最新刊期
期 2 ， 2019
- 摘要：In this paper, we investigated the rub-impact in the counter-rotating dual-rotor system. First we discretized the model of the counter-rotating rotor system and derived its FEM dynamical equations. Then we studied the rub impact fault caused by the sudden imbalance at the outer rotor and its influence on the response. The Wilson-θ method and other methods were employed to solve the equations. It can be seen that with the variation of rotating speed the Hopf bifurcation will occur. The quasi-periodic response exhibits tori twist in the Poincare section. It is found there exists a route to chaos where the quasi-periodic tori intersect each other gradually.关键词：Counter-rotating;Dual-rotor;Rub impact;Chaos
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发布时间：2022-09-22 - 摘要：Strip steel vibrations is inevitable in the rolling process of tandem mill, and the coupled model between elastoplastic body of strip steel and main drive system directly affects the overall dynamic performance of rolling mill. According to the movement mechanism of strip steel and main drive system, the main drive system was simplified to a two-degree-of-freedom discrete model and the strip steel was simplified to an axially moving Euler beam, the coupled vibration mechanical model of transverse and longitudinal vibrations of strip steel and torsional vibration of main drive system was established. Then, the nonlinear vibration differential equations of the coupled model were derived with Hamilton’s principle. The modified iteration method and the Kantorovich averaging method were used to solve the differential equations. Finally, by using the Matlab simulation, the influence of torsional vibration fundamental frequency of main drive system on strip steel vibration characteristics was discussed. The results can enrich the theoretical achievements on vibration of rolling mill, and it is valuable for transforming theoretical results into engineering applications.关键词：Strip steel vibrations;Torsional vibration of main drive system;Nonlinear coupled vibration;Fundamental frequency;Rotational inertia
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发布时间：2022-09-22 - 摘要：VMD has better band-pass filtering characteristic, which can non-recursively decomposition a real-valued multi-composition signal into a discrete number of quasi-orthogonal band-limited sub-signals with specific sparsity properties in the spectral. Modulation intensity distribution（MID） combined with VMD is applied to detect second-order cyclostationary components in gear fault diagnosis. Impulsive signatures generally represent the transients in the signals and are often caused by local defect in the gear of rotating machinery. Detecting these signatures is vital for mechanical signal processing and fault diagnosis. The impulsive signatures can be successfully extracted using VMD, meanwhile, Signal-noise can be separated to some extent. It is very useful tool to MID detects modulation components. However, when the analyzed signal contains multiple modulations usually mixed with other harmonic components, visual examination of the spectrum may not be accurate for identification of all carriers together with their modulation signals. Considering the shortcomings of MID in the analysis of multi-harmonic modulation signals, VMD is used as the signal preprocessing before MID analysis. Results of simulation and the experimental analysis have demonstrated the effectiveness of the method.关键词：Variational mode decomposition;Modulation intensity distribution;Gear;Fault diagnosis
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发布时间：2022-09-22 - 摘要：Boundary condition is an important issue in acoustic calculations, and free acoustic field is often simulated by non-reflection boundary in acoustic calculations. At present, the main simulation methods are radiation boundary method, characteristic acoustic impedance method and PML method in non-reflection boundary. Acoustic numerical calculations of non-reflection boundary were studied, the theoretical basis of three non-reflective boundaries was summarized. With plan wave incidence of free field for example, the acoustic absorption capacity and application of three kinds of boundary were analyzed and summarized. For the question of large incidence angle, PML method has the best non-reflective ability, radiation boundary method and characteristic acoustic impedance method will produce a greater error.关键词：Boundary;Acoustic field;Plan wave;Perfectly matched layer（PML）
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发布时间：2022-09-22 - 摘要：Aiming at the mechanical properties of plow head and dynamic charateristics of system under oblique cutting condition,cutting resistance of planning tool under oblique cutting condition was derived,and was treated as external excitation. Dynamic differential equation of plow system were established by using the finite element method,and were solved by using numerical method. The effect of oblique cutting velocity、cutting depth、cutting location、middle trough angle offset on dynamic charateristics of plow system. The dynamic charateristics of plow system were tested based on the mechanical test experimental platform. The test results and theoretical results were compared. The research results provided theoretical basis for working stability、fatigue life of key parts、process parameters optimization of plow system.关键词：Plow;Oblique cutting;Dynamic charateristics;Cutting resistance
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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, it proposes a recognition method based on ELCD（Ensemble local Characteristic-scale decomposition） permutation entropy and RVM. First, the vibration signal was decomposed by ELCD, then a series of intrinsic scale components were obtained; Secondly, according to the kurtosis of ISCs, principal ISCs were selected, then, calculate the permutation entropy of principal ISCs and combined into a feature vector; Finally, the feature vector were input RVM classifier to train and test to identify the type of rolling bearing faults. Experimental results show that this method can effectively diagnosis four kinds of working condition, and the effect is better than local Characteristic-scale decomposition method.关键词：Rolling element bearing;Fault diagnosis;ELCD;RVM
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发布时间：2022-09-22 - 摘要：Based on the axial high overload condition for trajectory correction fuze and the buffer structure of the bypass platform, the buffer dynamic model is established. The dynamic simulation analysis of the trajectory correction fuze platform is carried out by ANSYS/LS-DYNA. The cushioning characteristics are evaluated according to the stress distribution of the faulty parts in the platform. The influence of different buffer structures, cushioning materials and material parameters on the buffer protection performance of the platform is compared and analyzed. According to the simulation results, it is concluded that the buffer protection effect of the multi-cushion buffer structure is better, and the buffer protection capability of the platform is further improved by optimizing the material and material parameters of the cushion.关键词：Trajectory correction fuze;Rotation isolation platform;Buffer protection;Finite element simulation
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发布时间：2022-09-22 - 摘要：Improved averaging method was used to receive the vibration differential equation of the approximate solution, and the amplitude frequency response equation was obtained. By employing an averaging method, the transition boundary was calculated. The types of the amplitude-frequency responses were analyzed; secondly, the functions were also used for stability analysis by the linear system theory. Finally, the vibration isolation effect of different parameters on the system are analyzed. Increasing damping ratio weakened the vibration of the system, and strengthened the effect of vibration isolation.关键词：Averaging;Method nonlinear;Amplitude-frequency;Stability
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发布时间：2022-09-22 - 摘要：In order to better identification the degradation state of bearing, the degradation feature extraction method of bearing degradation state are studied. A degradation state feature extraction method for bearing named HHT relative spectrum entropy is proposed based on HHT for analyzing non-stationary vibration signal and relative entropy for characterizing the probability distribution difference among different signals. The analysis results of simulation signal demonstrate the availability and relationality of the proposed HHT relative energy spectrum entropy（HREE） and HHT relative singular spectrum entropy（HRQE） used as degradation feature. The degradation feature vector is composed of the two feature. The practical vibration of bearing with inner race fault and outer race fault which in different degradation state are analyzed, and the relevance vector machine is further used to identification degradation state and the results demonstrate the ability of the proposed method.关键词：Hilbert-Huang Transformation（HHT）;Relative entropy;Feature extraction;Bearing;Degradation state
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发布时间：2022-09-22 - 摘要：Constructing the optimal wavelet function is the key to realize lifting Wavelet de-noising.After determining the optimal decomposition level and effective threshold, it tries to introduce data fitting methodin the process of interpolation subdivision. By selecting different basis function, sample points and the dimensions of the basis function, the new wavelet function is constructed with different smoothness, shock and disappear moment, it introducesthe similarity coefficient to analyze the constructed wavelet function and select the optimum wavelet function.It combines with redundant lifting wavelettransform to improve the predict operators and update operators. The superiority of the wavelet function in vibration signal de-noising is verified by simulation and engineering data analysis, this method is helpful for bearing fault diagnosis.关键词：De-noising;Wavelet structure;Data fitting;Fault diagnosis
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发布时间：2022-09-22 - 摘要：The bolted rotor is a typical rotor structure with light weight, high strength, good rigidity, flexible selection of all kinds of wheel materials, etc., which is formed by pressing and combining several sections of rotors or discs and is widely used in aero-engines and gas turbines. Aiming at blind assembly, trail assembly and inconsistent assembly tightness of bolted rotor, and the degradation and loosening of bolt tightness in service, a quantitative detection method of bolt assembly quality based on GHM multiwavelet was proposed. Using the GHM multiwavelet with excellent characteristics such as symmetry, compactness, orthogonality, vanishing moment and high order vanishing moment, feature extraction of the bolted rotor assembly tightness states was performed. The quantitative detection index of assembly quality was defined by the relative energy band distribution based on multiwavelet. The experimental verification shows that the proposed method can accurately identify six kinds of bolt states from tightness to looseness.关键词：Bolt;Bolted rotor;GHM multiwavelet;Assembly tightness
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发布时间：2022-09-22 - 摘要：According to the long response time and can not achieve the bidirectional arrest of broken-belt catching device,broken-belt catching device with function of pneumatic control、vaulted arrest end and bidirectional arrest was proposed. The structure and working principle of catching device were explained. The arrest process of catching device was analyzed by using virtual prototype technology. The 1:2 experimental model of catching device was made by using the similarity theory. Feasibility of catching device was testified by experiment. The response time and catching force of the design model of catching device were obtained by using the dimensional analysis method. The results show that the contact between arrest plate and belt product little jitter, and has no effect on the catching results. The response time of the design model of catching device is 0.5 s. The catching force is 24.768 kN, and has little damage on the belt.关键词：Broken-belt catching;Response time;Catching force;Experimental test;Feasibility
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发布时间：2022-09-22 - 摘要：The size effects on the mechanical properties and defect evolution process of single crystal aluminum with a center crack under tensile loading have been simulated through molecular dynamic method. With the increase of model size, the yield stress and yield point decreased, while the fracture toughness increased. In the elastic stage, the deformation relies heavily on the point defects and surface defects in materials, while in plastic stage it depends strongly on the dislocation multiplication and its slip. The stress concentration at the crack tip is mainly associated with the phase transformation of the crystal structure near the crack tip due to the stress relaxation after phase transformation.关键词：Molecular dynamics;Size effect;Mechanical property;Defects evolution
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发布时间：2022-09-22 - 摘要：The safety coefficient given in the design codes of railway vehicle structure has certain experience. In this paper, based on the reliability theory, the method of reliability safety coefficient evaluation is adopted, which makes the selection of safety coefficient more reasonable. A certain type of high speed train carbody was taken as research object, the finite element model was established. Based on the code EN 12663-1, the static and fatigue loads were determined, which is considered the aerodynamic load in condition of high speed passing. After the static strength analysis of carbody, the fatigue strength was analyzed using the reliability Goodman curve of carbody material. Finally, established the relationship of reliability and safety coefficient, the safety coefficient of static strength and fatigue strength of the car body with different reliability were obtained. The results show that the static strength and fatigue strength of carbody meet to the requirement under the different reliability. With the increase of the reliability, the safety coefficient is reduced. The minimum safety coefficient of static strength under reliability of 99.90% is 1.3, and the corresponding load condition is the preparation condition combined with 1 500 kN longitudinal compression load. In aspect of fatigue strength, the locations with small safety coefficient mostly appear in the door’s corner and the window’s corner of the carbody sidewall. The minimum safety coefficient of fatigue strength 1.53, which has a certain safety margin. The dispersion of carbody stress and material strength have influence on the safety coefficient. In order to ensure the high reliability of the high speed train body, it can take measures to control the strength properties dispersion degree of aluminum alloy materials, reduce the stress concentration of the geometrical structure and reduce the working stress and so on.关键词：High speed train carbody;Static strength;Fatigue strength;Reliability safety coefficient;Aerodynamic load
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发布时间：2022-09-22 - 摘要：The parametric FE model of the main shaft for a 1.5 MW doubly-fed wind turbine was established with parametric language APDL of ANSYS in a command stream file. The structural strength of the main shaft under the 16 ultimate load conditions was checked according to the working load data. The results show that the maximum working stress 237.086 MPa found at dlc2.1 b is less than the permissible stress. The main shaft meets the requirement of static strength. In consideration of the randomness of the load parameters, the size parameters and the mechanical property parameters in practical situations, the static strength reliability analysis of the main shaft was executed by professional probabilistic analysis software NESSUS and ANSYS joint simulation. The results show that the structural reliability of the main shaft is 0.999 224 4, which is slightly lower than the required 0.999 9. According to the results of sensitivity analysis, improvement of the structural reliability can be achieved by increasing the mean of yield strength, decreasing the standard deviation of yield strength or increasing the mean of the size parameter R2.关键词：Main shaft of wind turbine;Parametric modeling;FEA;Reliability analysis;NESSUS
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发布时间：2022-09-22 - 摘要：To meet the requirements of shorter synchronization time and higher life for the synchronizer in transmission, mathematical models aiming at synchronization time and synchronizer life were established separately based on Newton’s second law and adhesive wear theory, M-B fractal contact model. The evaluation function was constructed by ideal point method to establish a multi-objective parameter optimization model with the two objectives. Using the AHP to determine weight value of the target in the multi-objective optimization model, and using the improved particle swarm algorithm to optimize the multi-objective parameter optimization model. The results show that the synchronization time is reduced by 8% and the synchronizer life is increased by 9% compared with that before optimization, the two objectives are improved better. The using of the improved particle swarm algorithm improves the performance of the synchronizer, and the application of the ideal point method effectively avoids the problem that the high order of magnitude dominates the multi-objective optimization.关键词：Synchronization time;Synchronizer life;Improved particle swarm optimization algorithm;Multi-objective
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发布时间：2022-09-22 - 摘要：In Isogeometric boundary element method（IGA-BEM）, Non-Uniform Rational B-Splines（NURBS） which are used for describing the geometric boundary in a computer-aided geometric design（CAGD） are employed as shape functions of Boundary Element Method. IGA-BEM not only can accurately describe the geometric boundary, but also unify the design model, analysis model and optimization model, so it can avoid the repeated meshing and mesh distortion problems in the optimization process and it also can improve the efficiency of the design, calculation and optimization. In this article IGA-BEM is combined with particle swarm optimization（PSO） to study the shape optimization of two-dimensional linear elastic structure. Compared with the gradient-based optimization algorithms, gradient-free PSO algorithm can avoid the complicated sensitivity analysis process and make the optimization process easier. The efficiency and accuracy of the combined isogeometric boundary element method-PSO are demonstrated through two shape optimization examples.关键词：Shape optimization;Non-uniform rational B-splines（NURBS）;Isogeometric analysis;Boundary element method;Particle swarm optimization algorithm
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发布时间：2022-09-22 - 摘要：Taking the left-front door of a type of car as the study object, the method which combined multipurpose optimal method with orthogonal experimental design was applied to parameters optimization design of the thickness of the door system components. Hyperworks software was used to establish a car door finite element analytical model on which a modal and stiffness analysis was performed, and then modal test and stiffness test were proceeded to testify and analyze the correctness of the model. Sensitivity analysis was conducted on each performance of the car door system with car door plate’s thickness being the variable; a car door plate thickness with comparative large influence on car door performance was selected as the controlling factor; a comprehensive performance evaluation function for car door system was constructed with the adoption of weighted sub-goals multiplying and dividing calculations; the orthogonal experimental design was applied to the parametric optimization design on car door system’s comprehensive performance. Finally, the best combinations of all components’ thickness parameters for car door system were got.关键词：Orthogonal experimental design;Parameter optimization;Finite element analysis;Sensitivity;Evaluation function
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发布时间：2022-09-22 - 摘要：This paper presents a finite-element approach to simulate the buckling process of the composite laminated plate containing a buried delamination. The delaminated composite laminates are analyzed using solid elements. In order to prevent the mutual penetration between the two parts above and below the delamination and to ensure coordinated deformation, a normal behavior of hard contact is applied at the interfaces of the delamination to take into consideration of the nonlinear contact effect between the debonded regions. Parametric analyses are conducted to investigate the effects of delamination depth, delamination length and aspect ratio on the buckling loads. Furthermore, buckling of a perfect laminate with the same geometrical parameters is simulated to obtain the critical buckling load. A comparison between the finite element prediction and the classic theoretical solution for the perfect laminate is carried out. It is found that they are in good agreement. The established model can simulate the buckling process of the composite laminated plate accurately.关键词：Composite laminated plate;Buckling;Delamination;Contact effects;Finite element analysis（FEA）
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发布时间：2022-09-22 - 摘要：Self-lubricating spherical plain bearings pad force of the state directly affect the contact performance, thus affects the service life. Therefore, based on the self-lubricating spherical plain bearing GE30 C, the finite element model（FEM） is established without changing the assembly size and axial swing angle. The evaluation index of the performance is determined and orthogonal test is carried out. The results were analyzed by comprehensive scoring method and range analysis method to obtain the characteristics of the major structural dimensions on the contact properties. The optimal size is determined and the contact performance.is improved. The results show that FEM can study the contact performance of the bearing and broaden the research method of the performance.关键词：Self-lubricating spherical plain bearing;Contact performance;FEM;Orthogonal test
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发布时间：2022-09-22 - 摘要：As an important structural component of a plane in its fatigue design,typical single-shear lap joint usually requires the analysis of its secondary bending. With the flat shells, by rational modelestablishing and analysis, the papergot the secondary bending of all fatigue detail points. At the same time, the paper validated the flat shells method. The calculation results and conclusionspresented in the paper are of reference value for the fatigue design of airplane’s typical single-shear lap jointstructures.关键词：Single-shear lap joint;The secondary bending;The flat shells method;Method validation
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发布时间：2022-09-22 - 摘要：the coupling relationship between the position of the moving platform and the attitude parameters is derived from the joint constraints of the spatial 3-RPS parallel mechanism, and the independent parameters used to describe the configuration of a mechanism is given. The geometric constraint of the mechanism is established by using the equal motion condition, and the inverse equation of the mechanism position is obtained. The relation between the velocity and acceleration between the components is established by using the first and two order derivatives of the constraint equations, thus avoiding the occurrence of composite joint variables in the equations of motion. The explicit relationship between velocity and acceleration among components is obtained. It proves that this method has the advantages of high computational efficiency and is helpful for the rapid solution and dynamic simulation of mechanism problems.关键词：Parallel mechanism;Position inverse solution;Velocity;Acceleration
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发布时间：2022-09-22 - 摘要：Food 3D printing as a new technology has been widely used in recent years. Base on the forming characteristics of 3D printing of fluidized food, the design scheme of the equipment was constructed by using the modular design idea. The 3D model of the equipment was first established in PRO/E. Then, the model was imported into ANSYS Workbench to carry out the finite element Static analysis and modal analysis. Static analysis results show that the maximum stress is less than the allowable stress and the strength meet the requirements. After that the first six modes of the modal analysis of the equipment was extracted and the food 3D printing experiment platform was built on the basis of the simulation. Moreover, the dynamic characteristics experiment of the food printing equipment as well as the discharge experiment were carried out. By comparing the dynamic characteristics experiment results with the simulation results, the validity of the finite element analysis was verified and the accuracy of the discharge port is up to the corresponding standard, which indicates that the designed 3D printing equipment meets the requirements.关键词：3D modeling;Food printing equipment;Modular design;Finite element analysis;Dynamic characteristic experiment
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发布时间：2022-09-22 - 摘要：According to the four rotor aircraft in a relatively complex near earth space, easily disturbed, and the emergence of jitter and out of control of motion stability, this paper investigated the motion stability of four rotor aircraft based on Lyapunov exponents method. First of all, the dynamics model of aircraft was established by Euler Poincare equation, and then the quantitative relationship between the structure parameters and the stability of the system were analyzed. Secondly, the stability analysis was carried out by Lyapunov exponential analysis. The Lyapunov exponent was calculated and the main parameters affecting the Lyapunov exponent were analyzed. The Lyapunov exponent spectrum of the corresponding attitude of the aircraft in the taking off and landing phases was calculated, The results showed that the stability of the taking off phase was better than that of the landing stage. Finally, in view of the poor stability of the four rotor aircraft during landing phase, the motion stability of the aircraft can be improved by changing the L value of the center distance of the rotor and the body.关键词：Four rotor aircraft;Dynamic model;Motion stability;Lyapunov index
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发布时间：2022-09-22 - 摘要：As a flexible high-speed dynamic sealing device,the finger seal has a good application prospect in high-speed sealing parts of aircraft engines and gas turbines. However,Under high-speed and high temperature conditions, friction heat and ambient temperature have a significant impact on contact strength and sealing performance of the finger seal. So exploring its influence mechanism becomes the key problem of finger seal design. Therefore,based on the actual working conditions,converting the friction heat to the heat flux density boundary condition,considering working temperature,a coupled thermal structural analysis model of the finger seal system is built,and the influence of thermal effect on the contact strength of the finger seal/rotor pair is studied,then it verified by tests. The results show that friction heat has an important influence on the contact strength of the sealing pair at high speed. Under normal temperature conditions,the local temperature of the finger seal rises above 370℃ because of friction effect,and the contact pressure at finger foot/rotor friction pair increases by nearly 10%. Under high temperature conditions,when the thermal effects are considered,local contact pressure is reduced by 90%. The performance test results show that,the maximum error between theoretical and test result is only 16.5% under pressure of 0.4 MPa,while the maximum error reaches 72.8% when thermal effect is not considered,which verified the necessity of thermal effect and the rationality of thermal analysis method. So the study provides an important reference for the design of finger seal under high temperature and high speed conditions.关键词：Finger seal;Thermal structural coupling;Friction heat;Contact strength;Heat effect
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发布时间：2022-09-22 - 摘要：According to the welded joints of cold formed hot-rolled automobile structural steel S420 MC and S500 MC, indentation tests on the cross-section were carried out to establish the constitutive relation for melting zone、heat affected zone and base metal. Based on ductile rupture and shear failure, a new failure model（micro failure model） for welding line was proposed, in which Kolmogorov integral equation was used to be a failure criterion taking account into the time correlation and damage accumulation. On the basis of the model, mechanical behaviors of welding line under the condition of impact load were simulated, then compared the results with two other numerical models（macro one-dimensional model and macro three-dimensional model）. The comparison results indicate that the simulation with micro failure model not only gives the uniform strength evaluation, but also can predict the time and area for initial ductile. Micro failure model could reflect the mechanical behaviors of laser welding line under impact load.关键词：Laser welding line;Ductile rupture;Shear failure;Damage accumulation;Nonlinear finite element
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发布时间：2022-09-22 - 摘要：In order to study the load test and load spectrum for fatigue reliability test of loader connecting rod, a method of connecting rod load test and load spectrum is presented. A kind of sensor is designed to measure the force of the connecting rod. The test experiment was carried out in primary stone, clay, sand and small stone under the conditions of these 4 kinds of material. By using the method of peak valley extraction and wavelet processing, the compression of the measured data is realized. By means of rain flow counting, the relationship between the mean frequency and amplitude frequency of the connecting rod load is obtained under the condition of synthesis, and they are subject to the normal distribution and three parameter Weibull distributions, and the load distribution of the mean value and amplitude distribution are independent of each other. The two-dimensional load spectrum and fatigue test program spectrum of the connecting rod are established, which can provide the basis for the reliability test and anti fatigue design of connecting rod structure.关键词：Loader;Connecting rod;Load test;Spectrum compilation
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发布时间：2022-09-22 - 摘要：Aiming at exhaust pipe cracking failure of a single cylinder diesel engine, thermo-mechanical coupling approach based on equivalent vibration and material temperature effect was presented, and then varied stress was simulated using Finite Element Method. According to the modified Miner law and linear cumulative damage theory, considering stress gradient, surface roughness and temperature, dangerous position of exhaust pipe structure is predicted. The results show that exhaust pipe cracking is due to lack of stiffness in upper and lower direction. There is a risk of thermal modal resonance, and insufficient safety factor causes failure. Fatigue safety factor of original and support improved is 1.06 and 1.6, respectively. The predicted results agree well with measurements.关键词：Diesel engine;Exhaust pipe;Fatigue analysis;Thermal mode;Thermo-mechanical coupling
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发布时间：2022-09-22 - 摘要：Mechanical damage can cause immediate or delayed failure of the pipe. The dent is the main form of mechanical damage. According to the Oyane ductile fracture criterion, the finite element method was used to simulate the axial simple dent caused by the construction stage. Analyzed the change of pipeline ductile damage degree in different pit sizes, pipe sizes and pipe pressures, the relationship between the dents depth and the ductile damage degree is obtained, which provides the theoretical basis for the safe design of the oil and gas pipelines with axial indentation during the construction stage.关键词：The construction stage;Axial simple dent;Oyane ductile fracture criterion;Dent depth;Toughness damage degree
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发布时间：2022-09-22 - 摘要：In this article, three dimensional elastic-plastic curved crack tip opening displacement under quasi-static loads has been mainly studied, and three dimensional curved crack tip opening displacement has been calculated as a practical application of a second order perturbation method, where the effects of quasi-static applied stresses and quasi-static normal and shear stresses on the boundaries of plasticity area are synthetically taken into considerations. Three dimensional curved elastic-plastic crack tip opening displacement has been calculated by numerical solutions, diagrams have been constructed to analyse the transformation relationships between curved crack tip opening displacement and three dimensional crack body geometrical measurement. Curved crack tip opening displacement will decrease when three dimensional crack body thickness increases. When crack body thickness increases evenly, three dimensional curved crack tip opening displacement will continuously decrease, furthermore, the decrease extent will be more and more slightly, and tend to plane strain state ultimately. Curved crack tip opening displacement will increase when external loads increase with the same crack body thickness. A new theoretical model where curved crack tip opening displacement was calculated has been established in three dimensional crack body.关键词：Three dimensional crack body;Curved crack;Opening displacement;Quasi-static applied stresses;A second order perturbation solution
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发布时间：2022-09-22 - 摘要：A prediction method of multi-axial creep life was proposed for notched bar metal specimen. Based on the Time-Hardening creep model, the stress distribution was simulated in the notched part during creep process. On the minimum section of the notch, the position where stress kept constant during creep process was defined as "skeletal point". According to the relationship between uniaxial tensile creep lives and stresses, the von-Mises equivalent stress of "skeletal point" was used to predict the multi-axial creep life of notched bar. The multi-axial creep lives of different P92 steel notched bars were predicted by this method and European multi-axial creep code respectively. The precision of predicted creep lives of two kinds of method are equal. Furthermore, the proposed prediction method is more simple and convenient for engineering applications.关键词：P92 steel;Notched bars;Multi-axial creep;Skeletal point stress;Creep life prediction
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发布时间：2022-09-22 - 摘要：It is the key for the development of green energy-saving belt conveyor to analysis and research on the rubber conveyor belt of steel core about its dynamic characteristics. Mathematical model of the rubber conveyor belt of steel core were established based on the space coordinate transformation theory. Then 3-D microscopic virtual simulation model were established by using parametric modeling, scanning and tensile of Pro/E software. The Moonery-Rivlin and Bilinear Isotropic model of ANSYS were used to define attribute about rubber covering and wire rope. Simulated dynamic characteristics of rubber conveyor belt of steel core under sinusoidal pressure by setting tied between wire rope and rubber covering. The result show that, under the axial displace load, the axial deformation of steel core presented layered distribution trend along wire rope section. The axial deformation of side strand’s side wire presented two-time-helix change distribution. Every side strand deformation amount was almost same and axial deformation of side strand’s side wire gradually enlarged along handed, the axial deformation amount of side strand changed remarkably relative to Core strand. The axial deformation amount of rubber covering exist little deformation amount in the middle port and large deformation amount all around. The average axial deformation of rubber is larger than the deformation amount of wire rope. which reveal mechanism of energy consumption about rubber conveyor belt of steel core, then that provide theoretical basis for research and development of green energy-saving belt conveyor.关键词：Conveyor belt;Microscopic model;Dynamic characteristics;ysteretic characteristic
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发布时间：2022-09-22 - 摘要：The abrasion of the shaft end of the cone bit is caused by many factors, In this paper, we mainly analyze the effect of the longitudinal vibration characteristic of the drill bit on the end of the tooth wheel on the wear and mechanism of the tooth axle end. And firstly, the longitudinal dynamic model of the three-cone bit is established, and on this basis, the vibration characteristics of the three-cone bit are analyzed, and the influence of the longitudinal vibration of the roller on the wear of the tooth wheel is explored, and the numerical model of fretting wear is established. It is found that the wear volume of the tooth axle end is mainly affected by the normal pressure of the contact surface of the tooth axle and the bearing and the tangential relative slip distance between the tooth axle and the bearing. At last, the paper analyzes the wear mechanism of the three-cone bit and has a positive effect on the study of the improvement of the life of the cone bit.关键词：Roller bit;Wear mechanism;Longitudinal vibration;Fretting Wear;Numerical calculation
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发布时间：2022-09-22 - 摘要：The High-frequency vibration tool is widely used in the packaging, footwear and other industries to make samples. At high speed, the tool often fails to meet the requirements due to noise and inaccuracy. Based on flexible multi-body systems dynamics theory and combined finite element analysis simulation method, a rigid-flexible coupling model of the high frequency vibrating tool was developed. Several useful conclusions are drawn that the reasons for tool failure are uneven stress on the eccentric shaft sleeve and big deformation for the linkage coincided with the practical. It also verified the model accuracy. Meanwhile, the flexible rod free mode and the tool mode under the constraint were analyzed, the resonance vibration frequency was obtained. The structure was improved by dynamic balance method, which effectively increased the operating frequency by balancing a part of mechanism inertial force and laid a theoretical foundation for the tool advanced optimization.关键词：The dynamics of the flexible multi-body systems;Flexible link;Co-simulation;Dynamic balance
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- 93
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发布时间：2022-09-22 - 摘要：In order to study the caving process of caving coal hydraulic support and the breaking law between immediate roof and basic roof,Taking the ZF15000/28/52 export caving hydraulic support as the research object, establish a three-dimensional simulation model by EDEM（an discrete element simulation software）,Taking Comprehensive consideration the effects of coal and rock particles and composition on coal caving,finally obtained the coal caving process with hydraulic support, the movement trend and velocity of coal and rock particles and the bond force chain of immediate roof and the basic roof,The simulation results are basically consistent with the actual coal caving process, which provides a new way to study the caving process of hydraulic support.关键词：Caving coal hydraulic support;Discrete element method;EDEM;Caving process
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- 295
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发布时间：2022-09-22 - 摘要：Aiming at the failure phenomenon of auto seat backrest adjuster under limiting operational condition, the finite element model is established to obtain the stress field and deformation field of all parts. And this work can provide guidance for the structural optimization design. The constitutive relationship law of all parts of seat backrest adjuster can be described well by elastic-plastic model and GTN model. By using the different flow stress models and damage parameters, the mechanic parameters of material which were in good agreement with the result of uniaxial tension test is obtained. On this basis, simulation of seat backrest adjuster is presented by the explicit dynamics method. The results show that fault shearing zones can be found at the boss root of chute. The present method can provide the guidance of structural strength check.关键词：GTN model;Flow stress model;Seat backrest adjuster;Strength analysis
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- 141
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发布时间：2022-09-22 - 摘要：Satellite antenna suffers complex dynamic environment during satellite launch. A new type of structure design of antenna used for data transmission was proposed, aiming at the problem of insufficient antenna installation space and view shade, because of big size of the optical camera. The structure dynamic characteristic of antenna was analyzed and optimized, and also the dynamic environment test was carried out. The results show that: the structure design of antenna meets the stiffness and strength requirements of satellite launch.关键词：Satellite antenna;Mechanically scanned;Anti-dynamic load design
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- 110
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发布时间：2022-09-22 - 摘要：In this paper, the vibration control method of train pantograph is studied. A dynamic equation based on Newton’s second law is established for the two element pantograph model. Magneto rheological damper is used to control the contact force fluctuation of pantograph catenary. A variable universe fuzzy controller is adopted as the control algorithm. The simulation results show that with the increase of train speed, contact force fluctuation is more obvious, this paper studies the power control method of arch vibration compared with the traditional fuzzy control and passive control method under the action of the contact force is not the average coefficient. When the magneto rheological damper is installed between the upper frame and the bow head, the contact force between the frame and the lower frame is lower than that of the lower frame, and the contact force of the pantograph catenary fluctuates less.关键词：Pantograph;pantograph catenary system;magnetorheological damper;Vibration control;variable universe fuzzy control
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- 198
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发布时间：2022-09-22 - 摘要：The composite material has the advantages of high specific strength and high specific stiffness, which could reduce the structural weight effectively when it was applied to the tail shaft of helicopter transmission system. The connection with the composite tail shaft and flange usually adopt riveting, the riveted area was the weakness of the tail shaft. In this paper, the riveting analysis model of composite tail shaft and flange was established by ANSYS ACP software. The Tsai-Wu failure criterion was adopted for the failure of the riveted joints. The riveting structure lost its function of carrying capacity when the failure zone of the riveting was more than the coverage area of gasket. By comparing with the results of static torsion test, the calculated results were in good agreement with the experimental results.关键词：Helicopter transmission system;Tail shaft;Composite material;Riveting carrying capacity
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- 208
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发布时间：2022-09-22 - 摘要：Aiming at the problem of radiated noise in automobile transmission housing, a method to find the exact location of effective reinforced concrete parts by using modal acoustic contribution analysis and panel acoustic contribution analysis is proposed. In this paper, the sound pressure curve and its peak frequency of the transmission shell are obtained by using the analysis method of acoustic boundary element. Then, by analyzing the contribution of modal acoustics at peak frequency, the modal order of the larger contribution to the noise is obtained, and the local area with large acoustic contribution is obtained from the modal cloud. Finally, the localized region of the acoustic contribution is analyzed by the acoustic section contribution analysis, so as to find out the acoustic Contribution to the larger and need to improve the specific parts. Furthermore, the structure of the transmission case is improved, and the improved structure is verified. The study shows that the method of reducing the radiation noise of the shell by means of modal acoustic contribution analysis and panel acoustic contribution analysis is an effective method to find out the specific parts of the shell that need to be improved intuitively and accurately, and the improved shell structure can be effective improved the noise characteristics of the shell.关键词：Transmission housing;Radiation noise;Modal acoustics contribution;Panel acoustics contribution;Structure improvement
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- 143
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发布时间：2022-09-22 - 摘要：Aiming at the problem of erosion in oil pipeline transportation system on solid particles in liquid-solid two-phase flow of tee pipes,the erosion area which is caused by solid particles what contain in oil can be simulated by using DPM erosion prediction model.Results show that the erosion location and the degree of solid particles are different from different types of tee pipe.The erosion of T pipe is mainly concentrated on the bottom of the horizontal pipe and the pipe wall near them.The erosion of tee pipe which has a sphere elbow is mainly concentrated on the horizontal pipe wall near the sphere,and the erosion degree is relatively small.关键词：Tee pipes;Liquid-solid two-phase flow;Erosion-corrosion;Solid particles;Numerical simulation
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- 551
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发布时间：2022-09-22 - 摘要：In order to study the vibration characteristics of gun barrel under the action of moving projectile in gun launching process, taking an artillery gun for example, based on the Euler-Bernoulli beam theory, the coupled equations of vibration of a moving projectile elastic tube coupled with the initial deflection of the tube body are established. Using the finite element software ABAQUS and the dynamic analysis software ADAMS, the rigid flexible coupling dynamic model considering the initial deflection is established, and the numerical results are verified. On the basis of the model, the law of the muzzle velocity and the mass of the projectile affecting the muzzle vibration characteristics are analyzed. The results show that the initial deflection of the tube body has a great influence on the vibration analysis results, and can not be ignored. In the case of the initial deflection of the tube, the larger the projectile velocity is, the larger the muzzle vibration amplitude is. When the velocity is constant, the larger the projectile mass is, the larger the muzzle vibration amplitude is.关键词：Projectile barrel coupling;Rigid flexible coupling;Initial deflection;Modal superposition principle
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发布时间：2022-09-22
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