Dynamic response of a finite beam resting on a Winkler foundation to a load moving on its surface with variable speed

2018 ◽  
Vol 109 ◽  
pp. 222-226 ◽  
Author(s):  
Niki D. Beskou ◽  
Edmond V. Muho
Keyword(s):  
Dynamic Response ◽  
Winkler Foundation ◽  
Variable Speed

scholarly journals The Influence of Valve-Pump Weight Ratios on the Dynamic Response of Leaking Valve-Pump Parallel Control Hydraulic Systems

2018 ◽  
Vol 8 (7) ◽  
pp. 1201 ◽  
Author(s):  
Haigang Ding ◽  
Jiyun Zhao ◽  
Gang Cheng ◽  
Steve Wright ◽  
Yufeng Yao
Keyword(s):  
Dynamic Response ◽  
Hydraulic System ◽  
Weight Ratio ◽  
Open Loop ◽  
Hydraulic Systems ◽  
Variable Speed ◽  
Weight Factors ◽  
Wide Range ◽  
Parallel Control ◽  
Valve Control

A new leaking valve-pump parallel control (LVPC) oil hydraulic system is proposed to improve the performance of dynamic response of present variable speed pump control (VSPC) system, which is an oil hydraulic control system with saving energy. In the LVPC, a control valve is operating at leaking status, together with a variable speed pump, to regulate the system flow of hydraulic oil simultaneously. Therefore, the degree of valve control and pump control can be adjusted by regulating the valve-pump weight ratio. The LVPC system design, mathematical model development, system parameter and control performance analysis are carried out systematically followed by an experimental for validation process. Results have shown that after introducing the valve control, the total leakage coefficient increases significantly over a wide range with the operating point and this further increases damping ratios and reduces the velocity stiffness. As the valve-pump weight ratio determines the flow distribution between the valve and the pump and the weight factors of the valve and/or the pump controls determines the response speed of the LVPC system, thus if the weight factors are constrained properly, the LVPC system will eventually have a large synthetic open-loop gain and it will respond faster than the VSPC system. The LVPC will enrich the control schemes of oil hydraulic system and has potential value in application requiring of fast response.

scholarly journals Dynamic Response of Bridge-Ship Collision Considering Pile-Soil Interaction

2017 ◽  
Vol 3 (10) ◽  
pp. 965 ◽  
Author(s):  
Hussein Yousif Aziz ◽  
HE Yun Yong ◽  
Baydaa Hussain Mauls
Keyword(s):  
Dynamic Response ◽  
Frequency Domain ◽  
Integral Transform ◽  
Simulation Models ◽  
Bridge Piers ◽  
Inverse Transformation ◽  
Winkler Foundation ◽  
Transient Vibration ◽  
Ship Collision ◽  
Shearing Strain

According to most countries’ norms, and to find the effect of the bridge collision the equivalent static method was designed for bridge-ship collision, ignoring the dynamic effects of shocks. It is sharply different from actual situation. So based on the theory of Winkler foundation, shearing strain theory of Timoshenko and potential energy variation functional principle of Hamilton, the simulation models of bridge piers was built considering the pile–soil interaction. Lateral transient vibration equation of bridge piers was concluded. Based on the theory of integral transform, the differential equation of the collision system and the boundary conditions were transformed with Laplace transformation; the analytical solution of the stress wave in frequency domain was concluded. And then the inversion of solution in frequency domain was carried out using Matlab based on the Crump inverse transformation. Finally the dynamic response law of displacement, normal stress and the shear stress of bridge piers were obtained.

scholarly journals Study on dynamic response of track structures under a variable speed moving harmonic load

2017 ◽  
Vol 14 ◽  
pp. 214-219
Author(s):  
Yan Qi Liu ◽  
Yan Zhang ◽  
Chun Fang Song ◽  
Long Long Xu
Keyword(s):  
Dynamic Response ◽  
Harmonic Load ◽  
Variable Speed ◽  
Moving Harmonic Load

Simulating the Dynamic and Steady State Response of a Rotor Resistive Controlled 1.5 MW Variable Speed Wind Turbine

2010 ◽  
Author(s):  
Jared B. Garrison ◽  
Michael E. Webber
Keyword(s):  
Steady State ◽  
Wind Speed ◽  
Dynamic Response ◽  
Wind Turbine ◽  
Power Output ◽  
Pitch Angle ◽  
Maximum Power ◽  
Variable Speed ◽  
Wind Speeds ◽  
Variable Speed Wind Turbine

Currently, wind and solar technologies only generate 0.77% and 0.014% of the U.S. electricity consumption, respectively [1]. Though only a small portion of total U.S. electricity production, both sources have seen significant growth recently. For instance, Texas has more than quadrupled its installed wind capacity over the period from 2005–2009 with new installations totaling over 9400 MW [2, 3]. These two resources are globally available and have the potential to generate massive amounts of electricity. As the amount of installed wind turbines continues to grow, gaining better knowledge of their operation and their dynamic response to changing wind conditions is important to ensure their smooth integration and safe operation. The goal of this research is to analyze the dynamic and steady state operations of a 1.5 MW variable speed wind turbine that uses an external rotor resistive control mechanism. The addition of the external generator rotor resistance allows for adjustment of the generator slip and employs a feedback controller that maintains constant power output at all air velocities between the rated wind speed and cut-out wind speed. Using the electronic programming language PSCAD/EMTDC the model simulates the dynamic response to changing wind conditions, as well as the performance under all wind conditions. The first task of the model was to determine which blade pitch angle produces a maximum power output of 1.5 MW. A sweep was used where the simulation runs over the entire range of wind speeds for a selected pitch angle to find which speed resulted in maximum power output. This sweep was used for numerous blade pitch angles until the combination of wind speed and pitch angle at 14.4 m/s and −0.663°, respectively, resulted in a maximum power of 1.5 MW. The second task was to evaluate the model’s dynamic response to changes in wind conditions as well as steady state operation over all wind speeds. The dynamic response to an increase or decrease in wind speed is important to the safety and life expectancy of a wind turbine because unwanted spikes and dips can occur that increase stresses in the wind turbine and possibly lead to failure. In order to minimize these transient effects, multiple controllers were implemented in order to test each ones’ dynamic response to increasing and decreasing changes in wind velocity. These simulations modeled the characteristics of a variable-speed wind turbine with constant power rotor resistive control. First, through calibrating the model the design specifications of blade pitch and wind speed which yield the peak desired output of 1.5 MW were determined. Then, using the method of controlling the external rotor resistance, the simulation was able to maintain the 1.5 MW power output for all wind speeds between the rated and cutout speeds. Also, by using multiple controllers, the dynamic response of the control scheme was improved by reducing the magnitude of the initial response and convergence time that results from changes in wind speed. Finally, by allowing the simulation to converge at each wind speed, the steady state operation, including generator power output and resistive thermal losses, was characterized for all wind speeds.

Study on High Dynamic Variable Speed Hydraulic Control System

2012 ◽  
Vol 271-272 ◽  
pp. 625-631 ◽  
Author(s):  
Hai Kuo Shen ◽  
Meng Nie ◽  
Shao Dan Zhi ◽  
Jin Bo
Keyword(s):  
Control System ◽  
Dynamic Response ◽  
Speed Control ◽  
Hydraulic Control ◽  
Variable Speed ◽  
Dynamic Variable ◽  
Low Speed ◽  
Control Precision ◽  
High Dynamic ◽  
Hydraulic Control System

A new type of high dynamic variable speed hydraulic control system is developed in this paper. In this system, a fixed displacement hydraulic pump is driven by an electrical motor which is controlled by a frequency inverter, so the discharge of the pump can be modified by changing the speed of the motor. A proportional directional valve is used to acquire higher low-speed control precision and faster dynamic response while the system is decelerating. In order to improve the dynamic response while the system is accelerating, an energy regulation device is employed in the system. The digital simulation results show that this system has higher efficiency than valve control system. Further more it has faster dynamic response and higher low-speed control precision than normal variable speed hydraulic control system.

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