最新刊期
期 6 ， 2021
- 摘要：When TMD is used in the nacelle or tower of the floating wind turbine, its stability can be improved, but the fatigue load of the tower base is increased. In order to solve this problem, the ITI Barge platform is taken as the research object, TMD is arranged inside the platform for vibration damping control, and the dynamic model of the floating wind turbine is established to study the change law of the front-after and side-side displacement of the tower top with the TMD mass, damping and installation position. The multi-island genetic algorithm is used to obtain the optimal TMD parameters, and the effects of without TMD control, nacelle TMD control and platform TMD control on the dynamic response characteristics of floating wind turbine are compared and analyzed. The results show that the front-after and side-side displacements of the tower top change significantly with platform TMD parameters. When mass and damping of the platform TMD at the same location are large, the front-after and side-side displacements of the tower top decrease significantly. When mass and damping of the platform TMD remain unchanged, the front-after and side-side displacements of the tower top decrease gradually with the increase of the TMD location. Under the action of wind and wave, the effect of TMD on the dynamic response control of floating wind turbines under wind load is more obvious, but the control effect of each part is different. The side-side displacement of the tower top, the platform roll angle and the tower base roll bending moment control effect are the most significant. In addition, compared with the nacelle TMD control, the stability of the floating wind turbine is better when controlled by the platform TMD.关键词：Barge platform;Tuned mass damper;Multi-island genetic algorithm;Dynamic response;Stability
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发布时间：2022-09-22 - 摘要：Extracting degradation features is an important part of Monitoring the health status of machinery. The performance of degradation features fluctuates or even declines with the continuous operation of the rotating machinery for a long time, which makes it difficult to extract and select degradation features. First, a feature mapping Algorithm library was used to extract features from the vibration signals and the original feature set was filtered based on Kolmogorov-smirnov（KS） test and Benjamini-Yekutieli process. Then, the optimal feature subset was searched in the supervised environment by combining BOGA with SVC. The accuracy of SVC and the dimension of subset were two objective functions of BOGA, the former was maximized, the latter was minimized. The performance of proposed method was verified by the experiment on the data set of hydraulic pump degradation state and the comparison with FRESHPCAa, ReliefF and JMIM on the case western reserve university bearing data set.关键词：Rotating machinery;Degradation state identification;Bi-objective optimization genetic algorithm（BOGA）;Support vector classifier（SVC）
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发布时间：2022-09-22 - 摘要：Aiming at the shortcomings of Grey Wolf Optimizer（GWO）, such as it’s easy to fall into local optimum and insufficient mining capacity, the paper improve the convergence accuracy and stability of GWO based on the improvement of control factors. The wind turbine gearbox vibration signal collected by the "Gearbox Reliability Collaborative（GRC）" project of the National Renewable Energy Laboratory（NREL）in the United States was used as the analysis object. After the collection of Ensemble Empirical Mode Decomposition（EEMD）, the fuzzy entropy of each eigenmode function component was calculated and the high dimensionality was constructed. Then feature vectors are used to reduce dimensionality using isometric mapping. The improved gray wolf algorithm is used to optimize the support vector machine to diagnose the gearbox fault feature set after dimensionality reduction. The results show that compared with GWO and PSO and GA, IGWO can effectively avoid falling into local optimum and improve the accuracy and stability of SVM diagnosis. It has the highest accuracy under different test samples, and the average accuracy rate can up to 93.17%.关键词：Wind turbine gearbox;Fault diagnosis;Improved grey wolf optimizer;Isometric mapping;Support vector machine
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发布时间：2022-09-22 - 摘要：Considering the influence of structural parameter uncertainty on response and the problem of large calculation of stochastic model updating, a stochastic finite element model updating method based on polynomial chaotic expansion and KL divergence is proposed. Firstly, Kriging model is constructed instead of finite element model analysis, then polynomial chaotic expansion model is constructed based on probabilistic collocation method and regression analysis, and the functional relationship between uncertain structural parameters and response is established to quickly estimate the mean value and standard deviation of response. Finally, the mean value and standard deviation of structural parameters are modified to minimize KL divergence. Taking three-dimensional truss as an example, the mean value and standard deviation of elastic modulus and density are modified to verify the feasibility of the proposed method. The results show that the proposed method has high updating accuracy and efficiency.关键词：Uncertainty;Polynomial chaos expansion;KL divergence;Kriging model
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发布时间：2022-09-22 -
FAULT DIAGNOSIS OF GEAR BROKEN TOOTH BASED ON IHPS/ISPS FILTERING AND HILBERT TRANSFORM DEMODULATION
摘要：Once the gear has broken tooth, there will be periodic shocks, which make the vibration signal of gear meshing modulated. So it is important for diagnosis of gear tooth broken to extract the modulation information effectively. Aiming at the problems that the fault signature is drowned by noise, the filtering parameters usually need to be set artificially, and the detection rate of tooth broken is low, this paper proposes Improved Sideband Product Spectrum（ISPS）,and a diagnosis method for gear tooth broken by combining adaptive filtering on IHPS/ISPS and Hilbert transform demodulation. Experiments show that this method can effectively extract the fault characteristic signal buried by noise and has great application value for the diagnosis of tooth broken.关键词：Tooth broken;IHPS/ISPS;Hilbert transform demodulation;Fault diagnosis- 4
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发布时间：2022-09-22 - 摘要：The impact resistance of composite honeycomb sandwich structure is studied by means of experiment and finite element analysis. The three-dimensional progressive failure criterion is established based on the VUMAT subroutine, and the accuracy of the simulation model is verified by experiments. The accurate simulation model is used to further study the impact resistance of honeycomb sandwich structure under different parameters. The results show that when the impact energy is lower than a certain value, the impact peak force increases with the increase of impact energy, and when the impact energy exceeds this value, the impact peak force will be stable; the smaller the impactor diameter is, the smaller the impact peak force is, the greater the absorption energy of honeycomb sandwich structure is; the increase of skin thickness can enhance the impact resistance of honeycomb sandwich structure, but the skin thickness has a greater impact on the energy absorption characteristics small.关键词：Composite material;Honeycomb sandwich structure;Low-velocity impact;Simulation analysis;Impact properties
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发布时间：2022-09-22 - 摘要：The residual compressive stress field introduced by shot peening can effectively improve the fatigue performance of the component, but decrease of the residual compressive stress cased by the cycle stress relaxation, thereby reducing the gain effect of residual compressive stress on fatigue performance, Therefore, in-depth study of the residual stress relaxation law will help to more accurately grasp its impact on fatigue performance.In order to systematically study the law of residual stress relaxation, the standard test piece of 2024-T351 aluminum alloy was taken as the research object, comprehensively considering the influence of stress amplitude、load conditions and the change of cold work hardening degree caused by shot peening on residual stress, a residual stress relaxation model was constructed based on theory. Through the tensile fatigue test, the relaxation model is verified based on the full life test data and the phase test data to prove the effectiveness of the model.关键词：2024-T351 aluminum alloy;Shot peening residual stress;Fatigue performance;Relaxation model
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发布时间：2022-09-22 - 摘要：The influence coefficient method and transfer function method are applied to the dynamic balance of aero-engine flexible rotor. The static transfer function of the flexible rotor is obtained by hammering on the experimental bench of the aero-engine flexible rotor. The low-pressure rotor of CFM56-7 B engine with typical high-speed flexible rotor was selected as the research object for numerical simulation, and the transfer function of the rotor system was obtained through ANSYS harmonic response analysis. The experiment and simulation results show that the transfer function method has better balance effect than the influence coefficient method, which can effectively reduce the vibration of unbalanced rotor and avoid the disadvantage of the influence coefficient method in starting the rotor several times. It has a good application prospect in the maintenance of aero-engine.关键词：Flexible rotor;Rotor bench;Transfer function;Harmonic response analysis
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发布时间：2022-09-22 - 摘要：Multi field and cross scale analysis is helpful to improve the forming quality and analyze the evolution law of microstructure in the process of spline forming, which has a very important guiding significance for process optimization, quality prediction and control. The thermal mechanical coupling model of cold rolling forming were established and simulated. The macro size of the simulation results and the evolution law of the microstructure in the forming process were analyzed, and the change trend of grain size under different process parameters was analyzed by changing the feed rate and friction coefficient. The influence of feed rate and friction factor on the grain size is obtained, which provided theoretical basis for further research on the evolution law of microstructure in materials and the integrated manufacturing of spline shape and properties.关键词：Spline;Cold rolling;Cross scale analysis;Grain size;Process parameters
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发布时间：2022-09-22 - 摘要：A comprehensive reliability allocation method, which is applicable to the cases of lack of data in design stage, as well as the complexity of the influence factors and uncertainty of expert evaluation, is presented based on the grey system theory. The key of this method is to modify the weights of influence factors which are associated with expert scoring data by grey correlation analysis before reliability indices are assigned linearly to each subsystem.Based on grey evaluation with 4 levels, the application of this method is illustrated with the reliability allocation of a rotary machine under the consideration that complexity, technical level, importance and environment condition are chosen as influence factors. Compared with the actual faults statistics results, the validity and feasibility of the method is verified.关键词：Reliability allocation;Grey system theory;Grey correlation analysis;Rotary machines
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发布时间：2022-09-22 - 摘要：Using the degradation distribution method to establish a reliability evaluation model for performance degradation data requires a number of strict assumptions, which are difficult to meet in practical applications. In order to avoid the shortcomings of the degradation distribution method, a data-driven reliability evaluation model of degradation data was proposed. Firstly, the non-parametric adaptive kernel density estimation was constructed to obtain the probability density function of the product degradation at each moment, at last the three-parameter Weibull distribution was used to fit the reliability at each time to obtain the reliability curve of the product performance. The K-S test proves that the model is stable and superior to the parameter method based on the case data, and it is not easy to be aggressive. The analysis method is convenient for practical engineering application.关键词：Degradation distribution method;Adaptive kernel density estimation;Degradation failure;Three parameter Weibull distribution
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发布时间：2022-09-22 - 摘要：Traditional FTA treats the failure probability as an accurate value, and only considers “normal” and “failure” states. However, as a complex electromechanical system, industrial robot system（IRS） has a great amount of cognitive uncertainties in the reliability assessment, so it is difficult to analyze the system using traditional FTA. Moreover, the mechanical structure in IRS will deteriorate caused by varieties of reasons, so it is very limited to describe the system state only by “normal” and “failure”. Aiming at the shortcomings in the traditional FTA, this paper uses T-S fuzzy FTA to analyze the reliability of IRS. Considering the maintenance cost of parts and components, the T-S fuzzy cost importance is proposed based on T-S model, and the weak links of IRS are analyzed from the perspective of maintenance economy. The results show that T-S fuzzy FTA can describe the multiple operation states of IRS, and the analysis result of T-S fuzzy cost importance is consistent with the common-sense conclusion in the industrial robot field, which provides a theoretical basis for the reliability growth of IRS.关键词：Industrial robot;T-S fuzzy FTA;Fault maintenance;Reliability analysis
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发布时间：2022-09-22 - 摘要：Aiming at the problems that traditional BP neural network surrogate model had deficiency of fitting accuracy and computational efficiency, the Mind Evolutionary Algorithm was used to optimize BP neural network and an improved BP neural network surrogate model reliability calculation method was proposed. Firstly, the Mind Evolutionary Algorithm was used to optimize the weights and thresholds of BP neural network to obtain the optimal initial value. Secondly, the Bayesian Regularization algorithm was used to train the optimized neural network to establish MEA-BR-BP neural network surrogate model and verify the effectiveness of the improved surrogate model used test function. Finally, the reliability calculation results were calculated with the Monte Carlo method. The results show that the proposed method improves the fitting accuracy and gives consideration to the calculation efficiency, which verifies the superiority and feasibility of the proposed method.关键词：BP neural network;Surrogate model;Mind evolutionary algorithm;Reliability analysis;Bogie frame
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发布时间：2022-09-22 - 摘要：The temperature of the cell has a great influence on the performance of the power battery pack, in order to reduce the maximum temperature and improve the energy density of a liquid-cooled power battery pack under high rate discharge condition, the cooling structure parameters of the battery pack module were optimized. Firstly, the electricity-heat model of single cell was established and calibrated, built the battery pack calculation model based on the cell electricity-heat coupling model. Then, the cell spacing and the inlet temperature of coolant were taken as the optimization variables, the maximum temperature and volume of the battery module were taken as the optimization objectives, the maximum temperature difference, the cell spacing and the inlet temperature of coolant were taken as constraints. Used the Latin hypertaxis method to establish a parameterized combination sample for the optimized variables, combined with the Kriging model and multi-objective genetic algorithm for the optimal solution. The optimization results showed that the maximum temperature decreased by 9.7%, the maximum temperature difference decreased by 12.5%, and the cell spacing decreased by 7.1%. Finally, according to the optimization results, the prototype was trial-produced and the bench test was completed, experimental test values and calculated results have a good consistency, so as to verify the reliability of the results and which was conducive to improving the heat dissipation performance and energy density of the battery pack.关键词：Power battery pack;Cooling performance;Kriging model;Multi-objective genetic algorithm
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发布时间：2022-09-22 - 摘要：Aiming at the complicated microstructure of the wire cloth in the compensator reinforced by wire cloth and the complicated interaction between the wire cloth and the bellow during service, the strength analysis of the compensator reinforced by wire cloth under the static-random vibration compound condition is established. The equivalent beam model is used to establish the finite element analysis model of the wire cloth. According to the working environment and mechanical performance characteristics of the compensator reinforced by wire cloth, a contact-coupling hybrid analysis method is established. The contact relationship between the bellow and the wire cloth is used in static conditions to simulate the non-linear interaction with the bellow. In the random vibration conditions, the interaction between the wire cloth and the bellow is established by coupling the radial degree of freedom of the wave peak of the bellow and the wire cloth in setting the coupling equation. The error between the static and dynamic analysis results of the model and the static and dynamic test results of the compensator with wire cloth is about 10%. The strength performance analysis of the compensator with wire cloth under the combined condition of static and random vibration analysis is carried out, and the influence of random vibration excitation in different directions on the compensator with wire cloth is discussed. The results show that the X-direction excitation has the greatest impact on the structure; the stress at the first wave peak of the bellow is the largest, which is a weak link in the structure.关键词：Contact;Coupling;Compensator;Bellow;Random vibration
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发布时间：2022-09-22 - 摘要：In order to study the structural characteristics of different types of bend-twist coupling blades, the NREL 5 MW wind turbine blade was used as the research object, combined with composite material laying design to establish finite element models of different BTC blades, the aerodynamic load of the blades were solved by CFD method. The modal, strength and buckling of the blades were calculated and the effects of different coupling regions and coupling angles on the structural characteristics of the blades were analyzed. The results show that the natural frequencies of BTC blades are mostly lower than that of the traditional blades. The skin-coupled blades have the smallest change and the fully coupled blades have the greatest influence; the BTC blades can reduce the internal von Mises stress and strain peak value and improve the fatigue life of the blade. The skin-coupled blades have the largest reduction and the spar cap-coupled blades have the smallest reduction. The skin-coupled blades have the best load reduction effect when θ=20°; the shear stress of the BTC blades are mostly higher than that of the traditional blades, only the maximum shear stress of the skin-coupled blades θ=20° is lower than that of traditional blades; the bend-twist coupling characteristics of the blades have a certain impact on its stability. The critical buckling load of spar cap-coupled blades have a large decrease, while other BTC blades have a slight increase, and the amount of the first-order buckling deformation is lower than traditional blades.关键词：Wind turbine blade;Bend-twist coupling;Secondary development;Composite material;Coupling region
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发布时间：2022-09-22 - 摘要：In order to clarify the effects of different working condition parameters and quantify their influence degree on bearing wear in the spindle system, the bearing wear in the spindle system supported by multi-bearing was carried out. Firstly, the calculation method of wear coefficient considering the lubrication state is introduced, and the wear depth model of the angular contact ball bearing is deduced. Second, the wear depth of the inner and outer raceways of the bearing is calculated based on the motion parameters and contact parameters of the bearing rolling elements obtained from the system model. The influences of spindle speed, bearing angular misalignment caused by mounting error, external loads and bearing surface roughness on bearing wear are discussed. The results show that the spindle speed has a significant impact on bearing wear, and the change of spindle speed leads to a great difference of bearing wear law. Without bearing angular misalignment, the sum of the wear depth of the inner and outer raceways of each bearing in the spindle system is the smallest. The change of external loads has little effect on bearing wear, but the increase in surface roughness can significantly increase the wear depth of the bearing.关键词：Spindle system;Angular contact ball bearings;Wear coefficient;Wear depth;Angular misalignment
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发布时间：2022-09-22 - 摘要：The A pile pulverizer was designed to solve the problem that pine wood pile was difficult to deal with.The abandoned spiral hob was used to treat the infected wooden pile, and the parameter-hobbing performance of the tool was studied. Firstly, The mechanical model of tool hobbing is established to analyze the relationship between pile and tool; Secondly, BBD method was used to set the three-factor three-level experiment scheme with feed, rotation and ABAQUS software is used to perform hobbing force simulation calculation, numerical fitting is carried out between the calculation results and the inluencing factors, and the interaction relation of each factor is analyzed to obtain the hobbing force prediction function model; Thirdly, according to the function and the simulation experiment, the optimum parameters are the minimum hobbing force when the feed speed is 60 mm/s, the rotation speed is 1 000 r/min and the hobbing depth is 15 mm. Finally, The results show that the correction coefficient of the function model is 92.4%, indicating that the function fitting degree is good and can accurately reflect the changing law of the hobbing force; Combined with experimental verification, the deviation between compute and experimental results is 14%～16.4%,indicating that the mathematic model has a good engineering reference value for actual hobbing.关键词：Pulverizer;Hobb;Hobbing simulation;Stake;Function model;Experimnet
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发布时间：2022-09-22 - 摘要：The influence of five geometric parameters of a negative Poisson’s ratio honeycomb structure on the cellular arc angle, length of connecting rod, outer thickness, thickness ratio and length-height ratio were studied. By using uniform test design method, the fitting equations of four evaluation indexes, energy absorption, specific energy absorption, peak crushing force and equivalent Poisson’s ratio were obtained. On this basis, the multi-objective optimization design was carried out, and the appropriate cellular geometric parameters were selected. The results show that the cellular arc angle and the length of the connecting rod have great influence on the specific energy absorption of the honeycomb structure, the outer thickness and thickness ratio have great influence on the peak crushing force and energy absorption of the structure, However, the outer thickness under equal strain has little effect on the equivalent Poisson’s ratio of the structure. The energy absorption and equivalent Poisson’s ratio of the structure are greatly affected by the length-height ratio. Compared with the original size, the optimized size comprehensively selected has higher energy absorption, protection and impact resistance effect, and the crushing force is much lower than the original size model and more stable.关键词：Negative Poisson’s ratio honeycomb structure;Cellular;Geometric parameters;Uniform test design;Optimization design
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发布时间：2022-09-22 - 摘要：Fiber/matrix interfaces exist in the transitional region between fiber and resin matrix in fiber reinforced composites. How to reasonably consider the interposition of interfacial phase is a critical problem in the failure analysis of composite structures. In this paper, a multi-scale finite element method is proposed based on three-phase representative volume element, by developing the microscopic failure criterion, damage degradation model and uncertainty model of material strength. The failure prediction of low temperature composite structure under thermal mechanical load is realized by the multi-scale finite element method. Moreover, the method is used to analyze the failure of composite laminates at five temperatures. The numerical predictions are in good agreement with the experimental results, which shows that the method can analyze the failure of composite structures at cryogenic temperatures effectively.关键词：Composite interface;Multiscale analysis method;Representative volume element;Microscopic failure criterion;Damage degradation model
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发布时间：2022-09-22 - 摘要：Taking pantograph frame as the research object, a load spectrum Compiling method suitable for accelerated life test of pantograph frame is proposed. Firstly, the coupling dynamic model of the pantograph was established based on the finite element method, and the load spectrum of the upper frame was obtained by multi-body dynamics simulation. The dynamic stress analysis method is used to convert the time-history data of the upper frame load into the stress spectrum of the weld concerned. At the same time, the statistical characteristics of the stress spectrum amplitude method are studied, the results show that the amplitude obeys Weibull distribution, and the eight-order one-dimensional loading spectrum is established by extrapolation of the parameter method. In order to facilitate the loading of the test bench actuators, a load back push method is put forward, and the error of the contrast acceleration spectrum is controlled within 6% through the test bench data. This method can provide reference for fatigue life test and life prediction of pantograph components.关键词：Pantograph frame;Acceleration life test;Load spectrum;Dynamics;Damage
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发布时间：2022-09-22 - 摘要：In order to explore the influence of different structural parameters on the aircraft lug structure crack growth life, using the combination of numerical simulation and test method, fatigue tests were carried out on different structural parameters 7075 aluminum alloy lug samples, the three-dimensional stress intensity factor calculation models of different lugs based on the ABAQUS software was established, the accuracy of the model is verified by comparing the finite element solution with the experimental results and analytical values. Finally, The fatigue crack growth life of lug with different structural parameters was calculated by the Paris formula and fracture mechanics method. The results indicate that under the same stress, with the increase of taper angle, the fatigue crack growth life of the lug structure increases rapidly, and the bottom chamfer have little effect on it.关键词：Lug;Aluminum alloy;Taper angle;Chamfer at the bottom;Crack growth life
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发布时间：2022-09-22 - 摘要：For cross welded joints, the behavior of microscopic short crack nucleation and early propagation of the weld toe was studied. Using the Voronoi method, a representative element（RE） with a side length of 150μm at the weld toe was established. Based on the distribution characteristics of the fatigue indicator parameter（FIP）, the fatigue life between FIP and microscopic short crack was constructed.The nucleation of microscopic short crack and their early propagation life were calculated. The results show that the calculated life of weld toe microscopic short crack nucleation and its early propagation is more consistent with the test life data, indicating the applicability of this calculation method; the calculated life of microscopic short crack nucleation and its early expansion accounted for a larger ratio of the overall fatigue life, so it has a non-negligible impact; affected by the microstructure of the grains, the propagation path of the early cracks presents an obvious tortuous shape.关键词：Microscopic short crack;Crack nucleation;Early expansion;Grain model
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发布时间：2022-09-22 - 摘要：Using the vibration excitation spectrum of IEC61373, the subway bogie obstacle detector was taken as the research object. The random vibration fatigue strength of the obstacle detector was studied by combining the finite element method and bench vibration test, and the remaining life at the fatigue weak points of the aluminum beam welded joints was predicted. Based on the frequency domain method, combined with Miner’s linear accumulation damaging theory, the simulation life results of the obstacle detector under acceleration excitation were obtained, then compared with the bench vibration testing results to verify the accuracy of the fatigue simulation analysis. Moreover, the sub-model boundary technique was used to separate the aluminum beam, and the stress spectrum of the fatigue weak points was equivalently converted. At last, the remaining life was predicted after inserting the initial cracks at the evaluation points. The result indicated also that it is reasonable to evaluate the remaining life of aluminum alloy welded joints with initial cracks based on fracture mechanics, which provides the certain reference for engineering applications.关键词：Metro obstacle detector;Welded joints;Random vibration;Fracture analysis;Life prediction
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发布时间：2022-09-22 - 摘要：In order to reduce the probability of crane safety accidents, this paper proposes a method to quickly calculate the remaining life of the crane based on radial basis function（RBF）neural network. Taking a bridge crane in a factory as an example, an ANSYS finite element model is established based on actual parameters, and the model is modified through on-site measured data, and a static analysis is performed to obtain the location of the fatigue calculation point. Firstly, taking position of the trolley and the lifting load as input layer, the equivalent stress value at any point as output layer to stimulate the typical working conditions of crane operation. Secondly, to obtain time stress curve at any point quickly by using the well-trained RBF neural network model. Finally, to evaluate the residual life according to the damage tolerance fracture mechanics method. The results show that the time stress curve can be quickly obtained from any node by using the radial basis neural network model, which greatly decreased cumbersome process and save the cost in the crane site measurement, and realize the fast acquisition of the time stress curve to calculate the fatigue remaining life. Completing the estimation of the remaining fatigue life of the bridge crane provides a reliable basis for the long-term safe use and later maintenance of the crane.关键词：Bridge crane;Finite element;Neural Networks;Remaining life
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发布时间：2022-09-22 - 摘要：In the engineering of aerospace and nuclear power engineering, the safety and reliability of small pipe（Outer diameter less than 2-inch, about 50 mm） has become one of the main factors restricting the safe operation. However, in the existing design codes, there is a lack of detailed technical requirements and evaluation criteria for small pipeline. In this paper, based on the experimental and FEA analysis, the fatigue and final fracture of pipeline components are discussed. The results show that the results of the fatigue crack propagation by experimental and FEA method are same, and they account about 3 % of the fatigue life in the study case. The critical failure mode is the plastic collapse, so it is to increase the critical crack size by increasing the tensile strength.关键词：Small pipe;Fatigue;Fracture;Crack propagation;Failure mode
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发布时间：2022-09-22 - 摘要：The prediction model of leaf springs fatigue crack growth under variable amplitude loads is mainly Schütz phenomenological model. However, the effect of the crack closure effect on fatigue crack propagation and the relationship between the parameters and the stress ratio wasn’t considered. The threshold value of the fatigue crack was only suitable for the special working conditions where the stress ratio is 0. Therefore, the Schütz fatigue crack propagation phenomenological model was improved, which caused the physical parameters meaning more accurate, suitable for different working conditions. The stress measured by the actual vehicle test was applied to the modified model to describe the progress of leaf spring fatigue crack growth under the variable amplitude load. The results show that the crack growth rate increases with the loading amplitude. The test results are in good agreement with the model prediction results, which provides a theoretical basis for the calculation of fatigue crack growth rate under variable amplitude load.关键词：Variable amplitude load;Crack growth;Stress intensity factor;Crack closure;Real car experiment
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发布时间：2022-09-22 - 摘要：Dynamic load produced in the working process of ultra-high pressure compressor is an important factor affecting the strength and life, and the coupling between thermal load and mechanical load is very serious. Based on the finite element method, this paper establishes the dynamic model of thermal load of ultra-high pressure cylinder up to 52 MPa in working cycle, predicts the functional relationship between dynamic response and steady-state response, and gives its action rule through the simulation analysis of cold start and hot start. The model can also be used to check the dangerous area of cylinder and optimize the structure of cylinder.关键词：High pressure cylinder;Dynamic characteristics;Thermal stress;Finite element analysis
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发布时间：2022-09-22 - 摘要：The plow bit is one of the key parts of the coal plow, and is the working part of the coal plow that directly contacts the coal and rock. When plowing the coal, due to the complex and tough coal seam conditions, especially when encountering hard minerals such as hard inclusions, the force on the plow bit increases sharply. The plow bit is impacted, which easily results in the failure of plow bit, such as plow bit head losing, plow bit body broken. And the consumption of plow bit is very large. Therefore, it is important to study the dynamic response of the plow bit when it is impacted during plowing. In this paper, the finite element simulation analysis method is used to conduct in-depth research on the dynamic response of the plow bit under impact. It provides theoretical references for the material selection of plow bit, the design and optimization of plow bit structure, the improvement of plow bit reliability, and the reasonable selection of the working parameters such as plow speed. It is of great significance to the design of China’s coal mining machinery and the development of coal industry.关键词：Coal plow;Plow bit;Impact;Dynamic response
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发布时间：2022-09-22 - 摘要：Based on the generation mechanism and transmission path of the roar, this paper expounds the corresponding control strategies for the roar of different paths. Aiming at the roaring noise in the accelerating car of a passenger car, the corresponding troubleshooting methods for different paths when the roaring sound is diagnosed based on the transmission path are introduced; and after determining that the problem comes from the structural transmission path of the intake system, further analysis: There is a mode with a corresponding frequency at the intercooler bracket, so the engine excitation is amplified here, and coupled with the body acoustic cavity mode, and finally forms the roar of the car; furthermore, it is clear that the intercooler installation bracket structure and the The optimized plan for cooling vibration isolation is to improve the mode of the intercooler support, improve the vibration isolation effect, reduce energy transfer, eliminate modal coupling, and solve the problem. This article has certain reference value for the roar control of passenger cars.关键词：Passenger car;Booming noise;Path analysis;Structural transfer;Modal coupling;Testing and diagnosis
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发布时间：2022-09-22 - 摘要：The existing gear hobbing simulation methods are difficult to follow the actual processing parameters, and the model obtained by the simulation does not measure the accuracy of the tooth surface. Therefore, they cannot provide effective guidance for the actual gear hobbing. Therefore, a high-precision gear hobbing is proposed. Simulation and accuracy verification methods. This method is based on the CATIA design platform, combined with the secondary development functions through commands such as translation, rotation, and Boolean operations in CATIA. After extracting the preliminary cogging model containing the main motion and the generated motion characteristics, the preliminary cogging model and the tooth blank are processed The simulation cutting of vertical feed motion completes high-precision gear hobbing simulation. The accuracy of the simulation model tooth surface was measured by establishing a standard tooth surface point set, and the error distribution of the simulation tooth surface was obtained, and the highest tooth surface accuracy error in the obtained simulation model was below 1 μm, which verified the correctness of the gear hobbing simulation method in this paper And simulation model accuracy.关键词：Involute helical gear;Simulation machining;Gear hobbing;Tooth surface error
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发布时间：2022-09-22 - 摘要：Combined diesel and gas gear system often works under heavy load, high speed, impact and other complex conditions. Tooth fracture can significantly affect the meshing quality of marine gear pair. Existing research mainly focused on characteristics of gear pair meshing stiffness based on given angle and number of broken teeth, the results of which showed a large deviation from the meshing stiffness in the actual form of broken teeth. To develop a computational method for gear pair meshing stiffness at any breaking angle, the broken teeth were divided into two forms, i.e. those parallel to the line of contact and those not parallel to the line of contact; their respective computing formula of the length of the line of contact of the gear pair at any broken angle was then derived, and the meshing stiffness of helical gear pair at any broken angle solved based on ISO stiffness calculation criteria. According to the results, when the broken teeth were parallel to the line of contact, as the length of the teeth increased, the time and severity of the impact on meshing stiffness both increased; after passing the broken teeth area, the stiffness would instantly return to normal. When the broken teeth were not parallel to the line of contact, within the broken teeth area, the single tooth meshing stiffness was zero, and general meshing stiffness reduced; when entering the non-broken teeth area from the broken teeth area, both the single tooth and general stiffness would gradually return to normal.关键词：Helical gear pair;Broken teeth fault;Meshing stiffness;Ocean shipping;Length of contact line
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- 203
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发布时间：2022-09-22 - 摘要：In this paper, the 3-D model of discontinuous contact of 2/3 lay length steel rope is established by ProE/5.0. Finite element analysis of discontinuous contact steel rope under axial tension and torsion load was carried out in ABAQUS. The wear test of wire rope was carried out on the discontinuous contact steel wire rope damage test bench, and the distribution of wear marks on the worn steel wire surface was analyzed by optical microscope（OM）. The results show that the equivalent stress, axial stress and axial deformation are spiral distribution along the axial direction of the wire rope; on the strand section, the equivalent stress increases gradually from the core wire to the side wire, the maximum value appears in the contact area of rope groove, the experimental results show that the steel wire surface also presents elliptical wear scar, which is consistent with the simulation results.关键词：Discontinuous contact;Wire rope;Wear scar;Stress and deformation
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发布时间：2022-09-22 - 摘要：Aiming at the problems of low efficiency, long cycle and difficulty in quality assurance in product design faced by most manufacturing enterprises, performing research on parameterized CAD and CAE technology, as well as the data transmission between software CAD and CAE, a general design method for optimizing the performance parameters of mechanical parts based on CAD/CAE integration was proposed. This method took Visual Studio as the platform, used APDL and C++ language for redeveloped ANSYS and Solid Works respectively, and developed a digital design system of mechanical parts based on CAD/CAE integration. After changing the parameter value, the system solves the finite element solution automatically and quickly, the solution results are automatically output to the specified path, and the solution results are automatically opened and locked. Taking the design of inner ring of driven plate for example, the three-dimensional（3 D） model and solution results were quickly obtained by this method. The research results show that this method is feasible and universal.关键词：Mechanics;Part;Performance optimization;Secondary development;Finite element analysis;CAD/CAE integration
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- 448
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发布时间：2022-09-22 - 摘要：In order to improve the durability of the rear sub-frame structure, a bench endurance test was carried out. Weld performance analysis was carried out for cracking in the test, the results showed that non-weld fatigue caused cracking. Through the endurance simulation analysis of the bench, the dangerous area of the original structure was found, and three optimization schemes was proposed. The performance requirements of each scheme are compared, and bilateral full welding is the best improvement scheme. The improved structure satisfies the durability test of the sub-frame bench, the endurance test of the vehicle’s twenty-four channels and four columns, and also shows that the simulation analysis method and improvement scheme are credible.关键词：Rear sub-frame;Durability;Bench test;Finite element analysis;Optimization scheme
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发布时间：2022-09-22
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