scholarly journals Applicability of a Three-Layer Model for the Dynamic Analysis of Ballasted Railway Tracks

Vibration ◽  
2021 ◽  
Vol 4 (1) ◽  
pp. 151-174
Author(s):  
André F. S. Rodrigues ◽  
Zuzana Dimitrovová
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Dynamic Analysis ◽  
Shear Stiffness ◽  
Shear Resistance ◽  
Railway Track ◽  
Fe Model ◽  
Inertial Effects ◽  
Layer Model ◽  
3D Finite Element

In this paper, the three-layer model of ballasted railway track with discrete supports is analyzed to access its applicability. The model is referred as the discrete support model and abbreviated by DSM. For calibration, a 3D finite element (FE) model is created and validated by experiments. Formulas available in the literature are analyzed and new formulas for identifying parameters of the DSM are derived and validated over the range of typical track properties. These formulas are determined by fitting the results of the DSM to the 3D FE model using metaheuristic optimization. In addition, the range of applicability of the DSM is established. The new formulas are presented as a simple computational engineering tool, allowing one to calculate all the data needed for the DSM by adopting the geometrical and basic mechanical properties of the track. It is demonstrated that the currently available formulas have to be adapted to include inertial effects of the dynamically activated part of the foundation and that the contribution of the shear stiffness, being determined by ballast and foundation properties, is essential. Based on this conclusion, all similar models that neglect the shear resistance of the model and inertial properties of the foundation are unable to reproduce the deflection shape of the rail in a general way.

Composite Drive Shaft Coupling for Future Rotorcraft: A 3D Finite-Element Analysis

1988 ◽  
Author(s):  
R. N. Margasahayam ◽  
H. S. Faust
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Analytical Techniques ◽  
Fe Model ◽  
Design Development ◽  
Element Analysis ◽  
3D Finite Element ◽  
The Finite Element Analysis ◽  
Comparison Of The Results ◽  
3D Finite Element Method

Abstract A finite-element stress analysis of a one-piece, integrated, all-composite shaft and coupling is presented. In addition to a brief discussion of design-driving parameters, some limitations of the analytical techniques used for design development are described. The 3D finite-element method (FEM) was then used to evaluate critical stresses and strains experienced by the shaft coupling. A comparison of the results from the finite-element analysis and those from static bending, axial, and torsional tests conducted on these prototype shafts yielded excellent correlation. Some important considerations in the development of the FE model and the correlation of results with tests, especially in the design of composite materials, are addressed.

scholarly journals A robust 3D finite element model for concrete columns confined by FRCM system

2019 ◽  
Vol 281 ◽  
pp. 01006 ◽  
Author(s):  
Majid M.A. Kadhim ◽  
Mohammed J Altaee ◽  
Ali Hadi Adheem ◽  
Akram R. Jawdhari
Keyword(s):  
Finite Element ◽  
Cement Mortar ◽  
Three Dimensional ◽  
Concrete Columns ◽  
Element Model ◽  
Fe Model ◽  
3D Finite Element ◽  
Composite Failure ◽  
Global Buckling ◽  
Fibre Reinforced Polymer

Fibre reinforced cementitious matric (FRCM) is a recent application of fibre reinforced polymer (FRP) reinforcement, developed to overcome several limitations associated with the use of organic adhesive [e.g. epoxies] in FRPs. It consists of two dimensional FRP mesh saturated with a cement mortar, which is inorganic in nature and compatible with concrete and masonry substrates. In this study, a robust three-dimensional (3D) finite element (FE) model has been developed to study the behaviour of slender reinforced concrete columns confined by FRCM jackets, and loaded concentrically and eccentrically. The model accounts for material nonlinearities in column core and cement mortar, composite failure of FRP mesh, and global buckling. The model response was validated against several laboratory tests from literature, comparing the ultimate load, load-lateral deflection and failure mode. Maximum divergence between numerical and experimental results was 12%. Following the validation, the model will be used later in a comprehensive parametric analysis to gain a profound knowledge of the strengthening system, and examine the effects of several factors expected to influence the behaviour of confined member.

Investigation of Pore Structures on Mechanical Properties of Porous Ti by 3D Finite Element Models

2013 ◽  
Vol 647 ◽  
pp. 683-687
Author(s):  
Mi Gong ◽  
Hong Chao Kou ◽  
Yu Song Yang ◽  
Guang Sheng Xu ◽  
Jin Shan Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Elastic Modulus ◽  
Yield Strength ◽  
Finite Element Models ◽  
3D Finite Element ◽  
Pore Model ◽  
Porous Ti ◽  
Pore Structures ◽  
Medium Porosity

The pore structures on mechanical properties of porous Ti were investigated by 3D finite element models. Calculated elastic modulus and yield strength suggested that square-pore models exhibit lower modulus and higher strength compared with another two kinds of shapes (circle and hexagonal). In addition, under the condition of medium porosity (58.96%), integrated property was found in square-pore model which elastic modulus was 26.97GPa, less than 1/3 of hexagonal-pore model; while the yield strength maintained 63.82MPa, doubled the figure of circle-pore model. Thus, models with square-pore structures show potential perspective as hard tissue replacements. Investigation on anisotropy of microstructure implies that the elastic modulus was affected more intensively than the yield strength.

Dynamic Analysis on Underlay Microstructure for Cu/Low-k Wafer during Wire Bonding

2009 ◽  
Vol 419-420 ◽  
pp. 489-492 ◽  
Author(s):  
Hsiang Chen Hsu ◽  
Pei Chieh Chin ◽  
Chin Yuan Hu ◽  
Wei Yao Chang ◽  
Chang Lin Yeh ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Dynamic Analysis ◽  
Element Model ◽  
Gold Wire ◽  
Stress Distributions ◽  
Test Fixture ◽  
Free Air ◽  
Intermetal Dielectric ◽  
Low K

Two major analyses were conducted in this paper. In the first, experimental procedures are accomplished to measure the tensile mechanical properties of ultra thin gold wire (=1mil) before/after electric flame-off (EFO). Characteristics of free air ball (FAB), heat affected zone (HAZ) and as-drawn wire have been carefully investigated by nanoindentation, microhardness and self-design pull test fixture. Secondary, with the obtained experimental material data, a comprehensive finite element model using software ANSYS/LS-DYNA is successfully developed to simulate the wirebonding. Dynamic analysis is performed to evaluate the overall stress distributions on the underlay microstructure of Cu/low-k wafer. Special emphasizes are focused on the Copper via and the intermetal dielectric (IMD)/undoped silica glass (USG) dielectric microstructure.

scholarly journals Numerical analysis of circular and square section concrete filled aluminum tubes under axial compression

2020 ◽  
Vol 14 (54) ◽  
pp. 169-181
Author(s):  
Pan Jinlong ◽  
Li Guanhua ◽  
Jingming Cai
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Axial Compression ◽  
Parametric Analysis ◽  
Concrete Strength ◽  
Fe Model ◽  
Fe Method ◽  
The Core ◽  
Aluminum Tubes ◽  
Core Concrete

In this paper, the finite element (FE) method was used to investigate the axial compressive behaviors of circular and square concrete filled aluminum tubes (CFAT). Firstly, the simulational results were compared with the experimental results and the accuracy of the proposed FE model was verified. On this basis, the FE model was further applied to compare the mechanical properties of both circular and square CFATs under axial compression. It was found that the circular CFATs have a better effect on restraining the core concrete than square CFATs. The parametric analysis was also conducted based on the proposed FE model. It was noticed that the mechanical differences of the two kinds of CFATs gradually decreased with the increase of the aluminum ratio, aluminum strength and concrete strength.

scholarly journals Finite Element Modeling of the Pulse Wave propagation in the aorta for simulation of the Pulse Wave Imaging (PWI) method

2008 ◽  
Author(s):  
Jonathan Vappou
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Aortic Wall ◽  
Pulse Wave ◽  
Coupled Model ◽  
Element Model ◽  
Relative Difference ◽  
Imaging Method ◽  
Fe Model ◽  
Wave Imaging

A large number of pathological conditions result in significant changes of the mechanical properties of the aortic wall. Using the Pulse Wave Velocity (PWV) as an indicator of aortic stiffness has been proposed for several decades. Pulse Wave Imaging (PWI) is an ultrasonography-based imaging method that has been developed to map and quantify the pulse wave (PW) propagation along the abdominal aortic wall and measure its local properties. We present a finite-element-based approach that aims at improving our understanding of the complex PW patterns observed by PWI and their relationship to the underlying mechanical properties. A Fluid-Structure Interaction (FSI) coupled model was developed based on an idealized axisymmetric aorta geometry. The accuracy of the model as well as its ability to reproduce realistic PW propagation were evaluated by performing a parametric analysis on aortic elasticity, by varying the aortic Young�s modulus between 20 kPa and 2000 kPa. The Finite-Element model was able to predict with good accuracy the expected PWV values in different theoretical cases, with an averaged relative difference of 14% in the 20kPa-100kPa, which corresponds to a wide physiologic range for stiffness of the healthy aorta. This study allows to validate the proposed FE model as a tool that is capable of representing quantitatively the pulse wave patterns in the aorta.

A Meta-Modeling Procedure for Updating the Finite Element Model of an Arch Bridge Model

2013 ◽  
Vol 540 ◽  
pp. 79-86
Author(s):  
De Jun Wang ◽  
Yang Liu
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Dynamic Analysis ◽  
Large Scale ◽  
Model Updating ◽  
Element Model ◽  
Fe Model ◽  
Large Scale Structures ◽  
Bridge Model ◽  
Scale Structures

Finite element (FE) model updating of structures using vibration test data has received considerable attentions in recent years due to its crucial role in fields ranging from establishing a reality-consistent structural model for dynamic analysis and control, to providing baseline model for damage identification in structural health monitoring. Model updating is to correct the analytical finite element model using test data to produce a refined one that better predict the dynamic behavior of structure. However, for real complex structures, conventional updating methods is difficult to be utilized to update the FE model of structures due to the heavy computational burden for the dynamic analysis. Meta-model is an effective surrogate model for dynamic analysis of large-scale structures. An updating method based on the combination between meta-model and component mode synthesis (CMS) is proposed to improve the efficiency of model updating of large-scale structures. The effectiveness of the proposed method is then validated by updating a scaled suspender arch bridge model using the simulated data.

Influence of Calcified Cartilage Zone Permeability in Mechanical Behavior of Articular Cartilage: A Finite Element Study

2009 ◽  
Author(s):  
Ali Vahdati ◽  
Diane R. Wagner
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Articular Cartilage ◽  
Mechanical Behavior ◽  
Independent Study ◽  
Cartilage Tissue ◽  
Fe Model ◽  
Mechanical State ◽  
Calcified Cartilage ◽  
Important Player

Articular cartilage (AC) disease and especially osteoarthrithis (OA) are debilitating conditions that are associated with huge social and economic burdens. To understand the factors involved in initiation and progression of OA, the mechanical state of the cartilage tissue must be first understood [1]. Biphasic and triphasic models developed by Mow and coworkers relate AC structure with its mechanical behavior and provided researchers with valuable models for AC biomechanics [2, 3]. Although much is known about AC and its mechanical properties, the zone of calcified cartilage (ZCC) has been sparsely studied. ZCC is very thin and highly interdigitated with subchondral bone (SB) which makes it very difficult to isolate for independent study [4]. It is well known that SB plays an important role in both initiation and/or progression of OA [5], thus ZCC may also be an important player in the pathology of the disease [6]. A few studies have investigated mechanical properties of ZCC, but conflicting results have been published on ZCC permeability. Although ZCC has been mainly assumed to be impermeable [7], recently Hwang et al. [8] suggested that ZCC may have even higher permeability than cartilage itself. We studied the effect of ZCC permeability on mechanical behavior of AC using a finite element (FE) model.

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