Non-Iterative Mode Shape Expansion for Beam Structures Based on Coordinate Decomposition

2013 ◽  
Vol 284-287 ◽  
pp. 503-507
Author(s):  
Fu Shun Liu ◽  
Wen Wen Chen ◽  
Chun Fu Peng ◽  
Wei Li
Keyword(s):  
Finite Element ◽  
Mode Shape ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Expansion Method ◽  
Element Model ◽  
Numerical Studies ◽  
Order Of Magnitude ◽  
Convergence Performance ◽  
Weighting Coefficients

The direct mode shape expansion method is an iterative technique, then one can conclude that the convergence performance maybe challenged when applied to three-dimensional structures. In addition, mode shape values at different DOFs (degrees-of-freedom) sometimes are not in a same order of magnitude, which will produce much error for the estimation of small values of unmeasured mode components. Thus, this paper proposed a non-iterative mode shape expansion method based on coordinate decomposition and neglecting modelling errors between the finite element model and the experimental structure. The advantage of coordinate decomposition is that the unmeasured components of mode shape values could be estimated with different weighting coefficients, even in a physical meaningful interval. Numerical studies in this paper are conducted for a 30-DOF (degree-of-freedom) cantilever beam with multiple damaged elements, as the measured modes are synthesized from finite element models. The results show that the approach can estimate unmeasured mode shape values at translational and rotational DOFs in x, y and z directions with different weighting coefficients, respectively; and better mode shape expansion results can be obtained when proper constraints are employed.

A Four-Node Tetrahedral Finite Element Based on Space Fiber Rotation Concept

2019 ◽  
Vol 11 (1) ◽  
pp. 67-78
Author(s):  
Kamel Meftah ◽  
Lakhdar Sedira
Keyword(s):  
Finite Element ◽  
Strain Field ◽  
Stiffness Matrix ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Field Tensor ◽  
Tetrahedral Element ◽  
Numerical Studies ◽  
Rotational Degrees Of Freedom ◽  
Tensor Approximation

Abstract The paper presents a four-node tetrahedral solid finite element SFR4 with rotational degrees of freedom (DOFs) based on the Space Fiber Rotation (SFR) concept for modeling three-dimensional solid structures. This SFR concept is based on the idea that a 3D virtual fiber, after a spatial rotation, introduces an enhancement of the strain field tensor approximation. Full numerical integration is used to evaluate the element stiffness matrix. To demonstrate the efficiency and accuracy of the developed four-node tetrahedron solid element and to compare its performance with the classical four-node tetrahedral element, extensive numerical studies are presented.

Modal Analysis Method for Blisks Based on Three-Dimensional Blade and Two-Dimensional Axisymmetric Disk Finite Element Model

2016 ◽  
Vol 139 (5) ◽  
Author(s):  
Wangbai Pan ◽  
Guoan Tang ◽  
Meiyan Zhang
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Modal Analysis ◽  
Degrees Of Freedom ◽  
Mechanical Energy ◽  
Three Dimensional ◽  
Element Model ◽  
Computational Time ◽  
Engineering Practice ◽  
Analysis Method

In this paper, a novel and efficient modal analysis method is raised to work on blisk structures based on mixed-dimension finite element model (MDFEM). The blade and the disk are modeled separately. The blade model is figured by 3D solid elements considering its complex configuration and its degrees-of-freedom (DOFs) are condensed by dynamic substructural method. Meanwhile, the disk is structured by 2D axisymmetric element developed specially in this paper. The DOFs of entire blisk are tremendously reduced by this modeling approach. The key idea of this method is derivation of displacement compatibility to different dimensional models. Mechanical energy equivalence and summation further contribute to the model synthesis and modal analysis of blade and disk. This method has been successfully applied on the modal analysis of blisk structures in turbine, which reveals its effectiveness and proves that this method reduces the computational time expenses while maintaining the precision performances of full 3D model. Though there is limitation that structure should have proper coverage of blades, this method is still feasible for most blisks in engineering practice.

Development and numerical validation of a finite element model of the muscle standardized femur

2003 ◽  
Vol 217 (3) ◽  
pp. 165-172 ◽  
Author(s):  
K Polgar ◽  
H S Gill ◽  
M Viceconti ◽  
D W Murray ◽  
J J O'Connor
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Element Model ◽  
Data Sets ◽  
Fe Model ◽  
Fe Method ◽  
Human Femur ◽  
Numerical Studies ◽  
Physiological Loading ◽  
Physiological Load

The human femur is one of the parts of the musculo-skeletal system most frequently analysed by means of the finite element (FE) method. Most FE studies of the human femur are based on computed tomography data sets of a particular femur. Since the geometry of the chosen sample anatomy influences the computed results, direct comparison across various models is often difficult or impossible. The aim of the present work was to develop and validate a novel three-dimensional FE model of the human femur based on the muscle standardized femur (MuscleSF) geometry. In the new MuscleSF FE model, the femoral attachment of each muscle was meshed separately on the external bone surface. The model was tested under simple load configurations and the results showed good agreement with the converged solution of a former study. In the future, using the validated MuscleSF FE model for numerical studies of the human femur will provide the following benefits: (a) the numerical accuracy of the model is known; (b) muscle attachment areas are incorporated in the model, therefore physiological loading conditions can be easily defined; (c) analyses of the femur under physiological load cases will be replicable; (d) results based on different load configurations could be compared across various studies.

Performance Enhancement of Three-Dimensional Soil Structure Model via Optimization for Estimating Seismic Behavior of Buried Pipelines

2017 ◽  
Vol 11 (05) ◽  
pp. 1750019 ◽  
Author(s):  
Tsuyoshi Ichimura ◽  
Kohei Fujita ◽  
Atsushi Yoshiyuki ◽  
Pher Errol Quinay ◽  
Muneo Hori ◽  
...  
Keyword(s):  
Finite Element ◽  
Degrees Of Freedom ◽  
Performance Enhancement ◽  
Three Dimensional ◽  
Element Model ◽  
Optimization Method ◽  
Buried Pipelines ◽  
Ground Structure ◽  
3D Finite Element ◽  
Ground Structures

Damage to buried pipelines due to complex ground responses has been reported at residential development sites and valley plains with complex ground structures. Three-dimensional (3D) ground amplification analyses using 3D, nonlinear, finite-element methods may be effective in predicting such damage; however, it is often difficult to construct ground structures that are capable of reproducing observational characteristics. In this paper, we propose a 3D ground structure optimization method using a 3000[Formula: see text] forward finite-element dynamic analysis with approximately 0.27 million degrees of freedom, enabled by combining an automated 3D finite-element model-generation method and a fast 3D finite-element wave propagation analysis method. This optimization method is capable of estimating 3D ground structure models that can reproduce observational data characteristics. The effectiveness of the method is shown through an illustrative example.

Space Rigid Frame Damage Identification Based on Finite Element Method and Experiment

2013 ◽  
Vol 405-408 ◽  
pp. 929-932
Author(s):  
Hong Yu Jia ◽  
Peng Fei Yue ◽  
Zhi Hua Fang
Keyword(s):  
Finite Element ◽  
Mode Shape ◽  
Damage Identification ◽  
Three Dimensional ◽  
Element Model ◽  
Three Dimension ◽  
Axial Mode ◽  
Shape Difference ◽  
Rigid Frame ◽  
The Finite Element Model

The finite element model of space rigid frame with no damage and damage were established by ANSYS and the physical model experiment was carried out. The damage identification methods include that variety rate of three-dimensional vibration mode, curvature mode, strain energy of element mode and axial mode shape difference. Consider identify result and measurement cost that the axial mode shape difference is a good label amount for three-dimension damage identification by vibration method and the single damage and combination damage could identified, which it was proved by the experiment result.

Nonlinear Analysis of Twisted Wind Turbine Blade

2016 ◽  
Vol 34 (3) ◽  
pp. 269-278 ◽  
Author(s):  
M. Yangui ◽  
S. Bouaziz ◽  
M. Taktak ◽  
M. Haddar ◽  
A. El-Sabbagh
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Degrees Of Freedom ◽  
Rotation Speed ◽  
Three Dimensional ◽  
Nonlinear Problems ◽  
Shell Element ◽  
Element Model ◽  
Angular Rotation ◽  
Triangular Shell Element

AbstractModal analysis is developed in this paper in order to study the dynamic characteristics of rotating segmented blades assembled with spar. Accordingly, a three dimensional finite element model was built using the three node triangular shell element DKT18, which has six degrees of freedom, to model the blade and the spar structures. This study covers the effect of rotation speed and geometrically nonlinear problems on the vibration characteristics of rotating blade with various pretwist angles. Likewise, the effect of the spar in the blade is taken into consideration. The equation of motion for the finite element model is derived by using Hamilton's principle, while the resulting nonlinear equilibrium equation is solved by applying the Newmark method combined with the Newton Raphson schema. Results show that the natural frequencies increase by taking account of the spar, they are also proportional to the angular rotation speed and influenced by geometric nonlinearity and pretwist angle.

Radial Truck Tire Inflation Analysis: Theory and Experiment

1981 ◽  
Vol 54 (4) ◽  
pp. 751-766 ◽  
Author(s):  
R. H. Kennedy ◽  
H. P. Patel ◽  
M. S. McMinn
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Element Model ◽  
Solution Procedure ◽  
Truck Tire ◽  
Truck Tires ◽  
Tube Type ◽  
The Finite Element Model

Abstract The finite element method is a useful tool in the design process to give deformations, strains and stresses in tires when they are loaded. To show this, a geometrically nonlinear, materially homogeneous, and generally orthotropic finite element model is described and used in the inflation analysis of radial truck tires. The element, a linear strain axisymmetric triangle, has three displacement degrees of freedom at each node in order to correctly model the three-dimensional states of strain and stress present in generally orthotropic structures. Two radial truck tires, a tube-type 10.00R20 and a tubeless 11R22.5, are analyzed both experimentally and analytically for inflation loading. Experimentally, cord forces are measured by cord force transducers, belt edge interply shear strain is measured by a pin rotation technique, sidewall growth is measured by a laser profilometer, and sidewall strains are measured with liquid metal strain gages. These values are compared with those predicted by the finite element model. The model works well for the tube-type 10.00R20 tire and above the mid-sidewall of the tubeless 11R22.5 tire. Further work needs to be done on the lower sidewall and bead area portions of the 11R22.5 tire model. The finite element model and solution procedure for the 11R22.5 radial truck tire is used for trend predictions. Several tire construction features, belt bias angle, belt end count, body ply end count, and bell skim stock modulus are varied, and their effect on inflation growth, strains and cord forces are predicted. The largest effect on inflation behavior was variation of the belt bias angle. The other features had minor effects. These predicted trends are important in giving the design engineer direction in creating new tire types or modifying current designs.

Substructural Damage Detection With Incomplete Information of the Structure

2012 ◽  
Vol 79 (4) ◽  
Author(s):  
J. Li ◽  
S. S. Law
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Degrees Of Freedom ◽  
Damage Identification ◽  
Model Updating ◽  
Three Dimensional ◽  
Measurement Data ◽  
Impulse Response Function ◽  
Element Model ◽  
Reconstruction Technique

This paper proposes a substructural damage identification approach without the information of responses and forces at the interface degrees-of-freedom. It is based on the response reconstruction technique using the unit impulse response function in the wavelet domain. The finite element model of the target substructure and acceleration measurement data from the damaged substructure are required in the identification. A dynamic response sensitivity-based method is used for the substructural finite element model updating, and local damage is identified as a change in the elemental stiffness factors. The adaptive Tikhonov regularization technique is adopted to improve the identification results with the measurement noise effect. Numerical studies on a three-dimensional box-section girder are conducted to validate the proposed method of substructural damage identification. The simulated damage can be identified effectively even with 10% noise in the measurements and a 5% coefficient of variation in the elastic modulus of material of the structure.

Computerized Three-Dimensional Finite Element Reconstruction of the Left Ventricle from Cross-Sectional Echocardiograms

1984 ◽  
Vol 6 (1) ◽  
pp. 48-59 ◽  
Author(s):  
P. E. Nikravesh ◽  
D. J. Skorton ◽  
K. B. Chandran ◽  
Y. M. Attarwala ◽  
N. Pandian ◽  
...  
Keyword(s):  
Finite Element ◽  
Left Ventricle ◽  
Finite Element Model ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Element Model ◽  
Left Ventricular Geometry ◽  
Six Degrees Of Freedom ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

A computerized method for the generation of a three-dimensional finite element mesh of left ventricular geometry is presented. The technique employs two dimensional echocardiographic images of the left ventricle. The echocardiographic transducer is attached to an articulated, computerassisted, position registration arm with six degrees-of-freedom. These six degrees-of-freedom record the location and orientation of the transducer, when images are obtained, referenced to an external point. Eence, the images are digitized and aligned relative to one another, then several interpolation and curve fitting steps are used to reconstruct a threedimensional finite element model of the left ventricle. The finite element model can be used for volume determination, stress analysis, material property identification, and other applications.

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