最新刊期
期 5 ， 2017
- 摘要：According to the characteristics that crack can cause changes in mesh stiffness,the four degree of freedom dynamic model of the single-stage gear transmission system with the gear crack fault is established and the nonlinear dynamic mechanism of crack fault is studied. The Runge-Kutta numerical method was used to simulate and analysis crack fault. The characteristics of the crack signal are studied by using the time-frequency analysis method,which provides a theoretical support for the gear crack fault diagnosis. On this basis,the dynamic characteristics of gear crack under variable load excitation are analyzed. Analysis shows that,under variable load excitation,the vibration wave forms are very similar to the variable load excitation; Cracks caused by the impact phenomenon on the waveform and meshing frequency and its harmonics appear sideband.Sideband spectrum of the meshing frequency is the rotating frequency of the fault gear; Under variable load excitation,the frequency components of the low frequency is related to the variable load excitation.关键词：Fault diagnosis;Variable load;Tooth root crack;Dynamic characteristics
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发布时间：2022-09-22 - 摘要：The large amplitude transverse vibration of stay cable on the cable-stayed bridges will be caused easily under external excitations,and the method by applying an axial control force to mitigate the transverse vibration was proved to be feasible. Due to the effect of axial force,the cable vibration control system has nonlinear features,which will result in the complicated and difficult solution. In this paper,the nonlinear discrete time control system model of the cable is established. The average linearization and the initial value linearization method were proposed according to bilinear characteristics of system control matrix,and the vibration reduction effect of linearization method has been analyzed theoretically. Taking the first three modal control system of the cable as an example,the simulation of vibration reduction effect was carry out. The results show that the vibration reduction effect of the proposed linearization methods is 5% lower than that of the nonlinear methods,and can also achieve good damping effect,and the mitigating effect of the two linearization methods are basically the same under the free vibration and random excitation.关键词：Stay cable;Vibration control;Nonlinear characteristics;Linearization method;Simulation
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发布时间：2022-09-22 - 摘要：In order to investigate the problem that steering wheel shake of a commercial vehicle at high speed,the approach of theory analysis combined with the road test is used to find out that the wheel is the cause of the steering wheel shake excitation source and transfer path of vibration is verified. Time domain and frequency domain analysis are carried out for response signals from all the measuring points which are arranged in the road test,and discovery the smooth road shake is most intense at the speed of 90km/h. Key component of the steering system in transfer path is optimized to cope with the problem of energy absorption in the process of steering wheel shake at high speed. Sensitivity analysis on the bushing stiffness of low control arm in a validated model for vehicle dynamics is carried out by using Adams/Insight in the downstream subsystem. Sensitivity analysis result shows that bushing stiffness X of low control arms,which has a greater impact on the target point. The phenomenon of steering wheel shake at high speed has been significantly improved after the simulation analysis and test validation.关键词：Steering wheel shake;Excitation source;Transfer path of vibration
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发布时间：2022-09-22 - 摘要：Establish the moving-platform velocity and acceleration relationship between all members and joints of 6-TPS parallel mechanism. The mechanism output speed is used as the independent variable,and set up the mechanism motion differential equations by Kane method. The equation can be used as a dynamic control model and be completely closed loop control of the mechanism. Using matrix norm,derive the perturbation relation of relative variation between the active joint driving force and inertia matrix and the acceleration,put forward the quantitative index of the mechanism acceleration performance and dynamic optimization. Conclude that mechanism acceleration performance indicators is in the singular path limit of the inertia matrix in the working space by an example,and can be used to select the working space of excellent dynamic performance.关键词：Parallel mechanism;Dynamics;Acceleration performance
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发布时间：2022-09-22 - 摘要：In order to extract the gear fault characteristics under the strong noise condition,a fault feature separation and extraction method was proposed based on a new time-frequency decomposition method,the frequency slice wavelet transform（ FSWT）. Firstly,the signal was processed with the FSWT to get its time-frequency distribution. Then the time and frequency intervals,which contain the fault feature, were chosen to do threshold de-noising in time-frequency domain. Through reconstructing signals from the characteristic frequency slices,separation and extraction of time-frequency features were realized.The proposed method was shown to be efficient by simulations and engineering applications. It has the ability to isolate the desired components from noisy signals. It achieves an ideal effect on feature extraction for gear fault diagnosis.关键词：Frequency slice wavelet transform;Time-frequency analysis;Gear;Fault diagnosis
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发布时间：2022-09-22 - 摘要：In waist-worn pedestrian navigation systems, the peak detection method accuracy will be reduced when pedestrian carries on activities ups and downs in-situ such as stooped to and fro,squatting up and down. To compensate this error,a pedestrian step detection method aided with angular velocity is proposed based on the analysis on body waist motion feature. This method first extracts body’s forward angular velocity and lateral one to judge whether pedestrian walks ahead. Then peak signal of vertical accelerometer output is used to detect steps in common. In 27 experiments,which pedestrian walked certain steps and interference of activities ups and downs in-situ were brought in,the average accuracy rate of peak detection method and this method was 85. 8%,98. 84% respectively. Experimental results demonstrate that the proposed method can effectively reduce step detection errors generated by walking ups and downs in-situ with a high reliability.关键词：Pedestrian navigation;Micro electro mechanical systems（MEMS）;Step detection;Peak detection;Movement feature
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发布时间：2022-09-22 - 摘要：Multi-excitation modal analysis was used to test the dynamics characteristic parameters of the boat-type paddy tractor hull after analyzing the damage of the boat-type paddy tractor shaft and bearing during the commissioning. According to the basic principle and method,the H1 modal was used to estimate the frequency response function,modal parameters were identified by the method of frequency domain poly-reference modal parameter identification,and the top 7 ranks of natural frequencies within 100 Hz and the top 3 ranks of vibration mode were obtained. The results show the lower first order natural frequency characteristic of the boat-type paddy tractor hull,and severe resonance would occur in the process of engine starting because the rotation frequency of the transmission and the vibration frequency of engine are closer to the first and second order natural modal frequencies. The analysis shows the direction to solve the problem of the intermediate shaft’s damage,and provide the basis theoretical for the design optimization of hull and structure.关键词：Multi-excitation;Multiple coefficient of coherence;Boat-type tractor;Modal analysis
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发布时间：2022-09-22 -
EFFECT OF LASER FORMING REPAIRING ON THE FOUR-POINT BENDING STRENGTH OF TITANIUM ALLOY I-SHAPED BEAM
摘要：The static and fatigue strength of laser forming repairing beam and forged beam were studied by four-point bending test,and the effect of laser forming repairing on the static and fatigue strength of TA15 titanium alloy beam was investigated. By contrast,laser forming repairing can generate dense and uniform metallurgical bonded interface zone in the repaired area of metal base,which make the similar static and fatigue strength between repaired beam and forged beam,and this technology would provide strong support for the repairing of crucial part.关键词：Laser forming repairing;TA15 titanium alloy beam;Four-point bending;Strength- 3
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发布时间：2022-09-22 - 摘要：There is no uniform standard for determining the parameters of the key factors in the process of vacuum arc brazing. The parameters of the vacuum arc welding equipment are determined by the experience. Starting from the basic principle of arc,the influence of the key factors in the process of argon flow,breakdown voltage,breakdown distance and tantalum tube diameter is analyzed. According to the requirements of vacuum arc brazing process,the influence factors are obtained,which are most advantageous to the arc establishment ’s value range. Through the experimental data to verify and improve the theoretical research,in order to improve the success rate of vacuum arc welding equipment to provide a reliable basis for the value of the parameters and the solution.关键词：Vacuum arc welding;Arc mechanism;Influence factor;Parameter value
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发布时间：2022-09-22 - 摘要：Through the experiments on mechanical properties of TC11 titanium alloy by 3D laser rapid prototyping,obtained the performance data of static tension,S-N curve,DFR value,and fracture toughness. Furthermore,compared and analyzed the TC18 and TC21 performance data. The results show that the comprehensive properties of TC11 laser forming titanium alloy are basically between TC21 and TC18. The defects of the internal defects such as non fusion or air bubble have great influence on the fatigue properties,and the follow-up needs to continue to improve the manufacturing process and reduce the internal defects,which can be controlled and ensure the safety of aircraft.关键词：3D Laser Rapid Prototyping;TC11 titanium alloy;Mechanical properties;Experiment
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发布时间：2022-09-22 - 摘要：It is important for related equipment in the safe and stable performance that the integrality quality of the fillet welds of rapid-cooling heat exchanger. However,a few defects of the weld can ’t be detected effectively based on the nondestructive testing methods of existing standard. This paper provides a measurable method for testing fillet weld of rapid-cooling heat exchanger which is phased array ultrasonic testing technique. A simulation block is made for validating the phased array ultrasonic testing system,which is according to the size and shape of a fillet weld on headers of rapid-cooling heat exchanger.Firstly,the size and placement of the probe is determined by simulating on software. Finally,the practicability of phased array ultrasonic testing on fillet weld of rapid-cooling heat exchanger is proved by testing artificial defects on simulation block.关键词：Rapid-cooling heat exchanger;Fillet weld;Phased-array ultrasonic testing
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发布时间：2022-09-22 - 摘要：Using strain-gage method for non-root flight load measurement some ground calibration data of 2-spar,3-spar and more than 3-spar airfoil structures with different span-chord ration were investigated where some different-level effects of loading inside strain-gage station have been found. The mechanism of the effect on loading inside strain-gage station was analyzed using3 D structure deformation continuity. Moreover the effects of loading inside station on strain-gage values were analyzed,and virtual load result from loading inside strain-gage station was given and discussed. The results show that airfoil span-chord ratio is an important factor relative with strain quantities when loading inside strain-gage station. For different bending-moment equation of certain airfoil the ratio of virtual loads and applied loads is-24. 1% 23. 4%,and for different shear equations the ratio of virtual loads and applied loads is-31. 2% -3. 7%.关键词：Flight load measurement;Loading inside strain-gage station;3D structure deformation continuity;Span-chord ratio
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发布时间：2022-09-22 - 摘要：To study the parametric resonance of series circuit and micro-beam coupling system subjected to the narrow-band random excitation, the stochastic differential equation of the micro-beam system subjected to narrow-band excitation is established. The frequency response equation of the system is obtained based on the method of multiple scales. Ito stochastic differential equation of system is derived. The first order and second order steady state response of the system are obtained and the corresponding to the amplitude-frequency curves are calculated. The influence of the system parameters on the response of the micro-beam is analyzed. The results show that the sufficient and necessary conditions for the stability of the parametric resonance are the same as the first order and second order moment stability of the system. The numerical simulation shows that with the increase of the width,thickness and length of the plate,the second order response of the plate amplitude is decreased. When the damping coefficient,the axial force and the distance between the two plates are increased,the second order response of the plate amplitude is increased.关键词：Micro-beam;Parametric resonance;The method of multiple scales;Nonlinear system;Narrow-band random excitation
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发布时间：2022-09-22 - 摘要：In order to solve the problem of the lack of reliability data and the uncertain factors in the product development stage,a reliability allocation model based on grey system theory was proposed. Considering 6 effecting factors such as the importance,complexity, technology development level, manufacturing level, working time and environmental conditions,combining with the expert experience and known reliability data,the relative failure relationship among fuel cell vehicle subsystems was elevated using improved method of solving index weight based on grey correlation. The reliability of each subsystem was allocated according to the comprehensive grey evaluation value. Compared with the actual failure data,the validity of this model was verified.关键词：Fuel cell cars;Grey system theory;Grey clustering analysis;Reliability allocation
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发布时间：2022-09-22 - 摘要：The reliability of the reaction force developed in the lubricated revolute joint for a slider-crank system considering realistic joint characteristic,namely,joint with clearance and lubrication in the revolute pair,and the randomness of the system parameters is presented. The continuous approach and the hydrodynamic theory are used to evaluate the contact force for the case of joints modeled as a contact pair with dry contact and the force generated by lubrication action respectively. The system dynamic model was set up based on Newton-Euler method,The prediction accurary of Support Vector Machine Regression is difficult to reach the target accurary because the selection of parameters isn’t accurate. In order to overcome this limitation,the parameters are pretreated through Genetic Algorithm to get the optimum parameters values. Then approximate function relation between random parameters and performance function is derived and the reliability of the reaction force developed in the lubricated revolute joint of the crank-slider mechanism is discussed by Monte-Carlo method. Finally,take an example to verify the feasibility and effectiveness of the proposed method.关键词：Clearance;Lubrication;Slider-crank mechanism;Support vector machine regression;Reliability
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发布时间：2022-09-22 -
MACHINE TOOL SPINDLE PERFORMANCE DEGRADATION RELIABILITY STUDY BASED ON ACOUSTIC EMISSION MONITORING
摘要：As one of core components of machine tool,the reliability of spindle is very important for improving machine tool quality. According to spindle performance degradation mechanism analysis,the acoustic emission signal is used to monitor and study the performance state of spindle. A reliability evaluation method is proposed for the long-life and less failure sample problem based on machine tool degradation path models. At last,this method is used to solve the machine tool spindle reliability assessment,which integrates virtual augmented sample method. It effectiveness and practicability is proved through experiment results.关键词：Acoustic emission;Machine tool spindle;Performance degradation;Reliability- 3
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发布时间：2022-09-22 - 摘要：In view of the electrical discharge machining has the characteristics of complex, time-varying and multiparameter,based on the feasibility of the electrical discharge machining of the monocrystalline Silicon,this paper has a comprehensive evaluation of the material removal rate and the surface roughness and other technology goals. Using central composite design experiments,it comprehensively inspects the influence degree of the peak current、pulse width and pulse interval to the material removal rate and the surface roughness in the course of the electrical discharge machining of the P type monocrystalline silicon,it obtains the second-order response model of the material removal rate and surface roughness respectively through the Response Surface Methodology,the result of the variance analysis indicate that the model has good fitting degree and adaptability. Aiming at improving the material removal rate and reducing the surface roughness to establish the process parameters optimization model,it designs genetic algorithm for solving optimization problem and get the Pareto optimal solution set. The experimental results show that the average relative error of the experimental results of the material removal rate compare with the optimized forecast results is 5. 8%,the average relative error of the experimental results of the surface roughness compare with the optimized forecast results is 5. 3%,which is showing that this algorithm can rapidly and efficiently implement the optimization of the process parameters in the course of the electrical discharge machining of the P type monocrystalline silicon.关键词：Electrical discharge machining;Monocrystalline silicon;Material removal rate;Surface roughness;Parameter optimization
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发布时间：2022-09-22 - 摘要：In the process of design shearer ’s ranging arm gear transmission system,by using the method of reliability design theory,derived gear strength and stress assumed to obey normal distribution when tooth surface contact fatigue strength and tooth root bending fatigue strength were taken as constraint conditions,and the volume of gear system as objective function,then genetic algorithm optimization toolbox of MATLAB was used to solve the optimization mathematic model. The results show that this method of optimization can improve gear transmission’s reliability,the volume and weight of gear transmission system are reduced too,which is beneficial to achieving products lightweight and reduceing production cost.关键词：Gear transmission;Reliability-based design;MATLAB optimization toolbox;Genetic algorithm
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发布时间：2022-09-22 - 摘要：Bolt joint is mostly used connection type in engineer structure for its simplicity and practicability feature,but the stiffness is changed for geometry alter which makes bolt joint design become the most important and it is essential to understand the dynamic characteristics of the whole structure. The preload and distance between centreline of bolt and prying force are discussed to confirm the affecting of stiffness. The results is shown that the initial stiffness of the structure is guarantee by preload,but the impact is more limited,preload increase of 100%,the initial stiffness increased by 13%. The distance between centreline of bolt and prying force is shorter the initial stiffness is greater,the distance is increased by 30%,the stiffness is reduced 60% reduction. Double exponential fitting formula is proposed and compared with the analysis results which provide stiffness calculation method is effect for bolt joint stiffness structures.关键词：Bolt joint stiffness;Prying force;Preload;Parameter fitting
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发布时间：2022-09-22 - 摘要：For the nonlinear problem of herringbone gear power transmission four heavy branch by analysis of backlash of the ship,combined with the theory of the concentrated parameter,considering the time-varying stiffness,mesh damping,brace stiffness and damping,dynamic model of backlash nonlinear factors. With herringbone gear loaded tooth contact method of simulation technology,put forward a method for accurate calculation of herringbone gear meshing stiffness excitation; By using the theory of the concentrated parameter,three-dimensional dynamic model of bending torsion coupling of the system is established;Based on the dynamic differential equations are solved with variable step four order Runge-Kutta method,obtained under the influence of backlash in the system without impact,dynamic load coefficient and amplitude of unilateral and bilateral shock state.The results show that Power four branch transmission system has a complex nonlinear characteristic,which is sensitive to the change of the tooth side gap,the influence of the backlash on the nonlinear characteristics is greater,and the system load changes from the side impact to the side impact of the system when the backlash is changed from 0 μm 150 μm; When the tooth gap is greater than a certain critical value,the dynamic characteristics of the system will not change with the increase of the gap of the tooth. To reveal the variation of nonlinear dynamic characteristics of herringbone gear power transmission for the four branching,the system dynamic equilibrium optimization design has laid a theoretical foundation.关键词：Herringbone Gear;Power four-branching;Loaded tooth contact analysis;Time-varying meshing stiffness;Nonlinear
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发布时间：2022-09-22 - 摘要：In order to study the drag reduction performance of non-smooth circular cylinder,the SST k-ω turbulence model was been used to simulate the flow around a circular cylinder and studied the drag reduction performance of a circular cylinder at the subcritical Reynolds number Re= 40 000. The sensitivity analysis of dimples ’ structure parameters,which include the depth,the inner shape and the distribution of dimples is carried out to study the influence of various parameters on the drag reduction of the flow around a circular cylinder. The results show that the circular cylinder with dimples has a good effect on drag reduction. Drag coefficient and lift coefficient decrease with the increasement of dimple depth first and then decrease increase.Moreover,the circular cylinder with dimples has the best drag reduction effect when h = 0. 015 D. The average drag coefficient of the circular cylinder with cylindrical dimples is 0. 923 while the average drag coefficient of the circular cylinder with spherical dimples is 0. 94. The average drag coefficient of the circular cylinder with dimples by diamond distribution is 0. 923 while the average drag coefficient of the circular cylinder with dimples by rectangle is 0. 973.关键词：Cylinder flow around;Dimple;Drag reduction performance;Drag coefficient;Lift coefficient;Strouhal number
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发布时间：2022-09-22 - 摘要：Stitched composite material not only suppresses delamination expansion, but also improves inter-laminar toughness and compressive characteristics after impact by introducing stitch in the thickness direction. Equivalent hole method simulates the initial damage of stitched plate. The finite element analysis method with damage evolution process based on threedimensional Hashin criterion with 3D solid element modelling laminates,3D bar element modelling stitch simulated the stitched composite laminates damage evolution effectively. The calculation results were in good agreement with the experimental data.关键词：Composite;Stitched laminates;Impact damage;Residual compression strength
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发布时间：2022-09-22 - 摘要：The interference between the rotor and stator has significant effect on the seal and mechanical performance of mudmotor. The suitable interference is significant to improve the performance of downhole motor. Based on the Hertz contact theory,the two-dimensional engagement model of rotor and stator was established. Through the balance theory of contact force system and the iteration method,the center trace of rotor and the normal interference were obtained. The profiles of rotor and stator were acquired through the measurement of two mudmotors which have different theoretical interference,and the calculated interferences were gained through the engagement model of mudmotor. Compared with the theoretical interference,the results show that the calculated interference values are a little larger. Meanwhile,two mudmotors‘ performance tests were conducted and the calculated interference can be more reasonable to explain the motor’s performance compared with the test data. Besides,when the calculated interference was in a range of suitable value,the downhole motor would have good performance.关键词：Downhole motor;Stator;Rotor;Engagement model
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发布时间：2022-09-22 - 摘要：On the basis of the theory of rigid-flexible coupling multibody dynamics as well as the transmission system of coal winning machine cutting part the transmission principle and structure parameters,the dynamic characteristics of coal winning machine cutting part drive system was researched for the problem about dynamic characteristics of coal winning machine cutting part the transmission system. The rigid-flexible coupling dynamics model of coal winning machine cutting part for gear transmission system was built in Recurdyn software environment. To the cutting force in drum three loads,Transmission Model was under full consideration of the flexible drive shaft in all directions feature and calculated the gear meshing force,strain and bearing junctioncontact. Results showed that 11 th gear mesh together is the biggest,11272634. 4N. The maximum contact force,912317. 98 N,is measured at the place of the shaft 5 bearings 1. Results provide a basis for optimum design of the transmission system and prediction of fatigue life.关键词：Coal winning machine;Rigid-flexible coupling;Dynamics;Contact dynamics;RecurDyn
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发布时间：2022-09-22 - 摘要：The most common type of pipe mechanical damage is dent defect,which is a major cause of leading to pipeline fatigue rupture. For further research on the security of the pipelines,it is necessary to establish a calculation model serving actual conditions. Predecessors have carried on the comprehensive analysis of dent with concave angle by stick model and spherical model. A distinguishing method between dent with concave angle and without concave angle is proposed in this paper,The online detection data of pipeline shows that the dent without concave angle is in the majority. Then calculation model of dents without concave angle—hoop stick model is presented,which is verified by Finite Element simulating the actual dimension.Finally,influence of the stick parameters to result of the dent simulation is studied. It turns out that the simulation of differentsized dents without concave angle can be achieved by changing the curvature radius of hoop stick. Further research also showed that dent without concave angle on pipeline safety cannot be ignored.关键词：Pipeline dent;Spot data;Dent without concave angle;Hoop stick;Finite element model
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发布时间：2022-09-22 - 摘要：For honeycomb structure,a analysis method based on equivalent theory combine with sub-model technology was proposed. The equivalent method based on sandwich plate theory is deduced and equivalent model of full height honeycombs structure is obtained. The global equivalent model of full height honeycombs structure is analyzed by finite element simulation,and sub-model analysis technology is applied to extract the region of interest from global equivalent model of full height honeycombs structure for detail analysis,the comparison of simulation and experimentation indicated the analysis method have better accuracy. Appling the analysis method for full height airfoil honeycombs structure,through simulation results investigated the relation between geometry parameters of full height airfoil honeycombs structure and per unit mass of instability failure load through simulations,moreover the result shows that per unit mass buckling load increases along with thickness of wing skin‘s and airfoil honeycombs structure cell’s wall grow,reduces along with thickness of airfoil honeycombs structure cell’s grows,besides in a bound which changes on the small side. Appling multi-objective optimization for full height airfoil honeycombs structure,the results show that per unit mass buckling load stay in great bound when the three geometry parameters of honeycombs structure’cell stay in a specifically bound.关键词：Full height honeycombs structure;Equivalent model;Sub-modeltechnology;Sandwich theory;Multiobjective optimization design
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发布时间：2022-09-22 - 摘要：In this paper,we study the rolling friction of the triangular tooth friction wheel and the flexible track under the condition of small deformation contact. According to the Crook ’s elastic plastic rolling friction theory,the flexible rail is established by the finite element model,and the rolling friction coefficient and rolling friction are analyzed. Rolling friction force measurement is designed to measure the rolling friction torque,the theoretical value and the calculated value are compared,and the suitable rolling friction model is obtained.关键词：Tooth type friction wheel;Flexible track;Rolling friction;Finite element;Nastran
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发布时间：2022-09-22 - 摘要：Buckling loads of honeycomb sandwich structure under compression and shear load was calculated by engineering algorithm and finite element method. Stability test on specimens was conducted to obtain buckling loads. The test results also verified the accuracy of the finite element method. The effect of core height on general stability problem of honeycomb sandwich structure for thin composite panels was discussed. The results show that it is increasing core height that could enhance flexure strength of composite honeycomb sandwich structure,but the spare carrying capacity descends. The strain of panels increases and indeed to exceed the allowable with only increasing core height.关键词：Composite;Honeycomb sandwich structure;Core height;General stability;Buckling loads
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发布时间：2022-09-22 - 摘要：Cold extrusion technology is a kind of high precision,efficient,high quality and low cost advanced production technology,in the modern production plays an important role. With the appearance of new lubricant,the new die material,the large press machine,bulk cold extrusion forming with high static strength material become possible. Though simulation the process of cold extrusion of scm435 alloy steel with thermo mechanical coupling numerical method,from shrinkage fit,placing the workpiece,extrusion,unloading,ejection of the workpiece,to cooling down workpiece and springback. Researched the change of the pre stress in each stage of the process of forming and the influence of temperature on the pre stress. On this basis,a concept of non-uniform interference quantity through piecewise sleeve and specific Process implementation are put forward,and in the research,the stress of the whole process of the two different structure is studied by using FEM simulation.关键词：Cold extrusion;Shrinkage fit;Shrink fit clearance;Non-uniform interference;Piecewise sleeve
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发布时间：2022-09-22 - 摘要：Considering physical properties variation of gray cast iron with temperature,difference mechanical behavior of material between compression and tension,relationship of elastic and plastic stress-strain of material,synthetically studied the temperature field,stress field,strain field and thermal crack strength of brake disc under different braking conditions,and revealed the opening mechanism of thermomechanical crack and crack distribution. Results of thermomechanical coupling simulation show the maximum temperature is 360℃ with initial speed of 180km/h,radial compression/tension stress are275Mpa/85 Mpa,circumferential compression/tension stress are 374 MPa/100 MPa,radial/circumferential plastic deformation are-4. 6 × 10-5/-6. 75 × 10-5. Results of thermomechanical opening calculation show stress intensity factor of radial crack ΔK6. 69 MPa·m1/2is larger than ΔK 5. 49 MPa·m1/2of circumferential crack,opening displacement of radial crack is larger than that of circumferential crack,which indicating radial cracks are mainly distributed on brake disc,and the sizes of radial crack are larger than that of circumferential crack.关键词：Themomechanical openning;Finite element calculation;Gray cast iron;Elastic/plastic strain
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发布时间：2022-09-22 - 摘要：In order to provide accurate temperature field of autoclave,and make preparation for stress analysis,temperature of autoclave tooth-locked quick opening structure was measured. Using ANSYS to simulate the temperature field,the result is compared with the measured data. It shows that the simulation result is consistent with the actual situation. The strength and fatigue life were evaluated by JB4732-1995,evaluation results meet the requirements.关键词：Autoclave kettle;Steady-state temperature field;Stress field;FEM;Low-cycle fatigue
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发布时间：2022-09-22 - 摘要：The displacement and strain modal parameters identification models of the vibrating screen were built based on modal theory,the variations of the displacement and strain modal parameters were analyzed for the vibrating screen upper beam with fatigue damage crack. The results show that the modal frequencies and the displacement mode shapes have no obvious mutation between intact and damaged upper beam,but the strain mode shapes have mutation peaks at the location of the fatigue damage crack,furthermore,the bending strain mode is more sensitive to fatigue damage crack than the twisting strain mode.Thus a fatigue damage indicator is defined by using the strain modal variable ratio between the intact and damaged upper beam,the fatigue crack size is determined by damaged degree of the upper beam,then the residual life of fatigue crack propagation of the upper beam is calculated by the Paris formula of integral form. The predictions of the damaged degree and the fatigue residual life of the vibrating screen upper beam are beneficial to dynamic optimization design,which can improve the service life of the vibrating screen.关键词：Vibrating screen;Upper beam;Strain modal analysis;Fatigue damage;Residual life
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发布时间：2022-09-22 - 摘要：In view of the problem that the triphase separator of offshore platform is confronted with serious partial corrosion which has less corrosion data and more corrosion factors. Grey prediction model is established for residual thickness of nozzle,at the entrance of separator,taking the phenomenon of the thickness with the corrosion reduction as grey global parameters. In view of the data are not pre-processed and the new information is not fully utilized in traditional GM（ 1,1）,moving the data and using the latest accumulated value as the setting condition to improve the original prediction model. Analyzing the problems happened in the process of improvement at the same time. The effectiveness of the improvement is proved by comparison with the accuracy of other three grey forecasting models. On this basis,the remaining life of the nozzle is calculated which could provide a reference for the management to develop the corresponding corrosion prevention plan.关键词：Separator;Corrosion;Nozzle;GM（1,1）;Prediction;Remaining life
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发布时间：2022-09-22 - 摘要：To reduce thenumbers of measuring channels,prepare period and amount of data during the large-scale whole vehicle customer road load measurements,in this paper a method,based on system identification,was described to estimate the cumulative fatigue damage of whole vehicle and components with statistic results of only a few measuring channels. An example of longitudinal wheel cumulativefatigue damage estimation was also given based on small-scale customer road load data of a certain A-level car. With good consistency between the estimation result and the actual value,this method was proved to be feasible and valid.关键词：systemidentification;Customer road load measurement;Cumulative fatigue damage
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发布时间：2022-09-22 - 摘要：Considering the uncertainty of the load,the fracture toughness,the yield strength,the tensile strength,and based on the failure assessment diagram technique（ FAD）,as well as combining with the finite element analysis results of crane structure,the probabilistic safety assessment for box girder of gantry crane is studied. Monte Carlo simulation is used to calculate the failure probability of box girder of gantry crane. The sensitivity of parameters are analyzed to identify the most important parameters that affect the failure probability of box girder of gantry crane. The results show that the yield strength is the most important parameter affecting failure probability,followed by the load and the fracture toughness. The research content provides a reference for the repair,monitoring and safety assessment of box girder of crane.关键词：Crane;Box girder;Probabilistic safety assessment;Failure probability;Sensitivity Analysis
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发布时间：2022-09-22 - 摘要：The structure of a complicated fixture is usually designed improperly using common methods,which are usually based on experience and formulas. Modal analysis of the fixture was performed based on the 3D finite element model,thus its natural frequencies and vibration modes were obtained to optimize the design. The natural frequencies、energy magnifying factor、scope of orthogonal motion and differences in vibration response among fixed points of the optimized fixture were analyzed to make sure the design meet the fixture design standardization. The result is verified through the vibration test and shows good performance of the fixture in vibration test.关键词：Fixture design;Finite element;Modal analysis;Random vibration;Test verification
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发布时间：2022-09-22 - 摘要：The 3D model of spindle reducer box of Boring and Milling Machining Center was established. The gear transmission was analyzed. The thermal load was found by calculating the heat flow of the gear and the heat generated of bearing.The calculated heat convection coefficient was defined as the boundary condition. The temperature field of the spindle reducer box was simulated. By thermal-structure coupling analysis,the thermal deformation results of the box and gears were obtained.Finally,the reliability of spindle box was verified according to the comparison of the simulation result against the nominal clearance.关键词：Boring and milling machining center;Spindle reducer box;Thermal characteristics;Reliability
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发布时间：2022-09-22 - 摘要：Parametrically building the crank 3D model by Solid Works and doing the FEA by Simulation. Select six parameters and take maximum stress as constraints to solve minimum volume of the structure. Using BBD to optimize the structure and finish 49 iterations. Solid Works can’t fully fit the data. Design the BBD by DOE software Design-Expert and input the simulation data. Then it fits the response surface functions about volume and stress and gets the optimal solution. Comparing with the conclusion of the reference,BBD shows application values on structural optimization.关键词：Box-behnken;Optimal design;Solidworks
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发布时间：2022-09-22 - 摘要：In order to improve the efficiency of coal mining and the service life of shearer,the failure mode and the reasons of cutting teeth were analyzed,and the influence caused by cutting tooth failure was described,in view of the selection,research and development design,manufacturing process and use of cutting teeth in different geological conditions,the countermeasures were discussed,and the quality of cutting teeth is improved by means of reasonable selection of the type of cutting tooth,the geometrical parameters,the optimized blade spiral angle,the application of tribology theory,the use of new cutting material,the surface strengthening and the operation of the workers. Which providing reference for the production of cutting teeth.关键词：Shearer;Pick;Failure mode;Countermeasure
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发布时间：2022-09-22 - 摘要：The problem of crack in the end of the crane girder is analyzed by using the 350 t casting crane in a steel plant.The finite element model is verified by the results of stress measurement. The finite element model is correct and the most dangerous condition of the main beam is analyzed. The results show that the maximum stress appears at the end of the main beam. According to the actual observation,the results of the finite element calculation,that the end of the main beam of the lower end of the curved plate,the end of the beam and the main beam end bending plate butt weld in the intersection,the stress concentration of the site,resulting in a crack in the main girder of crane. Finally,the reinforcement scheme is put forward,and the results show that the reinforcement effect is very significant.关键词：Casting crane;Main girder end;Crack;Finite element;Reinforcement
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发布时间：2022-09-22 - 摘要：For offshore crane in the operation process at sea,due to the suspension of lifting wire rope belongs to the flexible parts,also wind,wave and ocean environment to inflect the load. These cause the load swing. A new type of offshore crane telescopic sleeve stabilizer was proposed based on the work condition of crane at sea. It uses the casing of the rigid constraints to reduce the swing range of the load,and using the universal torque structure to reduce the stress of the casing. When the casing is moving through the universal torque structure. Rely on the spring dampers to store and release energy. By these methods to reduce the swing of load. The telescopic sleeve device was introduced. A mathematical model of the ship,crane and telescopic sleeve is established. The kinematics analysis of the simulation model is carried out by using Adams. Verify the obvious damping effects of the telescopic sleeve device. At the same time,through constructing the experimental platform for actual experiments,Verifying the telescopic sleeve device in the practical application of also has significant effect of damping.关键词：Offshore crane;Telescopic sleeve device;ADAMS;Kinetic modeling analysis;Anti-swing
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发布时间：2022-09-22 - 摘要：The method is to combine dynaform numerical simulation techniques and orthogonal experimental design to analyze the influence factors of intensity ratio,clearance between punch and die,thin side blank holder rate,friction coefficient,blank-holder force and thickness ratio to improve the quality of TWBs,. The research show that Strength ratio, friction coefficient,blank-holder force and the thickness ratio on the forming results is relative bigger. As a whole,tailor-welded sheet forming improved with the increment of the strength of parent metal,because the deformation degree of thin side parent metal reduce the weld-line movement for enhancing its ability to resist deformation. Friction coefficient and blank-holder force is not very big on the influence of the formability of tailor-welded sheet,but the bigger friction coefficient and the bigger total blankholder force affect on both sides of the base material of liquidity,finally,it affects the quality of the forming of the sheet metal.Thickness ratio should be carefully considered in the design of welding plate. Generally,the thickness ratio between 1. 0-1. 0and 1. 0-1. 4 improved the forming of tailor-welded blanks with arc-weld-line,the small and large of thickness ratio are not beneficial to tailor-welded sheet forming.关键词：U-shaped;Numerical simulation;Orthogonal design;Arc-weld-line;Range analysis
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发布时间：2022-09-22 - 摘要：Understanding the WOB and the law of tubular buckling is significant to handle workover operation efficiently and safely. Based on the simulation theory and the characteristics of workover string dynamics,a finite element model is established for the workover string. Then,the tubular in the wellbore is simulated by the model,and the simulation result is highly coincide with the experiment result. The strings in horizontal well is built,and the critical buckling load is analyzed in different friction coefficient and different annular clearance. The results show that: the sinusoidal buckling load and helical buckling load will increase with the friction coefficient,and the helical buckling load increase more rapidly; while with the increase of annular clearance,the buckling load will decrease. When the annular is larger than 35 mm,the helical buckling load is even smaller than sinusoidal buckling load.关键词：Horizontal well;Buckling;Workover string;Simulation
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发布时间：2022-09-22 - 摘要：The specimen is a reactor pressure vessel with a semi-elliptical surface crack with axial orientation and its 3D finite element numerical modeling is built. Based on J-A2 two parameters method,analysis is performed by considering constraint effect,at T = 561 K,p = 10 MPa. Three different aspect ratio（ a/c） and Ramberg-Osgood exponent（ n） is analylized,namely a/c = 1/2,1/3,1/5（ a = 20 mm,c = 40 mm,60 mm,100 mm） and n = 10,15,20. The corresponding J-integral and constraint parameter A2 is gained. The research results show that: J-integral increases with the decrease of aspect ratio a/c,and RambergOsgood exponent（ n） almost has no effect on J-integral. The increase of Ramberg-Osgood exponent（ n） will weaken the effect of aspect ratio a/c on A2. The most serious point is the deepest point of a crack.关键词：Semi-elliptical surface crack;High temperature and pressure;Constraint effect;J-integral;Constraint parameter
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发布时间：2022-09-22
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