最新刊期
期 2 ， 2022
- 摘要：Using Kirchhoff’s basic hypothesis and combining geometric equation with physical equation, the nonlinear vibration equation of axially moving thin plates was obtained by using Hamilton variation principle. In this paper, an axially moving strip plate with opposite hinged clamped boundary constraints under double-periodic line load was studied. Considering the first two modes and setting the displacement solution. By using Galerkin method and the method of multiple scales, the amplitude frequency response equation of the system under 1∶3 internal resonance and external excitation combined resonance under double-excitation was derived. By calculation examples, the characteristic curves of the first two resonance amplitudes varying with frequency tuning parameters and external excitation were obtained. The effects of the axial velocity of plate and the position of the external excitation force on the resonance characteristics of the system were discussed. The results show that the internal resonance characteristics of the system are obvious, and present the complex multi solution and combination resonance characteristics.关键词：Thin plate;Axially moving;Combination resonance;Line load;The method of multiple scales
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发布时间：2022-09-22 - 摘要：Due to the nonstationarity, complex transmission path, high system noise and serious modulation phenomenon of wind turbine gearbox vibration signal, the conventional spectrum analysis method was difficult to identify the fault location of gearbox. In order to solve the above problems, a fault diagnosis method of wind turbine planetary gearbox based on synchronous extraction（SET）and vold-Kalman filter（SEV） was proposed in this paper. This paper first describes the principle and process of the proposed method. The vibration signal of the generator bearing was extracted by the local energy maximum method based on SET（LMS）, and then the instantaneous frequency was accurately extracted based on the ward Kaman filter to obtain the complete phase information. Finally, the detailed fault location information of wind turbine gearbox was obtained by order analysis. Simulation and experimental analysis verify the effectiveness of the proposed method.关键词：Fault diagnosis;Wind turbine planetary gearbox;Variable speed;vold-Kalman filter;Synchronous extraction
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发布时间：2022-09-22 - 摘要：Precision milling technology has been widely used in the precision manufacturing in automobile, aerospace, microelectronics and other fields. Vibration during milling greatly affects machining accuracy and quality. In this paper, a method of cutting vibration signal analysis and optimization based on blind source separation is proposed in milling process. Firstly, combining Ensemble Empirical Mode Decomposition（EEMD） with Sparse Component Analysis（SCA）,the blind source separation of milling vibration signals was realized, so as to calculate the vibration contribution and analyze the main vibration factors of precision milling. Based on the analysis of vibration experimental signals, the order of influence of milling parameters on vibration was studied by Taguchi method. Finally, the optimization method of machining parameters is proposed.关键词：Milling vibration;Blind source separation;Contribution of vibration source;Taguchi method;Parameter optimization
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发布时间：2022-09-22 - 摘要：This article is a study on the physical properties of the scraper under torsion. At first, the process of the scraper conveyor passing through the curved section of the conveyor is analyzed, and then on this basis, the bending moment and the additional resistance of the curved section are analyzed with the aid of a computer based on the dynamic model. Introduce the Voigt elastic viscosity model as a processing method, establish the model, and then use MATLAB programming to realize the pre-processing of the analysis. Finally, through data simulation, the characteristic data of the system（torsion, vibration, speed, etc.） under different material loading conditions at different positions of the scraper through the bending section are obtained. The analysis results show that when the scraper passes through the bending section, the system will produce a certain torsional vibration; for the presence or absence of materials, the scraper can be regarded as being in the load and no-load stages. The torsional vibration intensity is more pronounced under no-load conditions than when the front and rear are loaded; for the entire scraper, when it passes through the bending section, the closer the scraper chain system（swing, vibration, Speed, etc.） the more significant the feature changes.关键词：Scraper conveyor;Torsion;Vibration;Bending section;Offset load
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发布时间：2022-09-22 - 摘要：In order to solve the traditional methods in the process of judging the fault type of the bearing caused by signal strongly nonlinear misjudgment wrongly, based on the chaos theory, the phase space reconstruction method（PSR） is used to restore the system dynamics characteristics and the convolution neural network（CNN） is used to learn and extract the effective nonlinear information from the chaotic sequence, proposes the PSR-CNN intelligent fault diagnosis method, visualizes the attractor trajectory, and analyzes the nonlinear characteristics of each fault signal. Taking the experimental data of rolling bearings as the research object, the PSR-CNN method is used to analyze and diagnose early bearing faults. The results show that the attractor trajectory of the early weak fault signal is not representative of the fault due to noise interference; after learning by CNN and extracting effective nonlinear information, the attractor trajectory has significant chaotic characteristics and shows a fault separable state. The fault diagnosis method using PSR-CNN has higher accuracy and better generalization performance than the CNN diagnosis model based on the time domain and frequency domain, and has greater advantages in convergence speed and stability.关键词：Convolutional neural network;Chaos;Bearing;Fault diagnosis
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发布时间：2022-09-22 - 摘要：Aiming at the problems that the minor fault features of wind turbine gearbox bearings are easily submerged and difficult to extract under the background of strong noise, a continuous average spectral negative entropy（CASN） is proposed to improve the empirical wavelet transform（EWT）. The CASNEWT method is used to decompose the fault signal of the wind turbine gearbox bearing, and then the obtained components are filtered and reconstructed by the spectrum negentropy criterion, and the reconstructed signal is analyzed by envelope analysis to accurately extract the fault characteristics. Finally, a feature vector set is formed and input to the support vector machine for fault diagnosis. The results show that the CASNEWT method retains the advantages of the EWT algorithm, which can effectively avoid the modal aliasing effect and the end effect, while greatly improving the robustness of the EWT decomposition algorithm to noise, removes the noise and retains the original signal characteristic information. Accurately extract the characteristic frequency of the fault to improve the accuracy of fault identification.关键词：Wind turbine gearbox;Fault diagnosis;Sliding window;Continuous average spectral negentropy;Improved empirical wavelet transform;Spectrum negentropy criterion
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发布时间：2022-09-22 - 摘要：In order to solve the vibration problem of clamp-lifting device, the joint mechanical analysis and modelings including clamp-lifting device, wheel and landing gear were carried out, and the system vibration differential equations including stiffness and damping characteristics of components were obtained by the frequency response method. The system vibration characteristics under an external displacement disturbance in horizontal and vertical directions were studied by MATLAB simulation.Then the influence of element stiffness and damping characterstics on device vibration was analyzed. The anti-vibration design and effect verification of the clamp-lifting device were carried out through ANSYS calculation and vibration simulation. The results show that the restraint mode and load distribution on wheels are optimized, the device stiffness is improved, the device deformation under load is reduced to 1/3 of the original, and the device vibration amplitude and time are reduced by more than 50% when disturbed. The 1 st～6 th order modal analysis shows that the resonance possibility of lifting plate is low. The research can provide a useful reference for an anti-vibration design in aircraft traction.关键词：Clamp-lifting device;Vibration model;Simulation analysis;Anti-vibration optimization
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发布时间：2022-09-22 - 摘要：Analyzing the influence of bearing parameters on the dynamic characteristics of spherical sliding bearings, which provided theoretical guidance for the operating stiffness, damping and stability of liquid spherical bearings. Taking spherical hybrid sliding bearings as the research object, established the mathematical model of lubrication analysis of spherical sliding bearings, the dynamic liquid lubrication equation under laminar flow was derived by the perturbation method, the partial differential equation of disturbance pressure was solved by the finite difference method, and the liquid was calculated numerically. The stiffness coefficient and damping coefficient of the spherical bearing were used to study the influence of the bearing speed, eccentricity, average oil film clearance and other parameters on the dynamic characteristic coefficient of the bearing through numerical analysis. The results show that the speed、 eccentricity and average oil film clearance have an important influence on the stiffness and damping of the oil film.关键词：Spherical hybrid sliding bearings;Liquid lubrication;Perturbation method;Dynamic characteristic coefficient;Data analysis
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发布时间：2022-09-22 - 摘要：Considering the current heavy mining and light digging in coal mines, limitations of the structural design of the fully mechanized excavation equipment, backward tunneling technology and other problems lead to inefficient tunneling. mining ratio is out of balance, at the same time, the comprehensive excavation equipment of the coal mine underground roadway is huge, the downhole environment is complicated, and the equipment is difficult to disassemble and assemble. It is difficult to analyze the mechanical properties of key components and cut efficiency improvement experiments under laboratory conditions. A method of active excitation assisted cutting is researched, this method is based on similarity theory, a similar model test bench with a ratio of 1:3 is established, modal experiments were performed firstly, the natural frequencies of the first six orders and the modal shapes of each order are obtained, the feasibility of the active vibration-assisted cutting experimental bench is verified, perform cutting experiments on the test bench separately with or without active excitation. With or without active excitation, the cutting contact force and cutting current change of the pick are measured. The experimental results show that during the same time period, when there is active excitation, the initial time for increasing contact force is 0.07 s earlier than when there is no excitation, longer duration, contact force is reduced by 0.12 kN compared with no excitation, after excitation, the average cutting current decreased by 1.12 A.Through the test bench based on Similarity theory, the active excitation vibration experiment and test can be carried out on the cutting arm of the road-header under limited laboratory conditions. Which provides a theoretical reference for selecting the best excitation-assisted cutting parameters. At the same time, it has opened up new ideas and new methods for the energy-saving and efficient work of the cutting machine cutting mechanism from the perspective of external excitation.关键词：Active excitation;Similarity theory;Experimental platform;Modal experiment;Cutting experiment
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发布时间：2022-09-22 - 摘要：To reduce the vibration of the diamond roller shaft during the dressing process through the experimental study of the diamond roller dressing process to improve the grinding wheel morphology and subsequent grinding surface quality. Firstly, the vibration mechanism of diamond wheel dressing is described, and the dynamic characteristics of dressing device have important influence on dressing process and subsequent grinding. Then diamond roller dressing dynamics model is established and the model is divided into two parts of the grinding wheel and diamond wheel, and by changing the diamond roller shaft support materials to change the contact stiffness, damping, and stiffness and numerical simulation calculation, analysis of diamond roller shaft in the use of steel support material and casting the vibration of the support material circumstances difference; Finally, through experimental verification, it shows that the surface quality of the subsequent grinding workpiece is different in the case that the vibration of the diamond roller shaft is larger and smaller. The numerical value of the vibration amplitude of the diamond roller shaft supported by the steel material was 1.5×10-6m/s~2, and the maximum value of the vibration amplitude of the casting material support was about 0.3×10-6m/s~2. The diamond roller shafts with supporting materials of steel and casting are used for dressing, and then grinding is performed. The surface of the workpiece ground by the former has burns, while the surface of the latter is qualified. The dynamic characteristics of dressing device have a great influence on the vibration during dressing. When other conditions remain unchanged, the greater the stiffness, damping and contact stiffness, the more stable the dressing process will be. The larger the vibration during the dressing process, the worse the surface morphology of the dressed grinding wheel, and the more likely the workpiece will be burned during grinding.关键词：Diamond wheel dressing;Dynamic model;Dressing vibration;Numerical simulation calculation
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发布时间：2022-09-22 - 摘要：In order to improve the tribological performance of the parts of mine internal combustion engine in wide temperature domain, cobalt matrix composites with different proportions of solid lubricants（7%MoS2+7%ZnO, 9%MoS2+ 5%ZnO, 11%MoS2+ 3%ZnO） were prepared by hot pressing sintering technology. The tribological properties of the composites at room temperature, 200℃, 400℃, 600℃ and 800℃ were tested by high temperature friction and wear testing machine. The microstructure, phase composition and wear mechanism of the materials were studied. The results show that the three materials show similar trends of friction coefficient and wear rate. MoS2 effectively improves the tribological properties of composites in a wide temperature range. The frictional and anti-wear effect of ZnO mainly plays a role at 800℃. The tribological properties over a wide temperature range are attributed to the sulfide films at moderate and low temperatures and the oxide films composed of ZnO, Co2O3 and chromate at high temperatures. The wear mechanism is abrasive wear at low temperature and oxidation wear at high temperature. The results show that the materials containing 9%MoS2+ 5%ZnO exhibit the best tribological properties over a wide temperature range.关键词：Hot pressing sintering;Solid lubricant;Friction;Wear
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发布时间：2022-09-22 - 摘要：In view of the effect of random uncertain factors such as the material properties of the turning shaft and different load conditions on its performance, and reduce its weight to improve fuel economy.Through the finite element modeling of the dump truck, the load analysis of the turning shaft is carried out according to the limit force under the actual working conditions, the first-order second moment method is used for reliability analysis, and the reliability index is used to reflect the influence of uncertain factors. The stiffness and dynamic characteristic values under static multi-conditions are set as objective functions, and the volume fraction and reliability index are used as constraints. A comprehensive objective function is established based on the normalized sub-objectives of the compromise programming method, the weight coefficients of the sub-objectives are determined by the analytic hierarchy process, and the multi-objective topology optimization design based on reliability constraints is carried out on the flip-axis structure. The results show that, compared with the deterministic topology optimization, the stiffness of the turning axis and the natural frequencies of each order obtained by the reliability topology optimization are more significantly improved, and the mass is reduced by 28.96% under the condition of satisfying the reliability. The experimental test and theoretical analysis results are basically consistent, verifying the feasibility of multi-objective reliability topology optimization design.关键词：Dump truck turning axle;Topology optimization;Reliability analysis;First-order second-moment method;Analytic hierarchy process
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发布时间：2022-09-22 - 摘要：Guided by the uncertainty theory, this paper considers the complex and variable working conditions of tents and expounds the feasibility of finite element analysis under the condition of uncertainty of both material and working conditions. It then proposes the topology optimization based on reliability. The scheme takes the reliability index as the constraint condition and transforms uncertain parameters into deterministic parameters, and then the variable density algorithm topology optimization is performed. Taking two typical structure frames of military and civil tents as examples, respectively, the stress of the frame under wind load is considered, and the feasibility of the design scheme and algorithm logic is verified. The results of the mechanical simulations show that the scheme not only obtains the ideal results, but also avoids repeated iterative scheme trial calculations, thus significantly reducing the time costs and workload of the R＆D process, thus promising optimal promotion value and applicability in the engineering fields.关键词：Uncertainty theory;Reliability;Topological optimization;Wind loads;Tents
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发布时间：2022-09-22 - 摘要：In order to solve the limitations of traditional methods in the reliability assessment of complex systems with multi-states and difficult to obtain accurate failure rates, and the problems of T-S fault tree in the system reliability analysis, such as complex calculation and inverse reasoning, etc., a reliability assessment method based on T-S fault tree and interval-valued fuzzy multi-state Bayesian network is proposed. Based on the analysis of the T-S fault tree, it is mapped into a Bayesian network. In the existing fuzzy Bayesian network reliability analysis method, the interval variable is introduced. Fuzzy processing is carried out to construct an interval-valued triangular fuzzy Bayesian network. Combining the characteristics of interval fuzzy subsets and Bayesian networks, a solution algorithm for leaf node failure probability, interval fuzzy importance, and interval fuzzy posterior probability is obtained under the condition of knowing only the root node failure status. Finally, the method is used to evaluate the reliability of the expansion system of the tunnel stacker, and it is verified that this method can accurately and effectively identify the weak links of the polymorphic system, and provide guidance for maintenance and diagnosis.关键词：Multi-fault state system;T-S fault tree;Interval-valued fuzzy Bayesian network;Reliability assessment;Telescopic transmission system
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发布时间：2022-09-22 - 摘要：Aiming at the problems of low accuracy and easy to cause resonance in the work of the flat sand system, the topology optimization design of the cantilever beam structure of the flat sand system is carried out in this paper. Starting from the internal material layout of the cantilever beam, taking the distortion energy density of the material as the optimization goal, the alterable density method was used to optimize the topology of the cantilever beam in the ABAQUS software, and the most reasonable material distribution is obtained. The optimization results show that when the applied load is 400 N required by the working conditions, the displacement of the front end of the cantilever beam decreased from 4.205 to 1.447 mm, which meets the requirements of the working conditions after optimization. The maximum stress decreased from 20.04 to 6.824 MPa. When the mass of the cantilever beam decreases by 41.4%, the 1 st order natural frequencies of the cantilever beam increased by 2.481 Hz, which is far away from the external excitation frequencies, and the dynamic performance of the cantilever beam is improved. The maximum displacement of the model after topological optimization is verified to meet the requirements of the working condition through the angle change test, which effectively improves the overall utilization of materials and provides a theoretical basis for the design of the flat sand system.关键词：Flat sand system;Cantilever beam;Finite element analysis;Topology optimization
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发布时间：2022-09-22 - 摘要：The surfaces of gear teeth are often subjected to spalling fault, which would deteriorate the functioning of gear transmission. In most of existing dynamic models of spalling gears, the load is treated as a constant while calculating the meshing stiffness. The resultant mesh stiffness thus the corresponding dynamic models are not able to truly reflect the meshing state of a gear pair as the load is varying during meshing process. To solve this problem, a new dynamic model of spalling gears is developed, wherein the meshing stiffness is calculated based on dynamic load. To be specific, the load change process of gear spalling meshing is expressed dynamically. The meshing stiffness is calculated through the coupling of dynamic load and dynamic model of gear. The numerical iterative method of Euler-Cromer was used to solve the dynamic equations of gear. The dynamic characteristics of the system were obtained when the spalling fault occurred. The comparison between the simulation results and the traditional spalling gear model shows that the proposed spalling gear model has a better accuracy.关键词：Spalling;Meshing stiffness;Dynamic load;Dynamic characteristics
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发布时间：2022-09-22 - 摘要：In order to study the influence of the three-dimensional appearance of the gear pitting pits on the stress concentration of the tooth surface, the effect of pitting pits with different shapes on stress concentration factor of gear was analyzed by finite element method. By changing the length, width and depth of ellipsoid pitting pits, the influence of different length-width ratio and depth-width ratio on stress concentration factor was analyzed, and the approximate calculation model of stress concentration factor of ellipsoid pitting pits was established. According to the contact fatigue test data of a gear, the calculation model established by this method was analyzed and verified, and the influence of the change of pitting pit size on the stress concentration factor of the gear was further analyzed and discussed. The results show that: the stress concentration of ellipsoid pits on the tooth surface was the most obvious, followed by conical pits, pentagonal pits and triangular pits when the basic size of pitting pits was the same. The stress concentration factor increases with the increase of depth-width ratio and length-width ratio of ellipsoidal pit.关键词：Pitting;Gear;Tooth surface;Dimensional change;Stress concentration factor
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发布时间：2022-09-22 - 摘要：Taking the DTU 10 MW wind turbine as the research object, the OO-Star semi-submersible platform floating wind turbine model is established, based on the blade element momentum theory and the radiation/diffraction theory to solve the wind load and wave load respectively, and the dynamic response of floating wind turbines under different environmental load directions is simulated, and the impact of different environmental load incident angles on its response characteristics is compared and analyzed. The results show that the incident angle of turbulent wind has a greater influence on the response of floating wind turbines to surge, pitch and yaw, while the incident angle of wave has a great influence on the sway and roll response. The heave response hardly changes with the turbulent wind and wave incident angle. As the incident angle of turbulent wind increases, the average power of floating wind turbines drops sharply, while the incident angle of waves has almost no effect on its average power. In addition, in the mooring system, the mooring tension of No.1 increases gradually with the increase of the incident angle of turbulent wind and wave, while that of No.2 mooring decreases gradually, while that of No.3 mooring increases first and then decreases with the increase of incident angle of turbulent wind, and increases gradually with the increase of incident angle of wave.关键词：Wind-wave misalignment;Floating wind turbine;Blade element momentum;Radiation/Diffraction theory;Motion response
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发布时间：2022-09-22 - 摘要：Abstact Taking into account the long-distance and heavy-duty working characteristics of the scraper conveyor, the harsh working environment and complex working conditions often lead to jams and chain broken accidents. In order to study the transient mechanical characteristics of the scraper conveyor’s stuck and broken chain, based on the elastic wave theory, the general equation of the chain longitudinal wave is established considering the resistance of the load, the boundary and initial value conditions are determined, and the mathematical model is analyzed and solved. Using MATLAB software, numerical simulation analysis was carried out on the dynamics of the scraper conveyor under the direct starting conditions and the stuck and broken chain fault conditions. Finally, combined with the virtual prototype technology, the multi-body dynamics simulation software ADAMS is used to analyze the dynamics of the scraper conveyor jam and chain broken conditions.The research results reveal the law of chain tension changes at the moment when the chain is stuck or broken.关键词：Scraper conveyor;Multi-body dynamics;Tension fluctuation;Fracture;MATLAB
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发布时间：2022-09-22 - 摘要：Aiming at the problem of unified modeling and simulation of system dynamics of simple swing jaw crusher driven by electric motor, the corresponding vector bond graph method was proposed. According to the constraint relation of the kinematic pair of the mechanism, the vector bond model of each component was bonded to each other, and the vector bond graph model of a six bar simple swing jaw crusher mechanism was made. By acting on the constraint force vectors of kinematic pair as the effort source vector at the corresponding 0-junction, the energy storage elements of the mechanism vector bond graph model were made have integral causality. Based on this, the vector bond graph model of the simple swing jaw crusher system was made, which takes into account the driving motor, crushing resistance force and the constraint force vector of the kinematic pair, and the unified computer modeling and dynamic simulation of the electromechanical system were realized. Compared with the results calculated by Newton-Euler dynamics method, the reliability of the proposed method was verified. The results show that the method described in this paper is effective, and its stylized modeling method improves the automation degree and reliability of electromechanical system dynamics modeling and simulation. In a movement cycle, the positive and reverse maximum of angular velocity for jaw crushing stroke and discharging stroke have little difference, and the time of crushing stroke and discharging stroke is close. At the beginning and the end of a motion cycle, the angular acceleration of the moving jaw and the constrained reaction force at both ends of the moving jaw will change greatly. In the final stage, the angular acceleration of the moving jaw increases from 0 to-83.36 rad/s~2, and the growth rate of the constrained reaction force at both ends is 2 576.44% and 249.10%, respectively. In addition, when the jaw is in the left limit position, the abrupt change of crushing force leads to large abrupt change of constrained reaction force at both ends of the jaw, with the reduction rates of 95.84% and 72.43%, respectively. This lays a foundation for the optimal design of the structure and parameters of the crusher, and further shows that the method presented in this paper has distinct characteristics and advantages.关键词：Vector bond graph;Simple swing jaw crusher;Unified modeling;Dynamic simulation;Causality
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发布时间：2022-09-22 - 摘要：In the process of applying cold-stretching process to normal pressure vessel, the vessel will undergo two stages of elastic and plastic deformations. If the plastic deformation occurs, the minor change of deformation in the vessel is sensitive to the pressure. Therefore, the reasonable control of the deformation in the vessel is one of the key steps in the cold-stretching process. The resistance strain gauges（RSG） were pasted in the main parts of the vessel to determine the relationship between the elastic deformation of the corresponding position and the cold-stretching pressure applied gradually. In addition, the verification of the reliability of the finite element（FE） analysis was carried out based on strain measuring results. In the plastic deformation stage, the FE was used to analyze the overall deformation law of cylinder, head and around the nozzle of the vessel under the cold-stretching pressure, meanwhile the position where the maximum deformation occurred in each part of the vessel was obtained. The results show that the local maximum deformation of the vessel is 8.24%, which appears inside of the nozzle root, and meets the requirement of local maximum deformation of no more than 10% in the current standards.关键词：Cold-stretching;Austenitic stainless steel;Pressure vessels;Deformation;Finite element
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发布时间：2022-09-22 - 摘要：Based on the modification of the single-roller-enveloped toroidal meshing worm drive, a parabolic modified roller-enveloped toroidal meshing worm drive is obtained. According to the spatial meshing theory and the transmission characteristics of the parabolic modified roller-enveloped toroidal meshing worm drive, the basic mathematical model is established; based on the mathematical model of parabolic modified roller enveloping toroidal meshing worm transmission, the basic characteristic parameters of the new worm transmission are deduced, and the meshing performance of the new worm transmission is further analyzed. The basic performance is very good.关键词：Roller;Meshing theory;Parabolic modification;Hourglass worm drive
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发布时间：2022-09-22 - 摘要：In order to explore the influence of different TPMS pore structures on the mechanical properties of the porous scaffold, TPMS expressed by implicit function was used as the basic pore unit to construct the micro-porous structure. TPMS porous scaffolds with different structural characteristics were constructed by defining the distance function, And AlSi10 Mg porous scaffolds were prepared by SLM. Finite element Method（FEM） analysis and mechanical test method were used to study the influence of different pore structure characteristics on mechanical performance of porous TPMS scaffolds and analyze the influence law of different distance function k values on porosity, elastic modulus, yield strength and failure of Primitive（P） and F-RD porous structure scaffolds. Finite element analysis and experimental results show that with the increase of distance function k, the elastic modulus and yield strength of the P unit porous scaffold presented an increasing trend, However, the elastic modulus and yield strength of the FRD unit porous scaffold showed a downward trend, Moreover, Comparing to FRD unit, P unit porous scaffolds were more likely to be crushing, through the control of the TPMS types and the distance function k value, the porosity, elastic modulus and yield strength of the porous scaffold can be effectively adjusted. The results provide a basis for the design of tissue-engineered bone scaffolds.关键词：TPMS;Pore structure;Mechanical properties;Porous scaffold;Distance function k
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发布时间：2022-09-22 - 摘要：Counterbalanced forklifts is a kind of industrial vehicles specially used for handling, loading and unloading, having a wide range of uses, and the working environment is becoming more and more complex. Research on the stability of counterbalanced forklifts is becoming more and more important, but stability has attracted less attention in the academic community. The deflection of portal frame channel steel is a key parameter of stability that cannot be ignored. Domestic design of portal frame channel steel is based on analogy, which leads to its high safety factor, waste of raw materials, and weak theory and computer assistance. This paper analyzes the influence on safety and stability of the counterbalance forklift, and studies the longitudinal stacking stability of the forklift. Through the force and deformation analysis of the forklift channel beam, a model of the longitudinal stability and deflection deformation of the channel steel is established. Verify the correctness of the model through experiments. Research on the stability of counterbalanced forklifts provides theoretical basis and guidance for enterprises in the design and development of forklifts, which is conducive to saving materials, improving the energy efficiency of forklifts and ensuring their safety and reliability. It has certain theoretical significance and engineering value.关键词：Forklift truck;Deflection;Model;Longitudinal stability
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发布时间：2022-09-22 - 摘要：In order to seek a lattice structure with better mechanical properties, a reverse Kagome lattice unit cell model is proposed based on the point group theory, and it is contrastively analyzed with the kagome unit cell model in the mechanical properties. The stress and strain theory is used to determine the key parameter of the reverse Kagome unit cell, which is the range of the inclination angle ω on the constraint condition of realizing the compression performance, shearing property and reaching the relative density and bearing capacity of the reverse Kagome. Combined with the finite element analyze results, it can determine the value of ω of this model under the best mechanical performance. An experiment of the reverse Kagome lattice model is performed to verify the correctness of the theoretical analysis. The research shows that when the tilt angle ω is 52°, the reverse Kagome lattice structure has the best compression resistance, and when the tilt angle ω is 38°, the shear performance of this structure is better; In terms of overall performance, the 45°inclination angle is better than the other two inclination angles.关键词：Point group;Lattice structure;Tilt angle;Inverse Kagome;Stress and strain
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发布时间：2022-09-22 - 摘要：The propagation path of cracks perpendicular to the interface of composite laminates usually takes many forms. By analyzing the stress field of crack tip during crack propagation, the driving force of crack tip is determined, in this way, the crack propagation path is analyzed. This article’s research object is the titanium-steel（TA2-Q235 B） composite laminate, a commonly used material for pressure vessels, the influence of the mismatch of elastic modulus and strength of the two materials on crack propagation is discussed by numerical analysis. The analysis results show that both two factors have a certain degree of promotion or inhibition of crack growth. When the crack propagates from a high-strength material to a low-strength material, the crack propagation rate increased and conversely decreased; when the crack propagates from a high elastic modulus material to a low elastic modulus material, the crack propagation rate increased and conversely decreased. No matter which direction the crack propagates from, the closer it is to the interface, the more obvious its effect will be. When the crack propagates to the interface, the crack propagation rate will decrease, or crack arrest will occur.关键词：Composite laminate material;Crack expansion;Elastic mismatch;Intensity mismatch
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发布时间：2022-09-22 - 摘要：In order to explore the influence of the size effect on the fracture strength of unidirectional continuous glass fiber reinforced polypropylene composites（unidirectional GF/PP composites）, the Zwick/Roell Z005 universal material testing machine was used to test different gauge lengths through orthogonal test methods.（60 mm, 100 mm, 200 mm）, unidirectional GF/PP composites with different widths（10 mm, 15 mm, 20 mm） are subjected to tensile test. The test results show that as the test size increases, the breaking strength of unidirectional GF/PP composites gradually decreases. Because the fracture strength of unidirectional GF/PP composites has a large dispersion, the distribution law of the strength of unidirectional GF/PP composites under different size conditions is obtained through the classic two-parameter Weibull strength statistical model, and the improved generalized The two-parameter weakest chain strength statistical model introduces the exponential parameterβto modify the influence of the spatial distribution of defects. The fracture strength data under different sizes are processed in a unified manner. The resulting failure function comprehensively reflects the size effect on the unidirectional GF/PP composite The effect of material breaking strength.关键词：Size effect;Fiber reinforced composite material;Weibull distribution;Breaking strength
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发布时间：2022-09-22 - 摘要：Subway safety is one of the important part in vehicle design. When lifting the whole vehicle, the axle box lifting lug cooperates complete the lifting function of the bogie with the frame limit stop. During vehicle operation, the fracture of lifting lug will affect the safety of vehicle operation. Firstly, the failure types of the lifting lug are analyzed, and the finite element simulation calculation of the lifting lug structure is carried out according to the vehicle design standard. It is obtained that the lifting lug structure meets the design requirements of static strength and fatigue strength. In order to further analyze the cause of fatigue fracture of the lifting lug, the position of the resistance strain gauge is determined according to the static strength results and fatigue failure position, and the on-line experiment is carried out on the stress condition of the lifting lug structure. Through the analysis of the experimental results, it is concluded that the main cause of fatigue fracture of the lifting lug is resonance. Finally, the lifting lug is optimized from the two aspects of structure and material. The finite element analysis and experimental results show that scheme 1 is the best scheme.关键词：Lifting lug;Crack;Fatigue;Damage
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- 124
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发布时间：2022-09-22 - 摘要：Anti-yaw damper is a key component of high-speed train suspension system. In this paper, through the measured performance degradation data of anti-yaw damper and the damping value setting of anti-yaw damper, the performance data of anti-yaw damper in different states are obtained. According to the dynamic parameters of a certain high-speed train in China, the dynamic model of the vehicle is established, and the influence on the dynamic performance of the vehicle is analyzed based on the performance data of anti-yaw damper in different performance states.The results show that: In actual operation, the performance change of anti-yaw damper has little effect on the force between wheel and rail; In the actual operation, the performance change of anti-yaw damper has a certain impact on the running stability of the vehicle, but the impact degree is limited. Under the simulation condition, the vehicle’s stability is always in a better state; The critical speed of the vehicle operation is sensitive to the performance change of anti-yaw damper.The simulation results of the measured performance degradation data show that with the use of anti-yaw damper, the critical speed of the vehicle decreases significantly; the simulation results of the damping value setting of anti-yaw damper show that appropriate increase of damping value is conducive to increase the critical speed of vehicle operation and improve the stability of vehicle operation.关键词：Anti-yaw damper;Damping curve;Degradation data;Damping value setting;Dynamic performance
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- 127
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发布时间：2022-09-22 - 摘要：In order to obtain the Johnson-Cook（J-C） constitutive parameters that can exactly reflect the plastic flow behavior of the workpiece material under the coupling effect of high temperature, high strain rate and large deformation occurred in high-speed cutting, and make it to suitable for the high-speed cutting simulation. The J-C parameters of Ti-6 Al-4 V was optimized with using the response surface approximation and multi-objective optimization methods to apply it to high-speed cutting simulation. Results show that the optimized constitutive parameters could describe the plastic flow behavior of the workpiece material accurately in a wide range of cutting speeds, and the simulated chip morphologies and the average cutting forces are in good agreement with the experimental results.关键词：High-speed cutting;Ti-6Al-4V alloy;Johnson-Cook constitutive model;Response surface method
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- 379
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发布时间：2022-09-22 - 摘要：To solve the problem that the Houfeng Seismograph’s directional function’s historical record was generally questioned. The analysis concludes that the spherical pendulum seismic measurement scheme may be a feasible restoration scheme with Rayleigh wave（the main component of non-local earthquakes） as wave source. A nonlinear complete mechanical model of the spherical pendulum under Rayleigh wave excitation is established. The equation of motion was derived. The approximate solution is obtained using the perturbation method. The results show that: the spherical pendulum restoration model has a directional response to Rayleigh waves. The magnitude of the directional response is related to the amplitude of the Rayleigh wave, as well as the frequency ratio and damping of the system. Combined with historical records to study the restoration models of the weather seismograph, the spherical pendulum model is the best restoration model for Zhang Heng’s Hou Feng seismograph in many aspects. This conclusion is an important theoretical basis to prove the historical authenticity of the Houfeng Seismograph.关键词：Houfeng seismograph;Rayleigh wave;Perturbation method;Spherical Pendulum
- 3
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- 51
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发布时间：2022-09-22 - 摘要：In order to study the influence of the structural parameters of the wound cylindrical honeycomb on the energy absorption characteristics, a finite element simulation model was first established. Then, using the controlled variable method, the influence of the side length of the corrugated sheet, the thickness of the corrugated sheet and the thickness of the flat sheet on the energy absorption characteristics of the honeycomb was systematically studied. Finally, the experiment is carried out and compared with the simulation results. The results show that as the side length of the corrugated sheet decreases, the thickness of the corrugated sheet and the thickness of the flat sheet increase, the average stress and volume ratio energy absorption of the honeycomb can be increased; reducing the side length of the corrugated sheet and increasing the thickness of the corrugated sheet can increase the mass specific energy absorption. The increase in the thickness of the flat sheet can reduce the mass specific energy absorption; the simulation model is accurate, and the results are in good agreement with the experimental results in the honeycomb deformation and energy absorption characteristics. This paper has done a more detailed study on the three parameters that affect the strength of the cylindrical honeycomb, which provides new ideas and theoretical support for the energy-absorbing components of the passive safety protection of rail transit.关键词：Cylindrical honeycomb;Structural parameters;Energy absorption characteristics
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- 141
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发布时间：2022-09-22 - 摘要：Based on material tensile test data of the vehicle powertrain anti-torsion rubber mount, parameters of the Ogden hyper-elastic constitutive model were obtained by using Abaqus. Then the ε-N fatigue curve of its rubber material was tested according to the strain fatigue theory of rubber. The finite element model was calibrated based on the stiffness test of the rubber mount. The fatigue life of the rubber mount was calculated and optimized according to the fatigue bench test. Finally, the fatigue life of the rubber structure in the whole vehicle driving endurance test was predicted.关键词：Powertrain anti-torsion mount;Rubber material ε-N fatigue curve;The finite element;Fatigue calculation
- 3
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- 161
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发布时间：2022-09-22 - 摘要：Combined with the high pressure and high temperature working condition and the characteristics of tooth and sliding ring combined seal, the mathematical model of the rotating slip ring type combined seal is established based on the theory of thermoelastic hydrodynamic lubrication. Furthermore, the elastic deformation of the tooth and sliding ring combined seal under the action of oil film pressure is obtained by the matrix method of deformation influence coefficient based on the theory of small deformation. Combined with the hydrodynamic lubrication equation, the temperature field energy equation and the viscosity temperature equation, the finite difference method is used to solve the thermoelastic flow pressure lubrication model. The oil film thickness distribution and oil film pressure distribution in the working process of the combined seal ring of the toothed slip ring are calculated by MATLAB. The results show that the roughness of the ring has a significant effect on the sealing performance. The film pressure increases first and then decreases in the axial direction, and fluctuates in the stable range in the circumferential direction.Moreover, the oil film thickness and pressure of the sealing ring decrease with the increase of the ambient temperature.关键词：Combination seal;Thermo elastohydrodynamic;High temperature and pressure;Oil film thickness;Roughness
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- 80
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发布时间：2022-09-22 - 摘要：Accurate calculation of the mode shape and natural frequency of the motor stator is the basis for reducing motor noise and vibration. At present, scholars have disputes about the setting of stator core and winding material property parameters. In this paper, the modal simulation analysis and experimental test of a 2.2 kW permanent magnet brushless DC motor stator system are carried out. First, to give the stator core and the winding materials, The finite element software is used to analyze the relationship between the motor modal frequency and the parameters of the anisotropic materials. According to the modal frequency variation law, a method for correcting the parameters of the anisotropic materials based on the modal frequency is proposed. The method can complete the finite element model parameter correction of the stator. Secondly, the modal experiment is carried out by hammering method to verify the accuracy of the finite element model and determine the effectiveness of the method for correcting the equivalent material parameters. And by this method, the stator material parameters of the stator can be quickly determined. The error of this experiment and simulation is within 3%, achieving the purpose of experiment and simulation benchmarking.关键词：Anisotropic material parameter correction method;Modal analysis;Modal experiment;Finite element analysis
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发布时间：2022-09-22
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