最新刊期
期 3 ， 2020
- 摘要：A damage detection method based on wavelet packet transform and replicator neural networks is proposed to carry out real-time damage detection of structures. Firstly,wavelet packet transform is used to decompose original vibration response signals to calculate the relative band energy of each band. The distribution of relative band energy reflects the characteristics of the structure to be detected. Secondly,the relative energy from healthy structure is taken as input to training replicator neural networks. Finally,the trained networks are used for damage detection in real-time. Experiments showed that the proposed method can detect single-position damage even under noise interference.关键词：Replicator Neural Network（RNN）;Wavelet packet transform;Relative band energy;Damage detection
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发布时间：2022-09-22 - 摘要：Aiming at the vibration displacement signals of cracked rotors is unstable and non-linear,and the fault features are extracted difficultly,and the sample collection is lacking in the initial stage of fault,the crack fault diagnosis method based on Variational Mode Decomposition and AR model is proposed. A number of Intrinsic Mode Function are obtained by VMD as the preprocessing of the AR model. The AR model for each IMF component is established. The variance of the model parameters and residuals is calculated by the least square method. The model parameters and the variance of the residual are used as the characteristic vector of the system state. From the Mahalanobis distance and setting the corresponding weighted parameters,the synthetic distance is used to diagnose crack fault of rotor. Through the analysis of the experimental data,the feasibility of the fault diagnosis method based on the variational mode decomposition and the AR model are successfully verified,which provides a method for the fault diagnosis of the rotor,and the shortcomings of AR model in the diagnosis of rotor crack fault are overcome.关键词：Cracked rotor;VMD;Auto Regressive model;Fault diagnosis;Mahalanobis distance
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发布时间：2022-09-22 - 摘要：Using ultrasonic non-destructive testing technology,when detecting the surface crack of the shaft,the micro crack echo signal is often covered by various noises,which causes the crack to be unrecognizable and positioned. In order to solve this problem,in this paper,a general cross-validation thresholding in synchrosqueezing wavelet domain approach is proposed to analyze the ultrasonic echo signals,and the characteristics of the crack echo signals are extracted from the time-frequency domain and localized. Based on synchrosqueezing transformation,the paper uses the general cross-validation method to estimate the threshold level of noise reduction,and does not depend on any prior knowledge. Specifically,by adding a preprocessing step based on kurtosis measurement and a post-processing step based on adaptive hard threshold processing,the efficiency of the threshold processing and the noise reduction effect in the time-frequency domain are improved,thereby realizing a useful distinction between noise and characteristic signals. Finally,the method is applied to the feature recognition of microcrack ultrasonic echo signals,and compared with the results of continuous wavelet transform. The results show that the method can identify the crack more accurately and extract the time point of crack occurrence,and then determine the specific location of the micro crack.关键词：Ultrasonic testing;Synchrosqueezing wavelet transform;General cross-validation thresholding（GCV）;Echo signal;Feature extraction
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发布时间：2022-09-22 -
DYNAMIC CHARACTERISTIC OF ROD FASTENING ROTOR SUPPORTED BY FIXED-TILTING PAD GAS-LUBRICATED BEARINGS
摘要：In this paper,the dynamic behaviors of the rod fastening rotor which is supported by the fixed-tilting pad gaslubricated bearings are studied. In modeling of the rod fastening rotor,the contact effect of the disks is taken as resistance bending springs with nonlinearity. Based on the boundary conditions of fixed-tilting pad gas-lubricated bearing,the differential transformation method is adopted to solve Reynolds equation,and the gas film force is obtained under the coordinate systerm of the single pad. The gas film force of the fixed-tilting pad gas-lubricated bearing is obtained by coordinate transformation and assembly method. The comparison of stability is implemented between cylindrical gas-lubricated bearing and fixed-tilting pad gaslubricated bearing,rod fastening rotor and integral rotor. Finally,taking the stiffness of the shaft as the control parameter,dynamic characteristic of rod fastening rotor is studied by improved Newmark method. At the same time,the influence of the preloads and pivot ratios on the dynamic behaviors of the system is also studied.关键词：Rod fastening rotor;Gas lubricant bearing;Fixed-tilting pad;Newmak method;Stability- 3
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发布时间：2022-09-22 - 摘要：The vehicle body is an important bearing component of the high-speed train. The fatigue test can accurately evaluate the fatigue life of the vehicle body. It can also verify the accuracy of the simulation calculation model,and can take into account the incomplete technical considerations in the simulation analysis. This article compares the domestic and international relevant standards to determine the load of the vehicle body fatigue test of the high-speed EMU vehicle including the vertical direction of the vehicle body,the longitudinal load and the lateral load of the center pin,and the longitudinal load of the coupler,and formulates the fatigue of the vehicle body according to the test load. The test plan was completed and the fatigue test of the entire vehicle body of the first high-speed EMU in China was completed. Fatigue test found that the weld hook inside the ribbed plate weld existed hidden dangers of fatigue and put forward an optimized program. The optimized scheme was further verified.Finally,the fatigue life of the body of the high-speed EMU was proved to meet the design requirements.关键词：Carbody of high speed EMU;Fatigue loads;Test plan;Optimization
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发布时间：2022-09-22 - 摘要：In order to achieve reasonable control of the surface integrity of the workpiece assisted by ultrasonic-assisted rolling. Taking GCr15 bearing steel as the research object,the rotational speed,feed rate and static pressure were selected as the main processing parameters. The ultrasonic-assisted rolling test was used to combine the gray theory,response surface method and genetic algorithm to ultrasonically assisted rolling GCr15 bearing steel. Correlation analysis was carried out on surface roughness,residual stress and hardness,and a grey correlation degree prediction model was established,and the model was optimized. The results show that the static pressure has the greatest influence on the surface integrity of the ultrasonic assisted rolling workpiece,the second speed and the minimum feed rate; the optimal processing parameters are the feed speed 25 mm/min,the speed 300 r/min,the static pressure 247 N; The corresponding surface roughness was 0. 299 μm,the residual stress was-376. 4 N,and the hardness was 759. 8 HV. The research results have important engineering significance for improving the surface integrity of ultrasonic assisted rolling workpieces and determining the optimal ultrasonic assisted rolling processing parameters.关键词：Ultrasonic-assisted rolling;GCr15;Grey theory;Correlation analysis;Optimization
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发布时间：2022-09-22 - 摘要：It has important theoretical significance and application value for analyzing the fracture failure process of 6061-T6 aluminum alloy to study the relationship between fracture strain and stress triaxiality and establish the fracture failure model. The quasi-static tensile tests and numerical simulations of 6061-T6 aluminum alloy smooth bar specimens and notched bar specimens were carried out by means of digital image correlation（ DIC） measurement technique and Abaqus software,respectively. The stress triaxiality of the latter was analyzed and corrected based on the results obtained,and a part of the Johnson-Cook（ J-C）failure model was obtained. The relationship between the fracture strain and the stress triaxiality of 6061-T6 aluminum alloy was established. The failure model was input into Abaqus for fracture numerical simulation. The simulation results were basically consistent with the experimental results,which verified the correctness of the failure model. It’s shown that the fracture strain of6061-T6 aluminum alloy decreases with the increase of stress triaxiality,and the J-C failure model can well describe the fracture failure behavior of 6061-T6 aluminum alloy under different stress triaxiality.关键词：6061-T6 aluminum alloy;Stress triaxiality;Fracture strain;J-C failure model;DIC measurement technique
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发布时间：2022-09-22 - 摘要：The thermo-mechanical fatigue（ TMF） behavior of casting alloy Ti-48 Al-2 Cr-2 Nb was researched. The tests were performed thermo-mechanically in-phase（ IP） at 400℃ ～ 800℃ . During TMF,tests strain was controlled. The result of this IP TMF was compared with 400℃ and 800℃ isothermal low cycle fatigue（ LCF）. The result shows that the fatigue life of Ti-48 Al-2 Cr-2 Nb alloy in 400℃ ～ 800℃ TMF condition is longer than 400℃ and 800℃ LCF within high strain region. Within low strain region,it is slightly shorter than 400℃ LCF and within the dispersion zone of 800℃ LCF. In this TMF condition,no evidence shows hardening or softening phenomenon. SEM analysis shows that inter-lamellar and inner-lamellar cracking and trans-lamellar tearing can be observed on the fracture surface.关键词：Ti Al alloy;Thermo-mechanical fatigue（TMF）;Low cycle fatigue（LCF）;In-phase（IP）
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发布时间：2022-09-22 - 摘要：In order to select the reasonable failure criterion of post-buckling analysis of stiffened composite panels,Lstiffener specimen with long post-buckling histories was designed and crippling test was conducted. FEA model with the consideration of progressive failure was established. Load-strain curve and buckling load and damage load were also presented. An excellent agreement is found between the analytical prediction and the experimental data. And the failure mode predicted is also consistent with the test results. The validity of analysis method is proved. Five different failure criterions are adopted respectively in the FEM analysis and damage loads as well as failure modes is obtained. The analysis results indicate that the validity of different failure criterion would be verified to avoid arbitrary selection of them by combination of L-stiffener specimen test and simulation. This work can provide reference to the post-buckling design and analysis of stiffened composite panels.关键词：Composite;Post-buckling;FEA;Failure criterion
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发布时间：2022-09-22 - 摘要：binocular photogrammetry vibration measurement method for considering the radial and tangential distortion parameters calibration by using the Levenberg-Marquardt algorithm based nonlinear optimization was proposed. As an example,the modal frequency identified of a wind turbine blade. The vibration images sequence of the blade was acquired synchronously by two cameras and the target was segmented by adaptive binary dynamic threshold method,the direction with fastest grayscale gradient of the coding point as the edge,the circle curve was fitted by the least squares and iterative method,and the precise suppixel central coordinates of the coding point in the dynamic consecutive images were obtained by the gray square centroid method.Each coding point is similar to a small "displacement transducer"that reflects the blade’s time domain vibration response.Finally,the blade’s natural modal frequency was obtained from the time domains response,and compared with the results of the finite element and Laser Doppler Vibrometry,the relative error of vibration frequencies less than 5%,which verified the reliability and effectiveness of binocular photogrammetry method.关键词：Binocular photogrammetry;Vibration measurement;Wind turbine blade;Laser doppler;Sub-pixel
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发布时间：2022-09-22 - 摘要：The dynamic characteristics are important factors that affect the accuracy of machine tools. Currently,the material combinations are an effective method that is often used. In order to research the dynamic characteristics of machine tool components,the sandwich structure of bolted joint was fabricated. Based on the theory of experimental modal analysis,the TST5912 dynamic signal testand analysis system was used to conduct hammering experiment on the structural parts with HT200 and QT500 materials as the base and constrained layer,the nitrile rubber（ NBR） and polypropylene（ PP） plate as the sandwich materials. By changing the base material,the constraining layer material,the sandwich material and the thickness,the parameters such as vibration mode,natural frequency and damping ratio of the sandwich structure are obtained. The experimental results show that the damping ratio of the rubber sandwich structure is larger than that of the plastic sandwich structure,and increases with the increase of the sandwich thickness. The thinner the base layer,the greater the increase rate of the damping ratio of sandwich structure components.关键词：Dynamic characteristics;Modal analysis;Hammering experiment;Sandwich structure;Damping ratio
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发布时间：2022-09-22 - 摘要：Oblique cutting is a working condition in fully mechanized mining whose main task is making it possible for long wall shearer to cut the coal seam,and it is a harsh working condition since the shearer is forced to be bent. In this study,dynamic characteristics in oblique cutting for the long wall shearer cutting unit gearbox（ SCUG） are investigated experimentally based on National Coal Mining Equipment Laboratory of China. Real oblique cutting process in coal mining is reproduced in this experiment and vibration acceleration data is obtained. The vibration data is analyzed in time domain,frequency domain and timefrequency domain for investigating the rules of dynamic characteristics for SCUG. Beat vibration phenomenon and the coupling of gear mesh frequencies are found in experiment,and they may cause local resonance and reduce fatigue life of SCUG. The impact of cutting load on beat phenomenon and frequency coupling is investigated,and some conclusions related to the impact of cutting load on dynamic characteristics of nonlinear gear system are obtained.关键词：Experimental study;Coupling frequencies;Beat vibration;Long wall shearer;Dynamic characteristics
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发布时间：2022-09-22 - 摘要：With the development of electronic packaging towards high power and high density,the interconnection structure is faced with the reliability problem induced by electromigration. Most traditional simulation methods are based on a single or two physical fields. Herein,a simulation method for obtaining the distribution of atomic concentration in interconnection structures under the effect of complete coupling of electric field,temperature field,stress field and atomic concentration field was proposed to predict the void at the minimum value of atomic concentration using finite element method. This method is applied to interconnect lead structure and interconnect welding ball structure,respectively. And the accuracy and reliability of this method are verified by comparing experimental phenomena,which provides a precise prediction method for the reliability analysis of integrated circuit design.关键词：Electromigration failure;Finite element;Multiple-physical fields;Atomic concentration
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发布时间：2022-09-22 - 摘要：The adaptive p-version finite element method is combined with bi-directional evolutionary structural optimization（ BESO） for the influence of calculation accuracy on the optimization result in the topology optimization process. According to the error control parameter setting,the element order is improved adaptively through the element energy error analysis,which effectively improves the finite element calculation accuracy,and the sensitivity filtering algorithm and the stabilization strategy are adopted to mitigate the checkerboard and iterative oscillation phenomenon. The feasibility of the method is verified by the example calculation of the minimum compliance topology optimization problem,the results show that the proposed method can improve the accuracy of topology optimization under rougher meshes,and obtain higher optimization efficiency and better optimization results.关键词：Adaptive p-version finite element method;Bi-directional evolutionary structural optimization;Element order;Minimum compliance
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发布时间：2022-09-22 - 摘要：The response surface model simulation experiment method is proposed on the basis of the influence of the dynamic characteristics of the structure on the comprehensive performance and the low efficiency of the engineering optimization design. By combining the ideas of the optimal design of space filling and Kriging interpolation to construct the initial agent model for optimal design of mechanical structure,and by using experimental design method,the error is bigger regional encrypted local encryption processing optimization,the approximate optimal solution and iteration of ideas,both inside and outside layer updating is established both in local and global space with high approximation accuracy of Kriging model. On this basis,Pareto optimal solution of the objective function is obtained based on the filter optimization algorithm and the multi-objective genetic algorithm.Finally,an example is given to demonstrate the effectiveness of the method.关键词：Axle-axle for light rail;Optimal space-filling design;Kriging;Response surface method;Screening optimization algorithm
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发布时间：2022-09-22 - 摘要：In the case of no-fault data,the failure probability combined with the Bayesian theory to study the confidence limit analysis to correct the unilateral confidence reliability evaluation. Based on the Weibull distribution,the distribution curve method was adopted to analyze,and the hierarchical priors distribution was constructed to give the comprehensive E-Bayes estimation of the failure probability,and the estimated value of distribution parameters were obtained by combining the least square method. According to the statistical property of the parameters,the pivot quantity of the confidence interval is constructed,and the interval estimation and reliability confidence lower limit of the Weibull distribution characteristic parameters are given.Taking the classical bearing test as an example,this method was compared with the calculation results of other methods,which proves the rationality and feasibility of this method in evaluating confidence reliability.关键词：Zero-failure data;Failure probability;Multi-layer E-Bayes estimation;Distribution curve method;Confidence interval estimation
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发布时间：2022-09-22 - 摘要：The ultimate goal of aircraft crashworthiness design is to protecting safety for occupants. In order to more accurately simulate the dynamic response and injury of the occupants during crash event,a crash simulation model of the fuselage section which including dummy and seat restraint system was developed using LS-Dyna,and the dynamic response of the structure and occupants is analyzed in detail when the vertical impact velocity is 9. 14 m/s,the analysis includes the energy absorption characteristics and failure mode of the fuselage structure,the mooring condition of the cabin facilities,the movement and injury of the occupants,etc.,and the validity of the crash simulation model is verified by comparison simulation results with the test data.Finally,the research on the evaluation method of civil aircraft crashworthiness was carried out. Through understanding and identification of relevant airworthiness clauses,advisory circular and standards,the comprehensively evaluation method to evaluating the crashworthiness of civil aircraft was proposed based on the survival space,the strength of mooring,the injury of occupants,the evacuation channel and the post-crash environment. The crashworthiness analysis of the fuselage section shows that the injury modes of occupant in the vertical crash environment are mainly lumbar and tibia injuries,the occupant’s maximum compression lumbar load is 6. 78 k N,and the maximum axial tibia load is 7. 46 k N during the crash process. The crashworthiness of the constructed civil aircraft is systematically evaluated by the comprehensive crashworthiness evaluation method proposed in this paper,it shows that the crashworthiness of this civil aircraft is good,except for the occupant’s lumbar load slightly exceeding the airworthiness limit and requiring corresponding design improvements,the other evaluation indexes are all in accordance with the requirements.关键词：Fuselage section structure;Dummy-seat-restraint system;Crashworthiness analysis;Crashworthiness evaluation;Numerical simulation
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发布时间：2022-09-22 - 摘要：In order to ensure the stability of the tunneling machine system under various working conditions. The architecture of human-computer interaction interface module and computing module was designed. The three-dimensional cartesian coordinate system of the cutting arm was established,and the whole process spatial pose of the tunneling machine was represented based on the transformation of spatial pose matrix. The cutting load was calculated,a synthetic determination method for multiboundary stability was proposed. In addition,the program implementing process was formulated,and a longitudinal tunneling machine dynamic stability analysis software based on VB and MATLAB platform was developed. The software can be used to calculate cutting load,global stability,hinge force and torque in the tunneling process of tunneling machine under different working conditions,and the results can be outputted through the interface in the form of graphics or Excel table,which can provide references for the design of the tunneling machine and the selection of key parts.关键词：Tunneling machine;Stability;Cutting load;Coordinate transformation;Simulation
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发布时间：2022-09-22 - 摘要：In order to analysis static and dynamic characteristics of a certain type electric wheel dump truck frame,the load information of key bearing connection sites of the fame was obtained by the rigid and flexible coupling multi-body dynamics analysis for the whole vehicle and the finite element model of the frame with welding details was constructed simultaneously.Then,the static analysis of the frame on the condition of static state with full load was carried out and its correctness was verified by using stress test on the mine road surface. The dynamic analysis of the frame under the conditions of horizontal bending,ultimate torsion and emergency braking with full load,stiffness analysis and modal analysis were conducted. The results can be illustrated that the stiffness of the frame under the ultimate torsion condition has some room for improvement to avoid frame failure.Therefore,the multi-objective optimization design for the frame stiffness under different conditions was carried out by utilizing topological optimization technology. The result shows that the reconstructed frame after optimization satisfies operating requirements of the whole vehicle and this analysis method also provides some reference experience for frame static and dynamic characteristics design as well.关键词：Electric wheel dump truck fame;Static and dynamic characteristics;Stiffness analysis;Modal analysis;Topological optimization technology
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发布时间：2022-09-22 - 摘要：Based on the fractal theory,the contact stiffness model of a single asperity at each deformation stage is obtained by taking into account the deformation state of the asperity at the four stages of elasticity,the first elastoplastic,the second elastoplastic and complete plasticity. We can obtain the related parameters that affect the normal contact stiffness of a single asperity. The frequency index is introduced and the critical value of frequency index in each deformation stage is obtained.According to the simulation results,when the fractal dimension D is set at 1. 1 ～ 1. 9,the value of dimensionless normal contact stiffness increases monotonically with the increase of D vaiue; when the frequency index of asperity is in each interval,the value of dimensionless normal contact stiffness increases with the increase of normal contact area.关键词：Joint interfaces;Fractal theoretical;Normal contact stiffness;Loading;Elastoplastic
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发布时间：2022-09-22 - 摘要：To study the pose state and coordinate transformation of different tool positions by establishing the interpolation equations,and obtain the mathematical model between the coordinate systems,and verify the validity according to the simulation results. Based on the five-axis CNC machine tool,the interpolation equations are established,and the interpolation models of different machining directions are analyzed; using the homogeneous matrix transformation method and the numerical assignment inverse algorithm,combined with the classical DH method in robotics,the mathematical model between the coordinate systems is established,and the pose state of the machine tool holder is realized,and the coordinate values of each axis motion are obtained.And kinematics equations; spatial trajectory planning and kinematics simulation using MATALB and ADAMS. Through simulation analysis,the results show that the pose and stability of the dynamic tool holder during the machining process meet the requirements of the previous design,and the overall motion performance of the machine tool is good. Conclusion: The tool is moving in accordance with the trajectory law of the design,which verifies the validity and rationality of the method.关键词：Pose state;Coordinate transformation;Interpolation model;D-H method;Trajectory planning
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发布时间：2022-09-22 - 摘要：Considering the influence of elastic deformation on the profile of the cycloid,a cycloid profile modification method for compensating elastic deformation is proposed.Based on the theory of cycloid profile modification,the coordinates of the meshing point of the cycloid were obtained. The coordinate transformation principle was used to fit the profile of the cycloid after elastic deformation,and the theoretical calculation of the contact force of the cycloid tooth surface was carried out. And the mathematical model of the profile modification of the cycloid with elastic deformation characteristics was established,which was solved by genetic algorithm and compared with the modification method without considering elastic deformation.The results show that compared with the modification method without considering elastic deformation,the fitting degree of the actual working tooth profile and the angle modification tooth profile is improved to 1. 52 times,and the contact force of the tooth surface is reduced to8. 27%,thus verifying the rationality and feasibility of the method.关键词：Elastic deformation;Profile modification;Optimized design;RV reducer
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发布时间：2022-09-22 - 摘要：Aiming at analyzing the influence of thermal load and mechanical load on the vibration characteristics and fatigue life of the exhaust system,the finite element model and modal test were conducted by modal analysis. The temperature field distribution of the exhaust system was obtained via CFD analysis. Finally,a frequency-domain called Dirlik was applied to analyze the vibration thermal fatigue life of this exhaust system. The results show that the structural modal frequency decreases under the temperature field distribution,and the fatigue life of the exhaust system considering temperature field distribution is 90. 8% lower than that not considering temperature distribution. Therefore,the temperature field distribution has significant effects on the fatigue life of the exhaust system,and it can’t be ignored during the development process.关键词：Exhaust system;Vibration fatigue;Fluid-structure coupling;Modal analysis;Temperature field distribution;Vibration characteristics
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发布时间：2022-09-22 - 摘要：In line contact thermal elastohydrodynamic lubrication,changes of temperature rise are generated on the two solid surfaces in contact with oil film,and the thermal stresses of the two solid surfaces are bound to be generated. The solid surfaces are constrained by the non-uniformly distributed oil film pressure. It is difficult to solve the thermal stresses on solid surfaces numerically. Both the theory of thermoelasticity and the principle of heat and pressure conversion were introduced into the line contact thermal elastohydrodynamic lubrication,and the numerical method was given to realize the numerical solution of linear expansion coefficients of solid surfaces and solve the numerical calculation of thermal stress and thermal elastic deformation.The numerical results of both the lubrication characteristics and the thermal stresses satisfying the convergence precision were obtained and the influence of the linear load changes on the thermal stresses were discussed by some examples. The research contents could provide reference for thermal elastohydrodynamic lubrication analysis and solid thermal stress analysis under constrained conditions.关键词：Line contact;Thermal elastohydrodynamic lubrication;Thermal stress;Thermal elastic deformation;Heat and pressure conversion
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发布时间：2022-09-22 - 摘要：To study the conveyor belt cover and roller resistance variation with the operation process of belt conveyor,based on the three components of solid model,considering the influence of temperature on the conveyor belt viscoelasticity properties,put forward and set up a three element four variables considering temperature thermal viscoelastic kinetic parameter model.Then using the variable temperature dynamic compression experiment,getting the dynamic loading force under different temperature and time of curve,through first-order Fourier series fitting and obtained the conveyer belt rubber layer is derived formula of the thermal viscoelastic Kinetic parameter model and the accuracy of the formula are verified,finally established contains parameters such as temperature,tape speed of conveyor belt rolling resistance coefficient calculation equation,analyses the various factors affecting the impact on the rolling resistance coefficient,and through experiment verification rolling resistance coefficient calculation equation for the test,the results of the study to guide saving energy running of the belt conveyor control to provide the basis.关键词：Temperature;Thermal viscoelastic kinetic parameter model;First order Fourier series;Pressure sinking resistance coefficient
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发布时间：2022-09-22 - 摘要：As one of the crucial components of the gearbox in the car,the Shafting-Yoke’s fatigue life directly affects the performance of the gearbox. The Shafting-Yoke of the manual transmission is taken as the research object,which adopting finite element software to analysis its fatigue stress and employing the dynamic simulation software to obtain its load spectrum. A method combining based on GL code predicting material S-N curve and Goodman mean stress correction was developed to calculate the fatigue life of Shafting-Yoke. The fatigue test of Shafting-Yoke shows that the location of damage and the fatigue life of ShaftingYoke of computer simulation and protracted-test are basically same,which proves the reliability and practicability of method promoted in this paper,it can play a guiding role for structure design and optimization of Shafting-Yoke.关键词：Shafting-yoke;Fatigue life;S-N Curve;Goodman mean stress correction;Protracted-test
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发布时间：2022-09-22 - 摘要：Stress concentration caused by holes in a component is always an important research topic in structural safety assessment. Many studies have been carried out on linear elastic materials under static loading,including the effects of hole shape,material anisotropy and loading direction on stress concentration. However,the coupling effect of the nonlinear stressstrain relationship and the strain-rate effect will lead to a great difference between the stress concentration for the plastic material and the existing linear elastic results when the material is under dynamic loading,especially for many kinds of metal materials with plastic deformation. Therefore,based on the Johnson-Cook model,the stress concentration at the hole root of a typical 45 steel plate under dynamic loading is systematically analyzed using finite element method. The results show that the plastic stress concentration factor depends not only on the loading magnitude（ strain） but also on the loading speed（ strain rate）. For the plate at plane stress state under the remote strain of 1%,the stress concentration factor at the circle hole for ε∞= 20/s is around 10%higher than that for ε∞= 0. 1/s,while the stress concentration factor at the elliptic hole with the shape factor（ minor axis/major axis） of 0. 5 for ε∞= 20/s is around 11% higher than that for ε∞= 0. 1/s.关键词：Strain-rate effect;Stress concentration;Visco-plastic;FE;Strain
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发布时间：2022-09-22 - 摘要：The calculation methods of the maximum principal engineering strain,maximum principal logarithmic strain,maximum principal Green-Lagrange strain,and maximum principal Euler strain and octahedron shear strain peak under uniaxial and multiaxial loading stress condition are studied. It is found that the five damage parameters can be calculated only by outputting the deformation gradient tensor of the dangerous area in the finite element analysis. Based on the fatigue crack initiation theory and the fatigue test data of dumbbell rubber test piece,the life prediction models are established by the above five damage parameters,and the accuracy of the five life prediction models is measured by the goodness of fit value. Among them,the life prediction model with octahedron shear strain peak as damage parameter has the best fitting value. The fatigue life prediction model is established based on the fatigue crack growth theory and the crack growth test data of one-sided notch,pure shear specimen. The life prediction model with octahedral shear strain peak as damage parameter and the life prediction model based on crack growth theory were used to predict the life of the same bushing product respectively. It is found that the life prediction model with octahedral shear strain peak as damage parameter has better prediction effect,and the predicted life is near the triple scatter line of the measured life.关键词：Rubber bushing;Multi-axial loading;Fatigue life;Crack initiation approach;Crack growth approach
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发布时间：2022-09-22 - 摘要：At present,the durability test specifications of whole vehicle road simulation bench generally copy the proving ground,which ignores the difference between loads of the two and results in unsatisfactory bench test results. So it is difficult to reproduce the durability test results of the proving ground. Based on the measured load data of proving ground and test bench. We studied the difference between the two. The equivalent transfer criterion of load from road condition to bench condition is formed by using the principle of equal damage,and the ‘proving ground-bench ’ load-damage equivalent relationship model was established. The Pareto optimal solution was obtained by using fast and elitist non-dominated sorting in genetic algorithms（ NSGA-Ⅱ） algorithm to solve the model. By optimizing the solution,the road condition cycle number of the road simulation test bench durability evaluation was obtained,and the test criterion of the whole vehicle bench durability was formulated. The bench test was carried out by the new specification. The comprehensive validation by damage and the cumulative distribution of load was carried out. The results showed that the criterion for evaluating the durability of the whole vehicle road simulation test bench obtained by the method was efficient and accurate,which can effectively reproduced the evaluation effect in the proving ground.关键词：Durability test;Equal damage principle;NSGA-II algorithm;Equivalent relationship model;Pearson correlation coefficient
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发布时间：2022-09-22 - 摘要：Composite stiffened panels always have defects at the bonding surface in preparation,which accelerates the debonding of the interface between skin and stringer,greatly affects the bearing capacity of the structure. The model of stiffened panel with prefabricated debonding at the interface of stiffened strip and skin was established with both cohesive zone model（ CZM）and virtual crack closure technique（ VCCT） in ABAQUS,and the rationality of model was verified by experiments. The distribution of energy release rate in prefabricated debonding leading edge was given and the effect of debonding position and area on stiffness and carrying capacity was analyzed. The results indicate that the contribution of type II energy release rate to damage initiation is the greatest; the bearing capacity of the prefabricated debonding structure is stronger than that is in the middle when it is located in outside; the carrying capacity of the structure decrease with the increase of prefabricated debonding area.关键词：Cohesive zone model;Virtual crack closure technique;Energy release rate;Debonding;Stiffness
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- 89
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发布时间：2022-09-22 - 摘要：Fatigue damage accumulation and strength degradation occur simultaneously and interact with each other during service of engineering structures. In order to establish an improved Corten-Dolan cumulative damage model that takes the effects of strength degradation in consideration,strength degradation coefficient was deduced by analyzed the strength degradation model,then the exponential parameter d in the Corten-Dolan model was defined as an exponential function related to the strength degradation coefficient. Effectiveness of the improved Corten-Dolan model was verified by fatigue test data of material and comparison with other references. The results show that the improved Corten-Dolan model predicts fatigue life accurately,prediction is more accurate than the traditional Corten-Dolan model.关键词：Fatigue damage accumulation;Strength degradation;Improved Corten-Dolan model;Fatigue life prediction
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- 338
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发布时间：2022-09-22 - 摘要：In this paper,a new type of moving roller bracket conveyor is taken as the research object. The simulation of Adams virtual prototype is carried out on the mechanical model of the roller bracket to obtain the contact force of the wheel and rail under two working conditions. On the basis of dynamic simulation,static simulation analysis of the conveyor under different working conditions was carried out by using finite element software Ansys to obtain the maximum stress and strain,and the safety factor of each component was calculated to verify the structural rationality. The dynamic response analysis of the reversing frame and the separation frame is carried out by using the New mark integration method in ANSYS workbench,and the displacement and acceleration transient values are obtained. The results show that after the load is applied,the contact force of the conveyor wheel rail will change,but the weak position of the roller carriage conveyor will not be moved,and the abnormal variation in the Z-axis direction indicates the uncontrollability of the lateral load. Provide a theoretical basis for the structural improvementof the moving roller carriage conveyor.关键词：Virtual prototype;Track;Pedestal;Roller bracket;Mechanical model
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发布时间：2022-09-22 - 摘要：Magnetorheological damper is a kind of intelligent actuator for semi-active control. The dynamical models of Magneto-rheological damper was analyzed in this paper. The model of the extended Bingham and the modified Bouc-wen which were used widely was established by using Simulink. Then the simulation was carried out and the advantages and disadvantages of the two models were comparative analyzed. Finally,a new dynamical model with few parameters based on the tangent function was proposed. The physical meaning of the parameters were illustrated by simulation. The simulation results showed that the curve of the new model was smooth and accurate. It can be used for the simulation and study on the Magnetorheological Damper.关键词：Magneto-rheological damper;Bingham model;Bouc-wen model;Tangent function;Matlab/Simulink
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- 713
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发布时间：2022-09-22 - 摘要：In the automatic stamping production,the stamping robot completes the clamping and conveying of workpiece through the actuator,and the positioning of the actuator is completed by the mutual cooperation of electrical control and stopper.During the auxiliary positioning of the stopper,the actuator will collide with the stopper,which has an adverse impact on the stamping production. Therefore,the impact simulation analysis and structural optimization design of the actuator are carried out.The 3 D solid model of the actuator was established by UG NX8. 5 software,and imported into ABAQUS software for fem simulative analysis to obtain the clamping force,acceleration and tilt angle and other parameters of the workpiece. From the analysis of simulation results,it can be seen that the clamping force on the workpiece is zero and the peak value is large,the acceleration of the workpiece changes sharply in a short time,and the tilt Angle after collision is large. Aiming at the above problems,the optimal design of the actuator is carried out,which effectively reduces the impact of collision on the actuator and improves the efficiency of stamping production.关键词：Stamping robot;Actuator;Collision;Finite element analysis;Optimization design
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- 388
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发布时间：2022-09-22 - 摘要：The load fluctuation of the transmission system are important factors that cause equipment fatigue,and the fatigue failure has been the most common failure mode of the transmission system. Therefore,a special vehicle lift mechanism transmission system has been regarded as the research object,the three-dimensional model of the main components of the transmission system has been established,and the influences of the bolt design on the load fluctuation characteristics of support bearing raceway of transmission system have been analyzed by the finite element and vibration frequency detection methods. The research results show that the bolt pre-tightening force in the transmission system change the contact deformation of the raceway of the supporting bearing and then affect the contact load of the supporting bearing. Under the combination influence of the bolt pretightening force and the external load,the supporting bearing contact load fluctuate greatly,which reduce the fatigue life of the supports bearing of transmission system obviously. The optimization of the wall thickness of the supports bearing,reducing the pre-tightening force of the bolt,and increasing the distance between the bolt hole and the supports bearing can effectively reduce the cyclic fluctuation load for the supports bearing of transmission system,thereby improving the fatigue life of the transmission system; the vibration of the transmission system was reduced after optimization. The research provides a theoretical basis for the comprehensive transmission improvement of the performance of transmission system,and the improvement of the fatigue life of the support bearing.关键词：Special vehicle;Lift mechanism;Support bearing;Contact load;Fluctuation characteristics
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- 91
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发布时间：2022-09-22 - 摘要：The constant spring support hanger is usually used for supporting the conveying pipeline and it can abstain additional stress when the conveying pipe had vertical displacement. The knife-type cam is the core component of the constant spring support hanger.The design accuracy of the cam curve has direct influence on the work load deviation of the constant spring support hanger. According to the Instant relationship between the outside force and the spring energy changes in the body coordinate system,The elliptic algebra Equation of cam rotation angle and load tube vertical displacement was derived by using energe method. The cam design formula was put forward through the transformation of the global coordinates and the body coordinate. Considered the actual structure of the constant spring support hanger,the cam curve formula considering the radius of the roller is derived. The comparative analysis shows that the design accuracy of the cam curve equation established in this paper is better than the traditional method. Considered the influence of the roller radius can improve the support constant of the constant hangers.关键词：Main-auxiliary model;Constant spring support hanger;Cam curve;Roller
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- 166
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发布时间：2022-09-22 - 摘要：According to the requirement of LPG tank car inner wall cleaning,a wall-climbing jet cleaning trolley was designed,which combined high-pressure water jet and mechanical brushing. By establishing the static and dynamic model of car wall cleaning,the minimum adsorption force equation for reliable adsorption of car and the minimum driving force equation for stable operation and steering of car were derived. The example analysis under different wall inclination angles shows that the main instability form of static adsorption is wall sliding,and the minimum adsorption force is 51. 8 N when the wall inclination angle is120 degrees. The main instability form of stable operation is differential steering,and the minimum driving torque is 2. 95 N·m when the wall inclination angle is 50 degrees. The prototype experiment proves that the research results are reliable,which provides a theoretical basis for the development of LPG tank car automatic cleaning equipment and the corresponding technical research.关键词：Tank car cleaning;Wall climbing jet car;Mechanical modeling;Example analysis
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发布时间：2022-09-22
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