最新刊期
期 3 ， 2015
- 摘要：Aiming at overcoming the deficiency of available methods for revaling the nonlinear dynamic behaviors of complex rotor-bearing system,a fluid-structure method which combined rotor dynamics with computational fluid dynamics based on dynamic mesh is proposed. This method presented in this paper first developed a rotor-bearing system,then calculated the transient oil field of journal bearing by using a dynamic mesh method for variable flow,thus calculated the shaft center trajectory for a dynamically loaded journal bearing. Finally,this method is validated with nonlinear dynamics analysis of a complex rotorbearing system. The results show that the proposed method can accurately solving the nonlinear dynamics of complex rotor-bearing system.关键词：Nonlinear dynamics;Rotor-bearing system;Fluid-structure interaction;Dynamic mesh
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发布时间：2022-09-22 - 摘要：In order to study effect that road roughness generated random excitation on the structural parameters of nonlinear vibration response of the vehicle system,random structural parameters of five- degrees-freedom nonlinear vehicle model were established,and the model parameters are considered as random variables,under the premise that between the tire and the body presence nonlinear spring to study the random vibration response of the model under random excitation. Road irregularity is considered to be a white noise process to establish the mechanical model,the nonlinear vehicle system was linearized by the energy difference method,a stationary covariance matrix for the random vibration responses was obtained by solving the Lyapunov equations,and the stable equivalent linear system parameters of vehicle were gained through iteration. The example calculation results show that this method can improve the accuracy and efficiency of computation.关键词：Five-degree-freedom vehicle system;Equivalent linearization method;Energy difference;Random parameter;Random response
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发布时间：2022-09-22 - 摘要：Based on the deficiency in the traditional nonlinear blind separation method of mechanical fault sources,i. e. the separation matrix parameter and nonlinear mixing parameter in the nonlinear blind source separation are usually optimized separately,which easily lead to have one without another and low learning efficiency. Quantum genetic algorithm is introduced into the nonlinear blind source separation of mechanical fault,a nonlinear blind separation method of mechanical fault sources based on the quantum genetic algorithm,which is named as QGA-NBSS method,is proposed. The proposed method can simultaneously optimize all parameters in the nonlinear blind separation,i. e. the separation matrix and nonlinear mixing function,obtain global optimal solution,and greatly improves the global convergence of the algorithm. The simulation and experimental results show that the proposed algorithm is effective.关键词：Quantum genetic algorithm（QGA）;Nonlinear blind source separation;Fault diagnosis
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发布时间：2022-09-22 - 摘要：The gear fault signal is often submerged by a lot of background noise,so it is hard for signal-noise separation and for further fault diagnosis. A novel diagnosis method is proposed to performance the pretreatment of gear fault signal based on morphological wavelet de-noising. This method combines the characteristics of identification from mathematical morphology and the characteristics of multi-resolution analysis from wavelet decomposition. Firstly the gear vibration signal is de-noised by using the morphological wavelet de-noising method. Then the fault features is extracted by calculating the power spectrum of de-noised signal. The principle and steps of method are given and its de-noising effect is evaluated by using some parameters. The simulated signal and actual signal is analyzed. The results show that the proposed method can suppress the noise interference greatly. After de-noising,the SNR is improved and the fault characteristic of signal is highlighted better. The accuracy of fault diagnosis of bearing is improved effectively. And the proposed method has good engineer practicability.关键词：Morphological wavelet;De-noising;Gear;Fault diagnosis
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发布时间：2022-09-22 - 摘要：The 3D model of the magnetic bearing-rotor was made by using solidworks and seamless link from solidworks to ansys workbench was realized. The gyroscopic effect of the rotor was considered. Also the nature frequency,the modal map and the campbell diagram of rotor system was got through the analysis. In addition,we consider the effect of unbalance force on the rotor. According to the Different locations,we conduct the unbalance harmonic response analysis,successfully verify the result of modal analysis. The verification show that the nature frequency of rotor system is reasonable,which can provide information about the vibration of system and the optimization of the dynamic characteristics.关键词：Magnetic bearing-rotor;Gyroscopic effect;Ansys workbench;Natural frequency;Unbalance harmonic response analysis
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发布时间：2022-09-22 - 摘要：Aiming at the problem that the fault feature of hydraulic system is not clear and difficult to diagnosis,a feature extraction method of faults is proposed in this paper which combines EEMD with correlation analysis. First,a group of IMF components of hydraulic fault signal was obtained by EEMD. Screened the IMF components strongly correlated with fault signal as a group of faults’ candidate IMF component set. Then screened the IMF components little correlated with normal signal as another group of faults’ candidate IMF component set. The intersection of two candidate IMF component sets were the main fault features of the original fault signals of IMF components. The main fault characteristic frequency of fault signal could be got by the spectrum analysis. Then use the cross-power spectrum of fault IMF component and normal signal to prove the validity of the feature extraction. The fault feature IMF components and fault frequency of hydraulic system leakage fault of the hydraulic simulator are extracted in this paper.关键词：Hydraulic fault;EEMD;Correlation coefficient;Feature extraction
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发布时间：2022-09-22 - 摘要：The semi-analytical finite element method is a method that use the finite element method to discrete the structure in the spatial domain,and then use the precise integration method in time domain to solve the problem. There are two ways of carrying out the method: one is processing time domain first,and then deal with spatial domain; the other is to deal with spatial domain first,and then time domain again. Because of its high precision and wide applicability,this method got a number of research and applications. In this paper,its application to the numerical simulation of propagation of ultrasonic,in a number of different angles to the calculation result is analyzed. The analysis results show that semi-analytical finite element method is suitable for the simulation of ultrasonic transmission,and it has high precision,high stability in the calculation.关键词：Semi-analytical finite element;Ultrasonic;Numerical simulation
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发布时间：2022-09-22 - 摘要：Experiments on the titanium alloy Ti-1023（ Ti-10V-2Fe-3Al） work hardening and work hardening layer depth was studied by down or up milling,first milling or quadratic milling in a new tool or the wear tool. The results show that titanium alloy Ti-1023 is milled in carbide cutting tools,down milling in work hardening and work hardening layer depth is smaller than up milling,new tool in work hardening is smaller than wear tool,the work hardening layer depth is less than 25 μm in new tool; the work hardening layer depth is up to 81 μm and quadratic milling causes the machined surface softening in case of tool flank wear VB = 0. 3 mm.关键词：Down milling and up milling;Tool wear;Surface work hardening;Titanium alloy Ti-1023
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发布时间：2022-09-22 - 摘要：The dynamic responses of the beam under the function of the moving loads are very important practical problem in the strength and stiffness designs and the strength and stiffness checks. The measuring technology of the sensors is no doubt one of the ripe methods in the detections of the structural stresses,The reasonable designs of the electrical measuring sensors are often based on the theoretical analyses,but the theoretical solution of this kinds of problems are often hard to be given. In this paper,the definite mathematical model was proposed before hand; and the model can be divided into two sub-problems considering of the linearity of the problem,then the method of separation of variables and the inherent function method were used to give the theoretical solutions respectively,an numerical example were introduced to give the deflection responses and the stress responses of the simply-supported beam and the dynamic responses of the capacitor of the sensor in order to illustrate the important effects of the dynamic effects. This method can be extended to study the dynamic responses of the beam with an elastic system moving on it.,the given theoretical conclusions have some references to the designs of new electrical sensors.关键词：Simply-supported beam;Moving load;Inherent function method;Dynamic response;Electrical measuring sensor
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发布时间：2022-09-22 - 摘要：S-N curves of 2524-T3 parental material,FSW joint,riveted joint were obtained by fatigue test of FSW comparative specimens. Result revealed that firstly fatigue cracks in FSW joints were mostly initiated from bottom of the weld seam. Secondly,fatigue behavior of thin plate was slightly better than that of thick plate. Finally,fatigue behavior of FSW joint was significantly better than that of riveted joint. S-N curves for variable thicknesses and stress ratios were fitted,which provided correlative data for application of FSW technology to aircraft structures.关键词：Aluminum alloy;Friction stir welding;Joint;S-N Curve;Fatigue
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发布时间：2022-09-22 - 摘要：Laser cutting technology is widely used in manufacturing industry. But the laser absorptivity of the aircraft skin material is low,and the laser cutting quality is poor,so laser cutting is not applied in manufacturing of the aircraft skin. In order to searching laser cutting performance of the aircraft skin and the change of its mechanical properties by laser cutting,the surface topography analying,micro-hardness testing and tension,compression and shear test were carried used laser cutting test sample.The test result show that the test sample emerged freeze slag after laser cuting,and its tensile strength decreased slightly,but compression strength shear strength retained original level. So laser cutting technology can be used in edge manufacturing of the aircraft skin by improving the laser cutting process and rising the laser cutting quality.关键词：Aircraft skin;Laser cutting;Micro-hardness;Mechanical properties;Freeze slag
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发布时间：2022-09-22 - 摘要：Wheel bolted joint,which is consisted of wheel,brake disc,bearing flange and the threaded fasteners which clamp the components,is a mechanical system. This paper discusses the clamp load of the wheel bolted joint,and takes the wheel and threaded fasteners as the research objectives. And this paper studies how the two components affect the clamp load of the joint. The result of this paper provides guidance to design a robust wheel bolted joint.关键词：Wheel;Clamp load;Fastener
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发布时间：2022-09-22 - 摘要：Unloading curve analysis is a popular method in nan-indentation testing process,while the physical signification of the power-law exponent is obscure. Based on the Sneedon’s solution to elastic indentation of plane half infinite space,a new model was presented to characterize the plastic unloading behavior of Berkovich tip. The residual stress among elastic-plastic stain regions was taken into accounted. The plastic unloading behavior of Berkovich tip was characterized approximately using parabolic tip and conical tip. Experimental results indicated that parabolic tip can characterize the plastic unloading behavior more accurate and the rationality of the new model was validated.关键词：Nanoindentation;Elastic indentation;Residual stress;Parabolic tip;Conical tip
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发布时间：2022-09-22 - 摘要：Contrapose the problems of hydraulic support connecting rod mechanical fracture,at the same external load force link mechanical to advance the sum of the absolute values,and minimum quality of the objective function,establishment of a multi-objective optimization model,to solve the optimization used the NSGA-Ⅱ algorithm,using fuzzy set theory method to choose the optimal solution,and has compiled into a visual computing program under matlab environment. This program applications optimized ZTC16044 /27 /50 advanced hydraulic support arguments,after optimization the length reduce 29. 28 kg,the maximum force reduce 349. 12 k N. ZTC16044 /27 /50 link mechanical fracture coal mine accident did not occur in continuous operation Hong Liu-lin,to improve the overall performance of advanced hydraulic support provides an effective way.关键词：Advance hydraulic support;Four connecting rod mechanical;Multi-objective optimization;NSGA-Ⅱ
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发布时间：2022-09-22 - 摘要：A orthogonal test optimum design methodology was applied in the intensity analysis of shuttle belt conveyer slewing bearing,the finite element analysis was used to analyze the structure of the belt conveyer’s lower supported structure in the condition of initial design. According to the condition that its stiffness meet for the requirements,but the strength can’t meet,four factors which is the muscle thickness,the rib number,the rib fillet radius and the thickness of upper cover plate was selected. Then experimental analysis of the structure within different factors was carried out using orthogonal test optimization design. By the analysis the index evaluation of each factor was gotten in this paper. At last the optimum factor combination was provided to make the stiffness. The optimization results show that the performance of the lower bearing’intensity can be improved significantly,the study can also provide a theoretical basis to optimize the same structure design.关键词：Belt conveyer;Slew platform;FEM;Orthogonal design;Index evaluation
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发布时间：2022-09-22 - 摘要：Geometry design of pin is usually performed on static shear strength criterion,ignoring the pin bending deformation and stress concentration of lubrication hole. The pin which is designed by static shear strength criterion appears premature failure. The design methods considering static shear,bending deformation and stress concentration proposed in this paper. Through the comparison among three design methods,it finds that the diameter designed with different method are different,which is associated with load and yield strength; The maximum contact stress of three stress distribution models have been analyzed,it finds that the contact stress calculated with different stress distribution models are different,which is related to load. The maximum contact stress increases with the increase of fit clearance.关键词：Pin design;Bending deformation;Concentration of stress;Fit clearance
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发布时间：2022-09-22 - 摘要：In practical engineering,punching cutouts on the structure results in forming flanging side simultaneously. This paper focus on the influence of flanged-cutout on the dynamic behaviors of a rectangular plate. The ANSYS software is used to evaluate the natural frequencies of the structure with different parameters of the flanged-cutout,such as size,flanging height and position. Numerical results show that the frequencies are highly dependent upon the parameters of the cutout,and the effect is related to the different boundary conditions of the plate. The results can provide references for the design of flanged-cutouts in engineering.关键词：Flanged-cutout;Rectangular plate;Dynamic behaviors;Natural frequencies
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发布时间：2022-09-22 - 摘要：To study the deformation and stress of ring-flexspline in harmonic gear under actual working conditions,an interference fit model is applied to solve the problem of assembling between the wave generator and flexspline with large deformation. Further more experiments are performed to test the validity of this method. Then the finite element numerical calculations of the whole harmonic gear are obtained under no-load and rated load on the base of the model. At last,the deformation and stress distributions law of flexspline in the no-load and load are analyzed by data processing. The results show that the stress distribution of the flexspline has its minor value along the neutral layer of flexspline ring,and the maximum stress is located on the tooth root which mainly is tangential. The deformation and stress increment of flexspline under rated load are0. 46% and 93. 6% respectively relative to the no-load. It also shows that the load has little effect on flexspline deformation,but a strong influence on its stress. The finite element analysis results which fit well with related literature calculations proved that the interference fit model is effective,so it can provide a more precise method to study harmonic gear drive in accordance with the actual working conditions.关键词：Harmonic drive;Interference fit;Ring-flexspline;Deformation;Stress;Load-bearing characteristics
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发布时间：2022-09-22 - 摘要：In order to discuss theoretically the effects of surface roughness on gearing contact fatigue stress,a mixed Elastohydrodynamic Lubrication（ EHL） model for heavy-duty gear transmission was established based on the transverse roughness features simulated by the fractal function,which were superimposed to the film equation. Applied the multi-grid method,40 groups of numerical calculations were completed. The results show that the average film thickness is almost linearly increased with an increment of the roughness value. But it is not simply the case that the less the roughness value,the better. When the roughness is less than a critical value,however,increasing roughness value is found to reduce the maximum principal shear stress on pinion subsurface. At the end,the quantitative relation between the maximum principal shear stress and the roughness is acquired based on the regression analysis of the calculation results.关键词：Transverse roughness features;Fractal function;Heavy-duty gear transmission;Mixed EHL
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发布时间：2022-09-22 - 摘要：Based on the relationship between shear stress and Hardness,using the linear regression method,the calculation formula of effective case depth of carburized gear was derived,and it was verified by example. The results show that the accuracy of the derived simple computational formula can meet the requirements for gear design. Using this formula,the effective case depth of gear was obtained,and the model for the distribution of effective case depth of gear was established.关键词：Carburized gear;Effective case depth;Shear stress
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发布时间：2022-09-22 - 摘要：The honeycomb core model was built by finite element method（ FEM）. And based on Hooke ’s law,the equivalent elastic modulus of honeycomb core influenced by the change of cell number was studied. The result indicates that the horizontal equivalent elastic modulus is affected slightly while the vertical equivalent elastic modulus is influenced severely by the changes of cell number in horizontal direction. The changes of cell number in vertical direction have a strong impact on the horizontal equivalent elastic modulus while that affect the vertical equivalent elastic modulus slightly. When the ratio of honeycomb core’s size in horizontal direction to that in vertical direction is less than 1. 3,the horizontal equivalent modulus is less than the vertical equivalent elastic modulus. On the other hand,the horizontal equivalent modulus is greater than or equal to the vertical equivalent elastic modulus. For the large-scale structure,a honeycomb core with similar proportion can be established to calculate the equivalent elastic modulus.关键词：Honeycomb core;Equivalent elastic modulus;FEM;Cell number
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发布时间：2022-09-22 - 摘要：With the increase of thermal and mechanical load of engine,the higher standards were required for materials,and the more serious challenges had been taken for the design technology. Based on simulation results of several cylinder heads,which had been strengthened,a relatively optimal frame cylinder head was obtained. The load carrying structures,which were interdependent,were included by bolt holes,the fuel injector holes,stiffeners of the top ceiling and the fire face. The results of reliability tests about mechanical fatigue and thermal fatigue revealed the structure of the Al- alloyed cylinder head under peak pressure（ 20 MPa） was reasonable.关键词：Cylinder head;Optimal design;Al-alloyed;Design scheme;Experimental verification
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发布时间：2022-09-22 - 摘要：Comparative analysis of International Standards Organization standard（ ISO） 281: 1990（ the equivalent of GB /T6391- 2003） and ISO 281: 2007（ the equivalent of GB / T6391- 2010） Calculation Method for Rolling Bearing Life was conducted. Differences between the meaning and selection of Life modification factor,as well as their effects on Rolling Bearing Life,were analyzed through calculations. The study indicates that the ISO 281: 2007 introduces the Life modification factor for systems approach,and the factor considers not only the two factors of the ISO 281: 1990 but also the fatigue stress limit of the bearing steel and the contamination in lubricant,which makes it easy and more reliable to estimate the influence of lubrication and contamination on bearing life.
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发布时间：2022-09-22 - 摘要：To study the buckling of bionics skew plates in the crane’s vein box girder,the dimensionless derivations of bucking balance differential equations for skew plates has been given when it is affected by the longitudinal load in the oblique coordinate,and the dimensionless equation of boundary conditions is also given. The calculation procedures are described in detail when the differential quadrature methods（ DQM） are used to solve the critical buckling load of simply supported skew plates. Finally,the elastic skew plate subjected to uniaxial loading condition is considered as the case study,and the DQM results are compared with the existing results to verify the accuracy of numerical solution procedures. At the same time,the affecting relation between the critical buckling load and structure parameters for the crane is discussed.关键词：Simply supported;Skew plate;Buckling;DQM
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发布时间：2022-09-22 - 摘要：Referring to the standard equipments and the classic design formulas,a structural style of the classic pressure shell is deduced by researching the structural strength of the non-standard equipments according to the design requirements. And the strength and the failure modes of the pressure shell are assessed by using the modified arc-length method to analyze the buckling instability. Considering the actual connective type of the pressure shell structure,the effect is analyzed that the head structural style makes on the pressure shell strength characteristic. Then,the research shows that the stability,the failure modes and the ultimate strength of the pressure shell have relationship with the contact radio of the head and the cylinder wall,and it can be known that the stability of the pressure shell can be effectively promoted by increasing the contact radio. When the contact radio is increased to a certain degree,the failure modes may be changed from the buckling failure to the yield failure.Meanwhile,the quasi-linear relationship is presented between the contact radio and the ultimate strength safety reserve factor,which the greater the contact radio and the higher the safety reserve factor.关键词：Pressure shell;Contact radio;Buckling pressure;Ultimate strength;Finite element analysis
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发布时间：2022-09-22 - 摘要：For two branches of power transmission gear,the bending- torsion- shaft coupling dynamics model and the corresponding nonlinear dynamical equations are established in this paper,with considering the varying mesh stiffness,backlash and the tooth profile modification as a time-varying backlash. Numerical solution of the equations into solving relationship obtained with the gear tooth profile modification Vice dynamic load factor,found a reasonable modification allows the separation power split tooth gear does not occur the teeth back impact. Using different modification the amount of each gear pair dynamic load factor peak contour,the optimum amount of modification,so that dynamic load factor smallest gear. Numerical results show that a reasonable tooth profile modification,the maximum dynamic load factor of the two branches of power transmission gear can be reduced by 3. 6 to 1. 6.关键词：Split path transmission;Gear dynamics;Tooth profile modification;Dynamic load factor
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发布时间：2022-09-22 - 摘要：The dynamic model of boom-system on concrete-pump was built,and the optimization analysis was done to obtain the maximum pressure of the compressed rod and the posture of boom system at the exact situation. Two methods were adopted to analyse the rod’s static and dynamic performance,which avoids the defects of single analysis method. A compression experiment was done on the rod using the Self-balance loading test bed. The experimental result tells that bias placing the rod has some effect on the stability of the rod and the stress distribution on its plate.关键词：Dynamic model;Compressed rod;Static and dynamic analyse;Bias placing;Stability
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发布时间：2022-09-22 - 摘要：Maintain a high level of integrity and reliability of pipelines for oil and gas pipeline industry is essential. Due to various reasons,there will lead to the pipeline failure. Among them,pipeline defect is the main reason to the failure of itself.And dent defect is one of the general defect types. Therefore,it is necessary to conduct a further study on pipeline defect. In allusion to type I plain dent existing on oil and gas pipelines,analyzing the relationship between residual stress which is on type I plain dent area and various parameters. Based on fatigue life model,obtaining the influence rule of residual stress on pipeline fatigue life. It is significant for the design of new pipeline and maintenance of in service pipeline.关键词：Plain dent;Residual stress;Pipeline internal pressure;Dent size;Pipeline size
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发布时间：2022-09-22 - 摘要：The fatigue tests of Plexiglas Resist45 PMMA at different frequencies were carried out and the S-N curves together with hysteresis loops were obtained. The results show that the fatigue life increases with frequency at low frequency domain. Creep damage and mechanical property rate-dependence are two attributes of frequency effect on fatigue life. And the frequency modified approach was employed to describe and estimate the fatigue life under different frequencies at low frequency domain and the calculated results are consistent with the experimental results.关键词：Polymer;Fatigue;Frequency modified approach;Life prediction;S-N Curve
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发布时间：2022-09-22 - 摘要：According to the actual circumstance of high-speed train in line operation four aerodynamic load cases are set up: pneumatic passing each other open wire,single train passing through tunnel,two trains passing by in tunnel and cross wind.Four types of aerodynamic load condition will be applied to the numerical finite element model of high-speed train car body. Then carry the fatigue strength of aerodynamic load analysis on the finite element model. The calculation data show that all maximum stress results under the four working conditions are less than the allowable stress of car body materials,the maximal displacement deformation occurred in the bottom of the car body. In the fatigue strength analysis,not only the vertical and lateral and aerodynamic loads combination is considered,but also a combination of longitudinal and aerodynamic loads is taken into accounted. According to the results of the fatigue assessment that a minimum safety margin is 2. 93 MPa,a minimum safety factor is 1. 083. Based on the results of the fatigue analysis that: car body structure meets the requirements of fatigue strength under the aerodynamic loads. The harsh conditions which are carried by car body at the same time are aerodynamic load and vertical load.关键词：High-speed trains;Carbody;Aerodynamic load;Static strength;Fatigue strength analysis
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发布时间：2022-09-22 - 摘要：For the reliability problems of large data samples and low prediction accuracy and statistics to predict the remaining life of the corrosion pipelines,the author proposed the gray prediction theory to predict the residual life of corrosion pipelines; For the problem of unable to do with non-isochronous data、larger errors in the process of background values construction and had not used new information fully of the traditional GM（ 1,1） model,the author optimized the traditional GM（ 1,1） model and the model is improved. It’sby using the constructed residual life prediction model of the corrosion pipelines and the optimized GM（ 1,1） model to calculate the remaining life of the corrosion pipelines that is the accuracy,accuracy,simple,feasible and pervasive method.关键词：Pipe;Forecasting;Corrosion;GM（1,1）;Development factor;Residual life
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发布时间：2022-09-22 - 摘要：Principle of compounding method and empirical method was compared and analysised. Based on the three boundary condition decomposition methods of structure with multiple site damage（ MSD）,stress intensity factor（ SIF） of MSD crack tips was calculated with compounding method and empirical method respectively,and compared with the result of FRANC2 D Simulation. Finally a more accurate calculation method of stress intensity factor of MSD cracks was raised.关键词：Multiple Site Damage（MSD）;Stress intensity factor（SIF）;Combination method;Empirical method
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发布时间：2022-09-22 - 摘要：Springback is an inevitable phenomenon in the stamping process,which not only affects the dimension precision,but also affects the structure reliability. Therefore,an accurate prediction of springback is the first important to decrease and control the springback. The material in the stamping process will undergo reversed loading,and shows different mechanical properties from monotonic loading. Therefore,the material work hardening model is one of the most important factors affect the simulation precision. This paper uses finite element method to study the springback in the punching of a flanging,and the effects of isotropic,kinematic and mixed hardening models have been discussed,which is verified by the experimental. The results show that the isotropic hardening model does not consider the Bauschinger effect,which leads to an overestimation of springback. The kinematic hardening model does not consider the effect induced by the quick stress-strain,which leads to underestimation of springback. The mixed hardening model considers both the Bauschinger effect and transient characteristics,showing a true stress and strain,which leads to an accurate calculation of bending residual stress and springback. The result of mixed hardening model is well consistent with the experimental.关键词：Springback;Hardening model;Residual stress
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发布时间：2022-09-22 - 摘要：In this article,elastic-plastic curved crack tip plasticity area in hardened material under quasi-static loads has been mainly studied,and 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 elastic-plastic curved crack tip hardened 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 hardening exponents.Curved crack tip plasticity area size will decrease when hardening exponents increase in hardened material. The decrease extent of curved crack tip plasticity area size will be more and more severe when hardening exponents increase evenly. Curved crack tip plasticity area size will decrease when external loads decrease with the same hardening exponents. A new theoretical model where curved crack tip plasticity area size was calculated has been established in hardened material.关键词：Hardened material;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：With the development of ocean engineering,increase in the number of project exploration of Marine oil and gas,natural gas and oil transportation engineering are increasingly developed. UOE production technology of high strength of X70 steel is widely used in oil and gas transportation project,and then the higher the strength of steel,the fracture toughness is lower. We need to determine the identity of the fracture toughness values. Material fracture toughness size can use critical crack tip opening displacement CTOD（ crack tipopening below） to measure. Critical CTOD is important parameters in elastic-plastic fracture mechanics,the size directly reflects the material’s ability to resist cracking. The bigger the critical value of CTOD show that the cracking resistance of materials,the better. Determining the critical value of CTOD is of great significance. On the basis of BS7448 specification of X70 steel critical fracture toughness CTOD was tested,and then by using ANSYS software of X70 steel in terms of CTOD define critical CTOD was calculated,and implement the test and simulation comparison and analysis,safety asses关键词：X70 steel;Crack tipopening displacement（CTOD）;ANSYS
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发布时间：2022-09-22 - 摘要：In the transmission lines,the safety operation of the tower-line system is very important,Therefore,the ANSYS analysis software can be used to establish and analysis the tower-line system of the transmission lines. In the process of analysis,the model of the beam-truss hybrid element-coupled is build,the ground gravity load,wind load and ice load can be calculated by theoretical calculation,and the tower-line system model and separated ground model are respectively analyzed for dynamic,and get the natural frequency of vibration with the tower-line system and the separated ground. Based on the result which is analyzed by the scholars,in order to verify the accuracy of the analysis in this paper. To make the calculated result contrast analysis by Ansys,and get the deformation of the maximum stress node displacement process about the both cases.关键词：Tower-line system;Ansys Analysis Software;Element-coupled;Dynamic Analysis;Natural frequency
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发布时间：2022-09-22 - 摘要：By the common method of profiling mould the design curve mode contour mapping method and calculation method. Calculation process is cumbersome,require computer-aided programming is complete,and the traditional mapping method also has the error,the accuracy is not high. In this paper,some production parts,for example,the use of Pro / E software will get into them by copying mode theory contour curve mapping coordinates,and generates high precision contoured cam profile curve theory and its entities to improve the profiling by mold design accuracy and efficiency. Practice has proved that this is an effective method.关键词：Pro/E software;Profiling mould;Design;Motion Simulation
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- 60
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- 2
发布时间：2022-09-22 - 摘要：Reconstructed cooling water jacket of cylinder head of engine based on slicing method was CFD stimulated.Velocity field,pressure field,temperature field,coefficient of heat transfer and distribution situation about each water inlet were analyzed according to stimulated results,and reconstructed quality of cooling water jacket was evaluated and uneven cooling performance,local area of low velocity and backflow was found. It was optimized in order to improve its cooling performance.Stimulating results optimized before and after show that cooling performance of cooling water jacket is obviously improved by optimized project. It can be referenced for designing and optimizing cooling water jacket.关键词：CFD Analysis;CFD Optimization;Cooling water jacket;Reconstruction
- 3
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- 80
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- 1
发布时间：2022-09-22 - 摘要：Fatigue life and cushion performance were both the core concepts for hand-held impact tools design. A research on dynamic performance of air nailer has been carried out base on impact stiffness theory and hyperelastic materials. Simualtion and test results show that dynamic method can accurately describe cushion in impact tool,it can also solve main problem in buffer research and development.关键词：Rubber buffer;Impact stiffness;Impact strength;Stress
- 3
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- 220
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- 1
发布时间：2022-09-22
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