. The experiment results of hydraulic pump fault diagnosis verified the effectiveness of the method.关键词：Fault diagnosis;Locality preserving projections;Label information;Hydraulic pump- 4
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发布时间：2022-09-22 - 摘要：In order to study the loosening life characteristics of bolts, the transverse vibration test of bolts was designed by using fatigue testing machine. The test compared the influence of displacement, velocity and acceleration to the loose of bolts by changing the frequency of transverse vibration. It shows that the transverse displacement amplitude is the main factor influencing the loosening of bolts. The loosening of bolts under five displacement amplitude were measured. The situations of loosening were showed by the rest preload-vibration times curves. Summarized the data, according to the S-N curve, drew the displacement-life（D-N） curve under different loosening situation（the percentage of the residual preload）. The results show: By the D-N curve, it is found that the bolt loosening life curve also have the characteristics of double straight line and high-low cycle, just like the material fatigue life curve.关键词：Test of loosening bolts;Transverse displacement amplitude;Loosening life curve
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发布时间：2022-09-22 - 摘要：In this paper, the quasi-static tensile tests and the dynamic compression tests of 20 CrMnTi were carried out using the tensile tester and Split Hopkinson pressure bar（SHPB） device at different strain rate to study the dynamic stress response of 20 CrMnTi steel. The results show that 20 CrMnTi steel has strain rate effect and plasticizing effect. But it is not very sensitive to strain rate change within the scope of dynamic compression experiment. In consideration of the adiabatic temperature rise, the Johnson-Cook constitutive model is modified. The results show that the revised Johnson-Cook constitutive model can well describe the mechanical performance of 20 CrMnTi under the dynamic impact load, which is important to reference value that 20 CrMnTi steel is applied under high speed and overload.关键词：20CrMnTi steel;Adiabatic temperature rise;J-C constitutive model;SHPB
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发布时间：2022-09-22 - 摘要：Aiming at the machining difficulty and low machining efficiency of titanium alloy, the influence of milling parameters of aviation TC18 titanium alloy on surface roughness, machined surface morphology and metallographic structure was analyzed in order to improve the quality of machined surface. Two prediction models（exponential model and multiple quadratic regression model） were established by using taguchi and optimization module design methods, and multi-objective genetic algorithm and response surface method were respectively used for parameter optimization aiming at improving surface quality and machining efficiency.The results show that: The order of influence of each parameter on the surface roughness is feed f>milling depth ap>milling width ae>speed of mainshaft n; The multiple quadratic regression model has higher significance and the surface topography obtained from the combination of response surface optimization parameters is optimal. The microstructure of the milling section of TC18 titanium alloy was observed.The results showed that the equiaxed α phase near the machined surface was elongated and strip secondary phase were precipitated.关键词：TC18 titanium alloy;Surface quality;Prediction model;Optimization design;Surface morphology;Metallographic structure
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发布时间：2022-09-22 - 摘要：For three groups of composite T700/MTM28 C-channels with different ply orientation, the load-displacement curves were obtained by axial crushing test. Based on initial peak load, mean crush load, specific energy absorption and crushing efficiency, the effect of ply orientation on crush deformation mode and energy-absorbing characteristics were investigated. The results show that the stable progressive crushing processes are observed during experiments, and various macroscopic failure modes are also presented, such as interlayer cracking, bending fracture, local buckling and shear failure. The [0/90]3 s specimens absorb the largest energy, the [45/90/-45/0]3 specimens absorb the middle energy, while the [45/-45]3 s specimens absorb the smallest energy. The energy-absorbing characteristics can be improved by reasonable design, such as adding 0° plies and 90° plies to ±45° plies.关键词：Composite;C-channel;Ply orientation;Failure mode;Energy-absorbing characteristics
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发布时间：2022-09-22 - 摘要：Using the method of ultrasonic dispersion and the mechanical ball grinding the graphene mixing in titanium aluminum substrate, pressed by cold pressing molding and vacuum hot-pressing sintering technology of titanium aluminium alloy self-lubricating composites reinforced preparation of graphene. Using scanning electron microscopy（SEM）and transmission electron microscopy（TEM） and energy spectrum analysis（EDS）on microstructure and mechanical properties of the self-lubricating composites were studied. The results showed that graphene in the uniform distribution of titanium alloy substrate and graphene not interface reaction of titanium aluminium alloy, composite material density is better. When the amount of graphene is 0.3 wt%,self-lubricating composite material yield strength increase from 469 MPa to 555 MPa. The hardness of the self-lubricating composite was 11% higher than that of matrix, up to 468 HV; with the increase of the content of graphene composite material hardness and yield strength increases gradually, while graphene content is 0.7 wt %, reached the maximum hardness and yield strength of the composite material.关键词：Grapheme;TiAl based alloy material;Microstructure;Mechanical properties
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发布时间：2022-09-22 - 摘要：The fatigue crack growth（FCG） phenomenon always exists in large mechanical structural. Influenced by varied kinds of random factors, the safety evaluation of structure in FCG is under great uncertainty. Based on the reliability theory, this article derived the joint limit state equation of fatigue failure and static strength failure, and the parameters which have great influence on the fatigue crack growth rate（load level, crack initial length and material parameter） were selected by the sensitivity analysis. And then these parameters were regarded as random variables. On this basis, the optimization mathematical model of reliability index was established, and then the reliability index under the multiple failure modes of structure was calculated in every cycle based on the SQP method. A specific computation example was given, and the curve of reliability criterion in multiple failure modes was used to compare that in single failure mode. The results indicated that the reliability analysis based on multiple failure modes was reasonable, and the evaluation of reliability could be obtained in fatigue crack growth process.关键词：Crack growth;Reliability;Optimization mathematical model;SQP;Multiple failure modes
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发布时间：2022-09-22 - 摘要：Based on the ANSYS Workbench finite element software, the ultimate static working state of the dental plate of clamping pliers when drilling the drill string is analyzed elastoadically. The stress of the contact between the dental tooth and the drill pipe was analyzed by linearization principle, and the classification was identified and evaluated. And then the key parameters of tooth plate as the object of study, through the orthogonal experiment results of the poor analysis, combined with the actual processing capacity to determine the final optimization program. Finally, the contact stress between the dental plate and the drill pipe was measured by the pressure film, and the rationality of the optimization scheme was verified, and the pressure applied is linearly related to the maximum stress of the tooth plate.The test method provides a new way for the same type of equipment. It is of great engineering significance to ensure the safe, reliable and effective operation.关键词：Clamping pliers;Tooth plate;Stress linearization;Orthogonal experiment;Parameter optimization;Stress test
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发布时间：2022-09-22 - 摘要：The existing adaptive growth technique deducted the optimization iteration formula according to the condition named Karush-Kuhn-Tucker condition. It is high efficiency and good, which is aimed to strain energy and bound to the volume against optimization problem of stiffener distribution for plate and shell structures. However, different optimization iteration formula, which deducted by different kinds of problem, is poor and difficult to generalize, especially for the optimization problems with more than one constraint. Against with the lack of adaptive growth technique, a new method that is moving asymptotes（MMA） is suggested by this article and the adaptive growth technique is applied to truss structure topology optimization design. The design of typical truss structures with single constraint and multiple constraints is discussed, and the multi load cases are studied. The results of numerical examples show that the proposed method can obtain clear information of rod distribution and dimension, and has high design efficiency and good applicability. It is convenient for practical machining and has a good application prospect.关键词：Adaptive growth technique;Method of moving asymptotes;Truss structure;Topology optimization
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发布时间：2022-09-22 - 摘要：A stepping-type excavation,support and anchor combined unit in a full-mechanized excavation roadway was designed. The structure and the work principle of the unit were presented. The dynamic model of multi-degree of vibration system was established by using Newton′s second law, and the system dynamics model with temperature dependent characteristic was furtherly introduced. The simulation model of the combined system of the anchor and anchor was established by using Matlab. The dynamic behavior of the system under 20 ℃ and 40 ℃ temperature was solved and analyzed. The results showed that the temperature change environment had a great influence on the system dynamics, which made the amplitude and frequency of the system had different degrees of increase. When the system was in the environment of 20 ℃, the vibration amplitude of each part was within the acceptable range, and the vibration amplitude of the cutting part was the largest, and the range was between-12 mm to +12 mm. When the temperature increased to 40 ℃, the vibration amplitude and vibration frequency of each component were obviously increased, but the increase of the longitudinal beam was the most obvious, and the cutting part had the weakest influence.关键词：Stepping-type excavation;Support and anchor combined unit;Dynamics model;Characteristics of temperature distribution;MATLAB
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发布时间：2022-09-22 - 摘要：The hunting conveyor as research object, the hunting conveyor motion based on Serpenoid curve shape description, and carries on the discrete design and time domain expansion, using MATLAB software to find the optimal parameters of interval turning movement of the conveyor system. The simulation analysis is carried out on three kinds of working conditions, such as serpentine motion, left turn and right turn, and the variation of the steering angle is obtained under different working conditions. Finally, according to the frame turning experiment of vehicle hunting conveyor angle, verify the validity and rationality of the turning motion control parameters.关键词：Serpenoid curve;Discrete design;Time domain expansion;MATLAB;Turn movement
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发布时间：2022-09-22 - 摘要：A method of forced angular displacement loading based on ABAQUS software is proposed. In order to improve the efficiency of pretreatment, the type of model elements is selected as C3 D8 R and C3 D10 M suitable for contact analysis according to the structural characteristics of the threaded joints. In this method, the mechanical constraint is treated by balanced penalty function. The boundary conditions are established at the bolt head according to the way of obtaining the pretightening force in engineering. The pretightening force is defined by imposing a forced angular displacement on the rigid element. This method is simpler and more practical than other methods. Finally, the relationship between pretightening force and torsion is obtained by analyzing the thread connection structure of skirt plate lock with this method. The error between the results and the experimental results is within 8%, which is within the range of theoretical calculation. The validity of this method is proved.关键词：Preload;Loosening prevention;Numerical simulation;Torque
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发布时间：2022-09-22 - 摘要：Based on the design scheme and parameters of the wheeled mobile ship loader, the overall design of the ship loader was carried out. According to the structural characteristics of the boom of the wheeled mobile ship loader, the characteristic parameters were extracted, then the parametric model of the boom was established by using the APDL language of ANSYS, and the finite element analysis of the boom structure was carried out. Finally, the boom structure was optimized by using ANSYS software and optimization design technology. Under the condition of meeting the design requirements, the economy and reliability of the boom are realized. The results are as follows: because the lower articulation of the boom is close to the inlet and outlet, its force is also large, the head of the boom is equivalent to the cantilever beam and hangs the chute, the maximum stress of the boom appears at the lower articulation, and the maximum deformation occurs at the head of the boom; the total weight of the structure can be greatly reduced by adopting variable cross-section design of the boom structure.关键词：Wheeled mobile;Ship loader;Overall design;Boom;Parameterization
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发布时间：2022-09-22 - 摘要：Aimed at the presetting problems of the roll bending force during vacuum hot rolling of Q345 R/316 L stainless steel clad plates, a three dimensional thermo-mechanical finite element model of rolling for stainless steel clad plates was proposed by using the FE software MSC.MARC. Four boundary conditions of model bending roll force are set 0 kN, 300 kN, 500 kN and 800 kN respectively. The distribution law of reduction of the base plate, the bending deformation of the roll system and semi-loaded roll gap in the width direction of the clad plate under different bending roll forces were studied by numerical simulation. The distribution law of interfacial stress and strain under different bending roll forces was analyzed. According to the judgment condition of interface bonding condition, the optimum bending force was set. The simulation results show that the shape of plate appears high in the middle and low at the edge without bending force. When the roll bending force is applied, the shape of plate is obviously improved, and the optimum setting value of the bending force is 500 kN. Under the condition that the total deformation is constant, the increase of bending force will promote the deformation of the base metal and the cladding metal. Thus uniform stress-strain distribution and good coordinating deformation can be realized, which is beneficial to the interfacial bonding of clad plates.关键词：Stainless steel clad plate;Finite element model;Eelastic deformation of rolls;Bending force;Interface combination
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发布时间：2022-09-22 - 摘要：Considering the welding thermal effect of round link chain on chain drive system of scraper conveyer natural frequency,welding process and heat treatment of round link chain were simulated by using ANSYS software,and the residual stress distribution were obtained. The round link chain stiffness were obtained and were compared with the experimental values. Scraper conveyer system natural frequency were solved under idle condition and full load condition by using MATLAB software. Eighth order natural frequency and eigenvalue were obtained. The results show that:the welding thermal have greater effect on natural frequency and eigenvalue of system. Natural frequency and eigenvalue of system under full load condition are less than the idle condition’s.关键词：Scraper conveyer;Natural frequency;Welding thermal;Round link chain
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发布时间：2022-09-22 - 摘要：An accelerated life test is designed and a kind of analysis method for solenoid valve failure based on multi-physics finite element model is put forward due to the uncertainty of failure mechanism and the lack of effective means to analyze faults. Firstly, the model of temperature field is built based on ANSYS finite element software and the temperature distribution of components is calculated. Then, the temperature is added to the mechanical stress field as the new load and the coupling stress is received based on the combined action of thermal stress and mechanical stress. Finally, a kind of degradation failure mechanism of the solenoid valve, through the comparison of experimental data and simulation results, is obtained based on the comprehensive analysis of temperature and coupling stress. The result shows the high temperature produced by coils can fail the insulation between coil wires. Meanwhile, the coupling effect of thermal stress caused by high temperature and the mechanical stress can squeeze coils resulting in the continuous short-circuit of coils. When the electromagnetic force of iron core is lower than its threshold, the iron core will not overcome the elasticity to move up and down and finally the failure of the SV will happen. This prediction method can be widely applied to the other fault diagnosis types of degradation failure of solenoid valves. The result can be provided for the optimization and researched on prolonging life of the solenoid valve.关键词：Multi-physics;ANSYS;Finite element model;Temperature field;Coupling stress;Degradation failure
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发布时间：2022-09-22 - 摘要：In order to solve the problem of complex housing shape and difficult forging forming of new lightweight aluminum alloy automobile differential housing based on the present production status of conventional casting molding and cast steel materials, a 7075 aluminum alloy automobile differential housing are used as the research objects, the finite simulation software Deform is used to simulate the isothermal forging type, and the experimental method is used to verify the accuracy of the simulation analysis. The results show that in the isothermal forging process of the differential housing, the blank is gradually formed into a differential housing with the shape of the fixed lower die under the motion action of die forging and pressing; the maximum equivalent stress mainly occurs in the complex shape and the transition point of sudden change of the differential housing; the tensile strength and the yield strength are different at different positions, but the variation range is small; with the increase of the isothermal forging temperature, the tensile strength and yield strength of the forged differential housing piece show the trend of first increasing and then decreasing, and the best isothermal forging is 425℃. The research provides an important reference for the optimization design and life improvement of the isothermal forging die of the differential housing and the production and application of the lightweight aluminum alloy differential housing.关键词：7075 aluminum alloy;Automotive differential housing;Isothermal forging;Deform
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发布时间：2022-09-22 - 摘要：The typical working condition of the vehicle comes from the city road cycle, the load distribution characteristics is obtained from the statistics and analysis on driving speed. With studying the effects of speed, acceleration, shock, gear and other factors on the load formation of the force transmission parts, the rotating mass scaling factor is adjusted. Take the wheel-side reducer for an instance, the conversion of the gear load is based on the parameters from vehicle and reducer, and the part load distribution corresponding to the vehicle speed is obtained. To explore the conversion method from the vehicle speed to the part load, and it provides the technological support for the lightweight design and the life analysis of parts in the reducer.关键词：Road cycle;Wheel-side reducer;Gear;Load conversion;Load spectrum
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发布时间：2022-09-22 - 摘要：As a main input of structural integrity assessment, limit load solutions of defective components are always the focus of attention. At present, limit load solutions for plates with semi-elliptical surface crack under multiaxial loading are an important research direction. Aiming at a plate with semi-elliptical surface crack under combined force and bending applied at the end sections of plate and stress applied at side surfaces of plate, limit load solutions are derived based on Von Mises yield criterion. The effect of stress applied at side surfaces can be known by yield curves shown in coordinate figure of n1. The solutions in this paper are the same as existing solutions for uniaxial load combined force and bending. At the same time, the solutions have been compared with the solutions for plates with rectangular surface crack under the same load conditions. The results show that rectangular surface crack instead of semi-elliptical surface crack will lead to overly conservative results when crack depth is larger along the thickness direction or crack length is larger along the width direction.关键词：Multiaxial loading;Semi-elliptical surface crack;Plate;Limit load
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发布时间：2022-09-22 - 摘要：Firstly, the experimental J-R curve and the predicting curves by the three models of 400℃ thermally aged Z3 CN20-09 M pipe and elbow were compared. The results showed that ANL model and H3 T model aren’t suitable for the prediction of low toughness CASS components, however the EDF model is better for low toughness CASS components prediction. All the three models present non-conservative prediction for the early crack propagation, but it doesn’t affect the threshold judgment. According to the comparison between experimental J-R curves and the predicting curves, the ANL model and H3 T model are more suitable for the thermal aging assessment of CASS Z3 CN20-09 M.关键词：Cast austenitic stainless steel;Thermal aging;Fracture toughness;Prediction models
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发布时间：2022-09-22 - 摘要：Hard coatings has the advantages of good wear resistance and high contact fatigue life which has been widely used in aerospace and aviation fields. However, the coating/subtrate interference will occur delamination failure under the heavy load, and the reliability of machine parts has been affected. Recently, study on the coatings failure mechanisms and the bonding ability of coatings is greatly focused on. The article adopting cohesive zone model combined with FEM analysis the delamination failure of the coating/subtrate interference. The results show that the simulation results based on the cohesive zone model coincides with the experimen results. On this foundation, the effects of different factors on the adhesion strength of coatings are studied. The bonding strength of coatings has been greatly increased by increasing the thickness and elastic modulus of coatings, and the carrying capacity has greatly improved.关键词：Coating failure;Cohesive zone model;Adhesive strength;FEM
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发布时间：2022-09-22 - 摘要：The virtual load method is studied in this paper for damage assessment of beam type structures. The main advantage of this technique is that damage assessment can be accomplished by using only the vibration modes of the current structure. A series of virtual load vectors are constructed to obtain the same pure bending states for different segments of the beam. And then the curvatures of these segments loaded in pure bending are compared to identify the damage locations and extents. It was found that the proposed method is very suitable for damage assessment of those existing beam type structures.关键词：Damage assessment;Beam type structure;Virtual load;Mode
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发布时间：2022-09-22 - 摘要：The research on the dynamic characteristics of roller bearings is mainly concentrated on steady condition, but the rotational speed fluctuations exist in many rotating machines, and it has important influence on the dynamic performance of rolling bearing. Taking cylindrical roller bearing NU306 as investigation object, a nonlinear dynamic finite element model for plastic material flexible contact of a cylindrical roller bearing was established. Based on explicit dynamic LS-DYNA, the dynamic simulations for nonlinear operation process under three different rotational speed fluctuations（rectangular fluctuations, sinusoidal fluctuations and random fluctuations） were made, and the angular speed curve and slipping rate curve of cage and the contact force curve of between roller and inner ring and cage were obtained. The finite element solutions of a cylindrical roller bearing under steady condition were compared with its analytical solutions, and the validity of the established finite element model was verified. The results show that the greater angular acceleration of rotational speed on the inner ring, the greater fluctuations of angular speed curve and slipping rate curve of cage, and negative slipping rate may occur when the fluctuation is serious. Rotational speed fluctuations influence the stability of cage mainly by changing the contact force between rollers in load zone and cage, and rotational speed fluctuations may lead to load zone range larger and make the peak load force of single roller reduce.关键词：Cylindrical roller bearing;Rotational speed fluctuations;Slipping rate;Contact force
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发布时间：2022-09-22 - 摘要：In view of the excess strength and the excessive quality of a comprehensive transmission box which belongs to special vehicle, it is necessary to optimize box further. In the optimization process, based on the empirical formula of the rotational torque a larger dynamic load factor is calculated by using traditional method,which reduces the subsequent optimization space. Therefore, the dynamic load factors in the process of stationary transmission are studied based on the load spectrum. Firstly, the box body was tested by bench test, then the load spectrum of the dangerous part was measured. Secondly, the dynamic load factors in a stationary time history were obtained by dealing with these load spectrum. Thirdly, the maximum likelihood method and the goodness of fit AD value were used to identify and validate these dynamic load factors. Finally the dynamic load factor was obtained at 99 th percentile. The 99 th percentile dynamic load factor was compared with the dynamic load factor obtained from the empirical formula. The results show that under the condition of smooth transmission, the empirical formula is larger, the structural design is conservative, and the 99 th percentile dynamic load factor is reasonable, which is helpful to the realization of the lightweight design.关键词：Load spectrum;Dynamic load factor;Distribution fitting;Goodness of fit;Transmission box
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发布时间：2022-09-22 - 摘要：Considering the time-varying meshing stiffness and gear backlash, a dynamic model of gear transmission system is established. The Floquet theory is used to obtain the approximate analytic solution and the stability boundary curve of the transmission system. The Newmark-β numerical simulation method was used to simulate dynamic characteristics of gear system. The effect of time-varying mesh stiffness, backlash and damping effect on dynamic characteristics are studied. The results show that the system may generate parametric resonance when the frequency of parameter excitation is equal to 2/n of the free vibration period of the derived system;The gear backlash leads to multi-value properties and amplitude jump phenomena; The nonlinear vibration response of the system will be decreased with the increasing of the external excitation amplitude, damping ratio and the decreasing of the internal excitation amplitude.关键词：Gear system;Time-varying meshing stiffness;Gear backlash;Stability;Vibration characteristics
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发布时间：2022-09-22 - 摘要：In order to study the lubricating property of low-speed heavy-duty bearing under the condition of different loads and speed, such as the oil film thickness, oil film pressure and changes of oil film velocity. Building model of fluid-structure interaction by using ABAQUS software, and it can get a conclusion: the oil film thickness distributes in rectangular section, the thickness of oil film between the rolling element and inner ring is thinner than that between rolling element and outer ring, the oil film pressure increases gradually at the entrance of the contact zone, and the oil film pressure at the inner raceway contact point is greater than that of the outer raceway. The oil film velocity of the liquid-solid intersection is greater than that of the free surface, and the oil film velocity is the fastest in the contact zone. With the increase of rotating speed, the oil film thickness and oil film pressure increase; with the increase of load, the oil film thickness decreases, and the oil film pressure increases.关键词：Low-speed heavy-duty bearing;ABAQUS;Oil film pressure;Oil film thickness;Oil film flow rate
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发布时间：2022-09-22 - 摘要：The establishment of micro channel LTCC（Low-temperature cofired ceramics, LTCC） substrate finite element analysis model of multi chip module and the thermal simulation analysis on it. The effect of different microchannel structures, microchannel diameter and fluid flow velocity on the heat dissipation performance was analyzed,Using orthogonal table design, nine multi-chip module models with different combinations of structural parameters were designed. Nine sets of temperature data were obtained and range analysis and variance analysis,The results show that the order of influencing factors on the heat dissipation performance is as follows: microfluidic structure, microfluidic channel diameter and fluid flow rate. When the confidence level is 90%, the micro channel structure and the micro channel diameter have a significant effect on the heat dissipation of the micro channel, and the flow velocity has little effect on the heat dissipation of the micro channel.关键词：Low-temperature cofired ceramics（LTCC）;Microchannel;Finite element analysis;Heat dissipation;Orthogonal design
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- 339
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发布时间：2022-09-22 - 摘要：Aiming at solving a horizontal stabilizer bar fracture failure, firstly, the forward horizontal stabilizer assembly model and the front suspension dynamics model were established based finite elements method and rigid flexible coupled multi-body dynamics method, the horizontal stabilizer bar displacement were extracted in limit working condition, so the strength analysis force displacement was 49.5 mm. And then the horizontal stabilizer bar was strengh analysised by adopting Nastran software, the analysis results show that the maximum stress was 977.6 MPa, it located in the horizontal stabilizer and stabilizer bar bracket and bushing joint position, there was a fatigue injury risk about it. The horizontal stabilizer bar was fatigue life analysised by adopting FEMFAT software, the analysis results showed that the minimum life was 3.37×10~4 times, the weakest place was consistent with the maximum stress position for strength analysis, it was below design requirements. And then the horizontal stabilizer bar was multi-objective optimization analysised by adopting Isight optimization integration platform, its optimal diameter was obtained, its fatigue performance meets the design requirements after optimization. The horizontal stabilizer bar bench test platform was established by loading with sine wave, the results show test results were agree with the fatigue simulation results,and it passed the test of the vehicle road. Finally, the horizontal stabilizer fracture problem was successfully solved. The analysis method combined finite elements, multi-body dynamics, fatigue mechanics, bench test and road test, It provided advanced scientific guidances for the similar structures fatigue strength analysis and optimization design.关键词：Horizontal stabilizer bar;Dynamics;Strength;Fatigue life;Optimization
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- 433
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发布时间：2022-09-22 - 摘要：The non-ideal cylindrical surface model based on profile measurement was built by using Geomagic Studio software, and it was imported into UG12.0 to create the aerostatic bearing simulation model, which can be simulated by using ANSYS WORKBENCH software. Ten groups of rotors and porous aerostatic bearings were selected as experimental objects, and the bearing capacities and stiffness values of the aerostatic spindles based on non-ideal cylindrical surfaces and global sizes were simulated and analyzed respectively. The bearing capacities and stiffness values of the aerostatic spindles above were measured on the modular tester of spindle’s comprehensive performances. Simulation and test results showed that among three global sizes, the bearing capacities of the gas films formed by the non-ideal cylindrical surfaces of rotors and bearings are closed to that of the gas films formed by two ideal cylindrical surfaces of rotors with least-squares diameters, and the stiffness values of gas films formed two non-ideal cylindrical surfaces are closer to their corresponding test results. Therefore, so the modeling method of the gas film based on two non-ideal cylindrical surfaces is more suitable for the stiffness evaluation of the aerostatic spindle.关键词：Aerostatic bearing;Non-ideal cylindrical surface;Modeling and simulation;Bearing capacity;Stiffness
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发布时间：2022-09-22 - 摘要：In order to study the vibration characteristics of the bolt structure of the excavator and the crawler frame, the WK-75 mechanical excavator was used as the research object, The RecerDyn multi-body dynamics simulation software was used to simulate the excavator movement process and extracted load spectrum, and Fourier transform of the load spectrum by MATLAB to obtain the load spectrum frequency. The natural frequency of the bolt structure is obtained by ANSYS Workbench finite element analysis software. The frequency of the load spectrum and the natural frequency are compared for the loosing condition of the bolt structure. It is of some reference value to the further study on the vibration characteristics of the connecting bolt of the excavator.关键词：Connecting bolts;Vibration;Mode analysis;Curve fitting
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发布时间：2022-09-22 - 摘要：Aiming at of solving the cracking problem of an alternator bracket. Firstly, the engine time domain-acceleration curve were tested, and they were converted to frequency domain acceleration curve. The alternator bracket was frequency response analyzed based on the frequency domain acceleration curve, the analysis results show that the maximum stress value exceeded the yield strength of the material. Secondly, the alternator bracket was vibration fatigue analyzed by adopting power spectrum density function, the analysis results show that the minimum life was lower than target, and it was consistent with the strength analysis weak region and actual failure position. Thirdly, the alternator bracket was optimal designed by adopting large scale generalized reduced gradient algorithm, it can meet fatigue and strength performance requirements after optimization. Lastly, the alternator bracket optimization scheme was certificated by vehicle road test, the test results show that the alternator bracket vibration amplitude is obviously decreased, and the alternator bracket cracking is avoided, so the cracking problem is effectively solved. A scientific references are provided for the high frequency response bracket failure solution by the analysis method and its optimization method.关键词：Alternator bracket;Frequency response analysis;Power spectrum density function;Vibration fatigue;Optimization
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- 240
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发布时间：2022-09-22 - 摘要：Problems such as strong vibration and low frequency acupuncture exist in four-panel needle loom developed by a Textile Machinery Company. In this paper, the vibration test and analysis of the whole needle loom are carried out to find out the causes of vibration.Through the kinematics and dynamics analysis of the motion mechanism of the needle loom, the exciting force is calculated and the solution is given.Through vibration test and dynamic balance testing, vibration and noise caused by machining and assembly errors are eliminated.Finally, it provides an effective solution to the problem that the vibration of the four-plate high speed needle loom is too large and the needling frequency is too low.关键词：Textile machinery;Needle loom;Vibration;Balancing
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- 97
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发布时间：2022-09-22 - 摘要：To lower the labor intensity, reduce energy consumption, improve efficiency, increase the service life of the pumping unit and achieve automatic adjustment of pumping unit, based on the CYJ10-4.2-53 HF type pumping unit, this paper completes the structure and parameter design of the crank automatic balance device. The key transmission part screw is selected and checked based on the fourth strength theory. ANSYS Workbench is used to analyze the finite element strength. It is concluded that the theoretical check is basically as the same as the simulation result, the theoretical calculation is feasible, and the overall structure meets the strength requirements.Finally, the pumping unit is tested in the field, the instrument measured its balance meets the requirements, the energy saving effect is satisfactory, and it has a certain promotion and application prospects.关键词：Pumping unit;Crank balance;Structural design;Theoretical calculation;Finite element analysis;Field test
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- 161
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发布时间：2022-09-22 - 摘要：The statics and dynamics analyses for the steel structure of a type of single-row, three-column, five-layer lift-sliding stereo garage were carried out based on the ANSYS software and the finite element modeling. Analyses proved the safety reliability of steel structure under the extreme conditions, and the weak points of steel structure were found out. The strain monitoring program at these weak positions was designed and finished. The results of analysis were substantial agreement with the experimental results. The maintenance and design personnel could also carry on the security evaluation to the steel structure of the stereo garage through the strain monitoring data, formulate the reasonable maintenance plan, optimize the design of the structure, and improve the service life of the equipment.关键词：Stereo garage;Steel structure;Finite element;Security evaluation
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- 370
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发布时间：2022-09-22 - 摘要：Temperature field and thermal-structure coupling stress field calculation were conducted to a main steam safety valve prototype for nuclear power stations using finite element software Ansys,and the stress of the valve subjected to operating pressure load and thermal stress was in compliance with the stress evaluation criteria. In addition,alternating stress of the pressure components for the specified cyclic operation application of loads and thermal stresses were calculated,and fatigue analysis was evaluated according to RCC-M code. Results indicate that the valve prototype is able to meet the requirements of fatigue failure criteria for the specified cycles and would have good prospects in engineering applications.关键词：Thermal stress;Safety valve;Finite element;ANSYS;Stress evaluation;Fatigue analysis
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发布时间：2022-09-22
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