Finite Element Modeling of a Highly Flexible Rotating Beam for Active Vibration Suppression With Piezoelectric Actuators

2007 ◽  
Author(s):  
Gabriele Gilardi ◽  
Bradley J. Buckham ◽  
Edward J. Park
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Vibration Suppression ◽  
Piezoelectric Actuators ◽  
Element Model ◽  
Flexible Beam ◽  
Lumped Mass ◽  
Time Step ◽  
Loop Control ◽  
Weighted Residuals

In this paper a new finite element model (FEM) is introduced for the analysis of a highly flexible beam undergoing large deformations due to fast slewing. The finite element model uses a novel absolute nodal coordinate formulation (ANCF) that employs a third order twisted cubic spline geometry. Galerkin’s method of weighted residuals is applied to discretize equations of motion derived for the beam continuum. The model exploits a synergy between the twisted spline geometry and the lumped mass approximation to halve the size of the matrix equations that must be solved on each time step. In the simulation of fast slewing maneuvers, a very slender beam is considered and the elastic deformations experienced are an order of magnitude larger than cases considered to date. Closed-loop control simulation results, using PD feedback for both hub and piezoelectric actuator control, show that the proposed schemes are effective in suppressing very large vibrations. These results show the potential of the proposed FEM as an effective design and simulation tool for analyzing a highly flexible beam undergoing fast slewing, and for synthesizing vibration controllers for piezoelectric actuators.

A SPECTRAL/hp NONLINEAR FINITE ELEMENT ANALYSIS OF HIGHER-ORDER BEAM THEORY WITH VISCOELASTICITY

2012 ◽  
Vol 04 (01) ◽  
pp. 1250010 ◽  
Author(s):  
V. P. VALLALA ◽  
G. S. PAYETTE ◽  
J. N. REDDY
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Virtual Work ◽  
Constitutive Relations ◽  
Beam Theory ◽  
Element Model ◽  
Higher Order ◽  
Time Step ◽  
Third Order ◽  
The Third

In this paper, a finite element model for efficient nonlinear analysis of the mechanical response of viscoelastic beams is presented. The principle of virtual work is utilized in conjunction with the third-order beam theory to develop displacement-based, weak-form Galerkin finite element model for both quasi-static and fully-transient analysis. The displacement field is assumed such that the third-order beam theory admits C0 Lagrange interpolation of all dependent variables and the constitutive equation can be that of an isotropic material. Also, higher-order interpolation functions of spectral/hp type are employed to efficiently eliminate numerical locking. The mechanical properties are considered to be linear viscoelastic while the beam may undergo von Kármán nonlinear geometric deformations. The constitutive equations are modeled using Prony exponential series with general n-parameter Kelvin chain as its mechanical analogy for quasi-static cases and a simple two-element Maxwell model for dynamic cases. The fully discretized finite element equations are obtained by approximating the convolution integrals from the viscous part of the constitutive relations using a trapezoidal rule. A two-point recurrence scheme is developed that uses the approximation of relaxation moduli with Prony series. This necessitates the data storage for only the last time step and not for the entire deformation history.

A Comparative Study of the Human Body Finite Element Model Under Blast Loadings

2012 ◽  
Author(s):  
X. G. Tan ◽  
R. Kannan ◽  
Andrzej J. Przekwas
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Human Body ◽  
Material Properties ◽  
Complex Geometry ◽  
Blast Loading ◽  
Element Model ◽  
Stress Wave Propagation ◽  
Brain Response ◽  
Time Step

Until today the modeling of human body biomechanics poses many great challenges because of the complex geometry and the substantial heterogeneity of human body. We developed a detailed human body finite element model in which the human body is represented realistically in both the geometry and the material properties. The model includes the detailed head (face, skull, brain, and spinal cord), the skeleton, and air cavities (including the lung). Hence it can be used to accurately acquire the stress wave propagation in the human body under various loading conditions. The blast loading on the human surface was generated from the simulated C4 blast explosions, via a novel combination of 1-D and 3-D numerical formulations. We used the explicit finite element solver in the multi-physics code CoBi for the human body biomechanics. This is capable of solving the resulting large system containing millions of unknowns in an extremely scalable fashion. The meshes generated for these simulations are of good quality. This enables us to employ relatively large time step sizes, without resorting to the artificial time scaling treatment. In order to study the human body dynamic response under the blast loading, we also developed an interface to apply the blast pressure loading on the external human body surface. These newly developed models were used to conduct parametric simulations to find out the brain biomechanical response when the blasts impact the human body. Under the same blast loading we also show the differences of brain response when having different material properties for the skeleton, the existence of other body parts such as torso.

Modeling and Analyzing of Vibration in Working Crankshaft with Cracks

2005 ◽  
Vol 293-294 ◽  
pp. 401-408
Author(s):  
Xuan Yang Lei ◽  
Gui Cai Zhang ◽  
Xi Geng Song ◽  
Jin Chen ◽  
Guang Ming Dong
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
The Other ◽  
Lumped Mass ◽  
Beam Elements ◽  
System A ◽  
Nonlinear Motion ◽  
Simplified Finite Element Model ◽  
Bearing System

In this paper, a simplified finite element model of the cracked crankshaft is proposed, and a new method for simulating the nonlinear vibration of operating crankshaft with several cracks is presented. For crankshaft, cracks occur frequently in the parts of crankpin-web fillet region and the edge of oil aperture because of fatigue or damage. According to the characteristic of those cracks, the cracked parts are modeled by the corresponding cracked spatial finite elements respectively, and two cracked elements are discussed in this study. The other, un-cracked, crankshaft parts are modeled by spatial Timoshenko beam elements. Flywheel and front pulley are simplified as lumped mass elements, and main bearings are simulated by equivalent linear springs and dashpots. In order to find the dynamic response of crankshaft-bearing system, a right-handed rotating coordinate system attached to crankshaft is applied. Based on the proposed finite element model, the breathing behavior of cracks in operating crankshaft is studied, and the nonlinear motion equation with variational stiffness is formed. Finally, a four-in-line crankshaft is taken as an example, and its vibration response corresponding to different kinds of crack are calculated and analyzed. Some conclusions are drawn, and a foundation is laid for diagnosing crack fault of crankshaft.

scholarly journals Finite Element Modellingand Simulations of Piezoelectric Actuators Responses with Uncertainty Quantification

Computation ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 60 ◽  
Author(s):  
Vinh-Tan Nguyen ◽  
Pankaj Kumar ◽  
Jason Leong
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Uncertainty Quantification ◽  
Composite Plate ◽  
Piezoelectric Materials ◽  
Three Dimensional ◽  
Piezoelectric Actuators ◽  
Element Model ◽  
Design Parameters ◽  
Hexahedral Elements

Piezoelectric structures are widely used in engineering designs including sensors, actuators, and energy-harvesting devices. In this paper, we present the development of a three-dimensional finite element model for simulations of piezoelectric actuators and quantification of their responses under uncertain parameter inputs. The implementation of the finite element model is based on standard nodal approach extended for piezoelectric materials using three-dimensional tetrahedral and hexahedral elements. To account for electrical-mechanical coupling in piezoelectric materials, an additional degree of freedom for electrical potential is added to each node in those elements together with their usual mechanical displacement unknowns. The development was validated with analytical and experimental data for a range of problems from a single-layer piezoelectric beam to multiple layer beams in unimorph and bimorph arrangement. A more detailed analysis is conducted for a unimorph composite plate actuator with different design parameters. Uncertainty quantification was also performed to evaluate the sensitivity of the responses of the piezoelectric composite plate with an uncertain input of material properties. This sheds light on understanding the variations in reported responses of the device; at the same time, providing extra confidence to the numerical model.

scholarly journals Seismic Vibration Mitigation of Wind Turbine Tower Using Bi-Directional Tuned Mass Dampers

2020 ◽  
Vol 2020 ◽  
pp. 1-22
Author(s):  
Wanrun Li ◽  
Qing Zhang ◽  
Zhou Yang ◽  
Qingxin Zhu ◽  
Yongfeng Du
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Wind Turbine ◽  
Bending Moment ◽  
Element Model ◽  
Seismic Vibration ◽  
Lumped Mass ◽  
Tuned Mass Dampers ◽  
Vibration Mitigation ◽  
Wind Turbine Tower

Wind turbines have been increasingly erected in earthquake regions to harvest abundant wind energy. However, the wind turbine tower is slender and lightly damping, which exhibits high susceptibility to earthquake-induced vibration. It is challenging to mitigate the seismic vibration of the tower. In this study, a bi-directional tuned mass damper (BTMD) is proposed to mitigate the seismic vibration of the wind turbine tower. Meanwhile, a lumped-mass finite element model (LFEM) and a coupled blade tower finite element model (CBFEM) are used to investigate the vibration mitigation performance of the BTMD. First, the BTMD and corresponding dynamic equilibrium equations are systemically introduced. Accordingly, the optimum stiffness and damping of the BTMD at different mass ratios are investigated. Then, the dynamic prosperities of the LFEM and CBFEM are compared. Subsequently, the seismic responses of the wind turbine with the BTMD are conducted using the LFEM and CBFEM. Meanwhile, the mitigation performances of the BTMD under uni- and bi-directional earthquakes are investigated. The displacement, acceleration, and bending moment of the wind turbine tower are analyzed in time domain and frequency domain. Note that the influential factors, including mass ratio and structural frequency, on the vibration mitigation performance of the BTMD are investigated. Results show that the proposed BTMD can significantly mitigate the peak values of the top displacement and bottom bending moment. However, the blade tower coupling effect and frequency variation of the tower would have influences on the mitigation efficiency of the BTMD. The results enable a better understanding of the seismic vibration mitigation of the wind turbine tower using tuned mass dampers.

Detailed Finite Element Modeling of US EPR™ Nuclear Island for Seismic SSI Analysis

2010 ◽  
Author(s):  
Mansour Tabatabaie ◽  
Basilio Sumodobila ◽  
Calvin Wong ◽  
Daniel E. Fisher ◽  
J. Todd Oswald
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Response Spectra ◽  
Element Model ◽  
Lumped Mass ◽  
Standard Design ◽  
The Us ◽  
Reactor Building ◽  
Fixed Base ◽  
Stick Model

The US EPR™ standard design currently under development by AREVA consists primarily of a nuclear island (NI) and several other significant structures outside of and in close proximity to the NI. The NI structures consist of the Reactor Building (RB), Fuel Building (FB), Safeguard Building 1 (SB1), Safeguard Building 2/3 (SB2/3), Safeguard Building 4 (SB4), and Reactor Building Internal Structures (RBIS) — all of which share a common foundation basemat. The Nuclear Island is embedded approximately 11.6 m below the ground surface. Seismic soil-structure interaction (SSI) analysis of nuclear power plants is often performed in the frequency domain using a lumped-mass stick and/or coarse finite element model of the structure. These models are designed to capture the global dynamic response of the system, the results of which provide the inertia forces that are used for foundation stability assessment as well as input to a static detailed finite element model of the structure for design. The in-structure response spectra is calculated from a separate dynamic analysis of detailed structural model on fixed base excited by the base motion developed from the SSI analysis or often by including single-degree-of-freedom (SDOF) oscillators representing the local response in the stick/coarse finite element SSI models. With recent advances in computer software and hardware technologies, it is now possible to perform SSI analysis of detailed structural models in the frequency domain. This paper presents the results of the seismic SSI analysis of the US EPR™ nuclear island using both a stick and detailed finite element representation of the structure. The soil profile corresponds to a medium stiff soil case used for the standard design. Because the EPR™ nuclear island is a complex, unsymmetric structure, the stick model consists of multiple interconnected sticks developed and calibrated against a detailed finite element model of the structure on a fixed base. Both models are analyzed using SASSI [1]. The results of the detailed finite element model in terms of maximum accelerations and response spectra, as well as total interstory forces and moments, are calculated and compared with those of the lumped-mass stick model.

Analysis of Influence to Electric Spindle Losses Caused by Carrier Ratio in Frequency Converter

2012 ◽  
Vol 614-615 ◽  
pp. 1234-1239
Author(s):  
Li Xiu Zhang ◽  
Meng Yuan Xu ◽  
Yu Hou Wu
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Frequency Converter ◽  
Core Loss ◽  
Element Model ◽  
Time Step ◽  
Minimum Loss ◽  
Solid Loss

Aiming at analyzing the influence to ceramic electric spindle and metal electric spindle caused by carrier ratio in frequency converter, in this paper, the time-step finite element model was built based on SPWM method. The changing law of the loss in different carrier ratios were gained by simulation. The result shows that the greatest impact by carrier ratio is solid loss, the least is core loss. The ceramic electric spindle is less impact by carrier ratio than metal electric spindle. Additionally, the corresponding carrier ratio with minimum loss in both ceramic electric spindle and metal electric spindle were found.

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