最新刊期
期 5 ， 2018
- 摘要：According to shearer vibration problems in the practical work,using multi-body dynamics theory,considering shearer support characteristics of guide boots and pin-rail,the friction between flat boots and middle trough,the connection characteristics between the parts of shearer,vibration angle of shearer,6 degrees of freedom dynamic model in the lateral direction of shearer was established. The axial direction of shearer drum load was used as an external excitation,and the effect of different haulage speed on lateral direction vibration characteristics of shearer were solved by using numerical analysis method. The results show that the haulage speed has great influence on vibration displacement of front and rear cutting unit when the range is 2 m/min 5 m/min,the displacement range of front and rear drum is 4. 994 1 mm 11. 262 3 mm、4. 842 0 mm 10. 791 7 mm,and the displacement range of front and rear rocker arm is 3. 199 1 mm 5. 709 7 mm、3. 046 3 mm 5. 236 9 mm. Research results provide the basis for shearer in the actual production process. Finally,the results of model is verified by experiment.关键词：Shearer;Haulage speed;Vibration;Numerical analysis;Experimental study
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发布时间：2022-09-22 - 摘要：In order to solve the problem that the fault feature information of rolling bearing is difficult to be separated,a new method of fault feature extraction is presented,which is based on the complementary ensemble empirical mode decomposition（ CEEMD） and fast independent component analysis（ Fast ICA）. First,analyze the CEEMD vibration signals,decompose them into intrinsic mode function（ IMF） components signal of different scales; then through the sensitivity evaluation algorithm,decompose and recombine the signals,and use Fast ICA to reduce their noise; in the end,conduct Hilbert envelope spectrum analysis to the signals separated by the Fast ICA,to obtain the fault feature information. This method is applied to the fault analysis of rolling bearing vibration signal,and was proved to be valid.关键词：CEEMD;Sensitive factor;Fast independent component analysis;Rolling bearing;Fault diagnosis
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发布时间：2022-09-22 - 摘要：The free vibration problem of the honeycomb sandwich structure with double cores was studied based on the Layerwise/Solid-Elements（ LW/SE） and Fixed-interface Modal Synthesis Technique（ FMST） of the dynamic substructure method. The governing equation and the total modal space of the honeycomb sandwich structure were assembled based on LW/SE and FMST,respectively,and the final governing equation on the basis of the modal spaces was assembled based on the governing equation and the total modal space. This method obtains the natural frequency of the honeycomb sandwich structure with double cores accurately and reduces memory requirement. The numerical results of the method are compared with those obtained by the 3D solid finite element,and good agreements are achieved.关键词：Layerwise/Solid-elements;Fixed-interface Modal synthesis technique;Dynamic substructure method;Honeycomb sandwich structure;Free vibration
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发布时间：2022-09-22 - 摘要：The effective low frequency fault feature hidden in gearbox measured signal is very weak for the influence of high frequency vibration and strong noise,and considering source noise,the extraction effect of low frequency fault feature with constrained independent component analysis（ c ICA） method directly is very poor. Aiming at this problem,a method of gearbox low frequency fault feature extraction based on wavelet transform and c ICA is proposed. This method can improve signal-to-noise ratio（ SNR） and nongaussianity of the analyzed signal,and enhance analysis effect of c ICA algorithm through wavelet multiresolution decomposition for the measured signal and reconstruction for some wavelet coefficients. But the analysis effect is not good for the c ICA method without WT denosing. Low frequency fault feature extraction experiments with a missing tooth and a chipped tooth were analyzed,and the results show that this method can effectively reduce the influence of high frequency vibration and source noise,and extract gearbox low frequency fault feature,especially weak low frequency fault feature. The proposed method provides an effective approach for low frequency fault feature extraction and fault diagnosis of gearbox.关键词：Gearbox;Low frequency fault feature extraction;Wavelet transform（WT）;Constrained independent component analysis（cICA）
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发布时间：2022-09-22 - 摘要：Weight-adjusted variant second order blind identification（ WASOBI） algorithm had been used in fault diagnosis field,but it couldn’t separate source signal when the observation signal’s dimension was insufficient. This paper combined kernels with this algorithm to achieve underdetermined blind source separation,and applied it to multi-fault diagnosis. First,the collected single-channel signal was decomposed into multi-dimensional signal by kernels. Then the K-SVD source number estimation algorithm was used to estimate the number of sources. According to the estimated result,a positive definite matrix was reconstructed. Finally,weight-adjusted variant second order blind identification algorithm was applied to separate the source signals. The experiment results indicate that it can well diagnose the multi-fault on rolling bearing with single-channel mechanical signal,feasibility of this method is also validated.关键词：Single-channel signal;Weight-adjusted variant second order blind identification;Kernels;Source number estimation;Multi-fault diagnosis
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发布时间：2022-09-22 - 摘要：Based on the advantages of Bat Algorithm（ BA） that is easily to be realized,fast convergence speed,high efficiency and high universality,combining BA and blind source separation,a new method of mechanical failure blind source separation based on BA is proposed（ BA-BSS）. The BA-BSS method,as the target function of the sum of the absolute value of the kurtosis,seeks the maximum of the target function by BA,and then determines the optimal separation matrix. Simulation results show that the BA-BSS method is significantly superior to the traditional mechanical failure blind source separation based on Genetic Algorithm（ GA-BSS） in separation performance,algorithm convergence and operation speed. Finally,the BA-BSS method is successfully applied to the actual rolling bearing inner and outer mixing fault blind source separation,and the separation effect is very effective关键词：Bat algorithm;Blind source separation;Rolling bearing;Mixing fault
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发布时间：2022-09-22 - 摘要：Linear local tangent space alignment（ LLTSA） is a dimensionality reduction method which is easily used to pattern recognition. However,it is an unsupervised dimensionality reduction method and only use global neighborhood parameter,when it used to high-dimensional data for dimensionality reduction,its incapacity of using part sample class label information and self-adaptive adjust neighborhood parameter while the samples space distribution changed. Aiming at the problems above,a semisupervised neighborhood self-adaptive linear local tangent space alignment（ SSNA-LLTSA） dimensionality reduction method is proposed in this paper. In SSNA-LLTSA, the distance between different points is adjusted by utilizing part class label information,thereby a new distance matrix is formed and the neighborhood is constructed through this new distance matrix. At the same time, the neighborhood parameters are self-adaptive adjusted according to probability density of each sample point neighborhood. The experiment results of classical 3D manifold,UCI datasets and bearing fault diagnosis show that the algorithm overcomes the drawbacks that the LLTSA has no supervision and the use of global unified neighborhood parameters and it is more effective to find the low dimensional nature of the data for improving the recognition accuracy and has certain superiority.关键词：Semi-supervised;Neighborhood self-adaptive;Linear local tangent space alignment;Pattern recognition
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发布时间：2022-09-22 - 摘要：In order to quantitatively analyze characteristics of the hinge joint loads under actual working conditions,and provide basis for compiling the load spectrum of key components,a medium-sized excavator XE215 G was taken as the research object,whose hinge joint loads was obtained by two methods. The first is using the three-dimensional pin-shaft force sensor to measure the positive load,lateral load and offset load at the hinge joint of stick and bucket,and using the link rod force sensor to measure the link rod force,and then the other hinge joint loads could be calculated by the mechanical equilibrium equation; The second is using the measured pressure and displacement of the boom cylinder,stick cylinder and bucket cylinder to calculate all hinge loads indirectly by a kinetic model. Simultaneously,the stress-time histories of the large stress measure points on the boom and the stick were recorded. The hinge joint loads obtained by the two methods were in good agreement with each other,indicating that the test is reliable. For method 1,the relative deviations of fatigue damage of each measure point between including and excluding lateral load and offset load is less than 6. 98%,except for a measure point whose fatigue damage is obviously smaller than other points,which indicates that the lateral load and the offset load have little effect on fatigue damage. For method 2,the calculated stress of each measure point obtained by the load-stress transfer coefficient was compared with the measured stress of the corresponding point. The results show that they are in good agreement with each other and the most relative deviation between the calculated damage and the actual damage is 8. 33%,which indicates that the hinge load obtained from the method 2 can reproduce the stress and damage of each measuring point well. Under normal working conditions,the hinge joint load of theexcavator working device can ignore the lateral load and offset load approximately,while can be obtained by the simple and feasible method of measuring the cylinder pressures and displacements.关键词：Hydraulic excavator;Hinge joint force;Lateral load;Offset load;Fatigue damage
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发布时间：2022-09-22 - 摘要：In this paper,the research of the scraper conveyor is carried out,the force analysis of the adjacent middle pan group and the dumbbell pin is carried out,and the dumbbell pin load data is obtained by the dumbbell pin load test system. The ANSYS/ls-dyna software is used to simulate the nonlinear contact dynamics of the middle pan group and the dumbbell pin under the push-slip condition of the scraper conveyor. The contact stress of the dumbbell pin is the largest,and the maximum contact stress of the dumbbell pin occurs at the abrupt change of the dumbbell pin section,and the maximum contact stress of the dumbbell pin And the contact stress concentration between the two middle slots occurred at the joints of the dumbbell pin and the middle ditch. The simulation results were in accordance with the actual working conditions. This study provides a dumbbell pin load test program,and through the test simulation to verify its correctness and feasibility,while the middle slot and dumbbell pin structure size optimization method.关键词：Scraper conveyor;Middle pan group;Contact dynamics;Ansys/LS-DYNA
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发布时间：2022-09-22 - 摘要：A group of tests on uniaxial tension and low cyclic fatigue under constant strain amplitude at room temperature and 700 ℃ have been carried out for ultra-supercritical Inconel 617B alloy. Based on new method of finite-element-analysis aided testing on funnel specimen,we can get uniaxial tensile true stress-true strain curves until fracture. Then,fractured stress and strain,described equation of the true stress-true strain curves and parameters of the equation at two temperatures are obtained. At last,Evolutive behavior of cyclic stress,cyclic constitutive relationships,relationships between strain amplitudes and cyclic lives,ultra-supercritical temperature effects are studied. The results show that,ultra-supercritical temperature makes the elastic modulus of Inconel 617B,yield strength,ultimate strength,critical breaking stress,breaking strain and stress triaxiality of centre point on funnel root transversal surface after specimen necking decrease significantly. The curves obtained by FAT are well described by the new equation of the true stress-strain relationship. The finite-element-analysis shows that stress triaxiality of centre on funnel root transversal surface is the largest than other points,the maximum of fractured stress triaxiality at 700 ℃ is much lower than room temperature. 617B Inconel alloy performs obvious cyclic hardening characteristics at two temperatures. The cyclic stable life percent of 617B Inconel alloy reduces greatly and the anti-fatigue property weakens significantly under ultrasupercritical temperature. Manson-Coffin life-prediction model can describe the low cyclic fatigue life under two temperatures very well.
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发布时间：2022-09-22 - 摘要：According to the dual physical characteristics of the steel wire and the rubber possessed by the rubber conveyor belt with the steel wire core,the constitutive model of the entire conveyor belt is obtained by combining the constitutive model of the steel wire core and that of the rubber cladding. The Kelvin model is employed to describe the constitutive model of the steel wire,the standard solid model is employed to describe the constitutive model of the rubber cladding,the stress expression of the conveyor belt under the harmonic strain is derived by the parallel superposition combination of a standard solid model and the multiple Kelvin models,and the generalized constitutive model of the conveyor belt is established. The experiments of the dynamic strain loading on the steel wire and the rubber base body are performed respectively,and the parameters for the two constitutive models are obtained,and the prediction of the visco-elastic mechanics characteristics by applying the generalized constitutive model is performed. The experiment of the dynamic strain loading on the conveyor belt is carried out,the comparison between the experimental result and the computational result of the generalized constitutive model is performed. The result shows that by calculating the parameters of the steel wire,the parameters of the rubber cladding and the volume ratio of the steel wire to the rubber cladding,the visco-elastic mechanics characteristics of the conveyor belt can be described precisely,and the accuracy of the generalized constitutive model is high.关键词：Steel wire rope;Rubber conveyor belts;Kelvin model;Standard solid model;Visco-elastic
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发布时间：2022-09-22 - 摘要：as multi-spar composite box has been used for many airplanes,in order to assure structure security,it is necessary to study the mechanical properties of multi-spar composite box. Aiming at the buckling and postbuckling problems,buckling behavior and damage process of multi-spar composite box under bending-shearing load is researched in this paper. A self-defined nonlinear degradation rule was presented to simulate the propagation of the interface elements which were discretized with solid elements. In this model,the onset and propagation of damage can be predicted by quadratic failure criteria and mixed-mode strain energy release rate criteria respectively. cohesive elements are used to simulate the adhesive layer between skin and flange.composite structures were discretized with continuum shell elements. In this paper,a failure algorithm based upon Puck’s failure theory has been developed. Based on ABAQUS,a material degradation rule of composite was presented. The process of damage initiation,propagation and failure of the stiffened composite panels was simulated in detail. At last,a good agreement between tests and numerical prediction was observed.
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发布时间：2022-09-22 - 摘要：Hardness is the important factors to measure the quality of the gear. The gear processed by traditional technology has a lower tooth surface hardness because of the cut metal fibre. This article was based on copper,aluminum,steel Q235,for gear cold-beating. The gear organization change and its relationship with hardness distribution were researched on the basis of the material microstructure. In the experiment,the gear metal organization was not cut off after cold-beating,accompanying the crystal granular flow and the increasing dislocation density. Eventually,the gear organization was to be close strips fibrous tissue.It was found that the hardness and strength of the gear had a big enhancement after the two directions measurement of the tooth surface hardness distribution. This technology improved the processing surface organization and the overall quality of the gear.关键词：Cold-beating;Gear;Hardness distribution;Microstructure;Processing quality
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发布时间：2022-09-22 - 摘要：Through observing and analyzing the microstructure of the materials by SEM,the interfacial bonding and Strengthen Mechanism of silicone rubber reinforced by silica were investigated. Then,based on micro-mechanics and fracture mechanics theories,and the fracture energy of interface between silica and silicone rubber was introduced to reflect the interfacial mechanical characteristics,then the quantity was deduced that could reflect the reinforced effect of different silica feature and different silica content,and the analytical expression of reinforced material properties with fracture energy and the silica volume fraction were respectively observed. To prove the accuracy of the analytical expressions,the relative experimental data with theoretical curve were compared. This study provides the theoretical basis and technical support for the structural optimization and performance evaluation of silicon rubber and silicone foam material.关键词：Silica;Silicone rubber;Fracture energy of interfaces;Analytical expression
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发布时间：2022-09-22 - 摘要：For wear-out failure problem of synchronizer sliders in the tracked vehicle,the wear experiment and reliability estimation are developed to study in the paper. Firstly,Partial Least Squares（ PLS） Algorithm is used to process the test data and fit the mathematical expression between the wear rate and the influencing factors. The wear safety margin equation of slider is established based on the above expression. Moreover,a new hybrid reliability model and its convergence iteration algorithm are proposed based on the case that truncated random variables,fuzzy random variables,and interval variables are coexisting is studied. Finally,the example of wear reliability of synchronizer slider shows that the good convergence results can be obtained by the iterative algorithm,the hybrid reliability index has better adaptability,wear hybrid reliability index declines with the increase of the number of gear shifting. The approach proposed in the paper also provides a reference for the wear-resisting reliability design of synchronizer slider as well as giving the time of preventive maintenance.
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发布时间：2022-09-22 - 摘要：In order to achieve the effect of lightweight under the premise without weaken strength and stability of the structure,the main research object is based on the 2 AT gearbox which comes from the independent research and development of a car enterprises,establish its finite element model and its static analysis and modal analysis are carried out. Then,based on the analysis results,the stress,displacement,volume ratio and the first order natural frequency are the constraints. Finally,according to the optimization results,considering the manufacturing process and other requirements,the structure is improved in detail. The improved results show that the structural strength and the first order natural frequency are effectively improved,and the mass of the transmission case is reduced from 8. 238 kilogram to 7. 529 kilogram,which is reduced by 8. 6%,lightweight is realized.关键词：Gearbox housing;Topological optimization;Improved design;Lightweight
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发布时间：2022-09-22 - 摘要：Profile of a turbine disk was optimized in ANSYS Workbench platform and results suggested that disk stresses were decreased significantly while the disk mass was lightened as well. Present research demonstrates that ANSYS Workbench platform integrating geometry modeling,stress analysis and optimization module can minimize the difficulties of optimization work,the accuracy of surrogate model using Design of Experiments（ DOE） and Response Surface Method（ RSM） can satisfy engineering requirements and the application of combination optimization strategy involving DOE,RSM and Multi-Objective Genetic Algorithm（ MOGA） can obviously enhance the optimization efficiency.关键词：Turbine disk;Design of experiments;Response surface method;Optimization
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发布时间：2022-09-22 - 摘要：Taking the rotary worktable of a gantry machining center as the research object,the static and dynamic characteristics analysis and optimization design are carried out by using the finite element method. In order to increase the stiffness and reduce the weight of rotary worktable,the main design parameters are tested by Box-Behnken experiment design.Based on the design of experiment,sensitivity analysis is carried out for design parameters and the response surface model is established. Then,the multi-objective optimization algorithm is adopted to optimize the response surface model and combined with the production technique to determine the best optimization scheme. The results of optimization show that the maximum deformation is reduced by 36. 8%,the first natural frequency is increased by 5. 4% and the weight is decreased by 2. 6% by using above method to optimize the rotary worktable,which providing a new idea for the design and optimization of the rotary worktable.关键词：Rotary worktable;Finite element analysis;Sensitivity analysis;Response surface methodology;Multi-objective optimization
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发布时间：2022-09-22 - 摘要：In order to meet the design requirements of large wind turbine gearbox with high reliability,good dynamic characteristics and high robustness,based on the system dynamic model and considering the correlation among the failure modes,a multi-objective optimization design mathematical model is developed from the perspective of system dynamics,reliability,robustness and volume. An engineering example is present,the simulated annealing particle swarm optimization（ PSO） and interior penalty function method are used to solve the problem. The results show that the optimized design method and optimized design parameters can significantly improve the dynamic characteristics,reliability and robustness,and reduce the volume in the multi-stage transmission system of the load split type wind power increasing box.关键词：Wind turbine gearbox;Dynamics;Reliability;Robust;Optimization design
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发布时间：2022-09-22 - 摘要：Based on features and the principles of department of planetary gear kinematic,this thesis proposes a signal flow graph method to calculate the characteristic parameters of the complex planetary gear transmission system. To introduce the concept of signal flow graph to the single degree of freedom in the parameter calculation of planetary gear system,and adopt the solution to establish the ’XP’system,’PX’system,T-type compound system,∏-type compound systems and E-type mixed signal flow graph model of the system. Reuse the calculation rules of signal flow graph,and got a variety of planetary gear train speed relation of input and output of the transmission components,the conversion ratio of the transmission system. The method was intuitive,This way can do visual analysis of planetary gear transmission,and can deal with the characteristics of power flow analysis,A new technique for the complex planetary gear kinematic system characteristic parameter calculation of the research was provided.关键词：Single-degree-of-freedom;Planetary gear train;Kinematic characteristics;Signal flow graph
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发布时间：2022-09-22 - 摘要：In order to investigate the effects of finite element modeling parameters,such as the stiffness of flexible supporting structure and wind loads applying on tower,on the yaw bearing load distribution,a FE simulation model of MW-class wind turbine yaw bearing system was developed using Hypermesh and Ansys. Subsequently,the Hertz contact model was adopted to validate the nonlinear contact of the ball to raceway. Finally,the effects of varying stiffness of the restraint system,tower wind load and other factors on the performance of the bearing load distribution were discussed. The results show that with the increase of the length of the tower FE model,which means the decrease of restraint stiffness,load of the ball decreases and the theoretic fatigue life increases,and it tends to be constant when the modeling length of the tower is larger than 3 times of the yaw bearing’s diameter. Furthermore,considering wind loads applying on the tower,load on balls of the windward side decreases,while those of the leeward side increases,and the theoretic fatigue life increases.关键词：Yaw bearing;Load distribution;Flexible supporting structure;Wind loads
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发布时间：2022-09-22 - 摘要：The radial structural support made of epoxy FRP（ fiber reinforced plastic） of LNG fuel tank bears considerable compressive stress under impact load. However,it is hard to bear out of plane tensile stress and interlaminar shear stress. Thus,reasonable installation angle of pipes effectively guarantees the support ability of the epoxy FRP pipes. Based on it,the commercial finite element codes ANSYS with the method of fluid-structure coupling was used to stimulate the force condition of the epoxy FRP pipes,the correlation between the force of epoxy FRP pipes and installation angle of pipes was obtained. According to strength check of shear stress,radical tensile stress and the failure theory of Hoffman,the optimal installation angle of upper pipes was 30° and 60° of below the pipes. This study had an important reference value for safe operation of LNG fuel tank.关键词：LNG fuel tank;Epoxy FRP pipes;Fluid-structure coupling;Angle of pipes
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发布时间：2022-09-22 - 摘要：Contact pressure is stronger nonlinear along assembled length and hard to calculate in the interference fit with closed structure and micro dimension. A new method based on thin wall shell theory is presented to analyze the assembly pressure by solving integral equation. A simple model which is an assembly between thin wall cylinder with a fixed end and a rigid rotating shaft is solved. The results are compared with the results from ANSY,and in nice agreement. This method is easy to be applied on the design of the micro and high speed rotating machine.关键词：Mechanical design;Closed-connection;Integral equation;Interference fit
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发布时间：2022-09-22 - 摘要：The fatigue crack growth rate under different welding process was tested with standard compact tension specimen,the test data are processed by using incremental polynomial method and the crack growth rate curve under different welding process was obtained. The effect of different welding process on the crack growth rate was analyzed,the result show under the condition of the same crack length,the influence on fatigue life N,base material life < submerged arc welding life < heat affected zone life < manual welding life. and the fatigue fracture under welding process was analyzed,the mechanism of the crack growth rate under different welding process was discussed.关键词：Incremental polynomial method;Crack growth rate;Welding process;Fatigue fracture
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发布时间：2022-09-22 - 摘要：In order to ensure safe operation of heavy haul train and maintenance cost control of coupler,sub-models containing elliptical surface crack are established on fatigue crack zones of the coupler body and knuckle. Finite element method and interaction integral method are combined to analyze the stress intensity factor of the crack’s front edge in different parts under three opening modes,and identified the main propagation form; The stress intensity factor on different crack propagation stages in the traction platform of coupler body and traction surface of knuckle are analyzed and ensure the propagation path. The results show that the main propagation is I mode in traction platform and tail hole of coupler body,traction face and traction platform of knuckle,the crack propagation in lock chamber of coupler body is mainly the composite mode of II type and III type. With the length increase of crack,the stress intensity factor at the surface tip in traction platform zone and the knuckle traction surface is greater than the value in the crack depth tip,and when the crack extend to a certain size,the length of the crack along the surface is faster than the depth direction,and the actual simulation of crack propagation path is similar to the actual growth path to verify the accuracy of numerical simulation.关键词：Coupler;Sub-model;Surface crack;Stress intensity factor;Crack propagation
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发布时间：2022-09-22 - 摘要：The load data of Chinese users’ road and test field road is collected and analyzed in this paper. Through calculating the damage of each frequency band of load data,the corresponding test field feature matrix and user road target matrix are established,the equivalent load spectrum and damage model are compared,and a kind of damage model based on load frequency is set up. The model of damage correlation between user road and test field is obtained,the cycle number of different road is matched,and the optimal test standard is obtained. This paper provides a reference and technical basis for establishing a test field specification which conforms the user’s road characteristics accurately.关键词：Load frequency;Equal damage;Association model;Test Specification
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发布时间：2022-09-22 - 摘要：In order to study the fatigue life of the planet carrier in the actual working conditions,through the cutting experiment,the three-force loads was obtained,and the reconstruction function of the three-force load was established. The method of the SOR method was used to solve the reconstruction function. According to the roller structure parameters,the load torque of the planet carrier was performed. Using ANSYS Workbench transient dynamic analysis on the dynamics of the planet carrier,and the torque was loaded in the form of the time series to planet carrier,the results file to import ncode of planet carrier life prediction and simulation results show that: The service life of the output shaft and the side wall panel is small,which shows that the geometrical size of the output shaft is larger,and the stress concentration phenomenon exists.关键词：Regularization;Reconstruction;Planet carrier of shearer cutting unit;Fatigue life
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发布时间：2022-09-22 - 摘要：In this paper,the GTN damage model coupled with anisotropic yield criteria were implemented by establishing a user defined subroutine under the framework of LS-DYNA/Explicit finite element code. Taking 6016 aluminum alloy as the research object,the GTN damage parameters were identified by comparing the numerical and experimental tensile results. Using traditional inverse calibration method of regarding the force versus displacement curve as the only judgment criteria,a group of GTN parameters was determined,and also take into account of the fracture and the necking behavior,another group of GTN parameters was determined. Then the two groups of GTN parameters were applied to the tensile process simulation of 6016 aluminum alloy in turn. The results showed that the first group of GTN parameter cannot accurately reflect the actual fracture and the necking behavior,while using the second group of GTN parameters,the simulation results are in good agreement with the experimental results.关键词：Aluminum alloy;GTN damage model;Identification of GTN parameters;Judgement criterion;Fracture
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发布时间：2022-09-22 - 摘要：In this article,three dimensional elastic-plastic curved crack tip plasticity area under quasi-static loads has been mainly studied,and three dimensional curved crack tip plasticity area has been calculated as a practical application of a second order perturbation method,where the effects of quasi-static applied stresses and quasi-static normal and shear stresses on the boundaries of plasticity area are synthetically taken into considerations. Projected length of three dimensional curved elasticplastic crack tip plasticity area on straight crack extension line portion has been calculated by numerical solutions,diagrams have been constructed to analyse the transformation relationships between curved crack tip plasticity area size and three dimensional crack body geometrical measurement. Curved crack tip plasticity area size will decrease when three dimensional crack body thickness increases. When crack body thickness increases evenly,three dimensional curved crack tip plasticity area size will continuously decrease,furthermore,the decrease extent will be more and more slightly,and tend to plane strain state ultimately.Curved crack tip plasticity area size will increase when external loads increase with the same crack body thickness. A new theoretical model where curved crack tip plasticity area size was calculated has been established in three dimensional crack body.关键词：Three dimensional crack body;Curved crack;Plasticity area;Quasi-static applied stresses;A second order perturbation solution
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发布时间：2022-09-22 - 摘要：The 3 D FE models of reactor pressure vessel（ RPV） with an axial crackwere built. The aspect ratio of the crack is a/c = 1/2（ a = 30 mm,c = 60 mm）. The elastic-plastic fracture mechanics analysis of reactor pressure vessels with different cladding thickness（ h = 0 mm,4 mm and 8 mm） subjected to pressurized thermal shock（ PTS） transients was studied. The influence of cladding thickness on integrity has been discussed by using J-A2 method and J-Qmethod. The result shows that the Jintegral on the front of crack decreases with the increasing thickness of cladding. The Q and A2 valueincreases near the interface between cladding and base material. But the maximum of Q and A2 ofcladding on the front of the crack is near the deepest point of the crack and decreases with the increasing cladding thickness.关键词：Reactor pressure vessel;Cladding;Integrity of structure;Pressurized thermal shock
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发布时间：2022-09-22 - 摘要：The automated ball indentation method（ ABI） which is a new way to evaluate the mechanical properties of the materials has been studied in recent years. In order to explore the applicability of the ABI method to evaluate the fracture toughness of metallic materials,some ABI tests were performed by using the Q235B steel. The fracture toughness got from the ABI tests were compared with that from the conventional fracture tests. The results of comparison show that the error between the two methods was less than 10%. As a result,the ABI method can be used to evaluate the fracture toughness of the Q235B steel.关键词：ABI;Q235B;Fracture toughness
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发布时间：2022-09-22 - 摘要：Spring energized metal C-ring is an important basic component which is crucial to ensure the safety of nuclear power plant operation. The thickness of alloy lining which is one of the component part of metal C-ring will affect the sealing performance of C-ring. This article has built C-ring three-dimensional elastic-plastic finite element analysis model. Based on the reliability of the theoretical model which is verified by the experimental study,thickness of alloy lining on the mechanical behavior and sealing performance of C ring are discussed. The results show that under the same amount of compression,the thicker the alloy lining,the larger C ring stiffness slightly. But it has no obvious effect on the springback characteristic of C ring.When alloy lining thickness is small,the plastic strain value is higher which is adverse for the sealing performance. On the contrary,the greater thickness of alloy lining,the more uniform contact stress distribution,but too thick alloy lining can lead to sealing face wrinkles. So for millions of kilowatt nuclear reactor pressure vessel（ RPV） with a metal C ring,in order to ensure that metal C ring has good sealing performance,alloy lining thickness value of 0. 5-0. 7 mm should be recommended in the project,in order to ensure the sealing performance of C ring.关键词：Reactor pressure vessel;Metal C ring;Thickness of alloy lining;Mechanical property;Sealing performance
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发布时间：2022-09-22 - 摘要：To explore the damage of water jet to coal wall,built up the finite element calculation model of water jet breaking coal,applying software ANSYS/ls-dyna is used to numerically simulate the process of water jet breaking coal,the results show that the coal wall impact damage is most serious,the center around the center of coal wall damage is small,water jet shock wave attenuation faster. To explore the influence of different velocity of water jet to coal wall injury,the different velocity of water jet coal process in numerical simulation,the results show that with the increase of flow velocity,the stress of the coal wall are also increase,but the impact damage range is not big,around the center shows that increasing the velocity of shock wave attenuation speed. To explore water jet,affect the performance of coal winning machine cutting coal shearer drum is established in the presence of water jet conditions they finite element calculation model of coal,the two conditions of numerical simulation for the process of cutting coal,the results show that: under the condition of water jet and cutting tooth stress decreases,and with the increase of water jet velocity,the cutter tooth stress decreases,when the water jet velocity of 300 m/s,water jet assisted cutting coal and has good effect.关键词：High pressure water jet;Numerical simulation;The cutter tooth stress;Auxiliary cutting coal
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发布时间：2022-09-22 - 摘要：For the large deformation and distortion of the mesh on the numerical simulation of rubber,using the solving and transformation between grids of the adaptive technique of Abaqus software,the rubber model was remeshed several times. In this paper,the key parts of the packer were used as the research object and the final rubber deformation results were obtained by two remeshing before solving the mapping to the new mesh for further solving. The results of numerical simulation show that remeshing can reduce the occurrence of distortion and solve the problem of nonlinear analysis of large deformation caused by mesh distortion.Remeshing can improve the accuracy of data transmission between the old and new grid when the old mesh has a smaller distortion. It provides a significant research method for the sealing performance of the rubber,which also has some reference value for other hyperelastic materials.关键词：Large deformation;Remeshing;Packer;Rubber;Nonlinear
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发布时间：2022-09-22 - 摘要：In view of the 18 m~3 concrete mixing truck subframe has failure problem,based on the feasibility ofestablishing the subframe mechanical model,using the finite element to analyze the subframe static. Established the subframe finite element model,determined the different conditions in the working process of the mixer truck,it obtained the distribution of stressstrainunder different working condition through analysis the subframe static characteristic,the result of analysis indicated that there was failure phenomenon in maximum stress area of subframe under three working condition. Aimed at reducing stress and weight,it designed topological Optimization algorithm for optimizing the subframe structure,analyzed the light weighting result and stress statics characteristic of optimized subframe,the result indicated that the stress and weight of the optimized subframe lower than before,the failure problem of maximum stress areahas been solved,the optimized subframe can satisfy the enterprise design requirements.关键词：Mixing truck subframe;Static analysis;Failure;Topological optimization
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发布时间：2022-09-22 - 摘要：Three-dimensional crack growth was analyzed using damage tolerance design-based method and Franc3D to find cause of unexpected fatigue test failure of a turboshaft engine disk,showing that the crack propagation life was shorter than the test inspection interval which proved that damage tolerance design cannot meet the requirements and it was the major cause of the failure. Present research can provide damage tolerance design guidance for engineering application.关键词：Damage tolerance;Crack growth;Engineering application
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发布时间：2022-09-22 - 摘要：Aiming at the wear problem of the new-type metal belt type continuously variable transmission steel rope ring,the discontinuous contact geometry model and the finite element analysis model of the steel rope ring and the metal block in the WR-CVT transmission process are established,and the metal block and the steel rope ring are analyzed. The geometrical contact position and its stress and deformation; the results show that: the wire with the rope groove edge stress concentration,the maximum stress of steel wire is 1 273 MPa,the stress value is greater than the other strand wire stress,in the rope groove nonedge contact,The stress distribution of the wire in the strand is even and the maximum stress is 745. 6 MPa. The maximum difference between the steel wire is 0. 028 mm. The deformation of the wire in the strand is extremely poor,and the deformation of the steel wire loop and the steel wire in different sections is not uniform. Therefore,the wear of the steel rope ring at the discrete part of the bending section of the pulley is relatively serious,and it is relatively easy to malfunction when in the working state.关键词：WR-CVT;Discontinuous metal block;Wire rope ring;Stress and deformation
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发布时间：2022-09-22 - 摘要：The depth of the pipeline depression has different influence on the safety of X60 pipeline steel,combining Oyane ductile fracture criterion with numerical simulation method to study damage degree of the pipeline. Establishing three dimensional spherical concave defect pipeline model by finite element software and solving the model,discussing internal pressure influence of the pipeline and the indenter size on the relationship between the depth of sag and the damage degree of oil and gas pipelines.The results show that: when the depth of the pipeline depression is in a certain range the internal pressure is beneficial to resist ductile rupture. Once the depth of the pit exceeds 100 mm,the internal pressure will increase the extent of damage of the pipeline.In the case of the ratio of wall thickness to pipe diameter and the constant pressure in the pipe,the smaller the size of the indenter,the more serious the damage degree increases with the depth of the depression. Under certain conditions,when the pipe sag depth exceeds the standard 7% pipe diameter,the degree of pipe damage still meet the integral value I > 1. The Oyane ductile fracture criterion can be applied to the evaluation of sags in engineering projects because of the limitation of sag depth evaluation criteria.关键词：Pipe;Dent;Ductile fracture criterion;Damage degree;Numerical simulation
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发布时间：2022-09-22 - 摘要：In order to solve the problem that a input shaft of the agitator 34-M-2001 in a polypropylene device produce cracks repeatedly in the same key groove after a certain period of time. Considering the installation space,economic,practical and other important factors. This paper proposed an improvement plan and demonstrate the feasibility of the program. According to the main reasons for the crack caused by the input shaft and the fact that it is not suitable to change the structural size of other positions of the shaft. An improved scheme of changing the key connection mode of the shaft to the keyless connection mode was proposed. The theoretical analysis method and finite element method were used to demonstrate the improvement scheme. The results showed that the keyless connection could significantly improve the safety factor of the shaft; It could also avoid the occurrence of stress concentration in the key groove,so the maximum stress value of the shaft under rated operating conditions was greatly reduced. If the program is used,the mechanical strength of the input shaft could be greatly increased,and the service life of the shaft could also be effectively improved. The above researches have a certain reference value in improving the mechanical performance and service life of the key transmission parts.关键词：Shaft;Crack;Key connection;Stress concentration;Keyless connection
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发布时间：2022-09-22 - 摘要：According to the AC-type five-axis machine used in Lab,the kinematic matrix transformation of the five-axis coordinate is analyzed,and the mathematical relation between the tool axis vector and the angle of the rotation table is finally obtained. Then the inverse kinematics equation is established to realize the conversion of machine coordinates and programming coordinates operation. The corresponding post-processing program has been developed. The angle of the C-axis during the rotating shaft is greatly changed at the singularity configuration,which may exceed the system performance limit and lead to quality problems such as gouge on the surface of the workpiece. A method is proposed that the Cutter Location data could be adjusted to avoid the singular position by interpolation. VERICUT simulation of the tool path for the S surface is carried out,and the C-axis angle is actually reduced at the singular point,which verifies the correctness of the inverse kinematics equation and the feasibility of the proposed method.关键词：Inverse kinematics;Post processing;Singular region;Interpolation
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发布时间：2022-09-22 - 摘要：With the development of Micro-satellite,the number of satellites launched every year in the world is gradually increasing. As a key technology in micro-satellite,the release device is required as simple and reliable,without the production of redundancy. Of these release device,the pyrotechnic device is the most widely used. To avoid the formation of space trash by the broken hold-down rod,the unlocked rod needs to set the capture cap to limit its movement. So,the strength and structure form of the capture cap directly influence its functions. Based on the non-linear analysis software ABAQUS,the characteristics of the capture cap’s structure and its fixed form are studied and the weak position of the release device is located and verified. The results of simulation and electric explosion tests show that the weak position of the device can withstand the impact after the pyrotechnic release. This method can be applied to aeronautics and astronautics fields,providing an effective way for the analysis of various types of unlocking devices,such as satellite-rocket separation and rocket fairing separation.关键词：Release device;Impact dynamic characteristics;Strength;Electro-explosive test
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发布时间：2022-09-22 - 摘要：Cross section microstructure and fractography of a Auto high strength assembling bolt of 35 steel were observed by optical microscope（ OM） and electron scanning microscope（ SEM）. The hardness of the bolt was measured by HR-150A rockwell hardness tester. The fracture failure of the assembling bolt was analyzed. The results indicate that quenching and tempering treatment on the assembling bolt meet the national standard,but the strength was decreased by the quenching crack generated during quenching. The extension of quenching crack that due to the external force result in the fracture failure.关键词：Assembling bolt;Fracture;Fracture analysis
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发布时间：2022-09-22 - 摘要：one support frame was designed for the independent suspension of 8 × 8 off road chassis,on purpose of that connect two suspension brackets. The frame was damaged after vehicle enhance road test with the weld seam cracked and the bolt cut off. According to the failure performance,the model about independent suspension included support frame was built for failure analysis,and the failure was caused by uncoordinated deformation of different parts; the support frame is improved and verified by simulation and test.关键词：Independent suspension brackets;Support frame;Failure;Improvement
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发布时间：2022-09-22
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