最新刊期
期 2 ， 2018
- 摘要：In this paper,simulation and experimental studies of typical wear fault of the reciprocating machinery connecting rod big end bearing,explore the influence of the wear and tear on the lubrication parameters of the connecting rod big end bearing. Based on the Reynolds equation,by simulating different bearing wear situations: different widths,different depths and different positions, a comprehensive analysis of the associations between the degrees of wear of bearing and lubrication parameters,in particular the bearing temperatures. By installing the temperature sensor in the test unit connecting rod bearings,connecting rod temperature is on-line monitored,and the variation rules of temperature of the bearing under the state of wear are experimental confirmed.关键词：Reciprocating machinery;Connecting rod;Bearing;Wear;Online monitoring
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发布时间：2022-09-22 - 摘要：One of the most important characteristics of rolling bearing fault is that the fault components will induce the shock response of vibration. Aiming at the modulation characteristics of roller bearing fault vibration signals and the complex of traditional analysis method,the paper puts forward a rolling bearing fault feature extraction method based on extreme point probability density and auditory model. The method firstly conduct band-pass filtering with Gammatone filters,phase adjustment and extreme points extraction for signals,and then calculate the amplitude probabilitydensity of extreme points,Judging whether there is a transient impact composition by its derivation in filtered signals,then extractrelated extreme points to get the transient componentsat last. Considering the modulation characteristic of the vibration signal. The amplitude of impact is different over time. Sectional processing of the signal can extract the impact component that may be ignored because the amplitude is small.The method is applied to analysis the vibration signal of a certain type of wire cutting machine ’s rolling bearing. The experimental results show that this method can effectively extract the transient components from the rolling bearing fault signal.关键词：Ball bearings;Probability density;Auditory model;Feature extraction;Transient signal
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发布时间：2022-09-22 - 摘要：Variation of connecting rod ratio in reciprocating crankshaft system can affect the value of system equivalent moment of inertia. However,current traditional variable inertia formula does not consider this important factor,which induces certain errors during torsional vibration analysis. This paper aims to investigate the effects of connecting rod ratio on equivalent moment of inertia and torsional vibration. First,a modified variable inertia formula concerning connecting rod ratio is deduced and its accuracy is compared with traditional one. Then,torsional dynamic equation is established and the method of multiple scales is used to derive the average equation under primary resonance condition. The effects of connecting rod ratio on stable dynamics of the system are investigated. Moreover,traditional and modified variable inertia formulas are compared with exact variable inertia through a detailed single-cylinder crankshaft system. And the shortage of traditional one is pointed out. Finally,numerical results on system vibration characteristic based on different variable inertia formulas are shown to verify the importance of connecting rod ratio on system performances.关键词：Crankshaft;Connecting rod ratio;Variable inertia formula;Parametric excitation
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发布时间：2022-09-22 - 摘要：In order to study the traction speed of shearer drum load effect,the establishment of cutting part and the traction part are mutually coupled system dynamics model,and consider the cut cutting impedance is a random quantity,obey the law of normal distribution,using numerical simulation method to solve the problem and the results using statistical methods to calculate the shearer drum to force the average value and the standard difference; the results of the study show that,the drum to the mean and variance of the force with the initial traction speed of increased progressively. Finally,the accuracy of the model is verified by comparing the simulation results with the experimental measurements.关键词：Shearer;Drum’s three-axis force;Coupling dynamics;MATLAB
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发布时间：2022-09-22 - 摘要：Aiming at the problem that early fault characteristic signal of bearing in gear box is weak and affected by the environmental noise seriously,which makes the fault feature information is difficult to identify,a early fault diagnosis method of gear box is proposed based on dual-tree complex wavelet transform and minimum entropy deconvolution. Firstly,the dual-tree complex wavelet transform method was used to decompose the collected vibration signals into several components with different frequency bands.. However,due to the interference of noise,it was difficult to make a correct judgment from the spectrum of the components. Then,the component that contains fault feature was processed by using minimum entropy deconvolution to reduce the strong background noise and enhance the fault information. Finally,the Hilbert envelope spectrum analysis was performed to identify the frequency of the bearing fault. The effectiveness and superiority of the proposed method are verified by Simulation experiment of bearing fault in gear box and engineering application.关键词：Gear box;Dual tree complex wavelet transform;Minimum entropy deconvolution;Hilbert envelope spectrum;Bearing;Fault diagnosis
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发布时间：2022-09-22 - 摘要：Aiming at the fact that the fault diagnosis performance of support vector machine（ SVM） highly depends on the parameters selection,a fault diagnosis method based on improved artificial bee colony（ IABC） optimize SVM was proposed. In order to improve search ability of ABC,Levy flight strategy was introduced and improved the original ABC algorithm. Use the IABC to optimize SVM parameters can effectively improve the classification performance of SVM. Different fault type and different fault degree of rolling bearing fault diagnosis experiment results show that the IABC can obtain better parameters when compared with ABC,GA and PSO,improved the fault diagnosis accuracy of SVM and can applied to fault diagnosis efficiently关键词：Artificial bee colony;Levy flight;Support vector machine;Parameters optimization;Fault diagnosis
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发布时间：2022-09-22 - 摘要：Since the fouling accumulation in the heat exchanger equipment has produced great effect for safe and economical operation,it is particularly important to detect the fouling produced in heat exchanger equipment accurately and rapidly. Ansys finite element simulation software was used to establish the model of hollow and fouling pipelines. Research on the vibration characteristics of ultrasonic guided waves propagate in pipes and the influence of different sources for fouling detection. The optimum excitation frequency and period was obtained for fouling ultrasonic detection in pipes. After compared with the experimental studies,the results indicate that L（ 0,3） mode guided waves motivated by excitation signal with the 1 MHz central frequency and the 10 period signal is adapted to the fouling detection for 304 steel of outside diameter 25 mm and wall thickness 3 mm. The experiment results are in agreement with the numerical results. The guided wave mode and the optimal excitation frequency can be directly applied to the actual detection. The research results lay the foundation for the measurement realization of the fouling thickness in pipes.关键词：Ultrasonic guided waves;Finite element analysis;Detection of fouling in pipes
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发布时间：2022-09-22 - 摘要：To reduce the airborne vibration influence of airborne optoelectronic pod on quality,a small optical pod antivibration isolation system was designed according to multi-degree-of-freedom system vibration theory,vibration isolation theory and current vibration environment. This vibration isolation system can configure optical pod isolation system natural frequency effectively. The natural frequency of the isolation system was determined through multi-degree-of-freedom system vibration theory,instruct the design of spatial layout and relative positions,damping values and stiffness of isolators,and support structure. The simulation analysis of optical pod isolation system was conducted by using ADAMS/Vibration code module,the optical pod isolation system was tested on a vibration table,the experiment results of natural frequency were consistent with theoretical and simulation results,the error is less than 10%,and the isolation system has good vibration isolation performance near 92 Hz. The field test image effects also prove the damping effectiveness of small optical pod anti-vibration isolation system.关键词：Vibration isolation;Optical pod;Multi-degree-of-freedom system
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发布时间：2022-09-22 - 摘要：In order to analyze the feasibility of using magnetic memory testing technology to pipeline online inspection,it’s necessary to consider the effect of pressure on the pipeline defects magnetic memory signals. Based on the J-A force-magnetic coupling model a relationship between the relative permeability and stress was concluded. The relationship was imported in ANSYS software to carry out the co-simulation between mechanical and static magnetic. The results show that magnetic memory signals of defects have two characteristics—— radial magnetic field in the pipeline mutating from minimum to maximum and axial magnetic field appearing maximum. The magnetic field inside the pipeline decreases and defect’s magnetic memory signals decreases and then remains constant when the pressure increases. Magnetic memory testing technology can be used in pipeline online inspection.关键词：Pressure;Pipeline;Defect;Magnetic memory signal;Force-magnetic coupling;ANSYS
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发布时间：2022-09-22 - 摘要：The author prepared specimen of glass fiber-hollow glass microsphere/epoxy syntactic foam material. We have obtained the load-displacement curves by three point bending test,studied the influence of glass fiber content on the bending strength and bending elastic modulus. Through soaking test,we measured the curves of moisture rate of the specimen in H2SO4 and Na OH solution over time. Through the scanning electron microscopy images,we analyzed the effect of acid-base corrosion on the bending properties. The research results showed that when the glass fiber quality ratio is 10%,the bending strength of the composite reached the maximum value,rising by 27% than the specimen without glass fiber. When added more fiber,its strength is gradually reduced. Acid-base soaking corrosion greatly reduces the bending strength of syntactic foam material. The direct reason is that acid-base solution will corrode the interface of glass fiber and epoxy matrix. It also will corrode epoxy matrix.关键词：Glass fiber;Epoxy syntactic foam;Flexural properties;Acid-base corrosion
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发布时间：2022-09-22 - 摘要：The study on deformation and failure mechanism of materials,and the progressof NEMS/MEMStechnology and biotechnologypromote the development of multi-scale analysis method. However,Multi-scale connectionisthe key of multi-scale model. The finite element method（ FEM） and molecular dynamics simulation（ MD） were combined to simulate the multi-scale models,and the stress intensity factors（ SIF） and displacement mechanics parameters were adopted to connect and convertthecontinuum region and discrete molecular dynamics region,then three multi-scale model of two-dimensional silver crack propagationwasestablished to obtain the crack tip trajectory and the micro-scale crackpropagationprocess. The result is in good agreement with theory and experiment,and proves the rationality of the method.关键词：Silverplate;Crack propagation;Displacement coupling;Multi-scale numerical simulation
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发布时间：2022-09-22 - 摘要：Combining the four-prong legged acceleration system dynamic response,stability and sensitivity of support stiffness,a trapezoidal beam with variable cross section was designed and optimized. The dynamic model of the accelerometer was established and a relationship was found between the system dynamic response parameters and the beam rigidity. The trapezoidal variable cross-section beam rigidity-size relation was deduced with a bending mathematical model. The size requirements were raised by strength. By analyzing the system stability and sensitivity of the accelerometer,the beam rigidity was obtained.Compared with uniform cross-section under the equal rigidity in the no-detection direction,the trapezoidal variable section beam reduces the stiffness in detection direction with the equal stress on the critical section,improves the system sensitivity and dynamic output characteristics. However,quality greatly reduces.关键词：Trapezoidal cross-section beam;Four-prong legged accelerometer;Rigidity;Stability;Sensitivity
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发布时间：2022-09-22 - 摘要：In the process of designing lightweight of the steering knuckle,because of too many random variables and various factors,it is easy to result in poor optimization results. We consider the effect of the random parameter variable on stress and total volume and put forward the concept of comprehensive sensitivity. Through the dynamic simulation we get the steering knuckle bearing under three typical working conditions. By the finite element analysis,we obtain extreme load condition data and the initial static and reliability indicators. We use comprehensive sensitivity analysis theory to get the final design variables. Finally,we complete the lightweight design by establishing mathematical model. The results show that the lightweight design method based on comprehensive sensitivity can reduce steering knuckle weight and maintain good static and fatigue reliability effectively and can be applied in the engineering field.关键词：Steering knuckle;Comprehensive sensitivity analysis;Lightweight;Fatigue reliability
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发布时间：2022-09-22 - 摘要：In order to improve the life of the cone bit sliding bearing,eliminates the edge stress concentration phenomenon of the spherical floating sleeve end portion,the circular groove structure of Spherical floating sleeve was optimized by the combination of response surface methodology and the finite element method. the objective function was established by along the contact line of the middle stress σmand end stress σedifference between the floating sleeve of outer spherical surface and inner surface,σ1、σ2 was called objective function,The distance from the center of the circular groove to the floating sleeve surface h and the radius r of the circular groove and the distance from the center of the circular groove to the end face of the floating sleeve t was design variable,so the optimization of mathematical model was established. By regression analysis model,obtained the circular groove of optimal controllably parameters: r = 0. 53 mm、t = 0. 07 mm、h = 1. 10 mm. The finite element simulation analysis verified the reliability of optimal structure parameters,The results show that the optimized spherical floating sleeve of the inner surface and outer spherical surface of contact stress distributes more uniformity and reduces the edge stress concentration.关键词：Spherical floating sleeve;Response surface methodology;Contact stress;Finite element simulation
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发布时间：2022-09-22 -
DESIGN OF PARAMETERS OPTIMIZATION FOR AUTOMOBILE SUSPENSION BASED ON ARTIFICIAL BEE COLONY ALGORITHM
摘要：In view of defect of selecting parameters for automotive suspension system,optimizing method of determining the parameters based on local elitist strategy（ LES） and artificial bee colony algorithm（ ABC） was proposed through integrating great local seeking ability of LES and great global seeking ability of ABC algorithm.Through Matlab/Simulink software,The simulation of suspension system were carried out; in which integral white noise model were the road input. The simulation discovered that LES-ABC algorithm optimization algorithm has certain advantage compared with traditional algorithms and artificial bee colony algorithm. Riding comfort and handling performance could be enhanced through optimizing system parameters of automotive suspension.关键词：Parameters for automotive suspension system;Local elitist strategy（LES）;Artificial bee colony algorithm（ABC）;Optimizing method- 4
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发布时间：2022-09-22 - 摘要：The present torsional stiffness calculation and evaluation method only reflect the body stiffness and the torsion curves of the cross beam or threshold,it can hardly be used to evaluate the stiffness matching characteristics and the contribution of local region in body comprehensively. Aiming at this problem,a stiffness evaluation method based on regional contribution was proposed,with the strain energy and strain energy density as analyzed object. Meanwhile,a visualization method was proposed to visualize the regional contribution values. The methods above were applied to a domestic commercial vehicle. The contribution visualization model of body framework was established and the body stiffness matching characteristics were analyzed. The torsional stiffness matching was more reasonable after structure optimization. It indicates that the contribution visualization model can be used to evaluate stiffness matching characteristics of body and the contribution of each region intuitively,which gives guidance to structure stiffness matching design.关键词：Torsional stiffness;Regional contribution;Visualization;Stiffness matching
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发布时间：2022-09-22 - 摘要：In order to improve a machine moving beam’s comprehensive performances,which includes static and dynamic characteristics,it must have a reasonable beam ribs layout and structural properties. The crossbeam was simplified to get the mechanical vibration model,the maximum coupling deformation was solved by the theoretical calculation method. Using 3D software to establish the three-dimensional modeling of beam and ANSYS was used for static,modal analysis. Taking beam’s quality and the maximum coupling deformation,the maximum coupling stress,the first-order frequency as objective functions to judge the merits and drawbacks of crossbeam’s optimization,taking the crossbeam’s rib structure,the rib thickness,the angle of support stiffened plate as design variables for multi-objective optimization design. Orthogonal experimental method was used to design the orthogonal experiment with three levels and four factors. Using overall balance method to chose the optimal level,and then getting the best test program. The results show that: Theoretical analysis and simulation results are very similar. the beam with "井"type rib structure,rib thickness of 25 mm,the support stiffened plate tilted 55 ° design is the optimal solution.Compared with the original design,the beam deformation reduced by 7. 455% and the first-order frequency increased by 2. 956%,while the quality reduced by 473 kg. It shows that using the orthogonal experimental method to design reasonable levels and factors can achieve optimum results with fewer tests,and the orthogonal experimental method is valuable for engineering application.关键词：The moving crossbeam of machine tool;Optimization design;Orthogonal experimental method;Finite element analysis;Multi-targets
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发布时间：2022-09-22 - 摘要：Based on the finite element thought and optimization design method,the research of lightweight on the 12 meter bus body frame of a manufacturer had been made. By establishing finite element model of the body frame,horizontal bending and torsion limit of it had been simulated. Through free modal of bus body frame simulated,static and dynamic characteristics of frame had been analyzed. Taking first order bending,torsion frequency of the frame,bending and torsional flexibility as constraint conditions and the minimum volume as the objective function,to analysis topology optimization of it. That based on the results of topology optimization,selecting 371 groups of bars as design variables to have sensitivity analysis for the frame. According to the result of topology optimization and sensitivity analysis,combining the regulation of company for finalize the design product,lightweight of body frame has been put forward,which made skeleton quality reduced by 240 kg. Compared with original frame,vibration characteristics of the new one have been maintained,and strength improved significantly. Achieving lightweight goal of the bus body frame.关键词：Bus;Compliance;Topology optimization;Sensitivity analysis;Lightweight
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发布时间：2022-09-22 - 摘要：The planetary gear strength checking software has been developed by combined programming of MATLAB and EXCEL. Take the contact normal force from mining machinery dynamics simulation as the input of the software with other necessary gear’s design and material parameters,the software can achieve gear tooth surface contact stress and root bending stress checking. The shortages of unable to determine the gear force in traditional analysis,unable to solve bending stress and solve contact stress for a long time by using the finite element software have been solved. Taking the EBZ220 roadheader as engineering object,though the checking result,the roadhead cutting unit’s second stage planetary gear’s root bending stress does not meet the strength requirement,that means this roadhead Not suitable for cutting rock,whose f value greater than 8 at the speed 1. 38 m/min. this research provides a new concept and method for gear strength checking,which has theoretical significance and strong engineering application value.关键词：Planetary gear;Strength checking;Roadhead;Contact stress;Bending stress
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发布时间：2022-09-22 - 摘要：The FEM has been widely adopted to solve electromagnetic field problems. The accuracy of FEM is highly effected by the number of system units and the complexity of computational order,leading to low computational efficiency. In order to improve the computational efficiency of FEM,gradient smooth is introduced into numerical calculation of electromagnetic field,then a new method of ES-FEM is proposed. The electromagnetic field of infinite straight grounding slot and Electric Vehicle are simulated with MATLAB. The results shows that smooth gradient operation makes the discrete system closer to the continuous system,increasing the accuracy and the efficiency of FEM.关键词：Edge-based smoothed finite element method（ES-FEM）;Gradient smooth;Electric vehicle electromagnetic field;Numerical calculation
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发布时间：2022-09-22 - 摘要：In order to study the mechanical behavior and energy absorption characteristics of a metal circular tube with axial pre-compression under axial impact load. The finite element analysis was carried out based on Abaqus. A circular tube whoseR/t value is 15 was studied. At the same time,considering the influence of the initial geometric imperfections,the initial geometric deformation caused by pre-loading and boundary conditions,the corresponding control group was established in the finite element simulation. The simulation results are concluded as follows:（ 1） The deformation mode of the fixed end simply supported is more complex than the clamped case. Energy absorption characteristics and the corresponding deformation modes have a great relationship. When the asymmetric fold is more,the energy absorption characteristic becomes worse.（ 2） Initial geometric imperfections can induce circular tubes to produce non-axisymmetric folds,while the axial pre-compression tube is less sensitive to initial geometric imperfections,and the smaller pre-loading can counteract the effects of initial geometric imperfections.关键词：Metal circular tube with axial pre-compression;Axial impact;Energy absorption;ABAQUS
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发布时间：2022-09-22 - 摘要：Bolt interface’s characteristics that existed in aerostatic bearing were affected by many factors,such as part’s material of interface,surface topography,geometric accuracy of interface,interface connect forms and so on. The most important factor was bolt preload force. The characteristics of bolt interface were identified by finite element method（ FEM） and experimental modal analysis method. The influence of bolt preload force on bolt interface’s characteristics was analyzed. Two lows were concluded. Firstly,eigen frequency of interface increased with the increase of bolt preload force. Secondly,bolt interface could be counted as bonded interface in finite element emulation analysis,when the bolt preload force increased to a certain value.关键词：Aerostatic bearing;Bolt interface;Bolt preload force;Finite element emulation method;Experimental modal analysis method
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发布时间：2022-09-22 - 摘要：In order to solve the problem that the submarine has large cross dip and longitudinal obliquity,a double ball shell rotary docking joint skirt is designed. According to the working principle of the docking device,the posture equation and kinematics model of the butt skirt are derived,and according to its kinematic model to obtain the accident submarine at different angles that the direction skirt and angle skirt angle of rotation required. The sealing structure and sealing principle of key revolute joint was studied,the Yeoh model was used as the super-elastic constitutive relation curve of the O-ring to fit the corresponding material parameters. The finite element simulation of the sealing structure was carried out,the location of the dangerous section is obtained,and the reasonableness of the seal structure is verified by the analysis of the contact stress of the dangerous section. The docking skirt can be used to complete the docking task of the accident submarine with large inclination,strong current and low visibility. Greatly improving the rescue success rate,reducing the difficulty of rescue.关键词：Docking skirt;Kinematics;Finite element analysis
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发布时间：2022-09-22 - 摘要：Based on the ANSYS finite element software,the method of dividing the contact area of the four point contact ball bearing is proposed. Establish a uniform thin four point contact ball bearing 1/2 single rolling and ring and the bearing finite element model. Calculation and analysis of the grid cell size on contact characteristics of four point contact ball bearing accuracy influence and solve the bearing finite element model in the static radial force load distribution rules and obtained the thin-walled four point contact ball bearing,the more precise the elliptic contact area shape and four point connected contact state. Research shows that: for the calculation of the contact characteristics and the size of mesh generation approximate to 50 percent of the semi minor axis of the contact ellipse can get more precise results,for thin walled four point contact ball bearings,ball and the inner and outer rolling contact should force,the equivalent force and contact deformation and radial load is nonlinear ascending relationship,contact force and load distribution of the calculated results with the Hertz contact theory should be calculated values are in good agreement. The calculation results are more accurate to simulate the contact characteristics and load distribution of the thin wall four point contact ball bearing.关键词：Thin-walled four-point contact ball bearing;Hertz contact;Mesh refinement;Load distribution
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发布时间：2022-09-22 - 摘要：Forming limit is an important performance index and process parameter in sheet metal processing. In this paper,A method for the thermal incremental forming of liquid while supporting and heating was proposed. An inverted cone was studied as a research object. The influence of process parameters such as the temperature,the distance between the layer and the diameter of the tool head on the thermal incremental forming was studied by means of orthogonal test,and the theoretical analysis is carried out. The results show that the forming limit angle increases obviously with the increase of the forming temperature,and the smaller the distance between the layers increases with the increase of the layer spacing. The limit angle of the tool head diameter is not significant.关键词：Magnesium alloy;Incremental forming;Orthogonal experiment;Forming limit
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发布时间：2022-09-22 - 摘要：Considering the morphology of the weld toe,two kinds of FEA models for cruciform joints with arc-shaped weld toe and line-shaped weld toe were established respectively,and their local stress states were analyzed. Regarding the effective notch stress as the governing parameter,the fatigue life of the cruciform joints under cyclic tension load was estimated.Corresponding fatigue test was conduct to validate the estimating results. Research result shows that the morphology of weld toe plays important role on the fatigue performances of welded joints,and arc shape can describe the morphology of weld toe properly. Under cyclic tension load,cracks usually initiate at the weld toe,in detail,at the convex vertex of the weld arc which is near the end of the weld line. Effective notch stress method considering the morphology of weld toes can be utilized for the fatigue assessment of welded structures with satisfying accuracy.关键词：Cruciform joints;Weld toe morphology;Effective notch stress;Fatigue life
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发布时间：2022-09-22 - 摘要：A numerical simulation of transient temperature and stress field for a typical coke drum has been done in this paper by Abaqus secondary development. According to the result of simulation,a comparative analysis was done to explain the mechanism of circumferential and axial thermal stress. Under the considering of nested effect between coke and shell,the element node with a maximum Mises value was fond under a condition of proportional loading by the method of combined stress analysis.Based on the principle of the linear accumulation of fatigue damage,in order to calculate the theory life of the fillet weld connecting the skirt and conical head,the combined stress wave of the node before was divided into several whole cycles with Rain-Flow method. After that,when not considering of the nested effect,it is found that the circumferential stress would have a nearly 50 percent lower than the value calculated with nested effect considering. At last, a theoretical calculation of circumferential stress was carried on. It shows that the result given by FEA agrees reasonably well with the theoretical calculation value. Obviously,the result given by FEA was credible.关键词：Coke drum;Stress analysis;Fatigue cumulative damage;Nested effect;Rain-Flow method
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发布时间：2022-09-22 - 摘要：With the aid of ANSYS software,the overall model of the cryogenic storage tank was worked out for nonlinear analysis of the structure during vacuumizing with outside heating. It is found that the temperature difference between the inner vessel and out shell during outside heating will induce plastic deformations at the strips,which would damage the connect strength of the strips in transporting. An improved method was suggested to reduce the plastic deformation of the strips by heating the cryogenic storage tank inside and outside at the same time. And the proposed method was verified by finite element numerical simulation.关键词：Cryogenic storage tank;Vacuumize;Plastic strain;Strength analysis
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发布时间：2022-09-22 - 摘要：In order to discuss the rationality of fatigue analysis models of bogie welded frame,this paper regards box girder as the research object and establishes nominal stress model,structure stress model and notch stress model by aiming at different processing methods of main weld. Through stress characteristics,fatigue assessment,cumulative damage,and weld parameter influence of three models are compared. The results show that stress size and orientation under nominal stress model and structure stress model have higher similarity,it is reasonable to ignore the weld for nominal stress model on condition that stress value must locate in the weld toe front,where sets the strain gauges. Characteristics of notch stress model lie in describing local stress state and cycling performance of weld really,and its advantages are also reflected in conducting fatigue assessment on both weld toe and weld root simultaneously,for the reason that fatigue failure of box girder may occur in weld root,as shown in the computed results. Because structure stress model is not sensitive to changes of weld parameters,optimization of weld parameters only chooses notch stress model.关键词：Modeling methods;Welded frame;Box girder;Fatigue life;Weld parameters
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发布时间：2022-09-22 - 摘要：In order to solve the problem of safety assessment effectively for subsea oil and gas pipeline,the rules about pipeline residual strength changing with the defect geometric information such as length,width and depth were analyzed using finite element method（ FEM）,and on this basis the parameterized model of pipeline residual strength was obtained,and the unknown coefficients in the model were identified using improved genetic algorithm,thus the model can describe the quantitative relation between the residual strength and defect geometrical quantity. The experimental results show that the model is more reliable than the existing pipeline assessment criteria,it can be effectively used in residual strength analysis for subsea pipeline,the analysis results can provide theoretical basis for pipeline safety assessment.关键词：Subsea oil and gas pipeline;Geometrical quantity of defect;Residual strength;Parameterized model;Genetic algorithm
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发布时间：2022-09-22 - 摘要：To adjust the oscillation of renewable energy sources in the discontinuous generation of electricity,power plants will be used to stabilize the fluctuations. Power plants will start and stop frequently in the fluctuations,which exacerbated the fatigue creep damage of turbine rotor material,thus shorted the life of the power plants. In this paper,the progress in research onturbine rotor material have been introduced,and it is summarized that the damage evolution of rotor steel under low cyclic creep-fatigue loading and thermomechanical loading during start-up and shut-down process of ultra-super critical（ USC） steam turbine. In addition,several life assessment models used widely in engineering practice have been proposed. It provides a theoretical basis for optimizing the design,re-engineering and monitoring of the USC power plant components.关键词：9-10%Cr;Creep fatigue;Damage mechanism;Lifetimes models
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发布时间：2022-09-22 - 摘要：In order to study on the loading spectrum and fatigue life of hydraulic tension bars on shears,this paper solves the spatial mechanic problems of hydraulic tension bars by constructing spatial mechanical model and using partitioned matrix element segmentation method. Using experiment to test the operating load of hydraulic tension bars,this paper chooses the worst loaded one to simulate the fatigue life. The result indicates that the stress concentration part of hydraulic tension bar locates on the root of the first screw thread. The maximum stress point is close to the end point at the root of the first thread tooth,of which the number is 1386 MPa,the triple thread teeth bear over 50% of the full load; the position on which fatigue crack occurs first is at the root of the thread teeth in the screw part of the hydraulic tension bar; assuming that the daily continuously working time for shear is 12 hours,the hydraulic tension bar starts to crack at the 53 rdday. This research provides load data for hydraulic tension bar structural design,and also offers a new method of operating load monitor for shears.关键词：Shearer;Hydraulic tension bar;Loading spectrum;Stress contour;Fatigue life
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发布时间：2022-09-22 - 摘要：According to the damage tolerance design requirements to the engine life-limited parts,research on the fatigue crack growth tests of an engine power turbine（ high-strength GH4169） is carried out in this article. The crack growth behaviors of the turbine and the dispersion are obtained. Meanwhile,the three-dimension crack growth simulation is conducted and the results are compared with the test results. The result demonstrates that the crack propagation simulation result of the turbine has high accuracy,the analysis method has the value of engineering application.关键词：Turbine;Crack growth;Test;Simulation
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发布时间：2022-09-22 - 摘要：In order to study the fatigue life of the shearer’pick in the actual working conditions,the load was reconstructed by using the analytical continuation principle. The method of the conjugate gradient method was used to solve the reconstruction function. Using ANSYS Workbench transient dynamic analysis on the dynamics of the shearer drum, and will be the reconstruction of load loaded in the form of the time sequence to pick,the results file to import ncode of pick and pick-seat life prediction and simulation results show that: Life parts minimum zone appears in pick-seat and shearer drum blade welding,in drum pick in cutting coal and rock,pick-seat and a blade welding premises by the stress,and the existence of the phenomenon of stress concentration,welding to eliminate residual stress and grinding process.关键词：Regularization;Reconstruction;Shearer pick;Fatigue life
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发布时间：2022-09-22 - 摘要：In order to improve the crashworthiness performance of the thin-walled metal tube,it presents a nested square thin-walled tube structure. The nonlinear explicit finite element method is used to study the energy-absorption characteristics of the nested square thin-walled tube. The results show that: during the collision happening in the axial direction,the deformation mode of the nested square thin-walled tube is asymptotic telescoping deformation; the specific energy absorption of the nested square thin-walled tube is 25. 72 kJ/kg,which is about 1. 64 times and 1. 31 times higher than the ordinary square tube and symmetrical four cells tube; reducing the thickness of the embedded walls can achieve the lightweight design target and shortening the height of the embedded walls and ribs can effectively reduce the initial peak crushing force. The nested structure can effectively improve the crashworthiness of thin-walled tubes. The research results provide a reference for the further research and engineering applications of vehicle energy-absorbing element.关键词：Nested square thin-walled tube;Explicit finite element method;Crash worthiness;Axial impact
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- 253
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发布时间：2022-09-22 - 摘要：In this paper,the central groove scraper conveyor connecting system as the research object,the mechanics model of middle groove connection system different postures,and were to push the slide and Lycra two kinds of stress conditions in central groove connection system were analyzed. ANSYS software simulation analysis of its static strength and fatigue life,results showed that the central groove connection system weakest place in the passage of the ear and dumbbells fossa,fossa stress concentration dumbbell caused by this result and the actual work damage convex tip matches and proposed to increase the size of the dumbbell nest rounded to reduce stress concentration and reduce stress peaks to resolve this issue. The study was designed scraper conveyor system connecting central groove provides a reference and theoretical basis.关键词：Scraper conveyor;Middle groove connecting body;Static strength;Fatigue life
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- 132
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发布时间：2022-09-22 - 摘要：The sub-plate and insulation support ring were adopted in the design of pressure swing absorber,which resulted in severe stress concentration in the local structures. And the fatigue performance became worse. Finite element analysis was used to analyze this problem. The results show that the fatigue life is less than 16. 8 and 3. 07 percentage of the design life,which is far from the design requirements of pressure swing absorber. The previous structure design is not reasonable. Then,it is redesigned that the upper part of the ladder is fixed in the operating platform,the lower part of the ladder is fixed on the skirt or foundation,and the support ring is designed into suspender structure. The new structure can avoid the weldments between the accessories and the cylinder of pressure swing absorber. It can also prevent the fatigue crack initiation and meet the design requirements of pressure swing absorber.关键词：PSA;Fatigue;Sub-plate;Insulation support ring;FEA
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- 179
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发布时间：2022-09-22 - 摘要：The flow behavior and wall wear of a ball seat in frac sleeve with cone shapes have been studied numerically.The gas flow fields were simulated by means of standard k-εmodel. The effect of instantaneous turbulence on particle tracking was taken into account with the stochastic tracking approach in discrete phase model（ DPM） using Lagrangian method. The flow behavior during the cone part in ball seat was presented,and the changes of flow field and wall wear in ball seat caused by different cone shapes also can be predicted by CFD simulation. The results indicate that The distribution of the flow field in the large column section and the small column section of the ball seat is relatively uniform. Due to the wall effect of the sand,the flow field in the near wall has certain fluctuation. Optimized double cone structure can control the mainstream velocity gradient and sand concentration,and based on that this new design can reduce ball seat wear. Results obtained from the computer modeling have demonstrated the CFD is suitable for modeling an effect of wearing in ball seat on its performance.关键词：Frac ball seat;Cone geometry;Flow analysis;Wear;Numerical simulation
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发布时间：2022-09-22 - 摘要：With the research background of underwater non-contact explosion condition,base on the presenting Shockisolation theory and viscoelastic materials mechanical characteristics,the paper analysis the nonlinear problems of shock-isolation structures of viscoelastic composite materials,and the finite element model of shock-isolation structures based on the actual working conditions of physical prototype is built,the dynamical decay curves of shock-isolation structures in the condition of transient excitation is obtained with simulation,and proves the validity of the shock-isolation structures with experiments.关键词：Shock-isolation structures;Viscoelastic composite materials;Nonlinear finite element model;Transient response
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- 120
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发布时间：2022-09-22 - 摘要：In this study,CFD method is used to analyze the performance of an automobile tube type shutter radiator. The local iterative method based on the local model iterative calculation is used to calculate the heat transfer performance of the integral radiator. At the same time,the resistance characteristics of the radiator are simulated by using porous media instead of the dispersion zone. The results show that the simulated heat dissipation of the whole loose zone can be estimated by using the results of several local models. It is feasible to estimate the heat dissipating capacity of the radiator by averaging the total mass flow rate of the radiator as the mass flow rate at each flat tube inlet. The results of the local iteration method and the porous medium model simulation agree well with the experimental results,and provide a new idea for the performance analysis of the integral radiator.关键词：Radiator;Iterative calculation;Local iteration method;Porous media
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- 167
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发布时间：2022-09-22 - 摘要：In this paper,the Solid Composite finite element model is used to calculate the inter-laminar tension and shear stress of the composite curved beam under bending load,and then,the failure strength is predicted. The prediction can match the test results by comparison,show that the analysis of the composite inter-laminar failure is precise,and this method can be used in the aircraft design phase.关键词：Composite;Curved beam bending;Inter-laminar failure;Solid Composite
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发布时间：2022-09-22
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