Fully coupled model for simulating highly nonlinear dynamic behaviors of a bubble near an elastic-plastic thin-walled plate

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Wenbin Wu ◽  
Moubin Liu ◽  
A-Man Zhang ◽  
Yun-Long Liu
Keyword(s):  
Nonlinear Dynamic ◽  
Coupled Model ◽  
Dynamic Behaviors ◽  
Elastic Plastic ◽  
Highly Nonlinear ◽  
Thin Walled ◽  
Fully Coupled

scholarly journals Role of the hydrological cycle in regulating the planetary climate system of a simple nonlinear dynamical model

2005 ◽  
Vol 12 (5) ◽  
pp. 741-753 ◽  
Author(s):  
K. M. Nordstrom ◽  
V. K. Gupta ◽  
T. N. Chase
Keyword(s):  
Hydrological Cycle ◽  
Water Cycle ◽  
Coupled Model ◽  
Coupled System ◽  
Relative Distribution ◽  
Species Trees ◽  
Nonlinear Coupled System ◽  
Highly Nonlinear ◽  
Negative Feedbacks ◽  
Fully Coupled

Abstract. We present the construction of a dynamic area fraction model (DAFM), representing a new class of models for an earth-like planet. The model presented here has no spatial dimensions, but contains coupled parameterizations for all the major components of the hydrological cycle involving liquid, solid and vapor phases. We investigate the nature of feedback processes with this model in regulating Earth's climate as a highly nonlinear coupled system. The model includes solar radiation, evapotranspiration from dynamically competing trees and grasses, an ocean, an ice cap, precipitation, dynamic clouds, and a static carbon greenhouse effect. This model therefore shares some of the characteristics of an Earth System Model of Intermediate complexity. We perform two experiments with this model to determine the potential effects of positive and negative feedbacks due to a dynamic hydrological cycle, and due to the relative distribution of trees and grasses, in regulating global mean temperature. In the first experiment, we vary the intensity of insolation on the model's surface both with and without an active (fully coupled) water cycle. In the second, we test the strength of feedbacks with biota in a fully coupled model by varying the optimal growing temperature for our two plant species (trees and grasses). We find that the negative feedbacks associated with the water cycle are far more powerful than those associated with the biota, but that the biota still play a significant role in shaping the model climate. third experiment, we vary the heat and moisture transport coefficient in an attempt to represent changing atmospheric circulations.

Parametric Influences on the Nonlinear Dynamic Responses of a Rotor-Bearing-Foundation-Labyrinth Seal System

2017 ◽  
Author(s):  
Enjie Zhang ◽  
Yinghou Jiao ◽  
Zhaobo Chen ◽  
Wenchao Mo ◽  
Shuai Wang
Keyword(s):  
Nonlinear Dynamic ◽  
Labyrinth Seal ◽  
Rotor System ◽  
Operating Conditions ◽  
Dynamic Responses ◽  
Lubricating Oil ◽  
Geometrical Parameters ◽  
Dynamic Behaviors ◽  
Highly Nonlinear ◽  
Rotor Bearing

The modern engineering industries rely heavily on the reliable operation of rotating machinery, e.g., steam turbine and gas turbine. These rotating machineries are inevitable to be excited by the unbalance mass forces, the oil film forces and seal forces. Moreover, the turbines installed in an aircraft as well as vessel are also excited by the base vibration. In order to retain the healthy operation and prolong the interval between overhauls, an enormous amount of experimental and theoretical investigations have been focused on the dynamic behaviors of the rotor system. The dynamic characteristics of the rotor system influenced by the single source of vibration, such as unbalance, flowing lubricating oil, sealing medium etc., and combined sources of vibration have also been thoroughly researched. However, the dynamic responses of the rotor-bearing-foundation system subjected to labyrinth seal forces have seldom been studied. Furthermore, the previous analyses of the rotor dynamics mostly were linear. In fact, the fluid film forces are strongly nonlinear functions of the displacement and velocity of the rotor. As a result, the rotordynamics of the turbine is highly nonlinear. It is not accurate enough to be considered from a linear point of view. Applying the energy method, this paper established a dynamic model of the rotor-bearing-foundation-labyrinth seal system. The influences of the geometrical parameters and operating conditions, such as mass eccentricities, inlet pressure and rotational speed etc., on the nonlinear dynamic behaviors of the rotor system are numerically studied. The responses of the same system excited by one side of and both sides of base movement are also comparatively analyzed by means of spectrum cascades, bifurcation diagrams and whirl orbits as well as Poincaré maps.

Stress self-sensing in Amplified Piezoelectric Actuators through a fully-coupled model of hysteresis

2020 ◽  
Vol 579 ◽  
pp. 411894
Author(s):  
Valerio Apicella ◽  
Carmine Stefano Clemente ◽  
Daniele Davino ◽  
Damiano Leone ◽  
Ciro Visone
Keyword(s):  
Coupled Model ◽  
Piezoelectric Actuators ◽  
Fully Coupled

scholarly journals Dynamic Response of Floating Wind Turbine Under Consideration of Dynamic Behavior of Catenary Mooring-Lines

2017 ◽  
Author(s):  
Shuangxi Guo ◽  
Yilun Li ◽  
Min Li ◽  
Weimin Chen ◽  
Yiqin Fu
Keyword(s):  
Dynamic Response ◽  
Wind Turbine ◽  
Nonlinear Dynamic ◽  
Ocean Waves ◽  
Wave Frequency ◽  
Mooring Line ◽  
Mooring Lines ◽  
Restoring Force ◽  
Dynamic Behaviors ◽  
Floating Wind Turbine

Recently, wind turbine has been developed from onshore area to offshore area because of more powerful available wind energy in ocean area and more distant and less harmful noise coming from turbine. As it is approaching toward deeper water depth, the dynamic response of the large floating wind turbine experiencing various environmental loads becomes more challenge. For examples, as the structural size gets larger, the dynamic interaction between the flexible bodies such as blades, tower and catenary mooring-lines become more profound, and the dynamic behaviors such as structural inertia and hydrodynamic force of the mooring-line get more obvious. In this paper, the dynamic response of a 5MW floating wind turbine undergoing different ocean waves is examined by our FEM approach in which the dynamic behaviors of the catenary mooring-line are involved and the integrated system including flexible multi-bodies such as blades, tower, spar platform and catenaries can be considered. Firstly, the nonlinear dynamic model of the integrated wind turbine is developed. Different from the traditional static restoring force, the dynamic restoring force is analyzed based on our 3d curved flexible beam approach where the structural curvature changes with its spatial position and the time in terms of vector equations. And, the modified finite element simulation is used to model a flexible and moving catenary of which the hydrodynamic load depending on the mooring-line’s motion is considered. Then, the nonlinear dynamic governing equations is numerically solved by using Newmark-Beta method. Based on our numerical simulations, the influences of the dynamic behaviors of the catenary mooring-line on its restoring performance are presented. The dynamic responses of the floating wind turbine, e.g. the displacement of the spar and top tower and the dynamic tension of the catenary, undergoing various ocean waves, are examined. The dynamic coupling between different spar motions, i.e. surge and pitch, are discussed too. Our numerical results show: the dynamic behaviors of mooring-line may significantly increase the top tension, particularly, the peak-trough tension gap of snap tension may be more than 9 times larger than the quasi-static result. When the wave frequency is much higher than the system, the dynamic effects of the mooring system will accelerate the decay of transient items of the dynamic response; when the wave frequency and the system frequency are close to each other, the displacement of the spar significantly reduces by around 26%. Under regular wave condition, the coupling between the surge and pitch motions are not obvious; but under extreme condition, pitch motion may get about 20% smaller than that without consideration of the coupling between the surge and pitch motions.

Nonlinear dynamic behaviors of a rotor-labyrinth seal system

2006 ◽  
Vol 47 (4) ◽  
pp. 321-329 ◽  
Author(s):  
Songtao Li ◽  
Qingyu Xu ◽  
Xiaolong Zhang
Keyword(s):  
Nonlinear Dynamic ◽  
Labyrinth Seal ◽  
Dynamic Behaviors

Stick-Slip Compensation of Micro-Positioning Using Elastic-Plastic Static Friction Model

2008 ◽  
Vol 47-50 ◽  
pp. 246-249
Author(s):  
Min Gyu Jang ◽  
Chul Hee Lee ◽  
Seung Bok Choi
Keyword(s):  
Static Friction ◽  
Friction Model ◽  
Smart Structure ◽  
Asperity Contact ◽  
Stick Slip ◽  
Elastic Plastic ◽  
Highly Nonlinear ◽  
Bridge Type ◽  
Structural Parts ◽  
Rough Surface Contact

In this paper, a stick-slip compensation for the micro-positioning is presented using the statistical rough surface contact model. As for the micro-positioning structure, PZT (lead(Pb) zirconia(Zr) Titanate(Ti)) actuator is used to drive the load for precise positioning with its high resolution incorporating with the PID (Proportional Integral Derivative) control algorithm. Since the stick-slip characteristics for the micro structures are highly nonlinear and complicated, it is necessary to incorporate more detailed stick-slip model for the applications involving the high precision motion control. Thus, the elastic-plastic static friction model is used for the stick-slip compensation considering the elastic-plastic asperity contact in the rough surfaces statistically. Mathematical model of the system for the positioning apparatus was derived from the dynamic behaviors of structural parts. Since the conventional piezoelectric actuator generates the short stroke, a bridge-type flexural hinge mechanism is introduced to amplify the linear motion range. Using the proposed smart structure, simulations under the representative positioning motion were conducted to demonstrate the micro-positioning under the stick-slip friction.

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