最新刊期
期 6 ， 2015
- 摘要：To a Jeffcott rotor system with support looseness fault,a vibration differential equation with piecewise-linear stiffness was established by considering the system with one-side support looseness and the rotor with unbalanced extraneous exciting force. Incremental harmonic balance method was exploited to solve the nonlinear equation,and iterative algorithm was applied to gain the vibration periodic solution. Then the stability of periodic solution was judged by Floquet theory. Finally,the time domain waveforms,amplitude spectrograms,phase diagrams and the Poincare sectional drawings were obtained through a simulation example,the complicated motion characteristics of rotor system with support looseness was analyzed. Meanwhile,the validity of solving nonlinear system by incremental harmonic balance method was proved,and the results laid a theoretical foundation for the diagnosis of support looseness fault.关键词：Support looseness;Incremental harmonic balance method;Floquet theory;Fault characteristic
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发布时间：2022-09-22 - 摘要：Wave approach was used to analyze the vibration-isolating performance of approximate equal-mass hollow beam and solid blocking mass,and the effects of thickness and length on the transmission loss of hollow blocking mass were discussed.By designing the simplified model experiment of a flat plate construction with blocking mass,the tested results and theoretical values of transmission loss were compared. As a result,both trends were consistent with each other. The results also showed that the section size had an significant influence on the vibration-isolating performance of hollow-square steel blocking mass within mid and high frequency domain,and approximate equal-mass hollow blocking mass had a more obvious vibration-isolating performance than solid blocking mass within mid and high frequency domain.关键词：Wave approach;Hollow-square steel;Solid-square steel;Blocking mass;Transmission loss
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发布时间：2022-09-22 - 摘要：Base on the principle of damping reduction vibration and reference the periodic boundary conditions,through the acoustic bridge vibration energy transfer, this paper established a double-layer plate with the opening damping model;Considering the frequency-dependent properties of viscoelastic,through the finite element and boundary element numerical algorithm of calculating the radiation sound power,analyzes the periodic perforated damped sandwich plate structure acoustic radiation characteristics. Numerical calculation results show that in low and middle frequency band,periodic perforated damping sandwich plate can not only reduce the double plate radiating acoustic power,but also can reduce the use of damping materials,optimization of the whole structure of weight; Analyses the porosity and periodicity of the periodic opening damped sandwich plate structure influence the double layer plate structure acoustic radiation,found the inhibition of sandwich plate of acoustic radiation of the optimal opening porosity and periodicity,and the conclusion is verified by the experiments.关键词：Acoustic radiation;Sandwich plate;Damping;Porosity;Periodicity
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发布时间：2022-09-22 - 摘要：For the end effect of ensemble empirical mode decomposition（ EEMD）,considering the disadvantages that the extreme extension only uses the value near the endpoints and the support vector regression（ SVR） extension based on data points takes much time,a new SVR extension method based on extreme points is proposed by the combination of extreme extension and SVR extension. Firstly,extreme points near the endpoints are used as the SVR training samples to extend extreme value.Secondly,the average difference between the original signal time scales of the adjacent extreme points is used to control the shape of these extended extreme points. Finally,these points are interpolated to the required data points by Hermite. The method refers to the variation of signal endpoints,meanwhile,considers the information inside extreme points of the entire data sequence.Simulation and experimental short signal results show that SVR extension method based on extreme points not only can improve the accuracy and reliability of the EEMD decomposition,depress end effect effectively and solve the decomposition distortion caused by end effect,but also sharply reduce the number of SVR extension data points,distinctly shorten the time of SVR extension and increase the practicability of the method.关键词：Signal extension;Ensemble empirical mode decomposition;End effect;Support vector regression;Hermit interpolation
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发布时间：2022-09-22 - 摘要：Drive Train is a key component. It is very important to analysis of dynamic for design and control on drive train vibration of wind turbine. So,from the multi body dynamics（ MBS） perspective,combined with the theory of rotor dynamics and modal,SIMPACK professional dynamics software as a simulation platform,a certain type of 2 MW wind turbine high precision drive chain model was established. Then,the characteristic frequency and the kinetic properties of the drive train were analyzed.Last,the analytical results were verified through site test unit.关键词：Wind turbine;Drive train;Dynamic;Vibration test
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发布时间：2022-09-22 - 摘要：The ground seismic sensors is working basing on the dynamic response of the ground,the ground displacement and acceleration are the results of the propagation of the seismic focus in the crust,it is a complex dynamic problem of comprehensive consideration of the incident wave disturbance and the seismic response of the oscillatory system mechanism which needs to be solved. In this paper,the method of wave function series,the plane wave expansion and Newtonian dynamics equation were used to study the seismic response of the oscillatory system under the disturbance of the out-of-plane incident wave,and the variations of the relative displacement of the mass to the ground along with the disturbance frequency,incident angle are investigated,the numerical results of the given example show that the existence of the phenomenon of sympathy,and accord with the conclusion of vibration mechanics.关键词：Half-space;Ground oscillatory system;Wave function expansion;Response of vibrator displacement;Stress concentration coefficient.
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发布时间：2022-09-22 - 摘要：As to the strength test of seatbelts anchorages which is a quasi-static problem,through comparative analysis of central difference method（ explicit integration） and Newmark method（ implicit integration） in elastodynamics,this paper used explicit solution method in LS-DYNA to compute the seatbelts FE model of domestic minibuses exported to Australia. Lots of studies were carried out herein on two key parameters: calculation time and load curve,and certain evaluation indexes were selected,to gradually improve simulation results consistency with the real test. The methed can be extended to other quasi-static strength analysis problems and gives some useful conclusions on improving simulation accuracy.关键词：Anchorages for seatbelts;Quasi-static;Explicit integration;Simulation ccuracy
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发布时间：2022-09-22 - 摘要：The application performance of coatings are depended on their interface bonded condition when coatings are bonded with substrate,and the interface stresses of coatings directly influences on their strength properties. The equations about interface shear stress of coatings,which based on a model of interface restriction and uniformity strain theory,were deduced.These equations could be used to determine the interface shear strength of coatings. The accuracy of theory analysis and the effectiveness of testing method were further verified by experiment. The interface shear strength of yttria stabilized zirconia coatings was measured by a new tensile method. The coatings were discriminatively sprayed on three parts on specimens with different thickness,and which contributed to analyzing the relationship between coatings’ thickness and their strength properties.关键词：Coating;Interface;Stress;Tension;Strength
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发布时间：2022-09-22 - 摘要：Using different constant velocity drive shaft of Santana automobile with different service lives, the wear characteristics were investigated,including the external and internal splines as well as the inner and outer race of constant velocity joint. The results showed that the wear of external and internal splines for intermediate shaft was still satisfied the design standard if the service lives was less than ten years. The wear of external and internal splines for intermediate shaft exceeded the product design requirements when the Santana automobile was naturally scrapped. The wear of inner and outer race of constant velocity joint was still satisfied the design standard whenever the service lives were reached the scrapped requirement,The technical reference estimated strength and life of remanufactured constant velocity drive shaft will be provided by our experiments data and results.关键词：Wear;Involute spline;Raceway groove;Constant velocity drive shaft
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发布时间：2022-09-22 - 摘要：In order to study the static characteristics of rubber bushings during product developing,a FEM analysis is given to one rear control arm bushing with Mooney-Rivlin constitutive model in this paper. The loads（ compression displacement,Yaw angle,torsion angle） are obtained according to the motion of the bushing under limiting case. Then,we get the axial stiffness,radial stiffness,torsion stiffness and Yaw stiffness through the software ABAQUS. Comparing the computed results with the experiment data,we find that the computing method is reliable,and can provide theoretical guidance for future busing design.关键词：Rubber bushing;Mooney-Rivlin Model;Static characteristics
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发布时间：2022-09-22 - 摘要：Pseudo-rigid-body model of compliant parallel four-bar mechanism and compliant Roberts mechanism was analyzed and the coupling displacement of it was compared qualitatively. Using closed loop vector method,the characteristic point position of Roberts mechanism was determined. The displacement calculation model was established considering the central shift of rotation. Compared with the simulation results of finite element,the maximum relative error of this model is only 2. 43%. The symmetrical compliant Roberts mechanism was applied on micro-motion platform,a new structure of 3- PRR micro-motion platform is proposed. Using the functional transformation theory,the input and output relational matrix was established.Compared with the experimental results,the result shows that the maximum error of angle around z axis is 5. 60%.关键词：Compliant Roberts mechanism;The central shift of rotation;Finite element analysis;Micropositioning stage
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发布时间：2022-09-22 - 摘要：Drum is one of the important load-carrying components of cranes. The drum’s design,reasonable or not,is of great importance to the security of cranes. Multilayer drum is the current mainstream trend of the development of the drum. It’s significantly to explore the lightweight design. This paper takes a model of multilayer drum of tower crane for example. It sets up the APDL parameterized model according to the Ansys,a large universal software,and analyzes the strength and stiffness of the model. It takes the strength and stiffness as constraints based on the analysis and sets up the optimization design model that aims at the lightest weight. And the lightweight design of the drum comes true under the Design Opt module. In order to reduce the execution cycle of the ANSYS optimization method and improve the efficiency,it uses LM-BP neural network which has great nonlinear problem fitting ability and GA which has excellent global search ability in Matlab to realize this rapid optimization design of multilayer drum. Two discussion,which aim at lightweight design of the drum involved in this paper,have some reference value for the structural design and optimization of multilayer drum of cranes in the future.关键词：Multilayer Drum;ANSYS;LM-BP Neural network;GA;Lightweight design
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发布时间：2022-09-22 - 摘要：In order to optimize the layout of the large vibrating screen side panel stiffeners,Topology optimization design was applied in structural design of the side panel stiffeners. The topology optimization model of side panel stiffeners which were based on the goal of maximizing the lateral stiffness of side panel stiffeners was established. According to the pseudo density distribution of the topology optimization,the stiffeners would be rewired. The modal analysis and the harmonic response analysis were done for the panels before and after optimization. Compared with the original side panel structure,the new side panel’s dynamic stress was reduced by 56. 5%,Vibration displacement was reduced by 55. 3%. In addition,the first natural frequency was improved by 72. 03%,the natural frequency was far from working frequency effectively.关键词：Topology optimization;Artificial material method;Side panel stiffeners;Layout design
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发布时间：2022-09-22 - 摘要：To study the influence to high speed hydrostatic bearing’s performance from lubrication fluid characteristics of oil film,the thermal effect of lubricating fluid’s viscosity,density and specific heat capacity is considered,and put forward a method to solve the Navier-Stokes（ N-S） equations combined with a custom function program to introduce lubricating fluid relations under thermal effect. Take a fast sliding bearing as example,using this method to calculate and discuss the effect of various factors on the bearing performance,the performance parameters of bearing are compared with the situation of ignoring lubricating fluid features. Results show that the numerical distribution of the oil-film fluid properties have a significant change with the temperature as considering the lubrication fluid characteristics under thermal effect; Viscosity play a critical role on performance parameters of the bearing,while considering thermal effect,the density has a certain lower effect on oil-film maximum pressure,and the specific heat has capacity to influence the maximum temperature and friction power consumption of the shaft neck,so comprehensive consideration of lubrication fluid features is more in line with the actual working condition. The research results have guidance on the study of oil reservoir structure on the influence of fluid properties and the choice of lubricating oil,etc.关键词：Computational fluid dynamics;High-speed sliding bearing;Lubrication fluid characteristics;Thermal effect
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发布时间：2022-09-22 - 摘要：Dedendum fillet curve is an important factor that affects gear bending capacity and formed by tool conjugation.Consequently,it has great significance on improving bending capacity that the gear machining and top profile of gear cutter are researched. Given different gear machining,addendum coefficient and modification coefficient,the model of corresponding transition curve was established in order to improve bending load capacity of gear. The effect of gear machining and top profile of gear cutter on bending load capacity was investigated with broken-line section method and theoretical analysis was validated by finite element method. Applying the proposed model to the example gear,under the high modification the gear bending capacity machined by rack cutter with single arc is superior to that machined by rack cutter with double arc and pinion type shaper cutter,when the gear geometrical dimensions remain unchanged; the bending capacity of gear machined by pinion type shaper cutter with single arc is superior to rack cutter under the angular modification with modification coefficient of pinion being zero.关键词：Dedendum fillet curve;Gear machining;Broken-line section method;Bending load capacity
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发布时间：2022-09-22 - 摘要：HA / Zr O2 composite coating was prepared with optimized spraying parameters. Wear rate model of the coating was built with pin-on-disc tester basing on uniform design theory and the quadratic polynomial stepwise regression analysis method. Computational wear modeling based on the finite element method and the wear rate model was developed for artificial hip joint and the effect of joint clearance was investigated. It was proved by the experimental data that the wear rate model had a good forecasting effect within a wide range. The results of the wear simulation of artificial hip joint demonstrated that with the increasing of wear cycle,the contact stress on the contact surface of the joint decreased,while the worn area increased gradually,and the wear volume increased linearly but the growth rate of wear depth changed from fast to slow. What’s more,with the increasing of joint clearance,the wear volume of the acetabular decreased,but the largest wear depth increased.关键词：HA/ZrO2 composite coating;Wear rate model;Wear simulation;Artificial hip joint
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发布时间：2022-09-22 - 摘要：In order to research into the contact between the rolling element and the rollaway nest of the elastic composite cylindrical roller bearing,the finite element method and the classical Hertz contact theory are separately used to calculate the contact stress and being out of shape of the cylindrical roller bearing. The two results have the error of ten percent. Thus the finite element method is verified to be accurate in roller bearing. Since the contact pairs of the inner and outer confine of the two types of roller bearings are similar,the finite element method could be used in the research of the contact stress of the elastic composite cylindrical roller bearing. Calculation and analysis are made on the contact stress,contact half width,contact displacement and the distribution along the axial direction under different burdening. The results show that under a certain burdening,elastic composite cylindrical roller contact displacement and contact half width increase with the expansion of filling degree; Under different burdening,elastic composite cylindrical roller contact stress and equivalent stress both have the minimum value along with the expansion of filling degree,and with the increase of burdening,the change of the minimum value is organized. In terms of contact stress,the elastic composite cylindrical roller bearing is superior to the solid cylindrical roller bearing. Reasonable filling degree can reduce the contact stress of elastic composite cylindrical roller bearings and improve the"edge effect".关键词：Elastic composite cylindrical roller bearing;Contact characterizations;Finite element method;Filling degree
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发布时间：2022-09-22 - 摘要：The load bearing capacity of gear and rack system is a very important safety factor for the jack-up offshore platform,so there is an important engineering significant to improve and analyze gear and rack system to increase it. According to the main reason for the failure of the rack and gear,different fillet radius features on both ends of the rack and gear and rack modification were builded,and the effects of the different fillet radius and modification coefficient to the carring capacity of the rack were analyzed by finite element analysis. The results showed that the degree of stress concentration dropped significantly with chamfers on the rack,and with the increase of the fillet radius,the contact stress on the both ends of the rack deceases first then increases to a certain extent. Modification coefficient has a major influence on the maximum contact stress of gear,but has less impact on the racks’. When the fillet radius is in the range of 2 mm 6 mm,and the modification coefficient is 0. 5,the contact stress and bending stress of gear and rack system can get great improvements,and the load bearing capacity of gear and rack system is increased in the meantime.关键词：Jack-up platform;Gear and rack type jacking system;Fillet;Modification coefficient
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发布时间：2022-09-22 - 摘要：Overhead transmission line is mainly aluminum conductor steel reinforced（ ACSR）,which is prone to occur fatigue fracture and fretting wear because of the action of the long-time aeolian vibration. A finite element model of the contact between conductor strands was built to carry on the simulation on the stress distribution of the conductor in different static pretension and the dynamic mechanics in aeolian vibration. The results show that the contact stress of strands increase with the pretension,and the stress increment is maximal when the pretension increases from 20% T to 25% T. The contact point stress distribution in axis of the strand is uniform while the pretension is less than 20% T and is uneven while the pretension is more than 20% T. In the condition of arolian vibration,the stress in constrained position and the middle of the test conductor which is imposed vibration is the maximum. Meanwhile,the contact points stress distribution of the same layer is uniform and the contact stress of adjacent layers in axis is cyclical. The frequency has less impact on the amplitude and the fretting displacement.关键词：Overhead line;Aeolian vibration;Finite element mode;Contact analysis
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发布时间：2022-09-22 - 摘要：Base on the meticulous model of threaded bolt,one numerical method to research the dynamic response of structure with threaded bolt under pretension is presented. In the method,balanced penalty function method is used to deal with the thread contact problem,and the exponential pressure-overclosure is adopted. Pretension force is defined as a couple on the nut directly,since the helical model of the thread is obtained. Compared to the traditional pretension modeling method,it is not only simpler but also more reasonable. A method used to solve the static and dynamic coupling problem is presented,since the structure is under the static pretension force and the impact load synchronously. Firstly,the static response for the structure under pure pretension is analyzed. Then,the dynamic response is calculated taking the statically deformed state as the initial reference.For the mouth shape bolted structure,the numerical method presented in this article was used to study the dynamic response. The strain history of the thread bar was identical to the experiment results perfectly,and the maximal relative error of the pulse width or amplitude of the strain wave was less than twenty percent.关键词：Threaded bolt;Numerical method;Pre-tension force;Dynamic response
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发布时间：2022-09-22 - 摘要：Aim at difficulty to calculate the angular contact ball bearings’ axial carrying capacity in combined loads,considering the different of every roller suffered load and the actual contact angle,using deformation coordination principle and Hertz contact theory,the critical condition is that the actual contact angle is not exceed the safety contact angle,which any roller contact ellipse is not truncated. According to the above-mentioned and basing on a general algorithm of axial carrying capacity subjected to pure axial load,this paper proposed the improved algorithm to calculate the axial carrying capacity in combined loads. Relying on professional software analyzing,the improved algorithm has been well validated,and it is of engineering significance. Using the SKF 7316 BECBM bearing as an example,the above two algorithms are compared and analyzed. The results showed that: The radial load will make axial carrying capacity of angular contact ball bearing appropriately increase. The bending moment will make it significantly reduced,and with the increase of bending moment,the carrying capacity of axial load decreases faster. Compared with the radial load,bending moment is the dominant factor in changing of axial carrying capacity.关键词：Angular contact ball bearings;Combined loads;Safety contact angle;Contact ellipse;Axial carrying capacity
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发布时间：2022-09-22 - 摘要：This paper aims to study the forklift truck,which installs forklift in the middle section of a mast and creates the telescopic boom subjected to Bending and Torque Moment. FEA and Structure Optimization are carried out through ANSYS Workbench. Under the constraint conditions of size,strength,the stability against elastic buckling,and with board thickness and structure sizes as the design variables,disadvantageous working conditions are analyzed and optimized,all working conditions tested and verified,and optimal results and their rounds received under the goal of lightweight. This paper intends to find a way to fully realize the subjectivity to bending and torque moment,and lightweight design,and to work as reference for future lightweight design.关键词：Mast;Bending and torque moment;FEA;Structure lightweight
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发布时间：2022-09-22 - 摘要：The finite element method is applied to the numerical simulation test of a dumping truck drive axle housing contact region,in order to reflect the non-linear mechanical property the CCD method is adopted to guide the test,the RSM is fitted according to the result of the test. the variance analysis of the RSM show that the RSM can describe clearly and significantly the nonlinear problem of the self dumping truck driving axle housing,the guiding suggestions are put forward based on the analysis of the RSM.关键词：FEA;CCD;RSM;Driving axle housing
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发布时间：2022-09-22 -
RESEARCH ON THE STRENGTH OF METAL ADHESIVELY BONDED OF SINGLE LAP JOINTS BASED ON SINGULARITY THEORY
摘要：In order to study the influence of different metal materials on the strength of adhesively-bonded single lap joints（ SLJ）,The adhesive bonding of SLJs whose adherends were aluminum alloy,titanium alloy,copper alloy and cold rolled steel were separately tested under tension-shear loading in ANSYS software based on singularity theory. The results show that the singularity order and stress intensity factor of adhesive joints decreased with the elasticity modulus increasing,the strength of adhesive joints increased with the elasticity modulus increasing.关键词：Adhesive joints;Finite element method;Singularity;Singularity order;Stress intensity factor- 3
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发布时间：2022-09-22 - 摘要：A three-dimensional sliding model of micro-scale was established between two rough surfaces exhibiting fractal behavior,and the thermo-mechanical coupling factor in the process of contact was considered. The surface temperature in sliding processes was analysed using the finite element analysis taking into account Ti-6Al-4V elastic-plastic properties with material failure. The transient surface temperature distribution of the rough surface was presented. The numerical results showed that the surface temperature in initial time rise sharply and then tend to be temporarily stable until a new contacted asperity coming into interaction. With the increase of friction slide distance the surface temperature was to present the state of fluctuating. The values of highest temperature at contact zones were different,while the highest temperature at contact zone was higher relative to the greater interface shear strength. Compared with the experimental data of the literatures,it was concluded that the rationality of the simulation,these results also deepened understanding the reason of the friction and wear.关键词：Sliding model;Thermo-mechanical coupling;Material failure;The interface shear strength;The highest temperature
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发布时间：2022-09-22 - 摘要：Stress triaxiality is a key factor in controlling the fracture of materials. Based on new method of finite element aided testing（ FAT）,the full-range constitutive relationship of ductile materials could be obtained. Thus,the distribution and evolution of stress triaxiality at the root of a funnel specimen is able to be obtained by ANSYS APDL program. The comparison of the analyzed results with those obtained by Bridgman correction method is completed and the failure mechanism of funnel-shaped specimen is discussed. The full-range constitutive relationship,fracture stress,fracture strain of the four ductile materials are given. Therefore,the law of the distribution and evolution of stress triaxiality at the root of funnel-shaped specimens are investigated.关键词：Stress triaxiality;Full-range constitutive relationship;FAT method;Necking;Fracture
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发布时间：2022-09-22 - 摘要：For the motorcycle muffler exhaust pipe rupture fracture morphology and metallographic analysis. Assessment of heat affected zone average grain size of level 3,parent metal grain size grade for level 6. Crack initiation in the region of the welding arc,instantaneous overheat of the region may result in coarse grains,brittleness increases; With inclusions in weld not clean up the local strength is reduced,in the process of serving the stress concentration caused by crack initiation. Crack from the inside to the outside slowly expanding gradually,reached a tipping point instantly exhaust pipe before and after the break.关键词：Heat affected zone;The average grain size;Fatigue fracture
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发布时间：2022-09-22 - 摘要：Generally the settlement of spherical tank’s foundation is difficult to ensure complete uniformity. Especially the foundation has been used for years. There is always a certain differential settlement. Pillar stress of the tank will be uneven under differential settlement. The stress of a LPG spherical tank on use with multiple differential settlements is analyzed by elasticity model of finite element method. According to the analysis results under hydraulic testing pillar stress exceeds the yield strength of the material. Then elastoplastic model is established to analyze the impact of material nonlinearity of pillar. Through finite element analysis and experimental testing,whether the tank can be used is evaluated. Based on the analysis results the tank is recommended to use under low load and strong inspection.关键词：Differential settlement;Pillar stress;Spherical tank;Finite element method
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发布时间：2022-09-22 - 摘要：Troubleshooting,finite element analysis and structure optimization were carried out through 7 Diamonds analysis in view of electric automobile transmission housing crack. First, problems of manufacturing were found by 7 Diamonds troubleshooting; Then FEA of the transmission housing before optimization was implemented by Hyperworks 11. 0,proving the validity of cracking reason; Thirdly,3 structure aspects of transmission housing were optimized,then FEA of the transmission housing after optimization was carried,the stress distribution cloud image shows that the maximum stress reduces greatly and this conforms to the requirements of the strength; Finally,on the bench test 6 tests were verified,the results indicates that the optimization of transmission housing meets intensity and durability requirements and optimization scheme is feasible. So the method of structure optimization to solve the problem of housing cracking through 7 Diamonds analysis has significance in engineering project.关键词：Electric automobile;Structure of transmission housing;7 Diamonds;FEA;Strength;Durability
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发布时间：2022-09-22 - 摘要：Lightweight design on bridge crane exist the following problems by ANSYS: Mostly using static indicators as a design criterion,ignoring the dynamic performance; the whole process takes a long time; and the parameters optimized often should be rounded,weaken the effect. In this paper,taking the bridge crane with 20t- 22. 5m as an example,utilization of ANSYS and multidisciplinary design optimization software Isight,based on the theory of Latin hypercube design,BP neural network,Hooke-Jeeves algorithm,presenting a better and faster optimization method for main girder of bridge crane. By this method,optimization time shortened,and a decrease in mass of girder of bridge crane by 14. 84%.
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发布时间：2022-09-22 - 摘要：Considering the reflection and influences of nonlinear touch rolling bearing towards dynamic,the theme of this paper focus on the slight axe experiment flat roof and comprise pedestal as well as rolling bearing. Use the way of variable step size "Runge-kutta"to make a solution through the model of dynamic. On the other side,the bifurcation diagrams also investigate the mass eccentricity for different rotors and its rotate speed. By the way,the evident change of shaft stiffness and supporting damp appear more obvious. The orbits plot,Poincare pictures and its frequency spectrum analyzed the signal features under the various situations. Through the experiment we can safely draw the conclusion that with the increase of the speed,vibrancy is higher up,the area of periodic locomotion will become narrow,so keep clear of the chaos sedulously when it happen to add up speed. The shaft stiffness have a great influence to the rotors,bulky stiffness can improve the stabilization to the rotors. But it will pass the vibration to the rotors. Meanwhile,avoid the bulky mass eccentricity is necessary if you want to keep a normal area and lower the impact speed. Supporting damp makes difference to the rotors vibration,with the addition of supporting damp,vibrancy will be reduced,the area of Chaos locomotion will become narrow,the area of periodic locomotion will be higher up. As a result,the system will be stabilized.关键词：Rolling bearing;Nonlinear resilience;Rotor system;Bifurcation;Chaos
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发布时间：2022-09-22 - 摘要：The kinematics of parallel structures in machine tool play an important role in the machining precision,and this paper focused on the kinematics and modeling of gantry parallel structure to analyze the dynamic response performance of the structure. It took a gantry parallel structure with plane motion for example,decomposed the motions of parallel structure with parallelogram,gave a gantry kinematic model of the system. Motion control method was studied to establish a projection function of model by the inputs and output. Based on this,the optimization algorithm was proposed to obtain the optimal control parameters for parallel structure,and the method can greatly improve the quick response of the parallel structure.关键词：Parallel structure;Kinematics model;Dynamic response;Control model;Parameters optimization
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发布时间：2022-09-22 - 摘要：In order to avoid creating or modifying the huge amount of finite element model of the rocket engine,application of the RBF（ radial basis function） neural network which was used to predict structural frequency of the liquid rocket engine was analyzed. A high pressure staged combustion LOX（ liquid oxygen） / kerosene rocket engine was taken as research object. By considering the material differences between the inner and outer wall of the nozzle,the precise nozzle finite element model was established using the stiffness and mass equivalence principle. Then the finite element model of staged combustion rocket engine was established using the method of distributed parameter and the finite element model was modified by modal experimental data.The difference structural parameters which were chosen according to the structural sensitivity analysis were considered as training samples. Then the RBF neural network was trained using these samples,and the structural frequency was predicted by the trained RBF neural network. The results show that the RBF neural network can predict structural frequency of the rocket engine accurately and the prediction error was less than 1. 0%. This method also has a fast convergence pace and it can be widely used in the field of the structural simulation of the rocket engine.关键词：RBF（radial basis function） neural network;Staged combustion rocket engine;Numerical simulation;Structural analysis;Performance prediction
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发布时间：2022-09-22 -
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