最新刊期
期 2 ， 2017
- 摘要：In this paper,the slant crack is used as the object of study,nonlinear output frequency response function（ NOFRF） is introduced to fault diagnosis of rotor system with slant crack. The NOFRF values of slant crack changing with different crack angle and crack location and crack depth are compared,and some valuable conclusions are obtained. The experiment results show that the NOFRF values are very sensitive to different crack angle and different crack location and different crack depth. Therefore,the fault of the slant crack in the rotor system can be effectively monitored according to the change of the NOFRF of the system.关键词：Nonlinear output frequency response function（NOFRF）;Cracked rotor;Fault diagnosis;Crack angle;Crack location;Crack depth
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发布时间：2022-09-22 - 摘要：How to extract characteristic parameters from vibration signals with noise is a key problem of bearing fault diagnosis. A novel method based on Morlet wavelet-Singular Value Decomposition（ SVD） and Variable Predictive Model based Class Discriminate（ VPMCD） was proposed in this paper aiming to solve this problem. Firstly,Morlet wavelet transform was used to pre-process the signals in the time domain to obtain a time-frequency coefficient matrix,then SVD was applied to the matrix to remove noise and extract the weak fault information in the corresponding dimensions according to the singular value curvature spectrum; Secondly,the signal components near the optimal meature were selected,and the Shannon energy entropy were used as the characteristic parameters to construct the feature vectors,which were then used to establish the fault identification model based on VPMCD. Finally,5-fold cross validation method and Jackknife test method were adopted to verify the proposed method,and the results have demonstrated its effectiveness.关键词：Singular value decomposition;Variable predictive model;Wavelet transform;Energy entropy;Fault diagnosis
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发布时间：2022-09-22 - 摘要：The shearer is under complex impact when it works. and it makes the shearer cutting unit vibrate,which increase the burden of the spiral drum and rocker arm shell. Besides,it would bring bad effects to the shear performance of the shearer. In order to study its study the working stability,the vibration mathematical equations in vertical direction and horizontal direction was established by lumped parameter modeling method and solved by the software of MATLAB. And acquire the vibration characteristics when working in different angles of time and frequency domain. The 3D model of the shear cutting unit was established by rigid and flexible coupling method. By the dynamic simulation and analysis from the software of ANSYS and ADAMS,the dynamic response of the shear cutting unit was acquired. The study provide a new method for the analysis of the dynamic response and basis to improve the design and stability of the shear cutting unit.关键词：Shearer;Cutting unit;Lumped parameter method;Rigid-flex coupling;Vibration
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发布时间：2022-09-22 - 摘要：Aiming at the no stationary characteristic of a gear fault vibration signal,a method based on Ensemble local mean decomposition and Kernel density estimation is proposed in this paper. First,the vibration signal is decomposed to be a series PF component by ELMD,calculating RMS、kurtosis、skewness coefficient of PF components,which contains main fault information,then they are combined into a feature vector,the Classification based on kernel density estimation is proposed,multiple sets of vibration signal feature vectors are used to train and test,identify their fault condition. The results showed that this method can effectively identify the fault of rolling bearing,and it is better than the LMD method关键词：Rolling bearing;ELMD;Kernel density estimation;Fault diagnosis
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发布时间：2022-09-22 - 摘要：Established a two degrees of freedom model with discontinuous rigidity and damp for studying the response of the permanent magnet motor’s rotor and stator rubbing system,and there are abundant nonlinear dynamic behaviors when rubbing.the stability of periodic motions and the transitions to chaos though period-doubling bifurcations or Hopf bifurcations are studied based on Poincare mapping. In view of the case of multi-parameters,their influences on the bifurcation behaviors and chaos motions of rotor and stator rubbing system are analyzed in detail. The analyzed results provide theoretical bases for safely,steadily,unfailingly operating on high speed,and quicken the motor developments toward high speed.关键词：Impact and rubbing;Periodic motion;Period-doubling bifurcation;Hopf bifurcation;Chaos
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发布时间：2022-09-22 - 摘要：The actual working wind filed was established by the self-designed programs of wind shear and Davenport wind spectrum. Taking the 5MW wind turbine built in UG as the research object,the dynamic response of the wind turbine suffered interaction between blades and tower under different rotating speed was simulated by ANSYS based on unidirectional fluidstructure interaction（ UFSI）. The results indicate that owing to the interaction effect between blades and tower,the maximum displacement and stress of the blades and tower increase to a certain extent. The coupling effect leads to the phenomenon that the maximum stress of the blades changes its location from relative span 0. 5 to 0. 7,and several maximum stresses appear in the tower area. It’s necessary to consider the combined effect between the structural coupling and rotation to obtain the accurate operating parameters of the wind turbine.关键词：Wind rotor;Wind turbine tower;Fluid-structure interaction;Rotation effect;Dynamic response
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发布时间：2022-09-22 - 摘要：Linear local tangent space alignment（ LLTSA） is an unsupervised dimension reduction method,which will lends to remaining overlaps between faults when it is used to high-dimension fault feature for dimension reduction due to its incapacity of using part sample class label information. Aiming at this problem,semi-supervised linear local tangent space alignment（ SSLLTSA） dimension reduction method is proposed in this paper. In SS-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 construct through this new distance matrix. The improved method realized the combination of data intrinsic manifold structure and class label information,and more discriminative low-dimension features can been obtained. And then,the corresponding relationship between low-dimension feature and fault classes are established by using support vector machine（ SVM）. Dimension reduction with SS-LLTSA can effectively increase the discrimination of fault feature,and furthermore,SVM can further improve fault diagnosis accuracy with its excellent pattern recognition capacity. Finally,the effectiveness of the proposed method was verified through the fault diagnosis experiment of rolling bearing.关键词：Fault diagnosis;Dimension reduction;Semi-supervised linear local tangent space alignment（SSLLTSA）;Support vector machine（SVM）
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发布时间：2022-09-22 - 摘要：Aiming at the fact that the classification performance of support vector machine（ SVM） highly depends on the parameters selection,a parameters optimize method of SVM based on improved fruit fly optimization algorithm（ LFOA） was proposed. The steps of SVM parameters optimize based on LFOA was proposed,and the superiority of the algorithm in convergence speed and convergence accuracy when compared with some other methods is verified by simulation experiment of several standard datasets. Take the rolling bearing as experiment object,the common faults was diagnosed by LFOA-SVM The experiment results show that the LFOA improved the classification performance of SVM and has higher accuracy compared with FOA,GA and PSO,and can applied to fault diagnosis efficiently.关键词：Fruit fly optimization algorithm;Support vector machine;Parameters optimization;Fault diagnosis
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发布时间：2022-09-22 - 摘要：In order to solve the freezing adhesive problem on roller and belt during coal transportation process in winter,on the basis of referring to relevant freezing adhesive theory,inspired by bionics,we did the theoretical analysis and experimental research about the application of bionic convex hull geometry structure on the roller and belt. In theory,it is verified bionic convex hull geometry structure can increase the the water contact angle,to a certain extent,it can reduce the freezing adhesive strength. We referred to the existing anti-freezing adhesive experimental study,used the UHMW-PE,designed and processed a bionic convex hull template,the height is 1. 0 mm,projected radius is 1. 0 mm,the center distance is 6. 4 mm,and another same material smooth template,by homemade freezing adhesive strength test device,under conditions of-25℃ temperature and3 h freezing time,we tested the freezing adhesive characteristics of two kinds of templates with moisture content 40% of the coal slime. The results showed that the normal freezing adhesive strength and tangential freezing adhesive strength of bionic convex hull template reduced about 8% and 12% respectively,we verified the bionic geometric convex hull indeed had certain antifreezing ability from the experiment aspect,hope can be used in anti-freezing adhesive field.关键词：Bionics;Coal;Freezing adhesion;Convex hull;Water Contact Angle;UHMW-PE
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发布时间：2022-09-22 - 摘要：Acoustic emission（ AE） signals with different scratch speeds,feed rates and scratch depths were measured and analyzed for the oxygen free copper scratching with single diamond abrasive to research the cutting mechanism of oxygen free copper. The influences of the characteristic parameters,time-domain signals,frequency spectrum and power spectrum of the AE on the different scratching parameters were analyzed and discussed. The results show that the scratch depth has the significant influence on the AE signals. The effects of scratch speeds and feed rate on AE signals are not distinct. The main frequency of single diamond grit scratching on oxygen free copper is dominant on the frequency band of 0-170 kH z. The main frequency value of the power spectrum decreases with the increasing of scratch depths.关键词：Single diamond grit;Scratching;Acoustic emission;Oxygen free copper
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发布时间：2022-09-22 - 摘要：Low cycle fatigue tests were carried for 316 L stainless steel and the material cyclic property was simulated by finite element method. The test results show that the significant cyclic additional hardening can be observed in different strain ranges and it is more evident with increase in strain range. The mixing model combined with the nonlinear kinematic hardening and the isotropic hardening is used to describe the elastic and plastic behavior. The simulation results of stress-strain agree well with the test results for the second cycle in different strain ranges. The error of the maximum stress for first 20 cycles between the simulation results and test results depends on the strain range and the maximum error is 3. 20%. The energy approach is used to predict the fatigue life based on the test results and simulation results and the prediction results are in a factor-2 scatter band.关键词：316L stainless steel;Cyclic additional hardening;ABAQUS software;Mixing model;Fatigue life prediction
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发布时间：2022-09-22 - 摘要：The total strain-controlled low cycle fatigue（ LCF） behaviors of a directionally solidified（ DS） superalloy DZ406 at 950℃ and 1000℃ for R = 0. 05 were investigated. The results of LCF tests indicated that mean stress relaxation occurred under asymmetric straining. The rate of mean stress relaxation increased with the increasing of strain amplitude. All the LCF data obtain under various ratios were well correlated by a modified SWT approach for lifetime prediction,the all data fell into the factor of 3 scatter band. With the increasing of strain amplitude it appeared muti-fatigue crack initiations.关键词：DS superalloy;Low cycle fatigue;Strain ratio;Mean stress relaxation
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发布时间：2022-09-22 - 摘要：In order to meet the condition of high precision,efficiency and speed of modern NC machine tools and to improve the static,dynamic performance as well as lightweight design of their basic components,the design of bed saddle which is the key components of ADGM numerical control machine tool was optimized based on topology optimization method. Firstly,according to variable density method,which makes bed saddle quality be objective function and allows stiffness as well as natural frequency to be constraint condition was established,then the best structure layout of bed saddle was acquired as a result of topology optimization.Finally,the integral design of the bed saddle was accomplished,with the basis of best structure layout of bed saddle and the requirements of the reasonable design. Compared with the original design,new design reduces 13% of bed saddle’s weight,and the maximal displacement decreases 6%. Also,the first order natural frequency increases 8%,while the second order natural frequency increases 7%,and the third order natural frequency increases 6. 7%. The optimization result shows that the proposed method for bed saddle is feasible,thus providing the theoretical basis for the lathe’s basic components optimization design.关键词：Bed saddle;Structural design;Natural frequency;Topology optimization
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发布时间：2022-09-22 - 摘要：A newly-developed precision seeder,model 2BFQ-6,combined multiple field tasks of seeding rapeseed,including straw chopping,rotary tillage,fertilizing,precision sowing,and straw covering into a single operation,has been expanded and applied in major rapeseed producing areas of China. Unfortunately,its reliability does not meet the need of production,which restricts its popular. In this paper,product reliability test and fault analysis of the combined seeder was proposed to improve its product reliability. A brand new seeder was conducted to work in rice stubble field lasting longer than 30 hectare in Jianli County,Hubei Province,in 2013. Trouble-free working time and area,phenomenon of the fault,repair time and the cause of the fault of the seeder in the course of the work were recorded and used for fault characteristics analysis. The results show that the key components of the seeder,like the main frame,gearbox and rotary drive axis have not fault yet,even if they are undertaking the most of load in working. The facts prove design reliability of the seeder is relatively high. By contrast,the glitches frequently appear initially,which is certainly abnormal. It caution that manufacturing process should be improved,especially for sprockets assembling and welding. Another significant finding is that the bolted connection of rotary blade and base would be loosen at a period of 5. 9-hour,which lead to the fault of the rotary tillage unit. Fault analysis indicates that the period of early fault is 30 hours and the fault rate conform to the feature of a bathtub curve. Real productivity of the seeder is 0. 36 hm~2/h,one working shift productivity is 2. 16 hm~2/d and the availability coefficient of the seeder was nearly 70%. When assembling and welding process are improved,weak components and unreasonable belt drive structure are revised and the connection of rotary blade and base are preventative maintained,the availability coefficient will be increased more than 97% and the real productivity of the seeder will be promoted to 0. 45 hm~2/h.关键词：Availability coefficient;Fault rate;Precision seeder for rapeseed;Reliability
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发布时间：2022-09-22 - 摘要：In order to improve the strength and life of the spiral drilling machine,and reduce the weight of the drill pipe,it took the spiral drill pipe of the spiral drilling machine as the research object. On the condition of meeting the strength requirement,it selected the weight of the drill pipe to be the lightest as the optimization goal. The solid optimization model was established in the software of Pro/E. The strength analysis was proceeded in the software of ANSYS Workbench based on finite element method,as the result it selected the thickness of the drill pipe and blade,height,helix angle as the optimizing parameters by observing the stress nephogram to optimize the structure parameters of the drill pipe. The result indicates that the strength of the spiral drilling machine has improved obviously,the stress is reduced by 15. 8% and the weight is reduced by6. 4%. The life of the drill pipe has been extended.关键词：Spiral drilling machine;Spiral drill pipe;Finite element method;Structure optimization
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发布时间：2022-09-22 - 摘要：Combined with the actual structure and function characteristics of the human hip joint,3-SPS/S（ S for spherical pair,P for prismatic pair） spherical parallel mechanism is chosen as the prototype for the hip joint. After the inverse kinetic solution was solved,the singularity trajectory equations were established and the singular tracks were plotted. The static equilibrium equations of each component of the mechanism were established using the vector method. The curves of the exerted force on branches with the variety of poses were plotted by numerical examples,and then the mechanics unloading effect of the middle limb was analyzed. Through simulation analysis of the mechanism with ADAMS software,the force-time curves of the hinges fixed to the mechanism ’s branches corresponding to prescribed trajectory were obtained,which verified mechanics unloading function of mechanism. The research contents should possess certain theoretical guiding significance for the development and control of the hip joint of the humanoid robot.关键词：Hip joint;Spherical parallel mechanism;Singularity;Mechanics unloading
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发布时间：2022-09-22 - 摘要：The chain system is the key part of the scraper conveyor,the sprocket and the chain hoop is key component of the chain system. The engaging force between the sprocket and the chain hoop and the abrasion of the influence each other. In order to research the connection of the engaging force between the sprocket and the chain hoop,we first established the visual prototyping model based on the MSC. ADAMS and analyzed the touch dynamics quality between sprocket and chink hoop when the scraper conveyor starts and are operated for a long time. We acquired the change law of the contact resultant force tangential force and normal force when the sprocket and the chain hoop are engaging,and the maximum engaging force and the corresponding position. Finally we analyzed the engaging force when the sprocket and chain hoop during the engaging progress based on the software of LS-DYNA,and indicated that the maximum engaging force and corresponding position,which provides a reference for the study of the engaging dynamics of sprocket and the chain hoop.关键词：Scraper conveyor;Sprocket;Chain hoop;Contact dynamic;Mesh;ADAMS;LS-DYNA
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发布时间：2022-09-22 - 摘要：Scale of forming surface in cold roll-beating forming process is a major defect. Controlling scaly defects is an important method to improve forming surface quality. According to the basic principle of cold roll-beating forming,the reasons and impact factors of scaly generation are analyzed. The finite element model of cold roll-beating forming was established by the finite element analysis software ABAQUS and the red copper was selected as sheet material. Under the up-beating condition and down-beating condition,the effects of friction coefficient to scaly height and scaly interval were studied. The results show that scaly height increases with the increase of friction coefficient in down-beating,while decrease in up-beating,scaly interval almost invariant in both roll-beating ways. Cold roll-beating forming experiment was carried out in refit milling machine and cross section parameters of scale in forming workpiece surface were measured by Leica DCM3D. In terms of actual measurement condition,experiment results with simulation results are uniformly. The correctness of finite element simulation is verified by experiment.Provide reference for inhibiting strip defects by selecting roll-beating methods and process parameters and improving both workpiece surface quality and dimensional precision.关键词：Cold roll-beating;Scale;Friction coefficient;Rollers
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发布时间：2022-09-22 - 摘要：A 3D model of composite laminates with bolted joint is created by using the software ABAQUS. By introducing the 3D Hashin failure criteria and considering the tightening torque,the partition and the global degradation models were established. With this method,the failure process and the linking strength of single-lap,single-bolt joints were calculated. The results shows that the load-displacement curve by using global degradation model doesn’t degrade enough and the computing results are more accurate by using the partition degradation model. With the increase of thickness,the linking strength of bolted single-lap composite joints decrease all the time and the speed of degradation gets slower and slower. It means that with the increase of thickness,the lifting bearing capacity of structure reduces. It also indicates that the ultimate strength of laminate is enhanced with appropriate tightening torque and excessive tightening torque impairs the load carrying capacity of the structure.关键词：Composite;Single-lap single-bolt joints;Partition degradation;Thickness;Tightening torque
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发布时间：2022-09-22 - 摘要：For the study of coal winning machine end plate load characteristic of cutting pick,with MG500 type coal winning machine roller as the research object,USES the nonlinear dynamics simulation software ls-dyna screw drum of shearer and the finite element model of coal and rock was cut,the model was used to study the working condition of oblique bottom plate and mechanical characteristics of cutting pick load characteristics changing with the installation parameters. Research shows that:the oblique cut into the cutting process,the end plate cutting pick cutting resistance and cutting resistance moment with end plate cutter tooth circumferential tangential decreases with the increasing of the installation Angle,with the side plate cutter pick intercept increases; The eigenvalues of the drum cutting resistance moment with the increase of the circumferential tangential installation Angle of the decreasing trend with the slow,along with the increase of intercept its increasing trend also increases;For the roller with good cutting performance,end plate cutter tooth appropriate chooses the larger circumferential tangential installation Angle and low intercept.关键词：The disc cutter pick;The finite element model;Circumferential tangential angle of installation;Intercept
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发布时间：2022-09-22 - 摘要：Based on the design of a new type of automatic stair wheelchair,under the joint action of the drive motor torque and self-weight of users and wheelchair; we can obtain the stairs’ climbing time is 4. 3 second per level by calculation. Then with the help of the Transient Dynamic Module of ANSYS Workbench. Got movement characteristic curve of direct component mechanical foot 1 in the machine,and put forward the improvement scheme towards its unstable phenomenon; At the same time doing kinetics analysis,got the equivalent displacement of constructions of stair wheelchair and the change of time curve of equivalent stress of members of the gym agencies,completed kinematic analysis and dynamic analysis of mechanical system of flexible body of gym mechanism; Finally optimized the design of the ladder mechanism,the optimization result was reduced20. 74% than the quality of the original model,and reduced the manufacturing of raw materials,meanwhile provided theoretical basis for optimization design of this kind of wheelchair.关键词：New type of automatic gym;Transient dynamics;Simulation of flexible body;Optimization design
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发布时间：2022-09-22 - 摘要：Lack of accuracy of metal sheet single point incremental forming workpiece is an important factor restricting the development of the technology,radial accuracy is an important part of forming precision. The reasons which affect the radial accuracy in metal sheet single point incremental forming process were analyzed,the finite element model of single point incremental forming was established by the finite element analysis software ABAQUS and the 1060 Aluminum was selected as material of sheet,the impact of process parameters such as tool diameter,layer step,feeding speed,sheet thickness,forming angle on deviation were analyzed respectively. The correctness of finite element simulation was verified by experiment. The results showed that the radial deviation increases with the increase of tool diameter,step size,forming angle and sheet thickness,the feeding speed had no significant effect on the radial deviation.关键词：Single point incremental forming;Radial accuracy;Experimental research;Finite element analysis
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发布时间：2022-09-22 - 摘要：In order to improve the work performance and design efficiency of shearer drum,shearer drum aided design software has been developed by combined programming of Matlab and Excel,which can generate picks arrangement plot,load curves,cutting plot and TXT load text quickly,providing a basis for shearer drum modeling and dynamic reliability analysis;Considering the influence of the shearer traction speed,rotation speed and blade spiral angle on the drum’s cutting performance and loading performance,to find the design parameters that can let the whole performance get optimal; Based on the actual working conditions,the optimal design scheme have been found for new large mining height shearer,under the rated power of cutting motor,it guarantees cutting area can reached the maximum 12094mm~2,cutting specific energy consumption reached minimum to 0. 565 9 kW·h/m~3,providing a quick and convenient method for the design and optimization of shearer drum.关键词：Drum;Aided design;Working performance;Picks arrangement;Cutting plot
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发布时间：2022-09-22 - 摘要：Aiming at the loosening of bolt connection in the rotating mechanism under dynamic tension compression and shear load,the failure mechanism and its influencing factors are studied by using virtual prototyping technology and finite element analysis method. First,based on the virtual prototype technology,the load of failure bolt connection structure is extracted;Secondly,the finite element method is used to analyze the influence factors of bolt number,preload,thickness of the connecting piece and spring gasket. The evaluation index system of digital analysis is set up to guide the design of the measures for improving the anti loosening. In this paper,the design and research on the bolt of a servo device rotating mechanism is taken as an example. The method of digital design and analysis is carried out,which solves the problem of bolt connection loose. The conclusion shows that the improved design is consistent with the practical engineering,and bolt connection structure is free from loosening and failure.关键词：Bolt connection;Dynamic combined load;Failure mechanism;Evaluation criterion of bolt loose
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发布时间：2022-09-22 - 摘要：A new type composite rotary percussion drilling tool was designed by studying the conversion mechanism of rotary to reciprocating motion. High-frequency axial impact and vibration was generated by an impact and energy transfer mechanism consisting of a couple of mating cams. A new kind of high rock breaking efficiency method was provided by combining the high speed rotation of positive displacement motor（ PMD） with the high-frequency impact of impactor. Detailed structural design and working principle analysis was carried out on impact and energy transfer mechanism,righting and falling and abrasion proof mechanism,power and binding mechanism,using software Creo Parametric 2. 0. Three dimensional solid modeling and the whole assembly of impact and energy transfer mechanism was completed. Motion simulation and indoor principle verification test were carried through. Results show that rotary power can be transferred into followers’ reciprocating impact by the impact and energy transfer mechanism,and that the tool ’s working principle is feasible,and it has simple structure and a good application prospect.关键词：Rotary percussion drilling;Mating cams;Impact mechanism;Motion Simulation
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发布时间：2022-09-22 - 摘要：Based on the of theory heat conduction and thermal-elasticity,simulated the braking process of mine hoist. The changing laws of the boundary condition on the brake disc’s surface during braking were analyzed and the computing method of the convective coefficient was discussed emphatically. According to variable material properties and the actual dimension of brake disk,a 3-dimensional cycle-symmetric model of brake disk in mine hoist was established and the temperature and thermal stress distribution was researched under the different braking conditions. The article discussed the calculation method considering thermal stress,and analyzed and compared each method’s advantage with disadvantage. The results indicate that the temperature and stress distribution of brake disk are closely related to the braking initial velocity and braking acceleration. The simulation provides an important reference for the optimization of lifting speed and braking acceleration,and the design and development of high-performance brake system.关键词：Brake disk;Temperature field;Stress field;Numerical simulation
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发布时间：2022-09-22 - 摘要：A lot of drosses appear on surface of molten zinc in the process of continuous hot dip galvanizing. The drosses,if not cleared in time,adhere to the surface of hot galvanized sheet and lead to surface defect. The production of zinc dross is closely related to the physical fields of molten zinc and dross remove can change of the physical fields,so it is necessary to carry out systematic research on the physical fields. Through the standard k-ε turbulence model and the geometric model of galvanizing pot and molten zinc,the author finds out the distribution regularities of the physical fields（ such as speed,temperature and concentration field） and the laws of these physical quantities changing with time,and determines the distribution characteristics of the vortex. The theoretical calculations can be used to predict the distribution regularity of zinc dross and the danger zone of the dross removing operation,provide important theoretical basis for the design of dross removing robot,and ensure the quality of zinc coating and improve the efficiency of dross removing.关键词：Hot dip galvanizing pot;Zinc dross;Physical field;Danger zone;Quality of zinc coating
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发布时间：2022-09-22 - 摘要：Loading spectrum collected from proving ground contains large amounts of low-amplitude loads. For accelerating test,low-amplitude loads should be removed. Traditional spectrum compilation method generally based on stress or strain damage editing. However,obtaining stress or strain signal from engineering practice is difficult. Considering this problem,this paper proposed a new criterion to remove low-amplitude loads based on pseudo damage reserving. Taking a vehicle sub-frame fatigue test as an example,90% pseudo damage reserved spectrum is obtained by dealing with original load spectrum with this method.A comparison of accelerated load spectrum with original load spectrum was made in time,amplitude and frequency domains. It turned out that the accelerated load spectrum can be used for durability test instead of the original one. Finally,a bench test was conducted. The result shows the consistency of accelerated load spectrum and original load spectrum on the premise of saving durability test time. Also,the rationality of the load spectrum compilation method proposed in this paper was verified.关键词：Sub-frame;Pseudo damage reserve ratio;Load spectrum processing;Durability test
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发布时间：2022-09-22 - 摘要：A new fatigue damage model is established by introducing an isotropic damage variable into the LemaitreChaboche plastic damage theory. Based on this model,a fatigue life equation is determined,that can reasonably characterize the influence of the material property,tri-axial stress ratio and stress amplitude on the fatigue life of material. The fatigue life of gears is investigated. The results show that theoretical prediction fits well with the S-N curve given by practical measuring.关键词：Gear bending stress;Finite element analysis;Plastic damage theory;Fatigue damage model;Fatigue life
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发布时间：2022-09-22 - 摘要：As an important parameter to assess the crack pipe fracture toughness,stress intensity factor determined is particularly important. In order to solve practical engineering problems,most of them are three-dimensional crack problems,crack mouth widening energy release rate based on the principle of virtual work and bending theory,i. e. G*integral theory is proposed to solve the problem of flat-elliptic cross section cracked pipe with boundary,and the stress intensity factors which are related to G*integral are given under tensile load for flat-elliptic cross-section tube crack. The results show application of this method is simple,and closed-form solution can be obtained.关键词：Fracture mechanics;Flat-elliptic cross section pipe;G*integral;Stress intensity factor
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发布时间：2022-09-22 - 摘要：Only the fatigue damage of low amplitude loads was considered in the traditional spectrum compilation method.The strengthening effect of the low amplitude loads of components was neglected. In the present study,the program loading spectrum for a vehicle control arm durability test was developed. Then,the fatigue life of this control arm was predicted based on the traditional fatigue damage theory and the low amplitude loads strengthening theory respectively,the difference between these two theories on fatigue life prediction was compared and analysized. The bench test results shows that the fatigue life can be predicted more accurately by considering the strengthening effect of low amplitude loads,and it is significant to predicate the failure mode of durability tests and to estimate durability of mileage of auto components more accurately.关键词：Durability test;Fatigue life prediction;Low amplitude loads strengthening theory
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发布时间：2022-09-22 - 摘要：Fatigue failure of the airframe structure occurs almost in the hole position of the fastener hole,Structural fatigue fracture will lead to a catastrophic accident. PHM（ Prediction and Health Management） technology can be used to predict when fatigue failure may occur,thereby achieving self-service security and reducing the use and protection costs. Based on the failure physical model,the fatigue life prediction method of the joint is established in this paper. Firstly,the stress serious factor and the fatigue notch coefficient of the hole member are solved. Then,the elastic section of the strain-life curve is modified to make the local stress-which is suitable for the prediction of high and low cycle fatigue life. The results show that the error of the fatigue life prediction method is less than 17% compared with the fatigue test results,which shows the effectiveness of the proposed method.关键词：PHM;Stress severity factor;Local stress-strain method;Fatigue life
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发布时间：2022-09-22 - 摘要：A trussed supporting structure with carbon fiber trusses and titanium frames was designed to meet the requirements on precision and mass of a light-small off-axis three-mirror reflective space camera. After analyzing the common forms of the supporting structure for space cameras,a method of the supporting structure with the secondary mirror and the folding mirror fixed separately was determined according to the structure characteristics of this optical system. A dynamic size optimization was conducted to lighten the structure and improve the stiffness of this structure. After the size optimization the finite element analysis and vibration experiments were conducted. It shows that the supporting structure could satisfy the requirements on precision and mass of this camera,and the fundamental frequency reaches 291.4Hz under the condition that the mass of this trussed supporting structure is not more than 4Kg. The design scheme of this trussed supporting structure could provide some references to the other light-small space cameras with the same type.关键词：The supporting structure;The dynamic size optimization;The off-axis three-mirror reflective space camera;Truss
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发布时间：2022-09-22 - 摘要：Micro-engine was widely used in agricultural machinery and motorcycle equipment,especially in mower chain saws and other products by its advantages of simple structure,reliable operation and high efficiency. In this paper,ones built the3 D model for micro engines which was actually used,in addition,the steady temperature field of engine cylinder under rated speed was calculated by finite element analysis method of steady temperature field,finally,the key spots with high temperature distribution in engine cylinder radiator was obtained. A simplified model about the key parts of heat sinks is established to simulate the temperature influence law. Then,the influence of some main parameters like the spacing,number and thickness of the fins is studied. It is of theoretical significance to optimize the design parameters of micro-engine block structure and improve the heat dissipation of micro engine block.关键词：Micro-engine;Steady temperature field;Heat sink;Structural parameters
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发布时间：2022-09-22 - 摘要：A hydraulic mechanical arm is designed,which realizes the installation and disassembly of the converter and the mechanical and automation of the transport. In order to verify the rationality of the design,through the Pro/Engineer,ADAMS,ANSYS structural co-simulation platform,a key part of the mounting arm coupled to the flexible member is rigid virtual prototype model. According to the practical application of the mechanical arm,telescopic hydraulic cylinders to determine the scope,and its validation,ensuring that meet the requirements. By ADAMS kinematics and dynamics simulation analysis,mounting arm motion displacement curve and the mounting process load lifting arm high dynamic stress areas. Based on ANSYS software provides mounting arm modal constraints analysis,identify the natural frequency and vibration mode of mounting arm,optimize its structural strength and resistance to impact and improve the ability of vibration reference.关键词：Converter skateboard;Hydraulic manipulator;Virtual prototyping technology;Rigid coupling;Modal constraints
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- 141
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发布时间：2022-09-22 - 摘要：The progressive damage analysis technique was studied by using finite element method and test validation of the repaired aircraft wing composite panel with discrete-source damage. Firstly,an analysis model adopting the two dimensional LaRC05 and B-K failure criteria was established to indentify the initial damage of composite ply and interface. Then,a user defined subroutine UMAT of material failure criteria and degradation rule based on commercial software ABAQUS was programmed and the load carrying capacity of the repaired aircraft wing composite panel was analyzed. The numerical results indicated that: the FEM analysis method presented in this paper was viable for the large-scale bolted repair structure. The comparison between analysis and test indicates that the load carrying capacity and failure mode of numerical results agree well with test results. The errors of predicted load carrying capacity are within 5%.关键词：Composite wing;Stiffened panel;Discrete-source damage;Repair;Assessment method
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- 150
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发布时间：2022-09-22 - 摘要：The theoretical analyses of the ball grinding mill are very necessary for its strength designs and the estimation of its output,but there are a lot of difficulties in the mathematical modeling and theoretical analyses because of the many and complex influence factors. Here,the mechanical principles was used to analyze the percussive force computation problems of the materials in the roller of the ball grinding mill when dropped and collided with the roller,and the function of the percussive force and the dropping angle was given,and the optimization was done with half-division method by a numerical example,the corresponding results of the maximal percussive force and the dropping angle was obtained,The contrast results of the theoretical computations with the product specification parameters supplied by actual ball mill shows that the methods and conclusions in the paper are correct and workable.关键词：Ball grinding mill;Percussive force;Dropping angle;Mechanical analyses;Optimization
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发布时间：2022-09-22 - 摘要：The looseness or fall off of the clamp is one of the important factors for the failure of spacer bar. The research on the clamp strength is very important. Based on ANSYS finite element analysis software,non-linear emulation analysis is carried out. A reinforced spacer clamps was chosen as the object,using Mooney-Rivlin rubber constitutive model,simulating clamp for pre-clamping the wire by using pre-rigid displacement and simulating non-uniformloading conditions such as wire icing and winding by applying the tension along the line and rotarytorque load. Compared with experiment result,it shows that the strength and gripping performance of the new clamp satisfies the requirement of DL/T1098-2009,and the clamprubber spacer plays a role in reducing wear and protection. At the same time,the correctness of finite element model of spacer bar clamp is verified. It also provides useful reference for the clamp structure improvements,and lays the foundation for wind-resistant simulation analysis of high-voltage transmission line system.关键词：Spacer bar;Nonlinear finite element;Pre-clamping;Tension along the line;Rotarytorque
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发布时间：2022-09-22 - 摘要：In order to promote development of scroll compressor’s high speed and low vibration,and reduce its vibration and running noise,equivalent mechanical model and dynamic balance equation of the principal axis’ s transmission system were set up.Program of parametric finite element model for the principal axis assembly was developed on APDL language,and then its dynamic balance characteristic was improved based on that,and the location（ radius of the centroid R2 and R3） more reasonable of balance weight’s centroid was confirmed. The improving results indicated that,the principal axis could not only keep dynamic balance status,but also adapt more higher working speed,while decreased R2 and increase R3. Because of improving design,the first order natural frequency of the principal axis was increased by 9. 49 Hz,thus then its dynamic characteristic was improved effectively.关键词：Dynamic balance;Scroll compressor;Rotational radius;Vibration;Parametric;Improving;Finite element
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发布时间：2022-09-22 - 摘要：Since solar radiation has a great impact on the thermal environment,three dimensional temperature field of the passenger compartment was simulated by using ray tracing method based on RANS methods. The influence of the insulation glass on the passenger compartment temperature was also quantitative analyzed. The result of calculation shows that solar radiation and body heat flux have a significant impact on the temperature field inside the cabin. The application of the insulation glass can reduce the maximum intensity of the solar transmitted radiation by 14. 4 percent,consequently make the maximum temperature of panel area decreased by 3. 5 centigrade. The research results can be applied to optimize the thermal environment of the passenger compartment.关键词：Passenger compartment;Numerical simulation;Temperature field;Solar radiation;Insulation glass
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- 173
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发布时间：2022-09-22 - 摘要：In order to achieve the exoskeleton steady,reliable and long operation. Taking exoskeleton principle prototype hydraulic power unit as research object,using the method of Fourier series to establish the exoskeleton kinematics model,analyzing the characteristics of exoskeleton hydraulic system to get hydraulic power unit required heat dissipated power. Establish model of the exoskeleton hydraulic power unit and simulation the thermal of exoskeleton hydraulic power unit in ANSYS to analyze the exoskeleton heat dissipated power and temperature field,bring up an appropriate solving scheme.关键词：ANSYS;Exoskeleton;Thermal simulation;Hydraulic power unit
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发布时间：2022-09-22 - 摘要：Finite Element Analysis（ FEA） model of benchmark frame was established and the FEA model was validated by mode and stiffness test; The new develop frame’s mode and stiffness performance was evaluated by this FEA model. For the first torsion mode and the bending stiffness does not meet the requirements of SSTS,optimization design was carried out. Two optimization of increasing cross section and adding new part inside was proposed to improve the frame mode and stiffness performance; ProcessedP latts analysis to select the best optimization and completed the frame structure integrated performance development.关键词：FEA model;Mode test;Stiffness test;Optimization design
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发布时间：2022-09-22
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