最新刊期
期 6 ， 2017
- 摘要：Based on the basic equation of electromagnetic elastic motion and the expression of electromagnetic force,the electromagnetic vibration equation of the rectangular thin plate in transverse magnetic field is obtained. According to a rectangular plate with one side fixed and three other sides simply supported,time variable and space variable are separated by the displacement modal expansion and the method of Galerkin,and the two-degree-of-freedom internal resonance nonlinear vibration differential equations are obtained. By the method of multiple scales,the coupled characteristic equations of the first two order vibration modes are obtained under the case of 1∶3 internal resonance. By an example,the time history response diagrams and phase diagrams of the internal resonance amplitude are got. The effects of internal resonance characteristics with initial value and the thickness for undamped system and also the magnetic field intensity for damping system are discussed respectively. The results show that the system presents obvious nonlinear internal resonance characteristics.关键词：Rectangular current-conducting thin plate;Internal resonance;Magnetic field;Multiple-scale
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发布时间：2022-09-22 - 摘要：The bending stiffness of axis is an important influencing factor in the rotor dynamics. Rotor disc thickness has a great effect on the bending stiffness. The finite element software ANSYS is used to establish one-dimensional and threedimensional models of the traction motor rotor system for railway locomotive. The impact of the disc thickness on the critical speed is also analyzed. With the reduction of the disc thickness and concentration of disk mass,the first critical speed decreases linearly. In addition,when the disk mass is concentrated onto a very thin disk,the critical speed calculated by three-dimensional model is close to the calculation result of one-dimensional beam element method. Based on this way,the application range of a one-dimensional model is then discussed. Finally,unbalanced response analysis of three-dimensional model is given to discuss influence of different disc thickness,unbalance mass and damping ratio on the unbalance response.关键词：Bending stiffness;Disc thickness;Critical speed;Unbalance response
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发布时间：2022-09-22 - 摘要：The nonlinear approximation model of cracked rotor,to explain the nonlinear phenomena,is constructed. The nonlinear output frequency response function（ NOFRF） and the theory of nonlinear frequency spectral analysis are illustrated.Based on this theory,the simulation analysis of cracked rotor is accomplished. The analysis provides insight into how new frequency generates. Additionally,the nonlinear phenomena of cracked rotor,including the generation of super-harmonic components and sub-resonances are explained. Experimental result shows that the higher order NOFRF is sensitive to the racked rotor with cracks of different depth. This research study establishes an important theory basis for accurate fault diagnosis of cracked rotor.关键词：Cracked rotor;Nonlinear frequency spectral;Fault diagnosis;Nonlinear output frequency response functions（NOFRF）
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发布时间：2022-09-22 - 摘要：Extracting the information of frequency-amplitude of the track irregularity through the Hilbert-Huang Transform（ HHT） spectrum,the clustering analysis is carried on the track irregularity HHT spectrum for the railways of same operating condition,then we can get the track irregularity marginal spectrum standard（ character） matrixes that are proper for describing different operation speed and the dynamic indexes,which will affect the security and comfort operation of the railway,based on these,the model of track irregularity HHT marginal spectrum-mahalanobis distance is built for the differentiate of running speed for the railway line and macroscopic predicting of the rail sections that would serious affect the railroad’s security and comfort operation.关键词：Track irregularity;Hilbert-huang marginal spectrum;Mahalanobis distance;The standard（character） matices;Frequency-amplitude structure
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发布时间：2022-09-22 - 摘要：To improve cutting tool wear condition monitoring accuracy,wear condition monitoring method based on artificial bee colony-BP neutral network is proposed. Force sensor and vibration sensor are used to design monitoring platform. Matching pursuit algorithm is used to denoise for the signal. Characteristic parameters are extracted from time domain,frequency domain,and time-frequency domain. These characteristic parameters are reduced dimensionally by kernel principal component analysis,and fifteen parameters are ensured at last. Cutting tool wear condition recognition method based on artificial bee colony-BP neutral network algorithm is presented, and artificial bee colony algorithm is used to optimize neutral network parameters. The experimental result proves that the recognition accuracy is 78. 75% by BP neutral network and 100% by optimized BP neutral network algorithm respectively.关键词：Cutting tool;Wear condition monitoring;Matching pursuit algorithm;Kernel principal component analysis;Artificial bee colony-BP neutral network algorithm
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发布时间：2022-09-22 - 摘要：Aiming at the disadvantages of traditional method of stochastic resonance（SR）,for example,the SNR of output response is low and the self-adaptive time of parameters is long for single self-adaptive SR,and the parameters are hard to set for array-enhanced SR,a array-enhanced self-adaptive SR based on extremum disturbed and simple particle swarm optimization（tsPSO） algorithm was proposed,which has realized an effective and fast detection of the weak signals under conditions of large parameters under high strong noise background. Firstly,the parallel SR system was adopted to enhance the SNR of the final output response by analyzing the output responses of sub-systems with the theory of auto correlation analysis and composing them.Secondly,in each sub-system in parallel,the cascaded SR system was adopted to enhance the SNR of output responses further.Finally,the parameters in each sub-systems in parallel were optimized with the SNR of output response as the fitness function,and the sectioning search and tsPSO algorithm were used to shorten the self-adaptive time of the parameters at the same time. The effectiveness of the method in the paper were proved by the results of simulation experiment and engineering application.关键词：SR;Array-enhanced;Auto correlation analysis;Self-adaptive;Extremum disturbed and simple particle swarm optimization（tsPSO）
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发布时间：2022-09-22 - 摘要：The stiffness of unidirectional laminates will reduce due to damage under static tensile loads. By analyzing the failure process of unidirectional laminates,study on the effect of stiffness reduction caused by the longitudinal,transverse and shear stress components was conducted. A new model of stiffness progressive reduction considering loads and ply angles was established. The rationality of this model was verified by static tensile tests of series of T700/YPX3001 unidirectional laminates with different ply angles. A numerical simulation based on the proposed model of the failure process of unidirectional laminates under static tensile loads was implemented. The analysis results are in good agreement with experimental results.关键词：Composite;Unidirectional laminate;Stiffness reduction;Elasticity modulus;Numerical simulation
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发布时间：2022-09-22 - 摘要：The test method of fuselage panel subjected to shear load is an important technique for aircraft structure strength research. A new shear test method is proposed based on the property of aircraft fuselage panel subjected to shear load. "D"jig and arch angle connectors is designed to simulate the circular structure of fuselage,and the shear stress is applied through the torsional form of single closed box structure,consisting of "D"jig and fuselage panel through hinge. A test panel and a set of fixtures were designed and manufactured,and validation test were conducted. Validation test verifies the validity and engineering feasibility of this method,and the stress distribution of panel in test is uniform as well as in a good agreement with theoretical analysis. In addition,this test method avoids to design a transition section and a loading section with the similar length of aircraft fuselage panel,and saves assembly work and test expenses. The stability test of the fuselage panel on civil aircraft adopts this new method at present.关键词：Fuselage panel;Shear load;Boundary condition simulation;"D"jig;Arch angle connector;Shear stress
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发布时间：2022-09-22 - 摘要：Considering geometry structure characteristics of the manipulator being calibrated and using modified 5-parameter method to describe its geometric patameter errors,an end position error model of the manipulator is proposed. After the zero position calibration of the manipulator,measurement data used in calibration process is obtained by one time ballbar installation.An error identification model is built based on the geometric constraints of closed kinematic chain—composed of the manipulator and ballbar as well as the end position error model,then the manipulator geometric parameters errors are calculated using nonlinear least square iterative method. A calibration experiment is completed,and the errors of the manipulator are compensated by integrated error compensation method. Along two given test end point paths,the ballbar length variation decreased from0. 395 mm,0. 456 mm to 0. 005 mm,0. 010 mm respectively before and after calibration. The research shows that the calibration method is effective and correct,and the position accuracy of the manipulator is improved.关键词：Manipulator;Ballbar;Parameter errors;Calibration
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发布时间：2022-09-22 - 摘要：The different strengths induced by the different deformation modes for 304 austenitic stainless specimens were measured by using nonlinear ultrasonic wave technique. Results showed that nonlinear ultrasonic parameter increased with the increasing yield strength of 304 austenitic stainless steel induced by the tensile deformation,asymmetrical cyclic deformation and early symmetrical cyclic deformation. A power-law relation was proposed between nonlinear ultrasonic parameter and yield strength according to the dislocation string model of acoustic nonlinearity and the theory of flow stress of metallic material. The measured data was fitted by the power-law relation,and then the sensitivity coefficient of nonlinear ultrasonic parameter to strength λ under the condition of tensile deformation,asymmetrical cyclic deformation and symmetrical cyclic deformation was found to be 3. 27 × 10-7,6. 91 × 10-6 and 1. 95 × 10-5,respectively. Microstructures analysis indicates that the differences of the three sensitivity coefficient λ might be due to the different evolution mechanism of dislocation structures and the content of martensite in different deformation conditions.关键词：Nonlinear ultrasonic wave;Austenitic stainless;Deformation strengthening;Microstructures
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发布时间：2022-09-22 - 摘要：Aiming at virtual loads resulted from the loading inside strain-gage station,a method of considering the loading inside strain-gage station was given for flight load measurement based on superposition principle. Also the above method was applied to certain non-root flight load measurement,and the effects of the loading inside strain-gage station on load equation and measured flight load were discussed.关键词：Flight load measurement;Strain gage calibration;Loading inside strain-gage station;Corrected load equation
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发布时间：2022-09-22 - 摘要：In order to control and improve the manching quality of helical surface,studied method about the measurement,put forward a analysis method of machining error based on the data of contact digital measuring technique. According to the characteristic of spiral curved surface,the characteristic line is measured by using the custom fixture and the cross measuring head. The model of lead helix、measuring section extraction and machining error are proposed. To ensure the accuracy and efficiency,the model algorithm and data input and visualization is completed. The results of rotor machining error show that it can measure the helical surface meeting rapid detectio requirements through the method and has certain application value.关键词：Helical surface;Inspection method;Machining error;Data processing
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发布时间：2022-09-22 - 摘要：The accurate calculation of load-carrying capacity of integrally stiffened panels under axial compression is the key factor for designing and analyzing of wing panel,which is essential for the aircraft wing structural efficiency and weight control,it is necessary to study a method that can calculate the load-carrying capacity of integrally stiffened panels under axial compression accurately. This paper proposes the equivalent calculating method based on the bending resistance of stiffened panels,axial compression tests of stiffened panels have verified the accuracy of the calculation method for the three types skin effective width,influences of shot peening on compressive strength of wing stiffened panel are considered by comparison on crippling test results of shot peened and unpeened panel element,afterwards,a more perfect and accurate,practical engineering calculation method is established.关键词：Integrally Stiffened Panel;Axial Compression;Load-carrying capacity;Calculation method
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发布时间：2022-09-22 - 摘要：The earlier failures are always occurred in the H13 steel continuous extrusion-wheel die for section copper and its alloy. The experimental analysis on the microstructures evolution of the extrusion-wheel die after different service times were made,and the tests showed that the martensite resolved into tempered martensite and the hardness reduced gradually in the surface layer of the groove of continuous extrusion-wheel die in the early stage service. As service time delayed,the martensite resolution accelerated and large quantities carbides precipitated,and the thermal fatigue cracking initiated from the subsurface of the groove. After that the services proceed,the martensite resolved completely and carbides coarsen seriously. The fatigue cracks of the subsurface layer drove towards the surface and propagated into the interior of the groove on the assistance of the melting copper alloy,which resulted in failure of the groove of the continuous extrusion-wheel die.关键词：H13 steel;Copper and copper alloy profile;Extrusion-wheel die;Microstructure evolution
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发布时间：2022-09-22 - 摘要：Using two different kinds of three-point bend specimens,J-integral values calculated based on plastic area of under load-notch-opening displacement curve, according to GB/T 21143-2014 and GB/T 21143-2007, GB/T 2358-1994 appendix D two standards,combining with the two different methods to calculate the J-integral values. The results showed that with respect to the different crack extension △a,J-integral values from low to high values,the average relative deviation of two methods J-integral value < 2. 0%,illustrated with GB/T 21143-2007,GB/T 2358-1994 Appendix D combined two standards can also accurately calculate the J-integral values,a method of calculating the J-integral values using a three-point bending specimen was provided.关键词：J-integral value;Fracture toughness;Three-point bend specimen
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发布时间：2022-09-22 - 摘要：As a new smart material,dielectric electroactive polymer can be used to transforming mechanical energy such as wind power and water power into electrical energy. The energy harvesting mechanisms and working cycles of DEAP transducer were investigated. Three different cycles including constant charges,constant electrical voltage and constant electrical field were compared. Based on the working cycles,the energy conversion between mechanical energy inputted and electrical energy generated have been studied. With the proposed model of DEAP transducer,the force-stroke of generator in the stretching process with voltage on and the retracting process with voltage off were determined. With the force-stroke of generator,the energy generated and energy conversion efficiency were calculated. It is demonstrated that the stretch displacement and bias voltage are the main factors influencing the amount of electrical energy generated and the efficiency of energy conversion. In addition,the theoretical analysis results were validated by the experiments.关键词：Dielectric electroactive polymer;DEAP;Energy harvesting;Energy conversion
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发布时间：2022-09-22 - 摘要：Based on the synthesis of well-distributed Cu/CNTs composite powder,Cu/CNTs composite material was prepared by spark plasma sintering（ SPS）,and the sintering temperature is 650℃,the sintering pressure is 35 Mpa,the holding time is 10 min. We studied the microstructure and properties of Cu/CNTs composite material for various content of Cu/CNTs powder. The results show that CNTs distributed uniformly along the grain boundary in copper matrix and the CNTs-Cu interface with a certain binding force is formed and the conductivity、hardness、tensile strength are 82. 8% IACS、96. 4 HV、417 MPa,and the hardness as well as tensile strength are maximum when the percent of Cu/CNTs powder is 20%.关键词：Cu/CNTs composite material;Microstructure;Conductivity;Mechanical properties
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发布时间：2022-09-22 - 摘要：The defect arising from the thermal coefficient mismatch of different phases was an important factor of reducing strength in eutectic composite ceramic. Based on the equivalent inclusion method and the interaction direct derivative（ IDD）estimate,stress intensity factor of annular defect under residual stress field and applied loading was calculated,and annular defect stability was analyzed. And the influence of particle stiffness,shape and volume fraction was investigated. Results indicated that,the crack nucleation was most easily produced in the oblate particle; stiff particles caused average applied stress reduced in matrix,and it reduced greater when the stiff particle was prolate elliptic,while the soft particle had the contrary effect. Stress intensity factor of defect was controlled by residual stress as the defect extension was small while it was controlled by applied stress for large defect extension. Prolate elliptic particle was beneficial to improve strength.关键词：Inclusion;Defect;Defect stability;The equivalent inclusion method
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发布时间：2022-09-22 - 摘要：To suppress the brake noise of automotive disc brake systems,a stability analysis method of disc brake systems with random and fuzzy parameters was proposed. The proposed method was mainly based on the techniques of response surface methodology（ RSM）,complex eigenvalue analysis and reliability analysis. In the proposed method,the hybrid uncertainties existing in a disc brake system were described by random and fuzzy parameters,and the parameterized model of the damping ratio of unstable mode was established by RSM. The limit state function used to value system stable reliability was built up,and the reliability analysis was carried out for the uncertain brake system with random and fuzzy parameters. In order to explore the influence of system parameters on system stability,the parameter sensitivities were carried out by the global sensitivity analysis of Morris method. By introducing the proposed method for the stability analysis of a disc brake system with random and fuzzy parameters,the reliability and the parameter sensitivities were calculated. The numerical results show that the stability of this brake system can be improved by reducing the densities of back plates or by increasing the thicknesses of back plates.关键词：Random parameter;Fuzzy parameter;Complex eigenvalue analysis;Reliability analysis;Morris method
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发布时间：2022-09-22 - 摘要：In order to improve dynamic reliability and work efficiency of shearer,the rigid-flexible coupling model of SL1000 shearer was constructed,the stress and reliability information of rocker shell were obtained through dynamic simulation;Based on BP neural network,the rocker arm shell’reliability of other conditions were predicted,and the relationship between it and coal seams consistent coefficient、tract Dion speed、roller cutting depth were analyzed,and the traction speed of shearer was optimized. The combination of virtual prototyping technology and BP neural network provides a new concept and convenient method for the prediction of shearer’work reliability,and it has important theoretical significance and engineering application value.关键词：Shearer;Rocker arm shell;Reliability;Virtual Prototyping;BP neural network
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发布时间：2022-09-22 - 摘要：A robust-optimization-design method based on sensitivity’s analysis of the crane metal structure is described. It considers uncertain factors existing in the design of crane metal structure. And the multi-objective robust-optimization design model about crane metal structure is constructed on the bases of the sensitivity and the grey correlation theory. Taking the bridge crane girder as the research object and getting the best solution of the multi-objective optimization problems by grey-absolutecorrelation degree and the MATLAB optimization-design toolbox on the basis of the sensitivity analysis for its each performance.The results shows that when considers the uncertain factors of structure,the model about robust optimization design constructed in this paper and the grey correlation degree of multi-objective optimization method can ensure the steady and safety,and also can lose weight of the crane girder structure. The paper provides the technical guidance for the robust optimization of the other complex structure.关键词：Optimal design;Sensitivity design;Robust design;Grey relational degree
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发布时间：2022-09-22 - 摘要：On the basis of heat transfer theory,the bulk temperature field of constantly no clearance precision steel ball transmission is studied and the formulas of relative sliding velocity,maximum contact stress,and friction coefficient are derived.Meantime,the mathematical models of heat flux of engagement pairs and convention heat transfer coefficient of each region are established. By the use of FEM software,the bulk temperature field of engagement pairs are evaluated. Besides,the effects on bulk temperature field caused by design parameters and working parameters are analyzed. It is shown that the bulk temperature of central plate is higher than that of planetary plate and the bulk temperature field is apparently influenced by design. The research findings lay a theoretical foundation for the thermo-elastic coupling analysis and reliability study of constantly no clearance precision steel ball transmission.关键词：Constantly no clearance;Precision steel ball transmission;Engagement pair;Bulk temperature field;Heat flux
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发布时间：2022-09-22 - 摘要：It is difficult to optimize flexibility robustness because the robust optimization of multiple response for cell injection 3 RRR compliant parallel micro motion platform flexible parts are existed"under"deformation or"over"deformation. a new method is proposed to solve the robust optimization of multiple response which combine the Taguchi method and satisfaction function. Firstly,the hinge motion model compliance of micro-platform multi-directional is established and the response surface test design based on this model. Secondly,the taguchi method is introduced to analyze the stability of multiple response. Finally,the satisfaction function is used to taken the issues of multiple response optimization into maximal value of overall satisfaction and get the robust optimization design plan under the restriction of multiple response flexibility. Examples show that this method can provide a new solution for robust optimal design of the multiple response of flexible hinge.关键词：Multiple response;Taguchi method;Satisfaction function;Robust optimal design;Flexible hinge
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发布时间：2022-09-22 - 摘要：As for the smooth problems in the conjugate surface arising from hob tooth root and flank arc edge during the processing of new double helical synchronous belt’s pulley,the broken line generation mechanism at the conjugate tooth profile was investigated with spatial differential geometry and meshing theory. Through the undercut boundary curve characteristics analysis of the hob tooth profile surface,the parameter constraint conditions used to eliminate the pulley surface singularity was determined,and the eliminating profile singularity modification method by increasing the transition arc curve slope face on the hob tooth profile was proposed. Then the tooth profile hob practice model with undercutting constraints was built. The timing belt pulley’s hob tooth normal face profile parameters after modification was obtained based on coupling analysis of the modification pulley profile and double helical synchronous belt. The simulation shows that the pulley profile’s top curve after modification is smooth,it can reduce the abrasion during the meshing process and provide a useful modification method to improve the surface smoothness of the tooth belt.关键词：Hob;Timing belt pulleys;Tooth profile modification;Undercut boundary curve;Simulation
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发布时间：2022-09-22 - 摘要：A random variable with statistical property was built; by means of the statistical theory hypothesis testing,and using the sample data,the change rule of random variable distribution parameter was analyzed,the evaluation method of the pressure vessel burst pressure calculation formula precision was established. Based on 27 groups of steel thin-wall single-layer cylinder burst pressure measured data,related factors influence on the precision of mid-diameter formula and Faupel formula were studied. The research shows that:（ 1） For thin-wall single-layer cylinder,with the vessel materials yield ratio ranging from0. 488 9 to 0. 0. 966 0,and the diameter ratio ranging from 1. 010 to 1. 5,the yield ratio value is not obviously affect the standard deviation and mean value of mid-diameter formula corresponding to random variable; although yield ratio value is no significant effect on mean value of Faupel formula corresponding to random variable,but if experimental data of yield ratio was lower than0. 499 7,Faupel formula corresponding to random variable standard deviation is significant increase;（ 2） In above scope,middiameter formula corresponding to random variable coefficient of variation is less than Faupel formula ’s,and mid-diameter formula with higher concentration,for calculating steel thin-walled single layer cylinder burst pressures,mid-diameter formula is better than Faupel formula;（ 3） Adjust the materials yield ratio ranging from 0. 538 8 to 0. 966 0,and the diameter ratio ranging from 1. 013 3 to 1. 5 accordingly,the variation coefficient of Faupel formula corresponding to random variable is significantly decreased,and the concentration of Faupel formula is significantly improved.关键词：Pressure vessel;Burst pressure;Calculation formula;Yield ratio;Precision;Evaluation method
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发布时间：2022-09-22 - 摘要：Freeze fabrication process is a new modern green additive manufacturing technology. During the depositing process,the freezing time needed would change with the increase of the deposition layer. The paper established the temperature field model of deposition process and simulated the temperature change of deposition process using numerical simulation. The relationship of depositing time with initial temperature,the number of depositing layer,environment temperature during the ice part building process and waiting time between layer and layer was analyzed and the minimum waiting time was found with a better depositing efficiency. The experiment result is also agree with the model proposed.关键词：Freeze fabrication;Modeling and simulation;Numerical simulation
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发布时间：2022-09-22 - 摘要：Over-speed preloading is one of the important parts in the process of impeller manufacturing,it is a method of checking the impeller’s quality and a subtle strengthen treatment. To explain the mechanics principle of over-speed preloading,finite element models of the impeller are established and then we simulate the process of the over-speed preloading. Firstly,an elastic-plastic analysis is carried out on the semi-open impeller,and the results show that there will be residual stress generated in the high stress regions after preloading,which can reduce the maximal stress produced in the later normal loading. Secondly,analysis of the fatigue life of the semi-open impeller at two different conditions of the starting and stopping and the speed rotating is accomplished through FE-SAFE. By contrast with the results of processing with and without over-speed preloading,we can see that the treatment of over-speed preloading can improve the fatigue life of impeller in a great extent. Moreover,over-speed preloading can also avoid the occurrence of fatigue damage in some conditions of impeller’s speed rotating. Finally,fatigue analysis has been done for closed impeller in a variety of different loading conditions. The results show that the impeller treated with over-speed preloading can resist larger aerodynamic load and avoid fatigue damage.关键词：Impeller;Over-speed preloading;Residual stress;Fatigue life
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发布时间：2022-09-22 - 摘要：To solve the optimization problem of edge distance in titanium alloy sheet during a new aircraft development stage,a three dimensional FE model was built on ABAQUS platfom. The effect of edge distance on residual stress distribution was analysised with TC4 titanium alloy by interference-fit strengthening technique under cylic loading. The study indicates that a considerble reduction of fatigue life is found with a lower egde distance ratio（ L/D）,also,the location of fatigue damage is moving against the hole. Fatigue damage happens in the margin part with edge distance ratio（ L/D） less than 2.关键词：Titanium;Interference-fit strengthening;Edge distance;Finite element method;Fatigue life
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发布时间：2022-09-22 - 摘要：The fracture toughness of material are affected by the constraint at crack tip. In order to assess the structural integrity of cracked structure accurately,it needs to obtain the constraint dependent fracture toughness. In this paper,based on the unified constraint parameter Apand the unified correlation line with fracture toughness,a determination method of constraint dependent fracture toughness of structure is proposed. Furthermore,the constraint dependent fracture toughness and fracture bending moment of pipeline with different crack lengths and depths are calculated. The results show that the fracture toughness and fracture bending moment are depending on the crack tip constraint closely,the crack with a/t = 0. 5 and a/c = 0. 5 0. 6 will fracture easily. This study is with great significance of developing structural integrity assessment which incorporates constraint effect,increasing the reliability of structure,and so on.关键词：Constraint;Fracture toughness;Pipeline;Structural integrity
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发布时间：2022-09-22 - 摘要：The pure CO2 keeps in dense phase when the pressure is higher than the critical pressure and the temperature is lower than the critical temperature. The crack-driving force model for CO2 pipelines was established and solved based on Maxey’s fracture tip pressure-fracture propagation velocity correlation,the sonic-fracture velocity correlation and the BWRS equation of state. The proposed model was applied to simulate the crack-driving force of dense phase CO2 transmission pipelines at different temperatures and with different N2 concentrations. At the same operation temperatures,the crack-driving force decreases with increasing CO2 content in mixtures. When the CO2 content keeps a constant,the crack-driving force increases with increasing temperatures. In order to reduce the crack-driving force and the probability of fracture propagation,impurities in CO2 mixtures should be removed,and the pipeline should be operated at low temperatures as long as no phase transition occurs.关键词：CO2;Pipeline;Fracture propagation;Crack-driving force;Mathematical model
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发布时间：2022-09-22 - 摘要：The flexibility-based damage identification methods have attracted much attention in structural engineering field in recent years. In this paper,three derived sensitivity methods based on structural flexibility are presented for damage identification,namely,the diagonal sensitivity,the principal eigenvector sensitivity and the unfavorable unit load distribution sensitivity. Compared with the original flexibility sensitivity technique,the effect of truncating higher-order modes can be partly reduced in the derived sensitivity methods. A three-span continuous beam was used to illustrate the feasibility and superiority of the derived sensitivity methods for structural damage detection. Results obtained by the first four modes and only the first mode are both given for comparison. When the first four modes are used,it is found that the principal eigenvector sensitivity and the flexibility sensitivity methods can achieve more accurate results than those obtained by the diagonal sensitivity and the unfavorable unit load distribution sensitivity techniques. When only the first mode is used,one can see that the principal eigenvector sensitivity and the unfavorable unit load distribution sensitivity techniques are more effective than the flexibility sensitivity and the diagonal sensitivity methods. Consequently,it is necessary to chose suitable sensitivity technique for the specific engineering problem to get satisfactory detection results.关键词：Damage identification;Derived sensitivity;Structure;Flexibility
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发布时间：2022-09-22 - 摘要：This paper introduces an analysis method,which combines the crack fatigue prediction theory and rubber elastic structure optimization,to optimize the structure of a rubber bushing. Using stress in rubber as the optimization parameters,the method can predict fatigue life of the rubber bushing by applying crack energy density. In summary,using the fatigue result,this new analysis method can predict rubber fatigue life and provide optimized structure of rubber parts. This combination of the crack fatigue prediction theory and rubber elastic structure optimization ensures the convenience of engineering application and provides a guidance to reduce rubber structure developing time.关键词：Rubber bushing;Multiaxial loading;Crack energy density;Fatigue life;Optimization
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发布时间：2022-09-22 - 摘要：Results from an experimental and analytical study of a curved stiffened aluminum panel subjected to combined internal pressure and axial tension loads are presented. The behaviors of the crack propagation and characteristics of the residual strength for fuselage panel are investigated. Stress intensity factors associated with different crack lengths are analyzed by using ANSYS software,and the crack propagation cycles are predicted. The residual strength curves are calculated based on the linear elastic fracture mechanics by comparison of experimental results. Analysis results agree well with the test results. Both results can provide the bases for the damage tolerance design and assessment of fuselage structure.关键词：Fuselage panel;Longitudinal crack;Damage tolerance experiment;Crack propagation;Residual strength;Stress intensify factor
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发布时间：2022-09-22 - 摘要：In order to get the dynamic characteristics of wind turbinemain shaft bearing under different working conditions,tooka 1. 5 MW wind turbine manufactured by one turbine factoryas an example,the main shaftwassimplifiedabstractly and the axial and radial loadon main shaft bearingwere given by blade element theory. The 3 D model of main shaft bearingwasdrawn in UG and imported into ADAMS toestablish the multi rigid kinetic model of main shaft bearing,the interactionsbetween the balls of main shaft bearing and inner ring,outer ring and separator wereanalyzed under threedifferent working conditions. The analysis resultsindicate that the interaction forces between the balls of main shaft bearing and inner ring,outer ring and separator aremaximal during theemergency brake period of wind turbine,it is second during thesuddenvariation periodof the wind turbine revolving speedand it is minimalfrom starting until running steadily.关键词：Wind turbine generators;Main shaft bearing;Dynamic characteristic;Kinetic model
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发布时间：2022-09-22 - 摘要：In slim hole sidetracking drilling,88. 9 mm diameter direct type drill pipe can effectively reduce the pressure loss along the path and increase the rock carrying,also can transfer torque effectively,rotary drilling to improve drilling efficiency. In order to meet the actual needs,improving the carrying capacity of 88. 9 mm drill pipe joint in slim hole drilling,this paper presents a low tooth-double shoulder-special thread. By 3 D Finite Element analysis,the performance of thread connection were studied,including the stress in three-dimension under different loads and the limit torque under different axial tensile loads. And draw out the limit torque curve of the tool joint. Forming a quickly method to determine the tool joint limit torque under different tension. The research is of great significance for guiding the selection and optimization of the drill pipe joint,analyzing the limit load of the drill pipe joints and determining the the limit drill depth.关键词：Slim hole sidetracking;Drill pipe special button;3D finite element analysis;Stress characteristics;Extreme operating torque curve
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发布时间：2022-09-22 - 摘要：The hourglass mode emerging from the analysis of the lateral pressure for the submarine cable,which makes effect of the accuracy of the simulation results. Different hourglass control modes were adopted to find out the reasons for the formation of the hourglass. and emphasis on distinguishing the parts which have serious hourglass mode and the control method were introduced. Firstly this paper finds out which components have the serious hourglass mode. Then several control methods of the hourglass mode were studied and compared by adjusting the different hourglass control coefficient,the most effective control method was concluded and a more accurate result was got.关键词：Mechanical manufacture and automation;Effective control method;Hourglass control coefficient;Hourglass mode
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- 134
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发布时间：2022-09-22 - 摘要：Excessive deflection of the truck scale body is a primary cause leading to measurement error. The prestressedtreatment method of steel structure was applied to the welding procedure of the truck scale body and U-beam. The mathematical relationship model between the preload and the deflection and stress of the truck scale body was constructed. In addition,the prestressed-treatment process was carried out based on finite element method. The results show the deflection of the simulation results is consistent with the changing rule of the mathematical model. Therefore,the deflection of the truck scale body can be improved effectively with the prestressed-treatment method of steel structure,which can be able to improve its measuring accuracy.关键词：Truck scale;Rigidity;Prestress;Numerical simulation
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发布时间：2022-09-22 - 摘要：For a vehicle subframe appear crack problem in rig test process,using finite element analysis software Hyper Mesh establish the finite element model,of subframe,it analysis the strength and modal of subframe,and finite element analysis results are verified by fatigue bench test,results showed that cracking position is basically the same with finite element analysis,and put forward some improvement methods,stress of the improved subframe decreased significantly and the subframe completes the fatigue rig test.关键词：Subframe;FEM;Rig test;Sructure modification
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发布时间：2022-09-22 - 摘要：In order to improve the rotor power coefficient of Savonius wind turbine,the turbine of the wind energy utilization rate as the optimization goal,a wind rotor diameter、air gap and height as variables,and the Baez limit and related experimental results as constraint conditions,established the structure parameter optimization model of wind rotor,and use Matlab to solve the optimal structure size. In order to make the wind energy utilization rate higher,the wind turbine structure form is improved,and the 3D modeling is established,and the Workbench ANSYS is used to carry out the fluid structure coupling analysis,and the reliability of the optimized and improved wind rotor structure is verified.关键词：SavoniusWT;Wind rotor;Structure optimization;FSI;Number simulation
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发布时间：2022-09-22 -
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