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.

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.

scholarly journals Application of the erosion algorithm in modeling of structures behavior under impulse loads

2019 ◽  
Vol 221 ◽  
pp. 01003
Author(s):  
Pavel Radchenko ◽  
Stanislav Batuev ◽  
Andrey Radchenko
Keyword(s):  
Finite Element ◽  
High Velocity ◽  
Three Dimensional ◽  
Computer Software ◽  
Dynamic Loads ◽  
Complex Structures ◽  
Numerical Studies ◽  
Contact Surfaces ◽  
Fracture Of Materials ◽  
Solid Bodies

The paper presents results of applying approach to simulation of contact surfaces fracture under high velocity interaction of solid bodies. The algorithm of erosion -the algorithm of elements removing, of new surface building and of mass distribution after elements fracture at contact boundaries is consider. The results of coordinated experimental and numerical studies of fracture of materials under impact are given. Authors own finite element computer software program EFES, allowing to simulate a three-dimensional setting behavior of complex structures under dynamic loads, has been used for the calculations.

An Exact Three-Dimensional Beam Element With Nonuniform Cross Section

2010 ◽  
Vol 77 (6) ◽  
Author(s):  
M. Jafari ◽  
M. J. Mahjoob
Keyword(s):  
Cross Section ◽  
Stiffness Matrix ◽  
Degrees Of Freedom ◽  
Direct Method ◽  
Three Dimensional ◽  
Curved Beams ◽  
Element Analysis ◽  
Shear Loads ◽  
Line Passing ◽  
Exact Stiffness Matrix

In this paper, the exact stiffness matrix of curved beams with nonuniform cross section is derived using direct method. The considered element has two nodes and 12 degrees of freedom, with three forces and three moments applied at each node. The noncoincidence effect of shear center and center of area is also considered in this element. The deformations of the beam are due to bending, torsion, tensile, and shear loads. The line passing through center of area is a general three-dimensional curve and the cross section properties may change arbitrarily along it. The method is extended to deal with distributed loads on the curved beams. The stiffness matrix of some selected types of beams is determined by this method. The results are compared (where possible) with previously published results, simple beam finite element analysis and analytic solution. It is shown that the determined stiffness matrix is exact and that any type of beam can be analyzed by this method.

Prediction of Blade Flutter in a Tuned Rotor

1985 ◽  
Author(s):  
Jianmin Xu ◽  
Zhaohong Song
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Rotating Blades ◽  
Multiple Degrees Of Freedom ◽  
Strip Theory ◽  
Blade Flutter ◽  
Good Agreement

This paper is about blade flutter in a tuned rotor. With the aid of the combination of three dimensional structural finite element method, two dimensional aerodynamical finite difference method and strip theory, the quasi-steady models in which two degrees of freedom for a single wing were considered have been extended to multiple degrees of freedom for the whole blade in a tuned rotor. The eigenvalues solved from the blade motion equation have been used to judge whether the system is stable or not. The calculating procedure has been formed and using it the first stage rotating blades of a compressor where flutter had occurred, have been predicted. The numerical flutter boundaries have good agreement with the experimental ones.

Beam Element Structural Dynamics Modification Using Experimental Modal Rotational Data

1995 ◽  
Vol 117 (3A) ◽  
pp. 265-271 ◽  
Author(s):  
John A. Cafeo ◽  
Martin W. Trethewey ◽  
H. Joseph Sommer
Keyword(s):  
Finite Element ◽  
Cantilever Beam ◽  
Degrees Of Freedom ◽  
Element Model ◽  
Structural Dynamic ◽  
Modal Data ◽  
Structural Dynamic Modification ◽  
Dynamic Modification ◽  
Rotational Degrees Of Freedom ◽  
Fixed Beam

Structural dynamic modification (SDM) of a fixed-free (cantilever) beam to convert it into a fixed-fixed beam with experimental modal data is presented. The SDM focuses on incorporating experimental rotational degrees-of-freedom (DOF) measured with a novel laser measurement technique. A cantilever beam is tested to develop the experimental modal database including rotational degrees of freedom. A modal database from a finite-element model also is developed for comparison. A structural dynamic modification, with both databases, is performed using a Bernoulli-Euler beam to ground the free end of the cantilever beam. The hardware is then modified and a second experimental modal analysis of the resulting fixed-fixed beam performed. A finite-element model of the fixed-fixed beam also was created. Comparison of results from these four tests are used to assess the effectiveness of SDM using experimental modal rotational data. The evaluation shows that provided high quality experimental rotational modal data can be acquired, SDM work with beam elements can be effective in yielding accurate results.

Shape Memory Alloys: Material Modeling and Device Finite Element Simulations

2008 ◽  
Vol 583 ◽  
pp. 257-275 ◽  
Author(s):  
Ferdinando Auricchio ◽  
Alessandro Reali
Keyword(s):  
Finite Element ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Biomedical Engineering ◽  
Three Dimensional ◽  
Material Modeling ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Simulation Tools ◽  
Numerical Studies

The use of shape memory alloys (SMA) in an increasing number of applications in many ¯elds of engineering, such as biomedical engineering, is leading to a growing interest toward an exhaustive modeling of their macroscopic behavior in order to construct reliable simulation tools for SMA devices. In this paper we review a robust three-dimensional model able to reproduce both pseudo-elastic and shape-memory behaviors and we report numerical studies where it is used for the simulation of SMA-based biomedical devices.

A Complaint Mechanism with Freedom Degrees of One Movement and Two Rotations

2014 ◽  
Vol 551 ◽  
pp. 444-447
Author(s):  
Sheng Lin ◽  
Xi Kong ◽  
Chun Wang
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Finite Element Model ◽  
Stiffness Matrix ◽  
Degrees Of Freedom ◽  
Compliant Mechanism ◽  
Element Model ◽  
Theory Analysis ◽  
The Finite Element Model

Based on the method of Freedom and Constraint Topology (FACT), a compliant mechanism with 3 degrees of freedom is designed. The 3 DOF are one movement and two rotations, which belongs to Case 3, Type 2. The whole stiffness matrix of the compliant mechanism is obtained. The finite element model is established for statics analysis. The results of theory analysis and finite element method are closed.

Sign in / Sign up

Export Citation Format

Share Document