Study on the collapse of tapered tubes subjected to oblique loads

2008 ◽  
Vol 222 (11) ◽  
pp. 2025-2039 ◽  
Author(s):  
P Hosseini-Tehrani ◽  
S Pirmohammad ◽  
M Golmohammadi
Keyword(s):  
Finite Element ◽  
Cross Section ◽  
Numerical Models ◽  
Point Of View ◽  
Finite Element Code ◽  
Energy Absorber ◽  
Explicit Finite Element ◽  
Bending Deformation ◽  
Oblique Loading

In this work, several antisymmetric tapered tubes with an inner stiffener under axial and oblique loading are studied and optimum dimensions of the tapered tube are derived from a crashworthiness point of view. The importance of detecting these dimensions is optimizing the weight while the crashworthiness of tube is not damaged. By using an internal stiffener, crashworthiness is improved against oblique loads, and the sensitivity of tubes with respect to oblique loads and bending deformation is diminished. The numerical models have been developed using the explicit finite element code LS-DYNA. The crashworthiness of the optimized tapered tube is compared with that of an octagonal-cross-section tube which is known as the best energy absorber model in the literature. It is shown that an optimized tapered tube has an average of 29.3 per cent less crushing displacement in comparison with octagonal-section tube when both tubes have the same weights and the same peaks of crushing load. Finally, the orientation of loading is changed and the best orientation is proposed.

Free Warping Analysis and Numerical Implementation

2016 ◽  
Vol 825 ◽  
pp. 141-148 ◽  
Author(s):  
Karel Mikeš ◽  
Milan Jirásek
Keyword(s):  
Finite Element ◽  
Cross Section ◽  
Laplace Equation ◽  
Solution Algorithm ◽  
Point Of View ◽  
Warping Function ◽  
Numerical Implementation ◽  
Finite Element Code ◽  
The Finite Element Method ◽  
Cross Sectional

This article deals with the mathematical description and numerical implementation of the free warping problem. The solution of the warping problem is given by a warping function obtained by solving the Laplace equation with a corresponding boundary condition. An analytical solution is available only for a limited number of specific cross-sectional shapes such as ellipse or rectangle. For the solution of a general cross section, the Laplace equation must be solved numerically by the finite element method. From a mathematical point of view, the free warping problem can be described in the same way as the heat transfer phenomena, but in the numerical implementation, there are several features specific to warping analysis.The solution algorithm has been implemented in the OOFEM open-source finite element code [1] and verification has been done on several examples with known analytical solutions.

Modeling the Dynamic Frictional Contact of Tires Using an Explicit Finite Element Code

2005 ◽  
Author(s):  
Tamer M. Wasfy ◽  
Michael J. Leamy
Keyword(s):  
Finite Element ◽  
Frictional Contact ◽  
Time Integration ◽  
Friction Model ◽  
Finite Element Code ◽  
Normal Contact ◽  
Explicit Finite Element ◽  
Beam Elements ◽  
Coulomb Friction Model ◽  
Stiffness And Damping

A time-accurate explicit time-integration finite element code is used to simulate the dynamic response of tires including tire/pavement and tire/rim frictional contact. Eight-node brick elements, which do not exhibit locking or spurious modes, are used to model the tire’s rubber. Those elements enable use of one element through the thickness for modeling the tire. The bead, tread and ply are modeled using truss or beam elements along the tire circumference and meridian directions with appropriate stiffness and damping properties. The tire wheel is modeled as a rigid cylinder. Normal contact between the tire and the wheel and between the tire and the pavement is modeled using the penalty technique. Friction is modeled using an asperity-based approximate Coulomb friction model.

Development of a Nonlinear, C1-Beam Finite-Element Code for Actuator Design of Slender Flexible Robots

2017 ◽  
Author(s):  
Hidenori Murakami ◽  
Oscar Rios ◽  
Takeyuki Ono
Keyword(s):  
Finite Element ◽  
Large Deformation ◽  
Cross Section ◽  
Beam Model ◽  
Finite Element Code ◽  
Shape Functions ◽  
Lagrange Equations ◽  
Element Discretization ◽  
Flexible Robots ◽  
Actuator Design

For actuator design and motion simulations of slender flexible robots, planar C1-beam elements are developed for Reissner’s large deformation, shear-deformable, curbed-beam model. Internal actuation is mechanically modeled by a rate-form of beam constitutive relation, where actuation curvature is prescribed at each time. Geometrically, a curbed beam is modeled as a frame bundle, whereby at each point on beam’s curve of centroids a moving orthonormal frame is attached to a cross section. After a finite element discretization, a curve of centroids is modeled as a C1-curve, employing cubic shape functions for both planar coordinates with an arc-parameter. The cubic shape functions have already been utilized in linear Euler-Bernoulli beams for the interpolation of transverse displacement. To define the rotation angle of each cross section or the attitude of the moving frame, quadratic shape functions are used introducing a middle node, resulting in three angular nodal displacements. As a result, each beam element has total eleven nodal coordinates. The implementation of a nonlinear finite element code is facilitated by the principle of virtual work, which yields Reissner’s large deformation curbed beam model as the Euler-Lagrange equations. For time integration, the Newmark method is utilized. Finally, as applications of the code, a few inchworm motions induced by different actuation curvature fields are presented.

Collapse study of thin-walled polygonal section columns subjected to oblique loads

2007 ◽  
Vol 221 (7) ◽  
pp. 801-810 ◽  
Author(s):  
P Hosseini-Tehrani ◽  
S Pirmohammad
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Rigid Wall ◽  
Point Of View ◽  
Explicit Finite Element ◽  
Thin Walled ◽  
Oblique Load ◽  
Crash Behaviour ◽  
Vehicle Crashworthiness ◽  
Load Conditions

The present paper deals with the collapse simulation of aluminium alloy extruded polygonal section columns subjected to oblique loads. Oblique load conditions in numerical simulations are applied by means of impacting a declined rigid wall on the tubes with no friction in this task. The explicit finite element code LS-DYNA is used to simulate the crash behaviour of polygonal section columns that are undergoing both axial and bending collapse situations. In order to validate LS-DYNA results the collapse procedure of square columns is successfully simulated and the obtained numerical results are compared with actual available experimental data. Mean crush loads and permanent displacements corresponding to load angles have been investigated, considering columns with square, hexagonal, octagonal, decagonal, and circular cross-sections. It is shown that the octagonal cross-section has better characteristics from the point of view of vehicle crashworthiness under oblique load conditions.

Prediction of System Natural Frequencies Using an Explicit Finite Element Code With Application to Belt-Drives

2004 ◽  
Author(s):  
Tamer Wasfy ◽  
Michael Leamy ◽  
Rick J. Meckstroth
Keyword(s):  
Finite Element ◽  
Multibody Systems ◽  
Natural Frequencies ◽  
System Response ◽  
Finite Element Code ◽  
Frequency Range ◽  
Harmonic Force ◽  
Explicit Finite Element ◽  
Belt Drives ◽  
Time Histories

A time-accurate explicit finite element code is used to predict the natural frequencies of a typical class of flexible multibody systems — automotive accessory belt-drives. The system considered consists of a belt, two pulleys, and a tensioner. Two techniques are used to find the system natural frequencies: (a) applying a sharp impulse to the system and extracting the system natural frequencies from the resulting displacement/strain time-histories via an FFT; and (b) applying a harmonic force to the system and sweeping through a frequency range, while at the same time, monitoring for large system response. In the present paper a comparison between these two techniques is presented for a typical accessory drive. Also, recommendations are offered on how to best use each technique to efficiently extract the system’s natural frequencies.

Airbag Tire Modeling by the Explicit Finite Element Method

1997 ◽  
Vol 25 (4) ◽  
pp. 288-300 ◽  
Author(s):  
S. R. Wu ◽  
L. Gu ◽  
H. Chen
Keyword(s):  
Finite Element ◽  
Computational Procedure ◽  
Ford Motor Company ◽  
Feasibility Trial ◽  
Closed Volume ◽  
Finite Element Code ◽  
Explicit Finite Element ◽  
Shell Elements ◽  
Concept Model ◽  
Tire Modeling

Abstract An explicit finite element code FCRASH has been applied to both static and dynamic tire modeling. The computational procedure for predicting tire loads has been investigated. The typical tire model used in the simulation consists of a tire and rim. The tire is defined by membrane elements and the rim by rigid body with shell elements. The tire and rim form a closed volume. The airbag functionality in FCRASH, an explicit finite element code developed by Ford Motor Company, has been employed to simulate the test and to monitor the pressure and volume changes in the tire. Three static tire models (Taurus spare tire, P145/75R12, and P225/60R16) have been studied and the force-deflection curves are compared with test data. All of them exhibit a very good agreement. The standard spindle test for the P145/75R12 tire at three different speeds (10, 20, and 30 mph) is also simulated. The prediction of vertical and horizontal forces at 30 mph shows an excellent agreement with the test. The results for 20 and 10 mph are also reasonably good. The simulations for complex road conditions and full vehicle over bumps with a concept model are also performed as a feasibility trial. The CPU time used in both HP735 and CRAY computers for all these cases are comparable with other major CAE jobs. The experiments show that the explicit finite element code has a lot of advantages and strong potential to perform durability road load analysis with affordable computer costs.

A Bodner Type of Material Model for the Description of Foam Properties

2001 ◽  
Author(s):  
Yuzhao Song ◽  
Ziqi Chen
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Automobile Industry ◽  
Material Model ◽  
Finite Element Code ◽  
Foam Material ◽  
Element Analysis ◽  
Explicit Finite Element ◽  
Compression Strain ◽  
Foam Properties

Abstract A unified constitutive equation has been used to represent Foam material. It can describe the large compression strain, compression strain rate, tension strain and the bottom out behavior of various foams. The material has been incorporated into LS-DYNA, an explicit finite element code widely used in the automobile industry. An example is given to show an application of the material model in a low speed impact finite element analysis.

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