最新刊期
期 3 ， 2016
- 摘要：Tandem strip mill is a complex system composed of a plurality of working frames and auxiliary equipments,each frame is a multi-variable,nonlinear dynamic system,and interacts with the adjacent one by the moving steel strip. The strip mill system can be seen as a flexible multi-body mechanical system composed of multiple rigid and deformable bodies such as:frames,hydraulic equipment,roller system,moving strip et al. During the rolling process,relative movement occurs between the roll system and stock which contacting with each other at the same time. With the comprehensive consideration of roll system‘s vertical movement and work roll’s rotation,also with the rigid movement and elastic deformation of moving strip,this paper realizes the displacement field’s description of rigid body and deformable body in flexible multi-body mechanical system through dynamic analysis,and then determines the law of strong nonlinear inertial coupling and stiffness coupling effect caused by the system structural elements’ rigid motion and elastic deformation occurred simultaneously. Finally,the flexible multi-body system of tandem strip mill‘s coupling vibration mechanism model was established which can be used to analyze the roller system’s dynamic response and working stability.关键词：Strip rolling mill;Flexible multi-body mechanical system;Moving strip;Coupling vibration
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发布时间：2022-09-22 - 摘要：Advanced support equipment is mainly composed of two sets of frames which can be passed by each other,and it is belong to fully mechanized mining roadway roof temporary support equipment. In order to improve the stability and avoid the resonance of the advanced support equipment,based on the analysis of the working principle of the advanced support equipment,proposed the mechanical model of the support system,establish the dynamic mathematical model and the state space model of the advanced support equipment using the Lagrange method and the generalized space coordinate system. Using the Routh Hurwitz criterion as its dynamic stability judgment conditions,refer to the disturbance force mathematical model of commonly used in coal mine,combined with MATLAB and modern control theory,the vibration characteristics of the single support group of the advanced support equipment are simulated,and obtain the system dynamic response. At last,carry out modal analysis using experimental prototype and vibration testing system of advanced support equipment. The research results show that the frequency range of the easy to occur resonance is about 42. 353-42. 994 Hz.关键词：Advanced support equipment;Stability;State space;Modal analysis
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发布时间：2022-09-22 - 摘要：A general coupled dynamic model of the isolation system is established,which is composed of isolation object,nonlinear isolators and flexible foundation. By transforming the system dynamic equation into an expression of initial value problem of differential equation,the calculation method of transmitted power flow is deduced,which is put forward to evaluation and analysis of isolation effectiveness. Based on an example of vibration isolation system of a small unmanned aircraft engine,the Runge-Kutta method is applied to simulation and estimation of power flow transmitted through nonlinear isolators with hypothetical different stiffness characteristics. It is presented that properly designed nonlinear isolators such as endowed with paralleled negative stiffness or piecewise linear stiffness could effectively reduce the power flow transmission of isolation system.关键词：Nonlinear;Vibration isolation;Flexible foundation;Power flow
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发布时间：2022-09-22 - 摘要：There is some grinding pressure fluctuation on the rail grinding train operation,which affects the uneven surface of grinding rail. The dynamic model of rail grinding vehicle was established which gave full consideration to the grinding mechanism’s motion behavior and contact area behavior between rail and grinding wheel. Furthermore,the effect of the vertical irregularity of rail surface,grinding speed,rail corrugation and structure parameters of grinding vehicle on the grinding pressure fluctuation were explored in detail. The results show that the vertical irregularity of rail surface is the main cause of grinding pressure fluctuation. With an increase of grinding speed,the pressure fluctuation reduces. Certain wavelengths of rail corrugation result in the resonance of grinding mechanism,which causes the grinding pressure fluctuation peaks. The optimization of primary locating stiffness of grinding vehicle and the lightweight of grinding mechanism are beneficial to decrease the grinding pressure fluctuation and increase the grinding stability.关键词：Rail grinding;Pressure fluctuation;Grinding speed;Rail corrugation
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发布时间：2022-09-22 - 摘要：A type of aero engine compressor blade model was built based on finite element. Dynamics of the clamped constrained blade was obtained by modal simulation and the influence of centrifugal force on the vibration of blades was researched. And then,the modal test was carried out to validate the model and the simulation data. Vibration analysis of blade disc finite element model was carried out based on cyclic symmetry method. The vibration mode and frequency of the coupling system with different working speeds were obtained. The result shows that the natural frequency of the coupling system is lower in the same order when compared with a single fixed blade. The resonance frequency and the corresponding rotor speed could be obtained by analysis of Campbell contours. It provides reference for the fault diagnosis,reliability analysis and life estimation.关键词：Compressor blade;Blade-disc coupling;Vibration characteristics;Finite element
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发布时间：2022-09-22 - 摘要：Bridge crane and gantry crane are the equipments which are the most widely used in lifting field,and it is necessary to study its dynamic characteristics when the gantry crane is designed. Taking the L type gantry crane as an example,with the help of finite element method,the crane’s top six order natural frequency and vibration mode were obtained by modal analysis,and the frequency biggest impacting on the dynamic characteristics of crane was obtained by harmonic response analysis,then taking the frequency as index,the dynamic sensitivity analysis of its structural parameters was carried out. In the dynamic sensitivity analysis,the parameters which affect dynamic characteristics of the crane structure more greatly were obtained. By the way,the dynamic optimization model can be simplified. The results provide the basis for the further optimization of the structure and the reference for the dynamic design of other similar structures.关键词：L-type gantry crane;Dynamic characteristics;Finite element method;Modal analysis;Harmonic response analysis;Dynamic sensitivity analysis
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发布时间：2022-09-22 - 摘要：In order to analysis the torsional vibration of the camshaft,the dynamic experiment of valve train was conducted to calculate the dynamic torque in this paper. The torsional vibration and the critical speed can be obtained by the modal analysis,and then the relationship between the torsional vibration and working condition was analyzedto confirm the torsional vibration influence to the valve train. The results show that the torsional vibration changed with the camshaft speed,and influenced the valve timingin the out of the common working condition. The camshaft torque increased obviously by taking the torsional vibration into account. The camshaft max torque and the torsional amplitude value were 4. 5 N·m and 0. 06°in the rated condition.关键词：Valve train;Dynamic torque;Torsional vibration
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发布时间：2022-09-22 - 摘要：For the hazards caused by crack to wind tower in service process,acoustic emission（ AE） technology was applied for extracting the characteristic signal of the crack. The attenuation test for AE signal of the wind tower and three-point bending test for the wind tower material Q345 E steel were carried out. At the same time,proportionality coefficient of different types of AE signal at the same frequency band was extracted by using the wavelet analysis method. It is demonstrated that the AE signal decayed obviously at the weld joint compared to parent metal,meanwhile the signal can reached farthest 6 m in wind tower. There was a relationship between the bending damage level of steel Q345 E and AE signal response characteristic. The energy ratio coefficient of different types of AE signals in the same frequency band was significantly different. It shows that the degree of safety of wind power tower in service can be estimated qualitatively according to the AE technology.关键词：Crack;Wind tower;Acoustic emission technology;AE signal;Wavelet analysis
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发布时间：2022-09-22 - 摘要：In photoelasticity,the experiment gives only the difference of principal stresses and their directions. In order to obtain three plane stress components,the supplementary equations are required. Using oblique incidence method one can obtain the three plane stress components. Considering the experimental data is not accurate,multi-angle oblique incidence established nonlinear overdetermined equations are used to calculate stress components. Conventional method for solving nonlinear overdetermined equations is difficult,new particle swarm optimization algorithms are proposed for oblique incidence stress separation. Demonstration of the method on disc under diametral compression is performed using computer simulation. The method is effective and simple for stress separation,providing whole field stress components.关键词：Photoelasticity;Stress separation;Oblique incidence;Particle swarm optimization
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发布时间：2022-09-22 - 摘要：Durability experimental study is performed on single-piece specimens with through-hole and double-piece specimens with fastening holes of three different lengths on random loading. The weak area of structures is gained through threedimensional finite element analysis,considering pre tightening force of bolts and the interference fit between bolts and holes.Based on the results of durability experimental analysis,a new method is put forward to assess the initial fatigue quality（ IFQ） of structures and controlled stress curves are drawn to compare with this method. As a result,the method to assess IFQ of structures in this paper is proved to be effective. The IFQ of double-piece specimens with fastening holes is higher than that of single-piece specimens with through-hole. Furthermore,the IFQ increases with the decreasing of the length of the structure.关键词：Durability;Initial fatigue quality;Equivalent initial flaw size;Finite element analysis
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发布时间：2022-09-22 - 摘要：In traditional plane near-field acoustic holography reconstruction process,regardless of wave number domain filter or regularization method,they cannot solve their own ill-posed problem,and thus cannot improve the reconstruction accuracy. Plane near-field acoustic holography based on Compressive Sampling,translates traditional solved particle velocity into solving sparse coefficient,by effective using of the particle velocity sparsity,avoiding the reconstruction process of ill-posed problem. Combined with plane near-field acoustic holography based on Tikhonov regularization method, we analyze the reconstruction accuracy of numerical simulation. The results show that, plane near-field acoustic holography based on Compressive Sampling has a good accuracy in reconstruction process,especially in the border region of reconstructive surface.Finally,this method can effectively identify the source of the noise of the refrigerator,to provide an effective basis for noise control.关键词：Plane near-field acoustic holography;Compressive Sampling;Tikhonov method
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发布时间：2022-09-22 - 摘要：Schmidt factor of polycrystals is an important variable of structure fatigue life analysis. On the meso-scale,for textured and untextured polycrystalline,relationships between Schmidt factor and stochastic Euler angles of grains orientation are discussed respectively,the fact that face-centered and body-centered crystals with the same orientation presenting the same Schmidt factor is proved,the meso-scale probabilistic model of Schmidt factor is built,and the statistical simulation based on meso-scale is executed. The probabilistic distribution of the Schmidt factor of grains group in fatigue crack initiation zone is obtained,which can provide theoretical basis and effective engineering method for fatigue reliability analysis of the mechanical structure,especially micromechanical and micro electromechanical structures.关键词：Polycrystal;Fatigue reliability life;Schmidt factor;Probabilistic analysis
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发布时间：2022-09-22 - 摘要：JCO forming is widely used in production of large diameter submerged-arc welding pipes. However,more total number of bending deformation and low production efficiency of JCO forming have been the bottleneck problem that restricts the further development. To resolve this problem,this study investigates JCO forming process by multi-objective optimization. JCO forming is simulated using the FE code ABAQUS and the FE model is validated experimentally. A response surface method based on the radial basis function is used to construct a surrogate model; the genetic algorithm NSGA-II is adopted to search for Pareto solutions; and grey relational analysis is used to determine the most satisfactory solution from the Pareto solutions. The obtained optimal design of parameters shows good agreement with the initial design and remarkably improves the JCO forming quality.Thus,the results of this study provide an effective approach for improving production efficiency and reducing total number of bending deformation in JCO forming.关键词：Large diameter welding pipe;JCO forming;RSM;Genetic algorithm;Grey system theory
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发布时间：2022-09-22 - 摘要：Robust design is an effective way to improve the reliability of structure and crash safety by considering uncertainty in vehicle design. In the traditional optimization design of vehicle body,due to ignoring of uncertainty factors,such as processing,manufacturing and environment,leading to design goals such as collision performance or lightweight effect unstable. In this paper,by considering uncertainty factors,taking side impact of a car as an example,first of all,an accurate finite element model is established and verified according to relevant crash regulations,then,after building an approximate model and a deterministic optimization model,the optimal solution is obtained by sequential quadratic programming algorithm and the reliability analysis is used,finally the original vehicle B pillar is accomplished lightweight research and improvement by using six sigma robust design method. After robust optimization design,the results are carried out a comparative analysis with the original vehicle B pillar and also with the deterministic optimization results. The analysis results show that comprehensive improvements are obtained on the robustness of collision performance after robust optimization design of vehicle B pillar,meanwhile,the quality of vehicle B pillar have reduced 3. 2% compared to the original one.关键词：Lightweight;Robust design;Radial basis function;Side impact
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发布时间：2022-09-22 - 摘要：The traditional reliability evaluation is based on the failure data,which needs a large amount of statistical data and samples,and comprises the characteristics of long test cycle and high cost. To solve this problem,without failure data,a method of reliability evaluation was proposed which was based on the performance degradation data. The performance degradation model was built in the method which was based on the least square support machine. With the help of NSGA-II,the parameters optimization of the method above had been done,and the process of parameters optimization and reliability evaluation was given.Last but not least,the availability of the method is validated.关键词：Reliability evaluation;Failure data;Least square support vector machine（LS-SVM）;Parameter optimization
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发布时间：2022-09-22 - 摘要：For the pure electric vehicle rear crashworthiness requirements,this paper combined structural topology optimization with orthogonal design. Referenced a domestic pure electric car,by establishing vehicle tail’s topology optimization model,finite element model,size optimization model and for achieving optimal vehicle acceleration and energy absorption of car rear crumple zones under crash safety regulations,optimized the design of pure electric car tail. Eventually get a reasonable optimized configuration and realize the pure electric vehicle tail optimization of the crashworthiness design.关键词：Crashworthiness tail;Topology optimization;Orthogonal Design;Optimization design
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发布时间：2022-09-22 - 摘要：The complete-data likelihood function of Weibull distribution with multiple change points for IIRCT is obtained by filling in missing life data using inverse transformation method. The full conditional distributions of change-point positions and other unknown parameters are obtained. Every parameter is sampled by Gibbs sampler. and the means of Gibbs samples are taken as Bayesian estimations of the parameters. The concrete steps of MCMC methods are given. The random simulation results show that the estimations are fairly accurate and the effect is good.关键词：Complete-data likelihood function;Full conditional distribution;MCMC method;Gibbs sampling;Metropolis-Hastings algorithm
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发布时间：2022-09-22 - 摘要：Aiming at the current situation of the grinding hardening test has certain blindness,the optimization design of the grinding process of grinding dosage was studied in depth and optimization of cutting parameter was proposed according to the grinding wheel topography. Taking specific grinding energy as the optimization goal,establishing the mathematical model with the chip surface roughness and the space as constraint condition,a complete model of the optimization of the grinding hardening was finally got. 40 Cr was taken as the research object,simplex method and graphical method were used to get the best combination of grinding dosage. In order to the correct evaluation of optimal dosage of grinding hardening effects,experimental verification was conducted and the materials were studied with the change of cutting depth. By measuring grinding force during tests,calculating specific grinding energy and heat source intensity from theoretical perspective; by testing vickers hardness and observing the microstructure of specimens from the perspective of the experimental research to study grinding hardening effect. The results showed that the optimized data is relatively reasonable and grinding hardening experiment under its guidance can reduce blindness and improve the effect of reinforcement.关键词：Grinding hardening;Grinding dosage;Optimization design;Mathematical model;40Cr
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发布时间：2022-09-22 - 摘要：In the dual casing sidetracking,the oil casing wall,cement ring,technical casing wall and rock formations’ hardness are different,furthermore,in the process of dual casing sidetracking the bit in contact with the oil casing wall,cement ring,technical casing wall and rock formations are different,bit bending moment certainly exist. Considered the situation of that the sidetracking bit in actual contact with the oil casing wall,cement ring,technical casing wall and rock formations,established the bending moment mathematical model of the dual casing sidetracking drill bit,and combined with examples using MATLAB software solved the relationship between the drill bit bending moment and the drill bit horizontal moving distance under that Three different working conditions was given. Further reference the theory of metal cutting mechanics,researched cutting force and cutting torque of the drill bit in sidetracking the process,checked the sidetracking bit strength,provided technical advice to prevent the drill bit holded in and stuck fracture accident occurred in the dual casing sidetracking process. The analysis and calculation could provide the reference to designing the sidetracking bit and determinating construction parameters in the dual casing sidetracking process.关键词：Dual casing;Sidetracking;Sidetracking bit;Bit bending moment;Strength check
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发布时间：2022-09-22 - 摘要：Excavator engine hoods are usually formed by welding sheet parts and stiffeners together. Under the incentives of engine and road,the sheet parts are easy to produce serious vibrational response,which directly results in the deformation and the cracking of some weak positions of the structure. The finite element model of an excavator engine hood was established and modal analysis was conducted by using Hyper Works software. Its first four order natural frequencies and corresponding mode shapes in free state were obtained. The accuracy of the simulation results were verified by a modal experiment. Based on the results of the modal experiment and the modal analysis,the structure of the engine hood was optimized. Comparing with the original structure,the stiffness of the optimized engine hood increased and the maximum deformation of typical modes decreased significantly,which indicates that its dynamic performance improves obviously.关键词：Modal analysis;Engine hood;HyperWorks;Structural optimization
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发布时间：2022-09-22 - 摘要：Reciprocating compressor has many moving and damageable parts in which valve is the most frequently damaged component. A mathematical model of the valve movement was established according to its structure and motion characteristics.MATLAB and ANSYS software were used to study the transient motion law and the dynamic stress distribution of mesh valve.Then the impact of spring stiffness and transition arc on valve’s stress distribution was discussed. The results show that the stress generated by deformation is much greater than the impact stress. Maximum elastic deformation occurs in two thin elastic arms in which maximum equivalent stress generated. Changing the spring stiffness and the curvature of the transition arc can effectively reduce the stress and extend the life of the mesh valve. The results of the analysis have important theoretical significance for valve design optimization and the improvement of valve life.关键词：Reciprocating compressor;Mesh valve;Transient motion law;Dynamic stress distribution;Simulation study
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发布时间：2022-09-22 - 摘要：Currently,the production process of firecrackers is very complex and firecrackers need to be processed in the multi-station. Each station is fragmented and is far away. Firecrackers production needs long-distance transport for many times by human and it is difficult to realize the multi-station automatic integrated production. Consequently,the production efficiency is low. In this paper,a synchronous telescopic clamping mechanism is designed and it can automatically clip the fast dispatching hexagonal clamp based on the utility. Kinematics analysis of synchronous telescopic clamping mechanism is carried out by using ADAMS simulation software. It demonstrates that the new synchronous telescopic clamping mechanism can automatically clip the fast dispatching hexagonal clamp and the fixture can automatically clamp on hexagonal firecrackers cake. It provides a feasible method and has important practical significance for multi station automatic integrated production of fireworks.关键词：Firecracker;Fast dispatching hexagonal clamp;Synchronous telescopic clamping mechanism;Adams Simulation
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发布时间：2022-09-22 - 摘要：In other to simulate the contact relation between the body and the door of the large aerospace vacuum tank,propose a nonlinear finite element method by using the gap elements. Build the finite element model of a large aerospace vacuum tank by MSC. Patran and MSC. Nastran. Lead up the nonlinear contact elements to consider the contact,then take the strength analysis of the large aerospace vacuum tank in three conditions. Get the maximum clearance between the body and door are 0. 015mm、0. 017 mm and 0. 018 mm. Analyse the feasibility of using the gap elements to simulate the nonlinear contact. Prove that the simulation is effective. Provide a more exact method to analyse the strength of the large aerospace vacuum tank.关键词：Large aerospace vacuum tank;Gap element;Nonlinear finite element analysis
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发布时间：2022-09-22 - 摘要：In-plane stability calculation model of mast was set up firstly based on the thin-walled components flexuraltorsional theory. Theoretical arithmetic,according to the energy method and principle of stationary potential energy,and numerical simulation and verification of the derrick’s in-plane stability were conducted,and the results of theoretical calculation and numerical simulation basically tallied. Then,material nonlinear analysis was conducted on 5 kinds of structural steel masts.Results show that: maximum stress of the thin-walled derrick exceeds the yield strength of the material when linear buckling occurs in the lifting drilling process for the 5 kinds of structural steel masts and the type of instability is elastic-plastic buckling;The elastic-plastic buckling safety factor y becomes larger with the increasing of yield strength of materials,and the linear fitting function is y = 0. 00707x- 0. 01651; The steel materials that whose yield strength is greater than 313. 5 MPa meet the requirements of derrick’s in-plane elastic-plastic stability.关键词：Mast;Energy method;In-plane stability;Material nonlinearity;Elastic-plastic buckling
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发布时间：2022-09-22 - 摘要：This paper deals with a micromechanics-based model which is proposed for the finite strain deformation of filled elastomers based on generalized Eshelby ’s tensor and Mori-Tanaka ’s method. The present formulation leads to a clear explanation of the constraint effect of rubber-like matrix on the inclusions. Comparisons with experiments and other micromechanics models are conducted. It is observed that an improvement in predictive capability for the composite with randomly dispersed particles was achieved by the present method. Based on the latest experiment of single molecular chain,a compact network model is fatherly developed to reflect the microstructure effect on the stress-strain relations of rubbery polymer and the resulting composites.关键词：Polymer-matrix composites（PMCs）;Microstructures;Micro-mechanics;Analytical modeling
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发布时间：2022-09-22 - 摘要：Due to long-term used in the harsh environment,the functional degradation of the FPSO crane such as corrosion,fatigue crack,local failure occurred. The functional degradation could affect the normal use of the FPSO crane. According to the actual surveying data,the finite element model of the FPSO crane has been established by finite element software Ansys. The stress of high stress area has been tested according to the stress distribution of the FPSO crane. The calculation results of Ansys have been compared with the test data. The errors between calculation results and test data are in 14%,except of point 1941.The stress value of the most dangerous area is 247. 96 MPa,which is less than the allowable stress of the crane. Thus the strength requirement is satisfied. The relation between stress of key area of crane and the angle β of lifting has been analyzed. When the weight of lifting is close to the maximum working load,the working condition of β > 15°is preferred.关键词：Offshore platform;Box crane;Finite element mode;Stress testing;Strength analysis
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发布时间：2022-09-22 - 摘要：For the dynamics problems of flexible beams with large overall motion,nonlinear element dynamic equations are established,adopting the absolute nodal coordinate formulation（ ANCF）. Since the relationship of generalized accelerations and generalized forces is linear in the equations,a new absolute nodal acceleration finite element transfer matrix method（ TMM） for plane beam is proposed,combining the idea of TMM. Compared with traditional finite element transfer matrix method,transfer matrixes of the proposed method are derived without time-integration methods. Here ordinary differential equation numerical methods can be applied conveniently. Finally,the method is verified correct by an example,the beam with large overall motion and small deformation.关键词：Finite element;Transfer matrix;Nonlinear dynamics;Absolute nodal coordinate
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发布时间：2022-09-22 - 摘要：Hertz contact stress theory is the classic theory,it involves more complicated calculation process. In this paper,through theoretical analysis and numerical fitting,a relationship of the contact curvature function and contact elliptical rate was found,that is ln（ 1 / e） = 0. 224[ln[1 / F（ ρ） ]1. 407. Then,a elliptical rate is calculated directly by contacting curvature function,no longer need to process the look-up table and interpolation calculation that would be a kind of trouble and not accurate. At the same time,the stress states at a key point of contact body are found by elastic analysis results,and a method of the yield strength checking is estimated. It could bring convenience in engineering application.关键词：Contact stress;Yield strength;Curvature function;Ellipticity
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发布时间：2022-09-22 - 摘要：For reasonable planning of commonly used in the process of equipment manufacturing T-type pipe ring joint Welding path. This paper puts forward a kind of based on finite element Simufact. Weldingand Matlab simulation platform,the introduction of the constraint factors and improved pheromone update rule,to improve the traditional ant colony algorithm,in order to improve the update efficiency of pheromone of ant colony algorithm,and enhance the path of the algorithm in the continuous space search ability. The method to establish the T-type pipe ring joint welding simulation,and analyzes its corresponding welding path respectively,the results show that compared with the traditional ant colony algorithm,based on improved ant colony algorithm of welding path not only saves time resources,and reduce the waste of wire material. Parameters and condition,the welding efficiency increased by 7. 79%,compared to the 3-D welding path Movement distance,fell by6. 31%,and to improve the reliability of 2. 92%. As a result,the method for optimization of T-type pipe ring joint welding path is effective and feasible.关键词：T-type pipe ring joint;3-DWelding path;Finite element;MATLAB;Intelligent algorithm
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发布时间：2022-09-22 - 摘要：3-D finite element models of SOP（ Small Outline Package） were constructed,in which Anand visco-plasticity constitutive equation was used to describe the mechanic behavior of solder joint. The solder joint deformation and stress distribution with five kinds of lead shapes were researched. The experimental program for the identification of numerical simulation was performed with three kinds of lead shapes. Both experimental and simulation results showed that the solder joint life is closely related with lead shape. The lead shape with low stiffness can decrease the stress apparently. With decreasing the bending radius or increasing the standoff height,the component reliability will be enhanced. The numerical simulation result was congruous with experimental testing data,can able to reflect the factual behavior of SOP accurately.关键词：Lead shape;Finite element method;Small outline package（SOP）;Reliability
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发布时间：2022-09-22 - 摘要：How to select the appropriate target spectrum for iterative test is a key point to vehicle indoor road simulation testing,The conventional selecting method is to select the median fatigue damage spectrum as the target spectrum. Therefore,the method of selecting the minimum standard deviation spectrum as the target spectrum is introduced in this paper based on the load spectrum measured in proving ground. To verify the validness of this methodology,analyses and comparison between the two methods are conducted from numerical statistical analysis,rain-flow cycle damage distribution,shock response spectrum and fatigue damage spectrum. The results indicate that the minimum standard deviation spectrum is better than the median fatigue damage spectrum. Finally,the result of vehicle indoor road simulation test shows the methodology is right.关键词：Road simulation;Interaction;Load spectrum;Damage;Standard deviation
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发布时间：2022-09-22 - 摘要：In response to the need for management system of the pressure vessel of gathering and transportation in the offshore oil platform,the pressure vessel with oblique nozzles was researched by using Ansys and the local notch stress and strain approach.The computational methods for predicting the lifetime crack initiation and reliability was given. The lifetime crack initiation and reliability results of 60 degree-oblique nozzle was obtained in order to accomplish an example. The region of crack initiation was researched. The various dimensionless structural parameters affecting the lifetime crack initiation, which are the angle of inclination,the ratios of nozzle diameter / shell diameter,the ratios of shell thickness / nozzle thickness,the ratios of shell diameter /shell thickness,was studied. These research show that the local notch stress and strain approach which needs strain data of material and structural fatigue notch factor and structural stress-strain loading history can apply to predict the lifetime crack initiation and reliability of the real weld effect and the combined effect of multiple load to oblique nozzle. In the simple FEM models the region of crack initiation occurs at the crotch corner in the meridional direction of the cylindrical shell. The result narrow the search scope to cracks in real situation. The lifetime crack initiation is decreased with the smaller angle of inclination,the larger ratios of nozzle diameter / shell diameter,the larger ratios of shell thickness / nozzle thickness,the larger ratios of shell diameter / shell thickness.The results of the lifetime crack initiation is remarkably decreased when the angle of inclination is 30 degree. Considering the local notch stress and strain approach with inherent dispersion,the proposed approach which predicts the lifetime crack initiation with certain reliability is a simple and effective method. The research results can provide some referential value in order to formulate and optimize maintenance strategy of the pressure vessel of gathering and transportation in the offshore oil platform.关键词：Maintenance strategy;Design by analysis;Crack initiation;Reliability;Structural parameter study;Stress concentration;Finite element method
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发布时间：2022-09-22 - 摘要：Material damage state can be depicted by a restraining stress zone. A trans-scale fatigue crack model with coupling the macro / micro effects is developed. The proposed model can describe the whole process of fatigue failure from a microflaw（ fatigue source） to the final fracture. The distribution of restraining stresses depends on the material damage state in the restraining stress zone. A linear distribution of restraining stresses is assumed. Under the remotely applied uniform tension,the trans-scale crack model is analytically solved using Muskhelishivili approach. Analytical expressions of crack opening displacement and trans-scale strain energy density factor are obtained. The trans-scale strain energy density factor serves as the controlling parameter of fatigue crack growth from micro-scale to macro-scale. Numerical simulations for the whole process of fatigue failure are completed. By application of the present model,the experimental S-N curves of LC4 aluminum alloy plates under the different loading conditions are accurately re-produced. The scatter of fatigue test data owing to the microscopic effects is also reflected by the present model. Moreover,the influences of microscopic effects on the fatigue crack growth are also discussed.关键词：S-N Curve;Fatigue crack growth;Trans-scale crack model;Restraining stress zone;Strain energy density factor;Microscopic effect
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发布时间：2022-09-22 - 摘要：The article summed up the extraction method of load spectrum cycles based on flight parameters of aeroengine and summed up the removal methods of small cycles which speed amplitude were lower than 10%,then pointed the advantages and disadvantages of each method. Analyzed the speed cycles distribution of a certain type of aeroengine,calculated the influence of small speed cycles which amplitude is lower than 10% of high pressure rotor speed by Miner’s linear cumulative damage theory,compared the influence of different removal methods to damage calculation results and pointed the advantages and disadvantages of each method; Based on EGD-3 standards,put forward the extraction method of removing small cycles and verify its rationality by calculation,then define the sensitivity factor of removing small speed cycles in fatigue calculation as 0. 3% for a certain type of aeroengine.关键词：Aeroengine;Flight parameters;Load spectrum;Small cycles;Fatigue life
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- 186
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发布时间：2022-09-22 - 摘要：As the static implicit Finite Element Method（ FEM） is hard to simulate the wheels radial fatigue test accurately,this paper studies the simulated method with dynamic explicit FEM. It introduces the setting method of finite element,material performance parameter,tire,bolt pretention,weld,rotary drum,radial force,etc. It shown the distribution of stress and surface pressure of wheels,put forward a method to judge analysis result reasonable or not,and introduces the selection method of S-N curve for fatigue analysis. By comparing the FEA and test result,it knows that the dynamic explicit FEM setting method in this paper can get an idea analysis result.关键词：Radial fatigue test;Dynamic explicit method;Bolt pretension;Wheels surface pressure;Weld S-N curve
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- 115
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发布时间：2022-09-22 - 摘要：To determine whether stochastic subspace identification（ SSI） based on the output-only measurements can identify the doublet modes of cyclic symmetric structures accurately,taking a brake disc as an example,modal analysis based on SSI and traditional experiment modal analysis（ EMA） for the brake disc were performed and the corresponding moda Sl parameters were extracted. The results show the maximum error of natural frequency is only 0. 66% and the mode shapes coincide. The SSI based on the output-only measurements can also be applied to the cyclic symmetric structures to identify the modal parameters.关键词：Modal analysis;Stochastic subspace identification;Doublet modes;Cyclic symmetric structures
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- 231
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发布时间：2022-09-22 - 摘要：The connecting rod of high explosion pressure diesel engine was easily fatigue and fracture; the working dynamic load of connecting rod was obtained based on the multibody dynamics. And on this basis,the fatigue life danger zone was founded based on the dynamic stress recovery method,and fracture simulation was analyzed for the region. The results show that the operating cycles reduced from millions to ten thousand times after fatigue cracks taking place,so once the crack was founded,it was the best time to replace the connecting rod to avoid catastrophic accidents.关键词：Diesel engine;Connecting rod;Fatigue analysis;Fracture analysis
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- 235
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发布时间：2022-09-22 - 摘要：Based on Finite Element Analysis method,applying the ANSYS analysis software platform to deal with elastic stress and fatigue analysis of tooth-quick opening structure. The overall stress distribution is retained. Using the contact element method to simulate the contact behavior between the teeth,under the condition of meet the requirements of strength and fatigue resistance,Establishing the overall minimum weight of the tooth-locked quick-opening structure as objective function,Through the finite element analysis optimization design method,the general weight of quick-opening structure was reduced by 26. 97%after optimization analysis.关键词：Tooth-locked quick-opening structure;Elastic stress analysis;Fatigue analysis;Optimization design;Finite element method
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- 207
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发布时间：2022-09-22 - 摘要：A finite element analysis basing on transfer matrix method of multibody system for the parachute packing machine was finished in this article. After the research of multi-point cloud with the stress and displacement of the whole structure,considering the stress and deformation of the organization,the parachute packing machine has been optimized. It also has been verified by test that: the optimization has improved the working strength of the parachute packing machine,and the requirements of long time working at full capacity can be reached.关键词：Pneumatic parachute-packing machine;Ansys workbench;Finite element analysis;Body optimum design
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- 184
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发布时间：2022-09-22 - 摘要：To solve the problem of transition of the tower crane with high center of gravity,through sex difference,fixed transportation for the tower body and its attached parts being put down may be regarded as a fast and efficient method. Four-bar linkage was adopted to put down the towerbody,its working principle is introduced,then the force analysis of its components is carried,finally,its simulation and optimization is carried out through using MATLAB. The feasibility and practicability of the method are verified by numerical examples and engineering practice.关键词：Tower crane;Four-bar linkage;Force analysis;MATLAB;The optimization design
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- 79
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发布时间：2022-09-22 - 摘要：V-bar is the major fracture location of piano strings. It’s important to analysis the fracture mechanism of the string in the V-bar for the design and adjustment of the piano string. In this paper,a systematic analysis was performed for the decoration form,loaded modes and vibration of the strings. Three fractures of piano strings under the same key number,figure number and known service life was selected as the objects. A comparative analysis was performed to observe the fracture morphology with the Scanning Electron Microscopes（ SEM）. It is shown that surface abrasion arises because of the wear between the string and V-bar,which causes the stress concentration in this area. The repeated bending loads during playing lead to fatigue initiation and propagation over the string cross section. The final fracture occurred when the stresses exceed the breaking strength of the string. The fibrous fracture was observed under the SEM.关键词：Piano strings;V-bar;Wear;Fatigue;Fracture
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发布时间：2022-09-22 - 摘要：In an optical equipment carriage parts as an example,analyzed the problem of the sliding frame bearing and the sliding rod relative motion slide bar existed serious wear。Based on the failure analysis of the existing sliding structure of sliding structure,many optimization analysis is made,the optimal design scheme of sliding structure is obtained,and the design of the sliding structure is new。Practice to verify the actual service life of the new structure,the results show that the new structure can effectively reduce the sliding wear of the sliding rod。关键词：Sliding frame;Stroke bearing;Wear and tear;Optimization design
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发布时间：2022-09-22 - 摘要：According to the critical state selection issue of horizontal dynamic impact test in the pilot’s seat / restraint system for a certain type of general aviation aircraft. The critical state is selected through simulation analysis and test in the seat’s dynamic impact test,while the critical state is also validated by both simulation and test to ensure it can meet the safety requirements of airworthiness. The simulation analysis shows a consistency compared with the test on horizontal dynamic impact test,and this laid a foundation for future research works.关键词：Seat / Restraint system;Horizontal dynamic impact tests;Simulation;Verify
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发布时间：2022-09-22
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