最新刊期
期 3 ， 2021
- 摘要：Smart bearing is a structural unit of bearing set sensor. It has the characteristics of self-sensing,self-diagnosis,self-adaptation and self-regulation. It is one of the development directions of high-end bearing development at home and abroad.Firstly,Expounded the concept and key technologies of smart bearings. Secondly,the advantages and disadvantages of external smart bearing and embedded intelligent bearing are summarized. It is considered that embedded structure is the main direction of future research of smart bearing. According to the requirements of rolling bearing condition monitoring and diagnosis,the current application of smart bearing sensors,such as acceleration sensors,temperature sensors,lubricating oil quality detection sensors,torque sensors,and thin film sensors,are introduced. Finally,the development trend of smart rolling bearing monitoring technology is summarized and forecasted.关键词：Smart bearing;Sensor;Rolling bearing;Condition monitoring
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发布时间：2022-09-22 - 摘要：In order to study mixed-mode oscillations and synchronization shown by coupled Fitz Hugh-Nagumo oscillators under time delays,the influence of different time delays and coupling strengths on synchronization behavior of the system was investigated by using analysis method of nonlinear dynamics and MATLAB software. Firstly,according to the dynamics of two FHN oscillations coupled by a single time delay,there was small in-phase and large out-of-phase oscillations influenced by diverse time delays. More complex types of mixed-mode oscillations with varying coupling strength were displayed in a smaller range of parameters. Secondly,the dynamics of coupled FHN oscillations affected by the coupling strengths with two time delays was analyzed. The large amplitude oscillations in time series under different coupling strengths could irregularly switch between in phase or out of phase. The results indicate that the considered dynamical system is simple,but there is the phenomenon of inphase and out-of-phase dynamics. The observed phenomena show some similarities to the experimental model studied.关键词：Time delay;Coupling strength;Bifurcation;Mixed-mode oscillations;Synchronization
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发布时间：2022-09-22 - 摘要：In order to solve the problem of the lack of life characteristic characterization ability in the prediction of the remaining life of the rolling bearing,a method of the residual life prediction of the rolling bearing based on multi-resolution singular value decomposition and ECNN-LSTM is proposed. Firstly,the time-frequency information of vibration signals in onedimensional multi-space scale is extracted by using the multi-resolution singular value decomposition method,and the health stage is divided according to the standard deviation at the initial time. Secondly,a high-efficiency channel attention mechanism module was added to the two-layer one-dimensional convolutional neural network structure,and the convolution kernel was adaptively adjusted for multi-channel interaction without dimension reduction,so as to fully extract bearing degradation characteristics and establish effective life degradation indicators. Finally,MSE loss function is used to achieve the residual life prediction on LSTM.The feasibility and effectiveness of the proposed method are verified by Cincinnati whole life data.关键词：Rolling bearing;Remaining life prediction;Efficient channel attention mechanism;Multi-resolution singular value decomposition;Long and short term memory network（LSTM）
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发布时间：2022-09-22 - 摘要：Mechanical properties of compact tensile（ CT） specimens were studied by plane fracture toughness test,fracture morphology characteristics of both tip crack and blunt crack specimens were analyzed,and the influence of crack tip blunting on mechanical properties was quantitatively analyzed. The experimental results show that the fracture toughness value,the maximum fracture value,the plastic component and the maximum displacement calculated by the tip crack are all smaller than the corresponding values of the blunting crack. The blunting zone formed at the crack tip is conducive to inhibiting crack propagation and improving the ability to resist fracture,which can achieve the purpose of crack arrest. With the increasing of the curvature radius of the crack tip,there is an optimal blunt crack curvature radius. When the radius of curvature exceeds its value,the stiffness slightly degrades,and the proportion of the plastic component in the input energy of the external load increases. The fracture toughness is significantly improved,which enhances the bearing capacity of the specimen. The results can provide scientific basis for quantitative evaluation of the influence of blunting crack tip on mechanical properties.关键词：Blunting crackarrest;Plastic component;Fracture toughness;Mechanical properties
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发布时间：2022-09-22 - 摘要：The quasi-rectangular shield machine adopts the combined cutting form of two large circular spoke type cutter heads and two eccentric cutter heads whose force state is relatively complex. In order to investigate the thrust fluctuation of each cutter head,an in-situ detection method based on finite element analysis was proposed. Firstly,the calculation models of thrust and torque of cutter heads were established. By using the finite element analysis method,the relationship between the thrust of cutter heads and the stress of the detection points on the chest plate was obtained. By using the collected stress system,the realtime stress status of each detection point under the construction process was obtained. And then the actual thrust of the cutter heads and the thrust distribution of each cutter head were also derived by comparing the stress status with the simulation results.The experiment result shows that this method can measure the thrust of each cutter head in real-time,which provides theoretical guidance and reference for the structure design and safe operation.关键词：Quasi-rectangular shield machine;Cutter head thrust;Finite element analysis;Stress distribution;Thrust detection
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发布时间：2022-09-22 - 摘要：In order to study the ballistic resistance of TC4 titanium alloy under different impact angle,the experimental study on the high velocity impact of hemi-spherical projectile on TC4 titanium alloy target plate by light gas gun was carry out. The ballictic limit and failure mode was obtained. Based on experimental conditions,simulation model and material parameters had been validating through ABAQUS and the influence of impact angle on the ballistic resistance of TC4 titanium alloy had been further analyzing. The research result indicate that the main failure mode of TC4 titanium alloy against hemi-spherical projectile is petal-shaped failure caused by tensile shear and ductile holing; There exists an easiest penetration angle under which the projectile can penetrate the TC4 titanium alloy target most easily; The impact resistance of the target plate is closely related to the failure mode which is different under varying impact angel.关键词：Projectile;Target;Ballistic limit;Impact resistance;Numerical simulation
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发布时间：2022-09-22 - 摘要：In order to effectively excite the local vibration mode of the structure,analyze response information and identify the damage,a structural damage detection method is constructed based on the excitation points optimization and energy of signals at different damage states. Firstly,the dynamic model of the structure is established and used to calculate the modal shapes,and then the minimum value of non-diagonal elements of MAC matrix is used as the fitness function. Modified particle swarm optimization（ MPSO） is used to optimize the number and position of excitation points,and evaluate of different excitation points arrangement schemes by MAC non-diagonal mean value and root mean square（ RMS） criterion. Then,the corresponding position of the truss test model is excited,and the time-domain signal energy at the measuring point before and after the damage is calculated,so as to identify the damage position and damage degree of the structure according to its relative change. In addition,the method can still identify the damage position and damage degree of the structure after Gaussian white noise with the signal-tonoise ratio of 10 dB is added to the signals at different working conditions. The experimental results verify the feasibility of the method.关键词：Damage detection;Excitation points;Time-domain signal;Truss;Particle swarm optimization
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发布时间：2022-09-22 - 摘要：High speed milling of high hardness hardened steel has the characteristics of high cutting speed and high machining surface hardness,smooth and efficient milling can ensure quality and accuracy,while the generation of cutting vibrations limits the superiority of hard cutting technology. By designing high speed milling of high hardness（ HRC 48 ～ 68）hardened steel under different technological parameters,the cutting vibration signal was collected by LMS Test 9 A experiment analysis software,and the time and frequency domain analyses were analyzed,the relationships among the cutting vibration,the hardness and cutting technological parameters of the hardened steel were studied. The results showed that when the hardness of hardened steel increased,the friction between the rake face of the coated tool and the hardened steel increased,the friction resistance in the feed direction increased,and the amplitude of the vibration signal increased; the vibration signals generated by Ti Al N and Al Cr N coated tools were smaller than those of Ti Si N and Cr Si N coated tools; the addition of Al element in the coating design has a positive effect on suppressing and reducing cutting vibration of hardened steel; the changes of cutting parameters had different effects on the cutting vibration in the feed direction of the cutting tool; in order to obtain a lower cutting vibration amplitude and higher cutting efficiency,the cutting parameter value should be selected in preference to minimize cutting vibration.关键词：High hardness hardened steel;High speed milling;Coated tool;Cutting vibration
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发布时间：2022-09-22 - 摘要：In this paper,using 304 stainless steel material 1 mm in diameter to fuse electron beam deposition rapid prototyping,by controlling the wire feed speed,electronic beam intensity and molding parameters such as the same,choose different forming path was 180 mm × 40 mm × 20 mm of print samples,after tensile test,Its microstructure and mechanical properties were observed and studied. By electron beam additive manufacturing,dense block material without macroscopic defects can be obtained. The average particle size of 304 stainless steel printed is no more than 10 μm,and contains fine uniform precipitation phase. Sample to print,staggered reciprocating print and improved staggered reciprocating print under the path of tensile strength of about 683 MPa,878 MPa,970 MPa,respectively the three print path molding samples can reach the hardness and tensile strength of 515 MPa or requirements,tensile fracture analysis,staggered print mode fracture to ductile fracture,staggered reciprocating type fracture to brittle fracture. The staggered reciprocating printing and the improved staggered reciprocating printing method have better density,better tensile strength and other mechanical properties.关键词：Stainless steel;Electron beam freeform fabrication（EBF3）;Additive manufacturing（AM）;Microstructure;Mechanical property
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发布时间：2022-09-22 - 摘要：In order to explore the influence of different working conditions on the surface morphology of crankshaft and connecting rod of compressor,the roughness meter was used to measure the surface morphology characterization value of connecting and crankshaft based on the compressor reliability test. The results show that the working conditions of the compressor have a great influence on the surface morphology of the crankshaft and connecting rod. With the increase of work time,the Ra value of compressor parts surface increases,but the Rzvalue of connecting rod surface decreases obviously. The start-stop of the compressor also has some influence on the surface morphology of the moving parts. With the increase of start-stop times,the values of Raand Rzof connecting rod surface decrease,while the values of Raand Rzof crankshaft surface increase slightly.Through analysis it can be known that the crankshaft and connecting rod are in normal wear stage after running 672 h and 1 344 h at 43℃ . The connecting rod is still in the initial wear stage and the crankshaft is in the normal wear stage after 125,000 and250,000 start-stop cycles respectively at 25℃ .关键词：Compressor;Connecting rod;Crankshaft;Wear;Surface morphology
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发布时间：2022-09-22 - 摘要：Taking the aluminum alloy welded structure as the research object,the mechanical test and finite element analysis were used to study the performance of the welded structure. Four kinds of aluminum alloy materials,5083,6061,6063 and 6082,were selected for TIG welding,Through tensile test,hardness test and finite element analysis,four kinds of aluminum alloy materials,I-groove and V-groove,ER-5356 and ER-5087 welding wires,single lap and double lap connection methods and their welding processes are co MPared. A section of tower structure compression test is carried out. The results show that the welding properties of ER-5356 and ER-5087 are similar,V-groove and double lap welding are the best. The yield strength and tensile strength of 6061 aluminum alloy welding structure are 202 MPa and 290 MPa. The maximum allowable stress of a section of tower body is 60% of that of aluminum alloy welded structure. This research work lays a foundation for further exploring the application of aluminum alloy welded structure in transmission tower structure.关键词：Aluminum alloy welded structure;Mechanical test;Hardness test;Stress-strain relationship;Finite element analysis
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发布时间：2022-09-22 - 摘要：In order to provide a better evaluation basis to optimize blanking process,a blanking hole wall surface quality predict method was proposed,the method used DAMAGE figure maximum damage value to predict the quality. Taking CuZn40Pb2 alloy plate as research object,the positive and negative clearance blanking models were established. By analyzing each node displacement changes,damages and blanking forces,two kinds of blanking simulation results show that the positive and negative clearance blanking hole damages main reasons are: tensile tear and crush damage. According to the simulation of the micro-structure changes in two blanking processes,the blanking hole wall with positive and negative clearance damage extent and position distribution are obtained. The flaw probabilities on the fine blanking hole wall in the positive clearance was calculated to be 2. 96 times that of the negative clearance blanking. After the blanking test,the microstructure changes at the positive and negative clearance blanking observed under the light microscope was consistent with the prediction result. The quantification of the maximum value of damage by the DAMAGE figure can predict the wall surface quality of blanking holes,the punching process can be selected according to the maximum value of damage by the DAMAGE figure.关键词：CuZn40Pb2 alloy plate;Blanking;Quality;Predict
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发布时间：2022-09-22 - 摘要：In order to understand the formation mechanism of the residual stress of the lapping surface of laser crystal,a single particle model of a YAG crystal workpiece during lapping process was established by the finite element analysis software ANSYS. The material plastic properties of YAG crystal were studied,and the influence of mechanical action of abrasive particles on the distribution of residual stress of crystal surface was analyzed. The result shows that the residual stress of the lapping surface of YAG crystal is mainly compressive stress（ the maximum distribution depth is ≈ 3 μm） when the single particle load on the workpiece surface is 18 m N. However,there is tensile stress in the shallow surface layer（ depth < 150 nm）,and the maximum tensile stress exceeds the ultimate tensile strength of the material. The excessive tensile stress will induce microcracks on the crystal surface. When the single particle load is reduced to 2. 3 m N,the maximum residual tensile stress of the crystal surface is less than the ultimate tensile strength of the material,which can achieve the plastic processing of YAG crystal.关键词：Laser crystal;Lapping;Plastic property;Residual stress;Finite element analysis;Single particle
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发布时间：2022-09-22 - 摘要：In order to improve the design efficiency and performance of the cylindrical pressure structure,strength and stability analysis methods were determined,the initial scheme was analyzed. the second development of Abaqus software was carried out by using Python language,Abaqus was integrated with i Sight software,the parametric analysis flow of pressure structure was designed,could realize automatic modeling and analysis of cylindrical pressure structure. the most Latin hypercube method was used to selectting the sample points,the sensitivity analysis of the design variables were carried out,The comparison of the fitting accuracy shown that the response surface model had the highest accuracy,the approximate model of the cylindrical pressure structure based on the fourth-order response surface was obtained. the multi-objective optimization model was established,The second generation of non dominated sorting genetic algorithm was used to solving the multi-objective optimization problem,the results shown that the weight of the optimization scheme was reduced,while the ultimate strength was greatly improved,improved the performance of the cylindrical pressure structure.关键词：Cylindrical pressure structure;Parametric analysis;Sensitivity analysis;Approximate model;Multi-objective optimization
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发布时间：2022-09-22 - 摘要：In order to improve the assembly quality of the motor and reduce the total cost,it is necessary to optimize the design of the tolerances of the key components that form the air gap between the motor stator and the rotor. A multi-objective and multi-constrained mathematical model for radial tolerance optimization of a motor assembly was established with processing cost and mass loss cost as objective functions,tolerance values of key components as design variables,and assembly functions and economic processing capabilities as constraints. The model was solved based on the improved genetic algorithm,and the key component tolerances under the lowest total were obtained. Through CETOL 6σ simulation verification,the results show that the passing rate of motor assembly is increased by about 55. 7%,and the total cost is reduced by about 45. 2% with the optimized design tolerance.关键词：Tolerance;Multi-objective optimization;Genetic algorithm;Motor assembly;Optimization model
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发布时间：2022-09-22 - 摘要：Aiming at the problem that the vibration isolation effect of the engine mount system of an off-road vehicle is not ideal under idling condition,a dynamic model of the engine mounting system is established with the crankshaft center line and the rear end face of the first cylinder as the origin. In order to solve the natural frequency and mode shape of the suspension system,the method of combining the jorisk decomposition with the Jacobian method is used. At the same time,the suspension system is proposed by the improved particle swarm optimization tabu search optimization algorithm with the decoupling rate of the main direction of the system excitation force as the optimization goal. After optimization,the decoupling rate of the main direction of the suspension system is improved. Finally,ADAMS is used to verify and analyze the natural frequency and energy distribution of the optimized mounting system,which further verifies the feasibility of the optimization method.关键词：Suspension system;Natural frequency;Decoupling rate;Particle swarm;Tabu search
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发布时间：2022-09-22 - 摘要：As a kind of bionic robot fish,bionic killer whale played an important role in ocean development and scientific investigation. Based on the flapping wing movement theory,the bionic killer whale’s mechanism was analyzed,its instantaneous load was simulated by MATLAB. Based on the stress-strength interference theory,the bionic killer’s load reliability state function was established,the reliability index and reliability of bionic killer whale was calculated,combined with the reliability sensitivity analysis theory,the dimensionless sensitivity was obtained,analyzed the influence of the bionic killer whale’s design variables to reliability sensitivity gradient. This paper provides the theoretical basis,accurate data support and an effective numerical calculation method for the design and optimization of the bionic underwater robot with flapping wing theory as the propeller,which has important practical engineering significance.关键词：Bionic;Flapping wing;Numerical simulation;Reliability;Sensitivity
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发布时间：2022-09-22 - 摘要：In engineering problems,there is interaction between the layout of supporting locations and the distribution of structural material. Thus,simultaneously optimizing the topology of the structure and its supporting locations under a certain limit of material and supports is an effective approach to improve the mechanical properties of the structure. In this paper,supporting locations are described by continuous variables with the introduction of the independent supporting elements,then a hybrid optimization method of continuum structure and its supporting locations is proposed. The mathematical models of multi-objective optimization are established considering both the structural stiffness and the mean eigenvalue of the structure. The optimal solution of multi-objective optimization is determined by a certain decision factor. A simply supported plate under bending and bending-torsion loading conditions are optimized by the proposed hybrid optimization method. The results show that the distribution of material and supporting locations is clear,and the layout of supporting locations and the topology of structure can be effectively optimized at the same time. Compared with the design results from the standard topology optimization with given supporting conditions,the static and dynamic performances of the two examples are improved more than 30% and 88%,respectively. It is found that the proposed design method can satisfy the constraints,and remarkably improve the static and dynamic performance of the structure with a smaller number of supporters.关键词：Continuum structures;Locations of supports;Hybrid optimization;Solid isotropic material with penalization（SIMP）
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发布时间：2022-09-22 - 摘要：The lightweight design of C-beam structure which is a key structure component of bus air suspension will be mainly discussed in this paper. Firstly,based on parameterized calculating system,the finite element model that is in line with the actual working condition was established. Meanwhile,the maximum equivalent stress,bending stiffness and fatigue life analysis were completed. Then the central composite design experimental method was used,and the response surface model（ RSM） was fitted based on full 2 nd order polynomials,and design variables were screened according to sensitivity analysis.Finally,take the minimum mass as well as maximum bending stiffness as the objective function. At the same time,the maximum equivalent stress and the fatigue life of 500,000 cycles are taken as the constraint conditions. The optimization was conducted by NSGA-II multi-objective genetic algorithm,and in series Pareto non-inferior front curve was obtained,and the compromising solution was selected according to the actual design needs. The results indicate that the bending stiffness of the lightweight cbeam basically stay the same as before without changing the original material and meeting the constraint conditions,and the weight loss is 2. 68 kg and the weight loss ratio is 3. 6%.关键词：C-beam;Parameterization;RSM;Sensitivity analysis;Multi-objective optimization;Genetic algorithm
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发布时间：2022-09-22 - 摘要：Reconfigurable machine tools realize the processing conversion of each part in the part family through the exchange of its functional modules. However,due to the influence of machine structure layout and module weight,how to ensure the performance and accuracy of the machine tool under the condition that the modules are interchangeable is a difficult problem in the research field of reconfigurable machine tools. A mechanical interface device which can micro-adjust the module pose and ensure the stiffness of the machine tool is proposed in this paper. The comb-tooth joint surface and auxiliary supports used in the interface can realize the precise positioning and improve the connection stability between the machine-tool modules. The pose of the machine-tool module is adjusted slightly through the elastic-expansion-ball interface-unit deformation caused by the preload force exerted by the lock bolt on it. The preload deformation and connection stiffness of the interface unit are coordinated by different arrangement of the steel balls in it. The finite element analysis model of the mechanical interface is established,and the influence of different structure sizes and loading conditions on the stiffness characteristics of the mechanical interface is analyzed accordingly,which lays a theoretical foundation for the further application of the mechanical interface.关键词：Reconfigurable machine;Functional modules;Mechanical interface;Pose adjustment
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发布时间：2022-09-22 - 摘要：In order to solve the problems of high peak force and low energy absorption efficiency of traditional thin-walled square tubes during impact,the octagonal pre-folded tube was proposed by introducing creases on the surface of square tubes.The finite element software ABAQUS/Explicit was used to simulate the deformation mode and energy absorption under quasi-static compression. The results show that,compared with the square tube,the introduction of crease reduces the maximum peak force Pmax,increases the mean crushing force Pm,and forms the stiffness gradient crease tube,which produces a small crush force in the early stage of compression,which is beneficial to protect the main structure. With the increase of compression,the reaction force increases,and the energy absorption performance of the folded tube is improved Based on the study of the influence of the number of standard segments M,c/l,and b/t on the energy absorption performance of the pre-folded tube,the optimized structure of the pre-folded tube to improve the energy absorption performance of the pre-folded tube is obtained,which provides a reference for the application of the automobile energy absorption components.关键词：Pre-folded tube;Energy absorption;Stiff gradient
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发布时间：2022-09-22 - 摘要：Aiming at the problem of dynamic characteristic modeling of bolted connection structure considering the influence of roughness,a new model of bolted connection with rough surface joint surface replaced by spring damping model is established,which considers the influence of various factors such as bolt,gasket and rough joint surface on vibration characteristics. The model is based on the fractal theory of mechanical surface,and the calculation formula of the joint stiffness is obtained. Based on the finite element contact results,the spring layout of the spring damping model is determined,and the influence of the number of spring layouts on the vibration characteristics is studied. The experimental results show that the results of this method are very close to the experimental results,which show that this method is effective.关键词：Bolted connection;Rough surface;Vibration characteristics;Natural frequency
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发布时间：2022-09-22 - 摘要：At present,medical Ti-xNb-2Fe alloy is widely used,but it still needs follow-up finishing in order to obtain high precision surface quality. The simulation process of Ti-xNb-2Fe alloy was established,a modified Johnson Cook（ J-C）constitutive model considering the effects of strain,strain rate and temperature on flow stress was constructed. And a cutting physical parameters prediction method based on medical Ti-xNb-2Fe alloy was proposed in this work. First,the physical properties calculation software JMatPro was used to obtain the basic data of stress-strain curve of Ti-xNb-2Fe alloy during phase transformation,and the modified J-C model parameters were fitted by variable separation method. Then,on the platform of Advant Edge FEM finite element software,the flow stress model including phase transition was input into the software system through Fortran compiler. Finally,the data results of cutting force,cutting temperature and surface roughness simulated by J-C model and modified J-C model were compared with the physical testing results. The results indicated that the constitutive equation parameter A value and Bvalue decrease by 21% and 27% with the increase of trace element Nb content,respectively. The average percentage errors of cutting force,cutting temperature,surface roughness and physical testing results of finite element simulation using modified model were less than 25%,19% and 30%,respectively. The model can provide the optimization of process parameters for the follow-up finishing of medical Ti-xNb-2Fe alloy.关键词：Medical alloy;Constitutive model;Finite element simulation;Cutting force;Cutting temperature;Surface roughness
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发布时间：2022-09-22 - 摘要：As an important connecting and fastening part of wind turbine blade,blade root bolt plays an important role in the operation of wind turbine. In this paper,the connecting bolt between blade and pitch bearing of 2 MW wind turbine is taken as the research object,and a dynamic strength analysis model of blade root bolt of wind turbine is established under the conditions of three-dimensional turbulent aerodynamic load,gravity load and centrifugal force load. Under the condition of normal operation and partial bolt fracture failure,the stress distribution of blade root connecting bolt is obtained by finite element analysis.Compared with the traditional bolt strength analysis,this paper can get a more real trend of bolt stress change,the maximum stress value and its location. In order to provide theoretical basis for more accurate monitoring of some key points of blade root,it is of great significance to ensure the normal operation of wind turbine.关键词：Wind turbine blade;Bolt;Turbulence;Finite element;Stress
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发布时间：2022-09-22 - 摘要：In order to design the structure and static strength of the eight-channel constant speed universal joint inner sleeve. In this paper,based on the steel ball selection,the top-down design of structural parameters for the eight channel constant speed universal joint inner sleeve is carried out. The whole field static strength design of internal dangerous section was carried out. We matched the materials and heat treatments of dangerous section with the ideal static strength field. The static strength design was evaluated quantitatively. We carried out the static strength torsion test of constant speed universal joint assembly by using MTS static torsion testing machine,and the inner sleeve was subjected to a micro hardness test to verify the theory. The results show that the eight-channel constant speed universal joint inner sleeve designed according to the static strength design method of structure based on strength field can meet the strength and functional requirements.关键词：Eight channel constant speed universal joint;Stress field;Hardness field;Static strength field;Materials and heat treatment
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发布时间：2022-09-22 - 摘要：The engine suspension device based on magnetorheological fluid is designed,and the magnetic field simulation is performed by using Ansoft Maxwell. The vibration reduction principle of powertrain suspension system is presented and analyze its dynamics. The decoupling calculation model of magnetorheological suspension system is established, and the structural parameters of magnetorheological suspension system are optimized by fruit fly optimization algorithm.关键词：Magnetorheological fluid;Engine suspension;Decoupling and optimization;Fruit fly optimization algorithm
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发布时间：2022-09-22 - 摘要：For pipeline transportation,it is very important to reduce the transportation resistance consumption. In order to reduce the transportation resistance consumption,the application of non-smooth surface drag reduction technology is particularly important. By using the fluid mechanics knowledge and the numerical simulation software,establishing a pit theoretical model.The smooth surface and the pit surface with matrix arrangement were simulated and calculated based on the RNG k-ε model. Two kinds of surface flow fields were simulated respectively,and different drag reduction effects were obtained. Through calculation and analysis,we can conclude that under different working conditions,the surface of the pit with h = 0. 05 mm is better in drag reduction; analyzing the pit surface under 12 m·s-1 conditions,the average shear force is smaller than the smooth surface. Under the pressure difference,the fluid inside the pit generates a low-speed swirling gas,promotes the flow in the main flow region,and further reduces the total resistance.关键词：Pit reduction;Non-smooth surface;Low velocity swirl;Surface drag reduction;Numerical simulation
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发布时间：2022-09-22 - 摘要：The dynamic properties of the viscoelastic material have remarkable temperature-frequency effect. In order to characterize the dynamic properties of the viscoelastic material more precision,on the basis of the fractional constitutive model and the time-temperature superposition principle,the fractional time-temperature superposition model of the viscoelastic material with vertical factor（ VFTTS） was proposed. The DMA test was conducted on the viscoelastic material used in vibration control of engineering vehicle. The dynamic behaviors（ storage modulus,loss modulus and loss factor） under variable temperatures（-75℃ ～ 65℃） and frequencies（ 0. 5 Hz,1 Hz,2 Hz,3. 3 Hz,5 Hz and 10 Hz） were analyzed. Meanwhile,the master curves of the storage modulus at the reference temperature 5℃ are obtained by the VFTTS model and the FTTS model（ only with horizon factor）. The fractional standard linear solid model（ CFSLS） was used to validate the accuracy of the above two models. The results show that the prediction ranges of the frequencies of VFTTS model and FTTS model are the same. The superhigh frequency predictions between 1. 086 × 10-8 Hz and 1. 240 × 1011 Hz are realized. The relative errors of the two models are 6. 07% and13. 22%. In summary,the VFTTS model has broad prediction ability and higher accuracy.关键词：Viscoelasticity;Fractional order;Time-temperature superposition;Vertical factor;Master curve
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发布时间：2022-09-22 - 摘要：The truss-type pipe-pulling robot serving the large centrifugal pipe casting machine has important influence on the accuracy due to its large travel and heavy load. By using finite element method,the thermo-mechanical coupling static deformation law of long-span X-direction beam was analyzed and the structure was optimized. The static deformation law and dynamic time-domain response of Y-direction beam were analyzed. The results show that the thermal-mechanical coupling deformation of the optimized X-direction beam is about 0. 15 mm,which is 3% of the original scheme; The deformation of Ydirection beam is about 0. 67 mm,its dynamic response converges,the transition time is short,and the vibration times are about1. 5. The analysis results show that the static characteristics and dynamic response of the robot can meet the engineering needs.The engineering application was carried out,and the practical results are in good agreement with the finite element analysis. The conclusion is of great significance to casting automation of centrifugal casting pipe.关键词：Centrifugal casting pipe;Pipe-pulling robot;Static characteristic;Thermo-mechanical coupling;Dynamic response
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发布时间：2022-09-22 - 摘要：A fatigue life prediction methodology is proposed based on weight-averaged maximum shear stress range plane.Firstly,based on modified Wang and Brown’s reversal counting method,a new approach to the determination of the critical plane is proposed under multiaxial variable amplitude loading. For the entire loading history,the orientation angle of the critical plane is determined through averaging the orientation angles of maximum shear stress range planes with largest normal tensile stress in all counted reversals. The weight function is defined as the ratio of maximum shear stress range for every counted reversal to the largest shear stress range for all counted reversals. The accuracy of the proposed critical plane approach is verified using experimental data of 7050-T651 aluminium alloy notched tubular specimens. Then,the proposed determination approach of critical plane is combined with multiaxial high-cycle fatigue criterion and Miner damage rule to establish the fatigue life prediction methodology under multiaxial variable amplitude loading. Finally,the proposed fatigue life prediction methodology is verified by the experimental data of 7050-T651 and 2024-T4 aluminum alloy notched tubular specimens,and the results show that the proposed methodology has good prediction results.关键词：Multiaxial fatigue;Critical plane;Variable amplitude loading;Life prediction;High-cycle fatigue
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发布时间：2022-09-22 - 摘要：The Compact Tension Shear（ CTS） specimen proposed by Richard is a commonly test type used in mixed ModeI/II loading. The formula of stress intensity factors（ SIFs） for the CTS test has already given by relevant literature. Since the formula appeared in different forms in the subsequent research,it is very necessary to determine the correct formula of SIFs for the CTS test. By comparing the various formulas obtained by the literatures with the normalized SIFs‘ curve in Richard’s original articles,this paper identifies the correct formula of SIFs for the CTS test in Richard’s original articles. CTS specimens made from general-purpose Polystyrenes（ GPPS） under mixed Mode-I/II loading were investigated to verify the correctness of the formulas of SIFs provided in Richard’s original articles. Compared the SIFs calculated by using the formulas appeared in the literatures and the extended finite element method（ XFEM） by Abaqus. Finally,the formula of SIFs for CTS test can be determined.关键词：Stress intensity factors;Extended finite element method（XFEM）;Finite element method;CTS test
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发布时间：2022-09-22 - 摘要：The effect of angle misalignment of bearing on bearing fatigue life in spindle system with non-ideal installation conditions was studied in this paper. For achieving this,firstly,the analysis model of multiple bearings-spindle system was introduced. The solution method for multi-degree-of-freedom system model was proposed,and the validity of the model was verified. In addition,taking the four bearings-spindle system as the research object,the uncertain angular misalignment was considered and the angular misalignment was assumed to be normal distribution. Based on the system model,the contact force distribution of balls of bearing was analyzed under different spindle speeds and angular misalignment. Finally,the fatigue life of each bearing was calculated by the life theory. The results show that the uncertain angular misalignment can lead to significant dispersion of bearing life. For the preloaded bearing of system,the fatigue life without angular misalignment is the upper limit of that with angular misalignment. With the decrease of spindle speed,the bearing life without angular misalignment is significantly greater than the minimum bearing life with angular misalignment.关键词：Angular misalignment;Angular contact ball bearing;Multiple bearings-spindle system;Fatigue life
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发布时间：2022-09-22 - 摘要：In order to study the law of residual strength degradation of metal materials in the process of fatigue,a residual strength degradation model is established based on the definition of fatigue damage. The correctness of this model is verified by the previous experimental data. By comparing with the calculated data of other scholars ’ models,it is shown that the model proposed in this paper improves the calculation accuracy. At the same time,an improved equivalent damage model is proposed based on the residual strength degradation model,from which the fatigue cumulative damage model is derived. The cumulative damage model is applied to the estimation of fatigue residual life under two-stage load. And the influence of different loading sequence on fatigue life under variable amplitude load is explored. Combined with the experimental data,it is verified that the model can accurately estimate the fatigue life under two-stage load.关键词：Strength degradation;Loading order;Cumulative damage;Life prediction
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发布时间：2022-09-22 - 摘要：The optimization of process parameters in the high pressure forming process of bridge shell is studied. According to the structural characteristics of the bridge shell parts,the process of high-pressure forming in the bridge shell is determined;the relationship between the process parameters is determined by artificial neural network modeling,and the influence of each process parameter on the forming results is analyzed by orthogonal test method,and the optimal combination of process parameters is obtained,that is,the axial displacement feed amount is 17 mm,the feed time is 0. 1 s,and the hydraulic loading peak value35. 5 MPa,loading time 0. 25 s. The numerical solution is obtained by substituting the optimized process parameters into the finite element simulation software DYNAFORM, which verifies the correctness of the optimization results of the process parameters. At the same time,the internal high pressure forming test is carried out. The error between the simulation results and the test results of the thickness value of the axial internal high pressure forming is 3. 1%,and the error of the radial results is1. 3%. The agreement between the test results and the simulation results is within a reasonable range.关键词：Driving axle housing;Process parameter optimization;Artificial neural network;Orthogonal test;Foring test
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发布时间：2022-09-22 - 摘要：On the basis of realizing the radar function,the radar base is required to be light and rigid. A radar support base is designed and the load-bearing condition of the structure is analyzed. The finite element method is used to analyze the structure of the radar pedestal,and the strength and deformation of the radar pedestal are obtained. The equivalent stress value of a node is compared with the theoretical calculation results to verify the reliability of the finite element simulation results. According to the results of finite element analysis,the structure of the radar base is improved. Analyze the influence of the size of each component on the quality,maximum stress and maximum deformation,determine the optimization variables,and optimize the radar base structure with multiple objectives. After optimization,the mass of the radar base is reduced,and the mechanical performance is significantly improved. This is the design and optimization of the radar base structure. Provide a theoretical basis.关键词：Radar pedestal;Finite element method;Structure improvement;Multi-objective optimization
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发布时间：2022-09-22 - 摘要：To solve the problem of relative position installation between welding robot with welded parts,the workspace flexibility of the robot is analyzed. Firstly,the D-H method is used to model the kinematics of the robot,and the working space of the robot is solved by Monte Carlo method. Then,by means of the concept of service ball,a calculating method of flexibility suitable for the welding part is proposed,and the flexibility in the working space of the robot is solved. In the end,the influence of various parameters on the flexibility is analyzed,and through the genetic algorithm to optimize flexibility,the more flexibility of the robot workspace is obtained. This study provides a reference for the relative installation position between robot with welded parts and can ensure the reliability of welding.关键词：Welding robot;Flexibility;Genetic algorithm;Optimization
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发布时间：2022-09-22
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