Analysis of dynamic behaviour of low vibration track under wheel load drop by a finite element method algorithm

2008 ◽  
Vol 222 (2) ◽  
pp. 217-223 ◽  
Author(s):  
J-Y Zhu
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Field Experiments ◽  
Dynamic Behaviour ◽  
Dynamic Properties ◽  
Numerical Procedure ◽  
Railway Track ◽  
Load Drop ◽  
Wheel Load ◽  
Element Method

According to finite-element method (FEM) analytical solution (based on penalty algorithm) and the control equations of wheel—rail contact (developed from point-to-surface contact elements), the vibration responses were simulated for the two alternative railway track structures impacted by a falling wheel-set. The dynamic behaviour of low vibration track (LVT) is investigated based on this numerical method, which is verified by the field experiments. The results show that, when compared with the conventional short sleeper buried track (SSBT), the LVT is more beneficial for the reduction of track structure vibration levels — thanks to its properly matched stiffness under rail and block. Furthermore, it is demonstrated that the proposed wheel-load-drop FEM numerical procedure and field experiment can effectively and economically study the dynamic properties of track structures.

scholarly journals Influence of Retardation Time on Viscoelastic Behavior of Plane Beams Modeled by the Nonlinear Positional Formulation of the Finite Element Method

2021 ◽  
Vol 2021 ◽  
pp. 1-22
Author(s):  
Juliano dos Santos Becho ◽  
Marcelo Greco
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Rheological Model ◽  
Iterative Process ◽  
Numerical Procedure ◽  
Viscoelastic Behavior ◽  
Retardation Time ◽  
The Finite Element Method ◽  
Divergence Problem ◽  
Element Method

A numerical procedure is presented to avoid the divergence problem during the iterative process in viscoelastic analyses. This problem is observed when the positional formulation of the finite element method is adopted in association with the finite difference method. To do this, the nonlinear positional formulation is presented considering plane frame elements with Bernoulli–Euler kinematics and viscoelastic behavior. The considered geometrical nonlinearity refers to the structural equilibrium analysis in the deformed position using the Newton–Raphson iterative method. However, the considered physical nonlinearity refers to the description of the viscoelastic behavior through the adoption of the stress-strain relation based on the Kelvin–Voigt rheological model. After the presentation of the formulation, a detailed analysis of the divergence problem in the iterative process is performed. Then, an original numerical procedure is presented to avoid the divergence problem based on the retardation time of the adopted rheological model and the penalization of the nodal position correction vector. Based on the developments and the obtained results, it is possible to conclude that the presented formulation is consistent and that the proposed procedure allows for obtaining the equilibrium positions for any time step value adopted without presenting divergence problems during the iterative process and without changing the analysis of the final results.

scholarly journals NURSE-2 DoF Device for Arm Motion Guidance: Kinematic, Dynamic, and FEM Analysis

2020 ◽  
Vol 10 (6) ◽  
pp. 2139
Author(s):  
Betsy D. M. Chaparro-Rico ◽  
Daniele Cafolla ◽  
Marco Ceccarelli ◽  
Eduardo Castillo-Castaneda
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Upper Limb ◽  
Numerical Procedure ◽  
Fem Analysis ◽  
Arm Movement ◽  
Assistive Device ◽  
Arm Motion ◽  
Element Method

Patients with neurological or orthopedic lesions require assistance during therapies with repetitive movements. NURSE (cassiNo-qUeretaro uppeR-limb aSsistive dEvice) is an arm movement aid device for both right- and left-upper limb. The device has a big workspace to conduct physical therapy or training on individuals including kids and elderly individuals, of any age and size. This paper describes the mechanism design of NURSE and presents a numerical procedure for testing the mechanism feasibility that includes a kinematic, dynamic, and FEM (Finite Element Method) analysis. The kinematic demonstrated that a big workspace is available in the device to reproduce therapeutic movements. The dynamic analysis shows that commercial motors for low power consumption can achieve the needed displacement, acceleration, speed, and torque. Finite Element Method showed that the mechanism can afford the upper limb weight with light-bars for a tiny design. This work has led to the construction of a NURSE prototype with a light structure of 2.6 kg fitting into a box of 35 × 45 × 30 cm. The latter facilitates portability as well as rehabilitation at home with a proper follow-up. The prototype presented a repeatability of ±1.3 cm that has been considered satisfactory for a device having components manufactured with 3D rapid prototyping technology.

A Maxwell's Second Equation Approach to the Finite Element Method Applied to Magnetic Field Determination

1987 ◽  
Vol 24 (3) ◽  
pp. 259-272 ◽  
Author(s):  
José Roberto Cardoso
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Undergraduate Students ◽  
Engineering Students ◽  
Numerical Procedure ◽  
The Finite Element Method ◽  
Cad Cam ◽  
New Formulation ◽  
The Galerkin Method ◽  
Element Method

The burst of modern computing systems like CAD/CAM has given rise to the use of the finite element method (FEM), which is, at present, the most used numerical procedure in the determination of fields in continuous media. Undergraduate students find difficulty in understanding the usual way of demonstrating FEM by variational analysis or the Galerkin method. This paper introduces a new formulation of FEM, based on a direct application of Maxwell's second equation, which can be easily understood by undergraduate engineering students.

Investigating the Rolling Contact Fatigue in Rails Using Finite Element Method and Cohesive Zone Approach

2018 ◽  
Author(s):  
Mohamad Ghodrati ◽  
Mehdi Ahmadian ◽  
Reza Mirzaeifar
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Grain Boundaries ◽  
Fatigue Damage ◽  
Cohesive Zone ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Wheel Load ◽  
Element Method

A micromechanical-based 2D framework is presented to study the rolling contact fatigue (RCF) in rail steels using finite element method. In this framework, the contact patch of rail and wheel is studied by explicitly modeling the grains and grain boundaries, to investigate the potential origin of RCF at the microstructural level. The framework incorporates Voronoi tessellation algorithm to create the microstructure geometry of rail material, and uses cohesive zone approach to simulate the behavior of grain boundaries. To study the fatigue damage caused by cyclic moving of wheels on rail, Abaqus subroutines are employed to degrade the material by increasing the number of cycles, and Jiang-Sehitoglu fatigue damage law is employed as evolution law. By applying Hertzian moving cyclic load, instead of wheel load, the effect of traction ratio and temperature change on RCF initiation and growth are studied. By considering different traction ratios (0.0 to 0.5), it is shown that increasing traction ratio significantly increases the fatigue damage. Also by increasing traction ratio, crack initiation migrates from the rail subsurface to surface. The results also show that there are no significant changes in the growth of RCF at higher temperatures, but at lower temperatures there is a measurable increase in RCF growth. This finding correlates with anecdotal information available in the rail industry about the seasonality of RCF, in which some railroads report noticing more RCF damage during the colder months.

Effect of Footfall Induced Vibration on Footbridges

2015 ◽  
Vol 802 ◽  
pp. 136-141
Author(s):  
Jia Hao Aw ◽  
Anwar Mohammed Parvez ◽  
Wael Elleithy
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Dynamic Behaviour ◽  
Dynamic Responses ◽  
Span Length ◽  
Varying Parameters ◽  
Vertical Displacements ◽  
Element Method

This paper presents the outcomes of investigating the dynamic behaviour experienced by composite footbridges and concrete footbridges when subjected to footfall induced vibration incurred by walking pedestrians. The study focuses on three set of varying parameters including bridge’s deck thickness, span length and width of footbridge. Models are generated and analysed using finite element method. Dynamic responses obtained from the footfall analysis are expressed in term of vertical displacements and accelerations. Data are tabulated and evaluated based on different parameters incorporated; meanwhile comparisons are made between concrete and composite footbridges. It was found that for both composite and concrete footbridges, the displacement and acceleration decrease exponentially with the increase of deck thickness. They also show decreasing trend with the increase of span length. Besides, an increase in displacement and acceleration is observed with the increase of footbridge width.

Studies of the dynamic behaviour of a primary sedimentation tank

1996 ◽  
Vol 34 (3-4) ◽  
pp. 213-222 ◽  
Author(s):  
Claës Lindeborg ◽  
Niklas Wiberg ◽  
Alexander Seyf
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Flow Measurement ◽  
Dynamic Behaviour ◽  
Measurement Data ◽  
Tracer Tests ◽  
Operating Conditions ◽  
Cross Sectional ◽  
Sedimentation Tank ◽  
Element Method

This study concerns the dynamic behaviour of a primary sedimentation tank in a municipal WWTP. It is a part of the effort to estimate the varying biological load on the activated sludge stage under different operating conditions. The primary settlers have been investigated with several methods: (i) cross sectional sampling of suspended solids; (ii) tracer tests with lithium-solution; (iii) finite element method (FEM); (iv) flow measurement with a turbine-type sensor; and (v) cross-sectional flow measurement with a cross-bar metering device. The choice of measurement positions, the number of samples and the methods selected for analyses have all been guided by the ambition to avoid erroneous conclusions due to odd single measurement data. The study demonstrates how modern graphical computer methods like Finite Element Method and MATLAB Toolboxes can be used to increase our understanding of the settler.

Simulation of the Turbulent Flow Inside the Combustion Chamber of a Reciprocating Engine With a Finite Element Method

1994 ◽  
Vol 116 (2) ◽  
pp. 363-369 ◽  
Author(s):  
Y. Mao ◽  
M. Buffat ◽  
D. Jeandel
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Turbulent Flows ◽  
Stokes Equations ◽  
Numerical Procedure ◽  
Turbulence Models ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Numerical Precision ◽  
Element Method

This paper presents numerical simulations of turbulent flows during the intake and the compression strokes of a model engine. The Favre average Navier-Stokes equations are solved with a k-ε turbulence model. The numerical procedure uses a time dependent semi-implicit scheme and a finite element method with a moving mesh (Buffat, 1991, Mao, 1990). Results of 2-D axisymmetrical calculations with and without inlet swirl are presented and compared to experimental data (Lance et al., 1991). The influence of different turbulence models and the numerical precision of the simulations are also discussed.

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