scholarly journals Modeling and dynamic characteristic analysis of dual rotor-casing coupling system with rubbing fault

2021 ◽  
pp. 146134842110393
Author(s):  
Bingqiang Li ◽  
Honggen Zhou ◽  
Jinfeng Liu ◽  
Chao Kang
Keyword(s):  
Dynamic Model ◽  
Rapid Development ◽  
Great Influence ◽  
Speed Ratio ◽  
Frequency Multiplication ◽  
Characteristic Analysis ◽  
Rotating Speed ◽  
Fem Method ◽  
Counter Rotation ◽  
Coupling System

With the rapid development of aero-engine manufacturing technology, the dual-rotor system has been employed in part of turbofan engine in order to improve the working performance of aircraft more efficiently. In this study, taking the counter-rotation dual-rotor as the research object, the dynamic model of dual rotor-casing coupling system is established by the aid of MATLAB. The dynamic frequency curves are in good agreement with the results in references and calculated by FEM method, that shows the validity and feasibility of the model. The local rub-impact dynamic model of dual rotor-casing coupling system is established, and rubbing analysis is carried out using Newmark- β method. The effects of rotating speed and speed ratio on local rub-impact response are deeply discussed. The results show that with the increase of rotating speed, combined frequencies and frequency multiplication components are more significant. In addition, speed ratio has a great influence on the periodic motion of the system. With the increase of the absolute value of the speed ratio, the whirl radius of the outer rotor and the normal rubbing force increase dramatically.

scholarly journals Analysis and optimization of the vehicle handling stability with considering suspension kinematics and compliance characteristics

2021 ◽  
Vol 13 (5) ◽  
pp. 168781402110155
Author(s):  
Jin Gao ◽  
Fuquan Wu
Keyword(s):  
Dynamic Model ◽  
Great Influence ◽  
Transient State ◽  
Transient Characteristic ◽  
Nsga Ii ◽  
Pareto Solution ◽  
Characteristic Index ◽  
Yaw Rate ◽  
Comparison Results ◽  
Force Calculation

The dynamic model of the front double wishbone suspension and the rear multi-link suspension of the vehicle are established. On the basis of detailed analysis of suspension kinematics, calculation method of wheel alignment angle and force calculation of suspension bushing, the influence mechanism of suspension bushing on the vehicle transient state is clarified, and the vehicle transient characteristic index is derived from the vehicle three-free dynamic model. The sensitivity analysis of the suspension bushing is carried out, and the bushing stiffness which has a great influence on the transient state of the vehicle is obtained. The bushing stiffness scale factor is used as the optimization variable, the vehicle transient characteristic index is used as the optimization target, and the NSGA-II optimization algorithm is used for multi-objective optimization. After optimization, one Pareto solution is selected to compare with the original vehicle, the comparison results show that the yaw rate gain, resonance frequency and delay time of yaw rate in the vehicle transient characteristic index are all improved, other optimization targets change less. In the steady-state comparison, the understeer tendency of the vehicle increases, and the roll angle of the vehicle increases but is within an acceptable range.

Synthesis of multi-input multi-degree-of-freedom fixed shaft gear transmission configuration for vehicles

2021 ◽  
pp. 095440702110652
Author(s):  
Xueliang Li ◽  
Zhihang Wu ◽  
Shujun Yang ◽  
Jibin Hu ◽  
Zengxiong Peng
Keyword(s):  
Electric Vehicles ◽  
Rapid Development ◽  
Synthesis Method ◽  
Theory Model ◽  
Gear Transmission ◽  
Degree Of Freedom ◽  
Speed Ratio ◽  
Multiple Parameters ◽  
Transmission Mechanisms ◽  
Derivation Method

The rapid development of dual-clutch transmission (DCT) and hybrid and purely electric vehicles stimulate the researches on multi-input fixed shaft gear transmission mechanisms. The multiple degree-of-freedom (DOF) transmission mechanism can achieve a wider range of speed ratio adjustment and more modes under certain space and weight constraints, which is an ideal choice for multi gear transmission. In this paper, a synthesis method of fixed shaft gear transmission configuration is proposed. Based on the established graph theory model, kinematic characteristics of the fixed shaft gear transmission configuration are studied and the shift sequence is determined. Using these characteristics, a derivation method from the basic configuration to the comprehensive gears and shafts configuration is proposed. Multiple parameters such as the synchronizer arrangement and speed ratios are optimized. Finally, the proposed method is vigorously verified by a seven-speed DCT with four DOFs. This method is comprehensive and systematic in designing fixed shaft gear transmission configurations, which can be applied to DCT, transmissions for parallel hybrid electric vehicles, and to some novel multi-input transmissions.

High frequency vibration analysis of ball bearings under radial loads

2016 ◽  
Vol 230 (4) ◽  
pp. 579-588
Author(s):  
Yang Zhao ◽  
Guihua Dong ◽  
Heng Liu ◽  
Fengtao Wang ◽  
Meng Li ◽  
...  
Keyword(s):  
Dynamic Model ◽  
High Frequency ◽  
Vibration Amplitude ◽  
Ball Bearing ◽  
High Frequency Vibration ◽  
Rotating Speed ◽  
Deep Groove ◽  
Deep Groove Ball Bearing ◽  
Bearing Load

The paper investigates the role of radial load and rotating speed on the high frequency vibration of a deep groove ball bearing. Firstly, a bearing dynamic model with 6-DOF balls was established, considering the interactions between balls, races and the cage. The dynamic model was solved by fourth order varying steps Runge-Kutta integration. The frequency spectrums of dynamic response of races were analyzed with yule-walker and FFT. Secondly, a verification experiment was done with different radial loads and speeds. Finally, compared with the numerical and experimental results, the similar trend of the high frequency vibration was emerged. Higher vibration frequencies result with increasing bearing load; higher vibration amplitude cause by more quickly rotating speed. That is because the nature frequencies of the races are excited by the contact and shock between balls and races when balls leave from the non-load to the load zone. The frequency spectrums were also affected by the interaction between the balls and cage.

scholarly journals Nonlinear Dynamic Characteristic Analysis of a Landing String in Deepwater Riserless Drilling

2018 ◽  
Vol 2018 ◽  
pp. 1-17
Author(s):  
Jun Liu ◽  
Hongliang Zhao ◽  
Simon X. Yang ◽  
Qingyou Liu ◽  
Guorong Wang
Keyword(s):  
Boundary Condition ◽  
Dynamic Model ◽  
Marine Environment ◽  
Lower Boundary ◽  
Dynamic Responses ◽  
Characteristic Analysis ◽  
Lower Boundary Condition ◽  
Response Characteristics ◽  
Proposed Model ◽  
Nonlinear Dynamic Characteristic

The landing string is an important component of deepwater riserless drilling systems. Determination of the dynamic characteristics of the landing string plays an essential role in its design for ensuring its safe operation. In this paper, a dynamic model is developed to investigate the dynamic response characteristics of a landing string, where a landing string in a marine environment is modeled as a flexible slender tube undergoing coupled transverse and axial motions. The heaving motion of the drilling platform is taken as the upper boundary condition and the motion of the drilling bit caused by the interaction between the rock and the bit as the lower boundary condition. A semiempirical Morison equation is used to simulate the effect of the load imposed by the marine environment. The dynamic model, which is nonlinearly coupled and multibody, is discretized by a finite element method and solved by the Newmark technique. Using the proposed model, the dynamic responses of the displacement, axial force, and moment in the landing string are investigated in detail to find out the influences of driving depth of surface catheter, platform motion, bit movement, and marine environment on the dynamical characteristics of the landing string.

Computer Simulation of the Hydropower Stations With Long Pressurized Pipelines and Far Transmission Line

2008 ◽  
Author(s):  
Jianxu Zhou ◽  
Chengmin Bi ◽  
Ming Hu
Keyword(s):  
Computer Simulation ◽  
Transmission Line ◽  
Water Flow ◽  
Rapid Development ◽  
Oscillation Mode ◽  
Elastic Model ◽  
Characteristic Analysis ◽  
Training Tool ◽  
Pressurized Pipelines ◽  
Hydropower Stations

With the rapid development of automatic technology and computer science in the hydropower stations, the computer simulation system named as simulator is developed quickly and applied widely especially as a modern training tool for field operators. In the project of power transmission from west to east in Southwest China, there are lots of hydropower stations with long pressurized pipelines and far transmission line, so their simulators are more complex to be built correctly to show the characteristic of hydraulic-mechanical-electrical system and its dynamic procedure distinctly in real time. Based on the characteristic analysis of hydraulic system and long transmission system, a new easily-decoupled elastic model of water flow in pressurized pipelines is given and recommended, and its application and the choice of appropriate model order are analyzed considering the effect of power system, furthermore, how to build the model of far transmission line is discussed in detail based on its state equations. The results indicate that, in order to realize the truthfulness and robustness of the simulator, the higher order oscillation mode of water flow in long pressurized pipelines should be introduced and the frequency property of far transmission line should be analyzed.

Reducing yarn hairiness in ring spinning by an agent-aided system

2019 ◽  
Vol 89 (21-22) ◽  
pp. 4438-4451 ◽  
Author(s):  
Peiying Li ◽  
Mingrui Guo ◽  
Fengxin Sun ◽  
Weidong Gao
Keyword(s):  
Textile Industry ◽  
Speed Ratio ◽  
Rotating Speed ◽  
Comprehensive Properties ◽  
Spun Yarn ◽  
Spun Yarns ◽  
Ring Spun Yarn ◽  
Yarn Hairiness ◽  
Yarn Tenacity

An agent-aided system (AAS) for improving comprehensive properties of ring spun yarns with the aid of viscosity and surface tension of the agent is reported in this paper. The mechanism of the humidification and friction process of the AAS was investigated, and related experiments were also carried out to verify the mechanism of analysis. The results confirm that the AAS can attach the fiber ends protruding out of a yarn body on the yarn surface and assist in twisting the fiber ends back into the interior of the yarn body, resulting in a significant reduction of the modified ring spun yarn hairiness. Moreover, the yarn hairiness is prominently reduced after the winding process. The experimental results also show that a speed ratio of 1.3 between the rotating speed of the cylinder and the output speed of the yarn leads to the greatest extent of harmful hairiness reduction (34%), which also corresponds to optimal modified yarn tenacity. Meanwhile, the modified ring spun yarns show a tight and smooth appearance, and the yarn evenness has no deterioration. In addition, the AAS is applicable to both cotton and viscose yarns with different yarn counts. Therefore, the AAS can potentially be used to reduce yarn hairiness for ring spun yarns and enhance the quality of ring spun yarns in the textile industry.

The Rotor Speed Control of 5MW Wind Turbine under Rated Wind Speed Using Adaptive-PID Controller

2012 ◽  
Vol 229-231 ◽  
pp. 2323-2326
Author(s):  
Zong Qi Tan ◽  
Can Can Li ◽  
Hui Jun Ye ◽  
Yu Qiong Zhou ◽  
Hua Ling Zhu
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Pid Controller ◽  
Turbine Rotor ◽  
Speed Ratio ◽  
Rotor Speed ◽  
Rotating Speed ◽  
Tip Speed Ratio ◽  
Variable Wind ◽  
Wind Turbine Rotor

This paper designed the controller of the wind turbine rotor rotating speed. This model of adaptive-PID through control the tip-speed ratio and count the values of PID for variable wind speed. From the result of simulation, the wind speed can run in a good dynamic characteristic, and keep the rotor running in the best tip-speed ratio at the same time.

Natural Science and Technical Peace Research: Definition, History, and Current Work

2020 ◽  
Vol 38 (1) ◽  
pp. 1-4 ◽  
Author(s):  
Christian Reuter ◽  
Jürgen Altmann ◽  
Malte Göttsche ◽  
Mirko Himmel
Keyword(s):  
Natural Science ◽  
Rapid Development ◽  
Great Influence ◽  
Peace Building ◽  
Biological Weapons ◽  
Cyber Warfare ◽  
Weapon Systems ◽  
Peace Research ◽  
Peace And Security ◽  
Chemical And Biological Weapons

Scientific discoveries and technological innovations have always exerted a great influence on peace and security. New civil and military technologies are revolutionizing warfare. Particularly striking areas are cyber warfare and the rapid development of uninhabited weapon systems. Issues of nuclear disarmament, missile defence or space armament as well as chemical and biological weapons remain urgent. The conference SCIENCE · PEACE · SECURITY ’19 aimed for an accurate understanding and fruitful discussions of today’s and tomorrow’s peace and security challenges. This includes natural science/technical as well as interdisciplinary contributions, focusing on problems of international security and peace-building as well as contributions dedicated to transparency, trust-building, arms control, disarmament, and conflict management. This special issue presents selected contributions based on discussions at the conference.

Flow Simulation Around a Rotating Circular Cylinder With Surface Roughness by the Vortex Method

2003 ◽  
Author(s):  
Tetsuhiro Tsukiji ◽  
Yuko Matsubara
Keyword(s):  
Surface Roughness ◽  
Circular Cylinder ◽  
Flow Simulation ◽  
Vortex Method ◽  
Uniform Flow ◽  
Speed Ratio ◽  
Rotating Speed ◽  
Rotating Circular Cylinder ◽  
Two Dimensional Flow ◽  
Good Agreement

The two-dimensional flow around a rotating circular cylinder with surface roughness in a steady uniform flow is investigated using a vortex method. The Reynolds number is 9500, while the rotating speed ratios of the peripheral velocity to the uniform velocity is 0–1.0. The surface roughness is distributed around the circular cylinder and its strength is 0.5% of the diameter. The viscous diffusion effects and the no-slip condition are considered. Before the calculation for a rotating circular cylinder with the surface roughness, the flow simulation for a circular cylinder in the steady uniform flow was conducted to confirm the present method. The development of the twin vortices and the velocity profiles behind the circular cylinder at the beginning of the calculation are compared with the previous experimental results. It is found that the calculated results are in good agreement with the experiments. The development of the vortices, the drag and the lift coefficients are computed by changing the rotating speed ratio for the circular cylinder both with the surface roughness and without it. The influence of the surface roughness and the rotating speed ratio on the vortex development, the drag and the lift coefficients are examined.

The Effect of the Carbon Fiber on Concrete Compressive Strength

2018 ◽  
Vol 1145 ◽  
pp. 106-111
Author(s):  
De Jia Liu ◽  
Mei Jun Chen ◽  
Li Xue ◽  
Fan He ◽  
Jian Hu
Keyword(s):  
Compressive Strength ◽  
Carbon Fiber ◽  
Construction Material ◽  
Rapid Development ◽  
Great Influence ◽  
Engineering Application ◽  
Fiber Reinforced Concrete ◽  
Engineering Practice ◽  
Curing Time ◽  
Compressive Strength Of Concrete

With the rapid development of construction, the high quality of the construction material is required. Mixing carbon fiber in concrete attracts more and more attention as it can reinforce concrete. However, the science research and engineering application of carbon fiber reinforced concrete is relatively few. In this paper, the effects of different mixing amount of carbon fiber and the sand ratio in concrete and the curing time of concrete and relationships between these factors were investigated. Proper carbon fiber and sand ratio can promote the compressive strength of concrete and it has a good resistance to cracking. The compressive strength of concrete with different mixing amounts of carbon fiber peaks when the sand ratio was 31% and the compressive strength was better when the carbon fiber mixing amount was 0.2% and 1% than any other ratios after 28 days. When the sand ratio was 31%, the compressive strength of carbon fiber mixing amount increased with the increase of curing time and it reached the top when the carbon fiber ratio was 0.8%. The mixing amount of carbon fiber also had a great influence on the early compressive strength to some extent. We anticipate that the research can offer certain reference for engineering practice.

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