最新刊期
期 2 ， 2020
- 摘要：Considering the influence of the nonlinear factor of bearing preload on the dynamic stiffness of bearing support,a dynamic model of grinding motorized spindle system is established. Considering the unbalanced force caused by the eccentricity of the rotor mass in the rotor system,the numerical integration method is used to study the nonlinear dynamic behavior of the motorized spindle rotor system under different preload and rotating speeds. The results show that the bearing preload is an important factor affecting the nonlinear dynamic characteristics of the motorized spindle rotor system. Rational selection of the operating parameters of the rotor system can improve the stability of the system.关键词：Grinding motorized spindle system;Bearing preload;Nonlinear dynamics
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发布时间：2022-09-22 - 摘要：The shuffled frog leaping algorithm（ SFLA） is a swarm intelligent optimization algorithm that combines competitive evolutionary strategy and limited random search. It has been applied to various optimization problems. This paper analyzed the advantages of the SFLA for global optimization problems,and established optimization BP neural network algorithm model（ SFLA-BP） based on SFLA,and carried on the simulation study. The planetary gearbox was taken as an engineering example,and its nonlinear characteristic was presented because of transmission path of fault vibration signals complicated and their coupling with each others. The kernel principal component analysis（ KPCA） was used to extract the time domain and frequency domain sensitive features,and the feature dimensions were reduced from 27 to 9. A neural network fault diagnosis system with 9-14-4 structure was established. This paper makes full use of the advantage of the global search of SFLA to realize fault diagnosis of planetary gear with different wear levels. The diagnosis results show that the SFLA-BP model has a smaller overall output error compared with BP neural network,and the diagnostic accuracy increases by 12. 5 %,and has achieved a more accurate identification effect on different degrees damage faults.关键词：Shuffled frog leaping algorithm（SELA）;BP neural network;Planetary gearbox;Fault diagnosis;Kernel principal component analysis（KPCA）
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发布时间：2022-09-22 - 摘要：A prediction model based on Deep Belief Network（ DBN） was proposed to accurately predict the cutting load of the shearer’s spiral drum. The DBN model uses 7 characteristic parameters which include 2 guiding boots,2 smooth boots,rocker arm vibration,idler shaft,and cutting motor current as visual input. By means of unsupervised level greedy learning,the higher level features are represented,the intelligence of the identification process is enhanced,and the complexity and imprecision of artificial features extraction are avoided. The test results show that the proposed method is suitable for predicting the load of the spiral drum of coal miner,which has strong characteristic extraction ability and better performance than BP neural network.关键词：Shearer;Spiral drum;Cutting load;Deep belief network
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发布时间：2022-09-22 - 摘要：In the intelligent diagnosis of planetary gearbox faults,the issue of "difficult extraction"of the vibration signal characteristics,the"quality difference"of the constructed eigenvector set and the"low precision"of the fault classification model based on the extreme learning machine. Put forward a state identification method for a planetary gearbox solar wheel for how to capture sensitive transient impact feature in the vibration signal and construct a high-dimensional eigenvector set and improve the fault classification accuracy of the extreme learning machine. Firstly,the vibration signals are respectively solved by fast kurtosis diagram and variational mode decomposition and several intrinsic mode function matching the center frequency fωcorresponding to the maximum kurtosis value are selected,find the value of improve multi-scale permutation entropy to construct the highdimensional eigenvector set. Secondly,the de-noising automatic encoder is used to make the input weight and threshold of the implicit learning node of the extreme learning machine satisfy the orthogonal condition to realize the layering of its hidden layers.Finally,the above eigenvector set is used as the input of the hierarchical extreme learning machine,and the fault classification model of the planetary gearbox solar wheel is established through training. The results show that the proposed method achieves the effective extraction of sensitive transient impact feature in the vibration signal of the solar wheel and the high quality construction of the eigenvector set,and also improves the classification accuracy of the intelligent diagnosis model.关键词：Sensitive feature extraction;Eigenvector set construction;Extreme learning machine;Planetary gearbox;Fault identification
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发布时间：2022-09-22 - 摘要：In this paper a new mobile wheel bracket conveyor structure as the research object,through theoretical analysis of mobile wheel bracket conveyor running,put forward the connection and pull role-key components of the wire rope running stable and safety requirements. On the basis of the virtual prototype model established by ADAMS,the macro model of ADAMS/View is used to model the wire rope micro model of the connecting roller bracket. Through the dynamic simulation of the conveyor’s motion system,the mobile roller bracket and the wire rope are fully run for one week. In this process,the dynamic characteristics of three adjacent sections of the wire rope at the commutator wheel are analyzed,and the speed of the wire rope position and the change curve of the displacement are obtained,and the mechanical characteristic curves of the shaft sleeve force between the wire rope,the wire rope and the bracket,the contact force of the wire rope and the reversing wheel are obtained. The results show that the movement trend of the wire rope is the same because of the effect of pre-tightening device,but there is a small deviation. And because of the vibration of the flexible body of the wire rope,the speed change of the Y axis and the Z axis in the stable transportation section is produced. In the transfer direction of the conveyor,the effect of the wire rope and the reversing wheel has a certain impact,resulting in a great change in the joint force of the wire rope and the sleeve force of the shaft,the bracket and the wire rope. Therefore,some measures should be taken to prevent the breaking of the wire rope at the transfer direction of the conveyor..关键词：Roller bracket;Steel wire ropes;Microelement model;Bushing;Virtual prototype;Dynamic characteristics
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发布时间：2022-09-22 - 摘要：This paper takes the support structure of a low-pressure rotor system of a marine gas turbine as the background.Considering the heel angle of the rotor system,a dynamic model of the rotor supported by asymmetric rolling bearing is established. The variable-step fourth-order Runge-Kutta method was used to solve the system’ s dynamic equations,and the nonlinear theory were used to analyze the simulation results. The study shows that the heel angle has no effect on the stability of the system at low rotational speeds. At high rotational speed,the heel angle mainly affects the 1/2 harmonic of the system,and the system has a single chaotic island or two chaotic islands. When the left or right tilt angle of the rotor system is the same,the heel angle has the same effect on the nonlinear dynamics of the system. The research results can provide a theoretical basis for the design,monitoring and fault diagnosis of the rotor system.关键词：Heeling angle;Asymmetrical support;Rolling bearing;Nonlinear
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发布时间：2022-09-22 - 摘要：The contact effect of the disks of the rod-fastening rotor is considered in this paper. The contact effect is equivalent to a bending resistance spring with nonlinear stiffness when the modal of rod-fastening rotor is established. The motion equation of the rod-fastening rotor system is derived. In order to solve the dynamics responses of the rod-fastening rotor,an effective calculation method is presented by combining the Wilson-θ method and Estimation-correction mechanism. At the same time,Floquet theory is adopted to analyze the bifurcation behaviors of the rod-fastening rotor. The comparison of the stability is implemented between the rod-fastening rotor and integral rotor. The results show that the rod-fastening rotor is more stable than the integral rotor. Finally,the dynamics behaviors of the rod-fastening rotor are analyzed by taking the speed of rotor,eccentricity of disk and stiffness of shaft as control parameter. The calculating results reveal periodic,quasi-periodic,3-periodic,5-periodic of the system.关键词：Rod-fastening rotor;Stability;Bifurcation;Wilson-θ method;Floquet theory
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发布时间：2022-09-22 - 摘要：The pull rod under eccentric loading exists extensively in engineering project,the computations of its stress and strength directly affect its reliability,especially its dynamic stress computations. The elastic dynamic mechanics were used here to study the computations of the bending stress and axial stress of the eccentric loaded rod under steady force,and the analytic expressions were given,numerical example was provided to show the variations of the amplitude of the bending stress and axial stress with the disturbance frequency,the theoretical analyses and the computation results of given example show that the amplitude of the bending stress and axial stress obviously depend on the disturbance frequency,which is different from that of corresponding static problems. The analyses and conclusions given here have some references to the dynamic reliability design.关键词：Eccentric loaded rod;Steady axial force;Bending stress;Axial stress;Disturbance frequency
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发布时间：2022-09-22 - 摘要：A series of multiaxial low-cycle fatigue texts were conducted on 316 L stainless steel. Additional hardening was clearly observed under non-proportional loading. Then four strain-based models were utilized for life prediction. The result show that the ASME model and Itoh model could not properly reflect the effect of non-proportional hardening on fatigue life,the ASME model tended to overestimate fatigue life,while the Itoh model contrary to ASME model. Fatemi-Socie model and Susmel model,which both based on critical plane approach,presented better prediction results. In order to overcome the deficiency of ASME model,a practical life prediction model for multiaxial low-cycle fatigue is proposed by means of modifying the plastic term of ASME equivalent strain. Evaluated by utilizing experimental data of six materials including 316 L stainless steel,the proposed model have a higher accuracy than similar models established through modifying ASME model.关键词：Multiaxial low-cycle fatigue;316L stainless steel;Life prediction;Strain-based model
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发布时间：2022-09-22 - 摘要：The influence of nitriding treatment on wheel/rail rolling contact fatigue and surface wear behavior of CL60 wheel was studied on JD-DRCF/M rolling contact fatigue/wear tester,the wheel surface nitriding treatment on the mechanisms of wheel/rail surface damage are compared and analyzed. The results showed that the surface nitriding treatment could form a uniform and dense white layer about 3 μm ～ 5 μm thick and a diffusion layer about 20 μm thick on the wheel surface. Under the wheel surface after nitriding process,the adhesive coefficient between wheel/rail was reduced by 11. 7% in dry condition,and reduced by 18. 4% in aqueous media,but the nitriding treatment still can keep the higher adhesive coefficient between wheel/rail system,which can prevent the occurrence of the phenomenon such as wheel-slip; Nitriding treatment not only significantly improve the wear resistance on the surface of the wheel,but also effectively reduce the wear of the rail sample,the amount of damage reduced by 58. 05% and 10. 77%,respectively. In short,the nitriding on wheel for wheel/rail system can effectively reduce the wear,improve the rolling contact fatigue resistance of wheel materials. The method is applied to the actual,it can effectively improve the service life of wheel/rail system,reduce the damage of wheel/rail material under the heavy-load condition.关键词：Rail wheels nitriding;Surface wear;Fatigue cracks;Rolling contact;Adhesive coefficient
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发布时间：2022-09-22 - 摘要：The wear resistance of shearer conical pick body affects the service life of pick directly.Based on the analysis and comparison of the existing conical picks wear technology,the wear mechanism of the non-smooth surface with concave in the bionics was analyzed and studied. A kind of pick body surface with a non-smooth shape was designed,and the new structure was conducted a simulated friction and wear tests. The friction and wear tests on the sixteen different parameters of the concave structure show that the wear resistance of the concave-shaped non-smooth surface structure is significantly improved which is compared to the smooth surface,and the bionic non-smooth structure of the concave shape is analyzed through orthogonal test to analyze the effect of the parameters on the wear resistance.关键词：Conical pick body;Bionic;Concave;Wear resistance;Orthogonal test
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发布时间：2022-09-22 - 摘要：To verify the fatigue life under high-low cycle combined loads of the blade the combined fatigue experimental technique was established. The orthogonal loads decoupling method was proposed based on the cylindrical rolled bearing and linear slide rail,and the coordinated loading control technique of a combined loads was presented by means of an external signal trigger. Then,the fatigue experiment of a certain type of ducted tail rotor fan blade under centrifugal load/Low Cycle Fatigue（ LCF） and aerodynamic load/High Cycle Fatigue（ HCF） was developed. The control precision of complex loads is superior to than ±1%,and the coordinated loading time interval is less than 0. 3 second. The experimental result indicates that the high-low cycle combined fatigue experimental technique can solve the technical problems of orthogonal loads decoupling and coordinated loading control,which provides the technical foundation for improving the high-low cycle combined fatigue life prediction precision of the blade.关键词：Blade;Combined loads;Orthogonal loads decoupling;Coordinated loading control;Experimental technique
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发布时间：2022-09-22 -
RESEARCH ON DYNAMIC STRESS OF CYLINDRICAL SHELL OF RADICAL PHONONIC CRYSTALS IN RADIAL WAVE BAND GAP
摘要：A semi-infinite periodic model of cylindrical shell of radial phononic crystals（ CS-RPCs） is constructed by alternate distribution of two homogeneous materials. A theoretical analysis of the propagation of radial waves from inside to outside is performed. The method of numerical analysis is used to discuss and analyze the appearance regularity of the surface localized modes with a finite period CS-RPCs. At the same time,the energy band structure is obtained by the eigenvalue method of the mechanical state vector total transfer matrix and then the numerical results are verified. Finally,the internal stress magnitude and distribution of the finite period CS-RPCs structure are analyzed in detail.The results show that the elastic band gap exists in the CS-RPCs,and the appearance of the surface localized modes is related to the wave velocity of the free surface. The stress concentration of radial phononic crystal structure is related to the wave velocity of loading surface.关键词：Radial phononic crystal;Surface localized modes;Wave velocity;Stress concentration- 3
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发布时间：2022-09-22 - 摘要：In order to achieve dynamic sealing in pressurized vessel considering non-leakage of harmful working medium,this study presents an optimal structure design of permanent magnetic coupling（ PMC）. For the optimization objective of increasing the torque transmission with limited magnetic material cost and decreasing the eddy-current loss of the magnetic coupling caused by the metal isolation cover,an improved partial swarm optimization method is designed to perform a multiobjective design optimization of the structure of PMC. After accurate computation,the optimal structure parameters of PMC are obtained. Then,a 3-D finite element model of PMC with the optimal structure is constructed to analyze the transmitted torque and eddy current loss,and an actual PMC device is manufactured for the non-leakage vessel application and the tested performance satisfies the technical demands,which provides theoretical reference for the PMC structural design in similar applications.关键词：Permanent magnetic coupling;Dynamic sealing;Improved partial swarm optimization;3-D finite element;Test analysis
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发布时间：2022-09-22 - 摘要：The reliability of composite laminates is analyzed by universal generating function method. Load,strength parameters universal generating function,complex operators and the corresponding performance structure functions are defined,the resistance of the single layer,resistance sequences and system resistance universal generating function are constructed respectively. The reliability analysis model of laminates is established based on the last ply failure criterion. In the complex operation of universal generating function, K-means clustering and like terms collecting techniques are used to reduce computational costs and improve efficiency. This method is applicable to the reliability assessment of structural systems,in which there are many random variables（ including non-normal random variables）,the performance function is non-linear,and failure correlation between resistance sequences of laminates that contain common failure elements and failure elements within the resistance sequences due to sharing the same random load source is considered. Two examples are given. The reliability value is close to the Monte Carlo simulation results. The new method can provide a new idea for reliability analysis of composite laminates.关键词：Composite laminates;The last ply failure;Reliability;Universal generating function;K-means clustering
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发布时间：2022-09-22 - 摘要：In actual production,the key components of the suspension such as the stabilizer bar,the rubber bushing and the spring are unstable due to the unstable manufacturing process,which greatly affects the vehicles’ smoothness and stability. In this paper,the McPherson front suspension is used as the research carrier,the stiffness characteristics of the components are taken as the noise variable,the hard point coordinate value is taken as the design variable,and the high-precision approximate model is established by the quadratic response surface method. Based on the same constraints, the sequence quadratic optimization algorithm is used to deterministic optimize of the suspension and the robustness design of it. The Monte Carlo simulation is used to analyze the robustness of each optimization result. The results show that the 6σ-based robustness optimization design not only optimizes the performance of the suspension but also has an advantage in terms of reliability.关键词：Suspension;Sequential quadratic programming method;Deterministic optimization;Robust optimization
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发布时间：2022-09-22 - 摘要：As study on the burst pressure probability distribution of single-layer cylindrical vessels is a basic work,the establishment of pressure vessels reliability design method was carried out to build precision evaluation system of pressure vessel strength calculating formula. The burst pressure probability distribution of single-layer cylindrical vessel was analyzed by using the hypothesis test method in the mathematical statistics theory,based on 84 sets measured burst pressure data of single-layer cylindrical vessel. Research results indicated that:（ 1） Based on the engineering practice of Chinese standard,the application range of the formula can be divided into the 3 groups according to the design pressure which are no exceeding 35 MPa,between35 MPa and 100 MPa,and no more than 100 MPa,respectively;（ 2） According to the relationship between design pressure and burst pressure,the actual burst pressure of the formula application range sample was no more than 105. 5 MPa,between 91. 0 MPa and 329. 6 MPa,and no more than 329. 6 MPa,respectively;（ 3） When the significance was 0. 05,the ratio of the samples measured burst pressure and mid-diameter formula and Tresca formula calculated values is 6 random variables with the normal distribution.（ 4） When the 2-sides confidence was 98%,the distribution parameters value range of 6 random variables were obtained respectively.关键词：Single-layer;Cylindrical vessels;Burst pressure;Probability distribution;Groups;Samples
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发布时间：2022-09-22 - 摘要：The essence of crashworthiness is to study the protection of people（ crew and passengers）,and the head injury of the occupants accounted for a large proportion in the crash. In order to investigate the influences of different impact velocity on the occupant ’s head injury under horizontal impact conditions,a comprehensive evaluation method based on occupant ’s Abbreviated Injury Scale（ AIS） and occupant’s injury risk probability to evaluate occupant injury is proposed,and a dynamic simulation model which including seat,restraint system and dummy was constructed by LS-Dyna software. Take the typical civil aircraft double-tube triple-seat as research objects,the effects of different horizontal impact velocity（ 8. 0 m/s,10. 0 m/s,12. 0 m/s,14. 0 m/s,16. 0 m/s） on the head injury of occupants,the stages and characteristics of injuries were analyzed. The results of dummies‘ dynamic response analysis shows that occupants may be severely injured in the head and legs during the aircraft’s longitudinal impact,occupant’head injury increases rapidly with the increase of horizontal impact velocity,and occupant’fatality rate increases exponentially with increasing horizontal impact velocity,the substantial leg movement of the occupants greatly increase the risk of injuries caused by collisions with other facilities in the cabin. In addition,the dummies ’ head trajectory,the peak load of seat belt is proportional to the horizontal impact velocity. Therefore,when the crash occurs,the horizontal impact velocity should be controlled deliberately（ the fatality rate was less than 10% when the impact velocity was13. 0 m/s,and more than 80% when the impact velocity was 16. 0 m/s）.关键词：Dummy-seat-restraint system;Horizontal impact;Head injury;Impact velocity;Numerical simulation
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发布时间：2022-09-22 -
DYNAMIC ANALYSES OF SOIL-STRUCTURE INTERACTION IN OFFSHORE WIND TURBINE ON TRIPOD IMPACTED BY A SHIP
摘要：The probability of collisions between offshore wind turbines and ships increases with the development of offshore wind farm. Based on nonlinear dynamic analysis method,through LS-DYNA to simulate the ship impact a 4 MW offshore wind turbine tripod,the paper compare p-y curve method and fixed bottom end constraint. The author has a comparison and analysis of energy conversion、maximum collision force、relationship of horizontal displacement and depth of soil、contact force、shear force and stress-strain. The results show that energy conversion of the pie column under the p-y curve is faster than that under the fixed bottom end restraint; the bottom end of the steel pipe column is more susceptible to be damaged when a ship impacts offshore wind turbine foundation under the fixed bottom end restraint method; the soil layer is from shallow to deep,in which shallow soil has the most influence on the stability of the pile and the horizontal displacement of three steel column gradually decreases,the improvement of the properties of the shallow soil can effectively improve the safety of the pile; the increase of the ship quality,the contact force and shear force are increasing; the difference in contact force between the curve method and the fixed bottom end constraint increases with the increase of the quality of the ship,and the shear force difference decreases.关键词：Offshore wind turbine;Tripod;Collision;Soil layer;Pile column- 4
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发布时间：2022-09-22 - 摘要：With the development of wind power generation technology,the requirements for various performances of wind turbines are higher. Aerodynamic noise problem has become a key research direction of the wind power industry. Designed to improve the aerodynamic performance of the blade and reduce noise,this paper aims to improve the aerodynamic performance of the blade and reduce the noise,optimize the airfoil structural equation based on the improved Hicks-Henne function,and combine the multi-objective particle swarm optimization algorithm to optimize the design of the S8035 airfoil. Further more,the optimized airfoils are evaluated using XFOIL software and simulations are conducted to investigate their aerodynamic noise and flow characteristics. The results show that the optimized blade has better aerodynamic characteristics and lower noise,which verifies the feasibility of the design method.关键词：Wind power;Airfoil structure;Aerodynamic Noise;Optimal design;Multi-objective particle swarm algorithm
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发布时间：2022-09-22 - 摘要：The output shaft is one of the core components of the gearbox of an oil rig,The reliability of the output shaft directly affects the service life and economic benefit of the oil rig. In this paper,the stress analysis of the structure of the original output shaft is carried out by using the finite element method; The optimization and improvement scheme is put forward,and the stress of the output spindle before and after the improvement is compared and analyzed,According to the analysis results,the final improvement scheme of the output shaft is determined,The results show that the safety factor of the improved output shaft is significantly improved,The modal of the output shaft is analyzed by finite element method,It is verified that the working speed of the output shaft is within the safe range. The research in this paper has certain guiding significance to improve the performance of oil rig output shaft.关键词：Oil rig;Output shaft;Finite element;Modal analysis
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发布时间：2022-09-22 - 摘要：The thin film composite often buckles due to mismatch strain between each layer induced by in-plane residual stress during manufacturing or service loadings in operation. The buckling behavior of a composite structure consisting of a thin film and a compliant substrate was studied by elastic stability analysis based on complex function theory. The buckling parameters under uniaxial and biaxial in-plane compression were calculated respectively utilizing an author compiled program. The result indicates the critical pre-buckling stress is an inherent characteristic determined by material and geometric parameters. Under uniaxial and non-equal biaxial compression stress,the critical pre-buckling stress decreases with the increase of film/substrate elastic modulus ratio,meanwhile there is only one nonzero buckling wave number in the direction of the plane. For the equal biaxial stress,the influence factors of critical pre-buckling stress and dimensionless wavelength depend on substrate/film thickness ratio. Any buckling mode that satisfied with the wave number equation could occur.关键词：Thin film;Buckling;Substrate;Elastic stability;Thickness ratio;Critical buckling stress;Wave length
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发布时间：2022-09-22 - 摘要：Joints are critical elements in designing safe and efficient vehicle structures made from composites. Aim to singlelap,single-bolt countersunk composites joints,a finite element model（ FEM） of the joint is established. Effectiveness of the FE model is verified. Based on this,the effects of laminate thickness on the secondary bending and bearing strength are studied. The numerical results demonstrate that the bearing strength of thin and thick composite joint are almost identical. In addition,the secondary bending effect of the thin composite joint is the least obvious when the bearing failure. The failure characteristics found in our study has direct implications when design of weight-saving of advanced composite structures.关键词：Compsoites;Mechanical fastener;Secondary bending;Bearing strength;Finite element model
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发布时间：2022-09-22 - 摘要：Shakedown analysis is a powerful tool for the ratchet ＆ alternating plasticity prediction of the pressure piping under thermal-mechanical loads. In order to achieve the shakedown analysis containing the synergetic influence of the kinematic hardening and the temperature-dependent properties of the material,a numerical method was developed. The presenting method is an extension of the two-surface model for shakedown analysis and is based on the basis reduction method. The idea is to transfer the nonlinear programming resulting from the shakedown analysis with kinematic hardening and temperature-dependent nature into an elastic perfectly plastic one which can be solved with less effort. Numerical examples indicated that the proposed method is accurate. This method has the potential to improve the accuracy of failure prediction for the piping suffering thermal-mechanical loads and therefore is of engineering values.关键词：Ratchet;Shakedown;Temperature-dependent properties;Kinematic hardening;Piping
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发布时间：2022-09-22 - 摘要：In order to study the effect of deformation parameters on the flow stress of EH40 steel plate during hot working,using Gleeble-3800 tester to perform thermal compression simulation of specimen,the true stress-strain curve of EH40 shipboard steel under temperature conditions of 0. 1 s-1～ 10 s-1 strain rate and 900℃ ～ 1 200℃ is obtained. By analyzing the curve,we find that deformation temperature and strain rate all have important effects on the dynamic recrystallization and dynamic recovery of EH40 plate steel,increasing the deformation temperature or reducing the strain rate is conducive to the occurrence of dynamic recrystallization during deformation,which contributes to grain refinement of the material. A hyperbolic sine model with ZeneHollomon parameters is adopted,the thermal deformation equation,activation energy of thermal deformation,and mathematical model of Z parameters were obtained. It is verified that the average error between the calculated value and the experimental value of the established constitutive relation is 3. 13%,which can well reflect the actual hot deformation behavior of EH40 ship-board steel.关键词：EH40 ship plate steel;Hot compression;Flow behavior;Constitutive equation
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发布时间：2022-09-22 - 摘要：This paper,focus on the crankshaft bending fatigue property prediction research,first analyzes the stress distribution fitting approach based on a stress gradient approach,then the fatigue property of the crankshaft with the same material but different structure is predicted,finally corresponding experiment verification is conducted. The results show that for the modified indirect defined theory of critical distance（ ITCD）,the predictions based on both the line method and point method are almost unanimity and may contain some errors. While for the direct defined theory of critical distance（ DTCD）,the critical line approach has a much better accuracy than the critical point approach,so this approach is much more suitable to be taken into the actual engineering application.关键词：TCD;Crank shaft;Fatigue property
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发布时间：2022-09-22 - 摘要：The acceleration effect in the process of collinear hole-edge cracks propagation of aircraft fuselage skin structure is mainly manifested by the interaction of stress intensity factors between multiple fatigue cracks. A modified approximate superposition method based on the Muskhelishvili complex function theory and truncated conformal mapping approach is proposed in this paper to solve the stress intensity factors of multiple hole-edge cracks under remote uniform tension. The influence law of stress intensity factors for three kinds of cracking mode is analyzed,including the cracks of equal length emanating from two holes,the cracks of unequal length emanating from two holes,the cracks of equal length emanating from three holes and the cracks of unequal length emanating from three holes. The results of examples show that the interaction between adjacent cracks is obviously and the dimensionless stress intensity factors increase rapidly when the crack tips approach each other.关键词：Complex variable function method;Multiple hole-edge cracks;Stress intensity factor;Crack interaction;Superposition method
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发布时间：2022-09-22 - 摘要：Research and establishment of customer service road-load characteristics are foundation and precondition for reasonable lightweight design of automotive structure strength. Traditionally method mostly based on parametric probability density estimation method to analyze statistical characteristics of customer service road-load. Based on large-scale data research of customer service road-load characteristics of a commercial vehicle,parametric and non-parametric method were respectively applied to study the probability density distribution model of typical customer service road-load characteristics. The results showed that the non-parametric method describe the customer service road-load characteristics more accurately than the parametric method. Therefore,the non-parametric method was applied to calculate the 90 th percentile of customer service characteristics. By applying non-parametric rain-flow matrix extrapolation method,the whole service life loads of shock absorber spring were estimated based on collected road loads data,and fatigue-testing specification was established. The results can provide reference for establishing the automotive structure fatigue testing specifications reasonably under the concept of user-association.关键词：Customer service road-load characteristics;Kernel density estimation;Rain-flow matrix extrapolation
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发布时间：2022-09-22 - 摘要：The flexible bearing is one of the key components of wave generator（ WG） in Harmonic Drive（ HD）. Its load and life studies are key to the reliable operation of HD. The flexible bearing has a significant flexural deformation of the ferrule after assembly which is different from the cam profile. Assumed that the amount of deformation of the inner ring is unknown. A set of deformation coordination equations was established. The load distribution of flexible bearings was studied. Furthermore,the fatigue life was calculated. Deformation characteristics of the flexible bearing after assembly were analyzed by finite element method（ FEM）. The comparison of results shows that the assumption is consistent with FEM and the load distribution is consistent. The fatigue life is affected by the load. It provides a reference for load analysis and fatigue life assessment of flexible bearings.关键词：Harmonic drive（HD）;Flexible bearing;Flexural deformation;Load distribution;Fatigue life
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发布时间：2022-09-22 -
PIECEWISE MODIFICATION METHODS OF CYCLOIDAL GEAR IN RV REDUCER BASED ON THE FORM GRINDING TECHNOLOGY
摘要：Form gear grinding technology has characters of high-accuracy,it’s grinding wheel can be modified flexibly,and replaces generating method gradually. A piecewise modification method of cycloidal gear was designed based on form gear grinding technology. This method used angel modification in working section and spline curves in other spaces. The isometric and shift combination modification method can not fit angel modification curve completely and dose not meet the conjugate mesh condition.Our method overcomes these disadvantages. Both methods were applied in the example of modification cycloidal gear in RV-20 E reduce. The results show the combination modification method has a high error relative to the objective curve. The piecewise modification method meets the conjugate mesh condition completely.关键词：Cycloidal gear;Piecewise modification method;RV reducer;Form grinding- 5
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发布时间：2022-09-22 - 摘要：In order to study the dynamic characteristics and fatigue life of the plow bit-holede in the cutting process,according to the coal sample property and structure and motion parameters of plow,the random load of BH38/2 × 400 type coal plow bit was calculated by a software system of coal plow design and calculation. The load was applied to the multi body system model of the coal plow.The dynamic stress and the deformation distribution of the bit-holder in the working process were obtained by dynamic simulation. The fatigue life of the bit-holder was predicted by the rain flow counting of the stress information.Research results show that: under the action of complex mechanics with coal,the load of plow bit is non-linear. Under the action of nonlinear load,the areas with higher dynamic stresses are mainly concentrated in the contact position between rectangular groove of bit-holder and the back of plow bit,and the position of the square screw also suffered higher dynamic stresse. The cumulative fatigue damage of the bit-holder was analyzed by rain flow counting method,and the fatigue life was predicted to be about 475. 7 days. According to the comparison between the test value and the calculated value of plow bit,combined with the practical application feedback of the plow,the accuracy of the simulation results was verified.关键词：Coal plow;Biholder;Random load;Dynamic characteristics;Fatigue life
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发布时间：2022-09-22 - 摘要：In this paper,the finite element method was used to simulate the thin-walled structure under axial impact. The influence of the cross-sectional shape and induced hole size of the thin-walled tube on deformation mode of structure and energy absorption capacity were analyzed. The results show that the impact force on the edge of the thin-walled tube is larger,as the number of sides of the section increases within a certain range,the parameters of the energy absorption index of the regular polygon and the star-shaped polygonal thin-walled tube are increasing. The initial peak force of the thin-walled tube with induced imperfection is reduced by 50% compared to the previous one. If the length of the thin-walled tube with induced imperfection is constant,as the width decreases,the energy absorption,average compressive force and specific energy absorption of the thinwalled tube gradually increase. The finite element analysis results were combined with the response surface method to optimize the design of thin-walled tubes with induced imperfection,and preliminary data and analysis results were provided for the optimal design of induced thin-walled energy-absorbing structures.关键词：Thin-walled structures;Energy absorption;Response surface methodology;Finite element analysis;Optimization design
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发布时间：2022-09-22 - 摘要：Aiming at the current situation that the energy absorbing unit of the re-directive crash-cushion squeezes the corrugated plates on both sides during the collision deformation,causing secondary damage caused by the wavy plate scattering,an "H"type energy absorbing unit configuration is proposed. According to Standard for Safety Performance Evaluation of Highway Barriers（ JTG B05-01-2013）,a TA grade re-directive crash-cushion is designed to meet the collision speed of 80 km/h requirement. Meanwhile,the finite element simulation model of vehicle and crash-cushion is established and combined with the collision simulation test,the collision safety of TA grade re-directive crash-cushion is comprehensively analyzed. It shows that the vehicle has no rollover,climbing or riding span. The maximum accelerations at each collision condition are 17. 3 g,16. 5 g,14. 6 g and 8. 1 g,which meet the requirement of the evaluation criteria for collision safety laws.关键词：Re-directive crash-cushion;Energy absorbing unit;Finite element;Collision safety
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发布时间：2022-09-22 - 摘要：The performances of spacecraft payloads and platforms on orbit are influenced by dimensional stability of spacecraft structure. This article had researched the test method of structure thermal deformation in the vacuum thermal environment simulated on the ground to improve measurement and verification method of the space structure deformation on orbit.It presented a single-camera and multistation photogrammetric measurement scheme,based on the analysis of related test methods and typical measurement systems. Then a camera protection system and a two-dimensional motion mechanism was developed. The camera can complete the image acquisition at different stations in a arc surface through the arc shaped guide of the motion mechanism in the vacuum thermal environment,and satisfy the measurement requirement of multistation. The influence on the camera calibration due to the optical window of the camera protection system had been discussed. Besides,the effect of the scene depth,the contrast of circular feature points and scale factor on the measurement accuracy was verified by the simulation and experiment,then a multi-exposure image processing method was proposed,which selecting the best circle center extraction and recognition results from circular feature point images taken from different exposures to fusion computation,ensuring better contrast and brightness images were obtained. Finally,the structure thermal deformation measurement method in the vacuum thermal environment proposed in this article was test and verified through a typical test piece,the test results all reached a measuring accuracy of 0. 043 mm,and it proved that this method can effectively meet the needs of thermal deformation measurement for the spacecraft structure in the future.关键词：Industrial photogrammetry;Thermal deformation;Environment test;Measurement accuracy
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- 148
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发布时间：2022-09-22 - 摘要：With development of heavy load train,the thermomechanical fatigue is the main failure form of wheel plate. The thermal stress was analysisbased on ANSYS softwarein this thesis. Uniaxial fatigue criterion and fatigue limit diagram of HaighGoodman was used to evaluate wheel plate fatigue. The effect of thermal stress on uniaxial fatigue of wheel plate was analysis. The result show that（ 1） Without consider brake thermal stresses,the fatigue resistance of each node of the new and worn wheel are satisfactory,and the manufactured stresses cause the fatigue weak position to transfer. The sections most prone to fatigue are located in 0 °、180 °and 40° ～ 60 °.（ 2） Considering brake thermal stresses,the fatigue resistance of each node of the new and worn wheel are satisfactory. Nevertheless,the mean stress of FPH and BPR not meet safety requirements.关键词：Thermomechanical fatigue;Railwaywheel plate;Brake thermal stress;FEM
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发布时间：2022-09-22 - 摘要：To determine the effects of shot peening on stiffened panel compressive strength,a typical shot peening residual stress was introduced by ABAQUS subroutine. Then,using temperature field equivalent method to transfer residual stress distribution to temperature boundary conditions. The local buckling and post-buckling characteristics of stiffened panels with different residual stress peak value and residual compressive stress depth are calculated respectively. The results show that,the influence coefficient of shot peening relate to the peak value of residual stress and the range of compressive stress depth. A simple determination method for influence coefficient of shot peening is given and the functions in engineering are amended. In the end,the residual stress distribution of a group of test specimens were obtained through shot peening simulation,the accuracy of amended method was verified by comparison of compression tests of shot specimens and unshot specimens.关键词：Shot peening;Residual stress;Stiffened panel;Buckling;Temperature field;Influence coefficient;Amend
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- 78
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发布时间：2022-09-22 - 摘要：Based on crawling patterns of arthropod such as spiders and crabs,a multi-legged robot with gear rod combination mechanism was designed by drawing method which met the requirements of predetermined trajectory. Solid Works software was used to assemble the robot parts. Motion module was used to make kinematics simulation analysis by adding a motor,and the velocity curve of claw-end was obtained,which verified the feasibility of the mechanism. In addition,the robot carried the TGAM EEG module to collect EEG（ Electro Encephalo Gram） data,and then sent it to PC through bluetooth serial port,and finally sent the data to Arduino platform to control the multi-legged robots to go forward at different speeds,so as to achieve the realization of brain wave control robot.关键词：Gear rod combination mechanism;Multi-legged robot;SolidW orks;Motion module;TGAM EEG module;Arduino platform
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发布时间：2022-09-22 - 摘要：Three kinds of air conditioning shroud are analyzed by using STAR-CCM+. The results show that the scheme 2 with circular arc surface structure on both windward and the scheme 3 with circular arc surface structure only on windward side are better. The data is verified by comparing with the wind tunnel test data without cross-wind condition. The influence of different diversion hood shapes on the intake and exhaust air of condenser and fresh air intake was evaluated by calculating the pressure distribution of intake and exhaust outlets of schemes 2 and 3. It provides a basis for the design of air conditioning shroud.关键词：STAR-CCM+;Resistance;Function;Optimization
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发布时间：2022-09-22
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