scholarly journals Dynamic Characteristics of Aerofoil at High Speed Change of Pitch Angle.

1992 ◽  
Vol 40 (458) ◽  
pp. 157-164
Author(s):  
Manabu SANO ◽  
Tomoaki MORINAGA ◽  
Hideyuki MATSUSHIMA
Keyword(s):  
Dynamic Characteristics ◽  
Pitch Angle ◽  
High Speed ◽  
Speed Change

Bearing Nonlinearity and Stability Analysis in High Speed Machining

1992 ◽  
Vol 114 (1) ◽  
pp. 23-30 ◽  
Author(s):  
Y. C. Shin
Keyword(s):  
Dynamic Characteristics ◽  
High Speed ◽  
System Stability ◽  
Successful Implementation ◽  
High Speed Machining ◽  
High Speeds ◽  
Machining Speed ◽  
Machining Chatter ◽  
Speed Change ◽  
Substantial Change

Elimination of chatter is an important problem for the successful implementation of high speed machining. Chatter is often related to the dynamic characteristics of the spindle system. The current study addresses the dynamic characteristics of angular contact bearings, which are the most commonly used type for high speed spindles, with respect to the speed change at high speeds, and reveals a very important fact on how the stiffness changes with respect to the speed change. It also illustrates how this characteristic is related to the system stability. Both analytical and experimental results show that there is a substantial change in stability zones in the high speed range and that the speed varying dynamic characteristics of a spindle must be properly taken into consideration in order to select a stable machining speed in high speed machining.

Dynamic Characteristics of the Combined Smart Bearing

2011 ◽  
Author(s):  
Yong Bok Lee ◽  
Kyung Min Lee ◽  
Jin-Taek Chung ◽  
Seung Jong Kim ◽  
Se Na Jeong
Keyword(s):  
Dynamic Characteristics ◽  
High Speed ◽  
Magnetic Bearing ◽  
Dynamic Force ◽  
Rotating Speed ◽  
Numerical Predictions ◽  
Efficient Performance ◽  
Speed Change ◽  
Hybrid Bearing ◽  
The Stability

The stability, reliability, efficient performance of high speed turbo machinery is very important, and accordingly has increased the demand for advanced bearings. In order to meet the advanced bearing needs, Heshmat proposed a hybrid foil-magnetic bearing [1]. The hybrid bearing combining the two bearings takes advantage of the strengths of each while compensating for each other’s weaknesses. This paper presents dynamic characteristics of the combined smart bearing (CSB) of different structure from Heshmat’s bearing. The CSB and test rig were designed, fabricated and carried out the test. Numerical predictions of Air foil bearing (AFB) and CSB were compared the dynamic force performance, and analysis of bearings are performed by finite element method (FEM). Experiments were conducted to determine the structural static and dynamic characteristics of AFB. The dynamic characteristics of AFB and CSB compared depending on the rotating speed change. The experimental results were obtained the dynamic characteristics of the CSB 50% higher than value of the stiffness effect. In addition to, the CSB 100% higher than value of the damping effect.

Unident: Providing Impact Sensations on Handheld Objects via High-Speed Change of the Rotational Inertia

2021 ◽  
Author(s):  
Shuntaro Shimizu ◽  
Takeru Hashimoto ◽  
Shigeo Yoshida ◽  
Reo Matsumura ◽  
Takuji Narumi ◽  
...  
Keyword(s):  
High Speed ◽  
Rotational Inertia ◽  
Speed Change

A modified damping model of vector form intrinsic finite element method for high-speed spiral bevel gear dynamic characteristics analysis

2021 ◽  
pp. 030932472110188
Author(s):  
Xiangying Hou ◽  
Yuzhe Zhang ◽  
Hong Zhang ◽  
Jian Zhang ◽  
Zhengminqing Li ◽  
...  
Keyword(s):  
Finite Element ◽  
Dynamic Characteristics ◽  
High Speed ◽  
Numerical Solutions ◽  
Bevel Gear ◽  
Spiral Bevel Gear ◽  
Vector Form ◽  
Good Efficiency ◽  
Spiral Bevel ◽  
Damping Model

The vector form intrinsic finite element (VFIFE) method is springing up as a new numerical method in strong non-linear structural analysis for its good convergence, but has been constricted in static or transient analysis. To overwhelm its disadvantages, a new damping model was proposed: the value of damping force is proportional to relative velocity instead of absolute velocity, which could avoid inaccuracy in high-speed dynamic analysis. The accuracy and efficiency of the proposed method proved under low speed; dynamic characteristics and vibration rules have been verified under high speed. Simulation results showed that the modified VFIFE method could obtain numerical solutions with good efficiency and accuracy. Based on this modified method, high-speed vibration rules of spiral bevel gear pair under different loads have been concluded. The proposed method also provides a new way to solve high-speed rotor system dynamic problems.

Dynamic characteristics of a drill in the drilling process

2003 ◽  
Vol 217 (2) ◽  
pp. 161-167 ◽  
Author(s):  
B W Huang
Keyword(s):  
Dynamic Characteristics ◽  
High Speed ◽  
Thrust Force ◽  
Time Dependent ◽  
Drilling Process ◽  
Improve Quality ◽  
Vibration Model ◽  
High Speed Drilling ◽  
Spinning Speed ◽  
Twisted Beam

The dynamic characteristics of high-speed drilling were investigated in this study. To improve quality and produce a higher production rate, the dynamic characteristics of the drilling process need to be studied. A pre-twisted beam is used to simulate the drill. The moving Winkler-type elastic foundation is used to approximate the drilling process. A time-dependent vibration model for drilling is presented. The spinning speed, pre-twisted angle and thrust force effects of the drill are considered. The numerical analysis indicates that the natural frequency is suddenly reduced as the drill moves into a workpiece.

scholarly journals Analysis of the dynamic characteristics of downsized aerostatic thrust bearings with different pressure equalizing grooves at high or ultra-high speed

2021 ◽  
Vol 13 (5) ◽  
pp. 168781402110180
Author(s):  
Ruzhong Yan ◽  
Haojie Zhang
Keyword(s):  
Dynamic Characteristics ◽  
High Speed ◽  
Rotation Speed ◽  
Dynamic Stiffness ◽  
Simulation Method ◽  
Perturbation Amplitude ◽  
Thrust Bearings ◽  
Supply Pressure ◽  
Ultra High Speed ◽  
Air Film

This study adopts the DMT(dynamic mesh technology) and UDF(user defined functions) co-simulation method to study the dynamic characteristics of aerostatic thrust bearings with equalizing grooves and compare with the bearing without equalizing groove under high speed or ultra high speed for the first time. The effects of air film thicness, supply pressure, rotation speed, perturbation amplitude, perturbation frequency, and cross section of the groove on performance characteristics of aerostatic thrust bearing are thoroughly investigated. The results show that the dynamic stiffiness and damping coefficient of the bearing with triangular or trapezoidal groove have obvious advantages by comparing with that of the bearing without groove or with rectangular groove for the most range of air film thickness, supply pressure, rotation speed, perturbation amplitude, especially in the case of high frequency, which may be due to the superposition of secondary throttling effect and air compressible effect. While the growth range of dynamic stiffness decreases in the case of high or ultra-high rotation speed, which may be because the Bernoulli effect started to appear. The perturbation amplitude only has little influence on the dynamic characteristic when it is small, but with the increase of perturbation amplitude, the influence becomes more obvious and complex, especially for downsized aerostatic bearing.

Development of High-Speed Response Electromagnetic Linear Actuator Using for Pneumatic Control Valve

2014 ◽  
Vol 532 ◽  
pp. 41-45 ◽  
Author(s):  
Myung Jin Chung
Keyword(s):  
Optimal Design ◽  
Dynamic Characteristics ◽  
High Speed ◽  
Design Method ◽  
Control Valve ◽  
Design Parameters ◽  
Linear Actuator ◽  
Analytic Model ◽  
Electromagnetic Linear Actuator ◽  
Quadratic Programming Method

Analytic model of electromagnetic linear actuator in the function of electric and geometric parameters is proposed and the effects of the design parameters on the dynamic characteristics are analyzed. To improve the dynamic characteristics, optimal design is conducted by applying sequential quadratic programming method to the analytic model. This optimal design method aims to minimize the response time and maximize force efficiency. By this procedure, electromagnetic linear actuator having high-speed characteristics is developed.

Switchmode Hydraulic Power Supply Theory

2005 ◽  
Author(s):  
Jianwei Cao ◽  
Linyi Gu ◽  
Feng Wang ◽  
Minxiu Qiu
Keyword(s):  
Flow Rate ◽  
Dynamic Characteristics ◽  
Power Supply ◽  
Power Loss ◽  
High Speed ◽  
Hydraulic Pressure ◽  
Hydraulic Systems ◽  
Hydraulic Pump ◽  
Hydraulic Power ◽  
Supply Pressure

Switchmode hydraulic power supply is a new kind of energy-saving pressure converting system, which is originally proposed by the authors. It is mainly applied in multiple-actuator hydraulic systems, and installed between hydraulic pump and actuators (one switchmode hydraulic power supply for one actuator). It can provide pressure or flow rate that is adapted to the consumption of each actuator in the system by boosting or bucking the pressure, with low power loss, and conveniently, through high-speed switch valves, just like a hydraulic pressure transformer. There are two basic types of switchmode hydraulic power supply: pressure boost and pressure buck. Their structures and working principles are introduced. The dynamic characteristics of two typical types of switchmode hydraulic power supply, the pressure boost type and the pressure buck type, were analyzed through simulations and experiments. The performances were evaluated, and improvements on the efficiency of switchmode hydraulic power supply were proposed.

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