Probabilistic Structural Analysis of Railroad Subgrade Using Finite Element Analysis

Author(s):  
Asif Arshid ◽  
Ying Huang ◽  
Denver Tolliver

The reliability of finite element (FE) based deterministic structural analysis of railroad trackbed has improved significantly due to ever increasing computational powers. However, the application of probabilistic methods to incorporate the material and geometric variabilities in these FE analyses is still profoundly underworked. In this study, the influence of variability in granular layers’ modulus and thicknesses values on the railroad subgrade performance have been investigated by applying probabilistic method and using a 3-dimensional FE based numerical trackbed model previously developed and validated by the authors’ research group. The influence of these factors is accounted for by changing their coefficients of variance (COV) while keeping their means constant. Preliminary results revealed that the variation in subgrade modulus is the most influential factor for subgrade performance, both in terms of progressive shear failure and excessive plastic deformations, followed by ballast modulus. Variations in depths, for the range studied, remained passive to the subgrade performance. The findings of this work is of particular significance in evaluating the subgrade performance while including the material and geometric variations, which may be caused by construction imperfections, weather changes, and/or rail operations.

2015 ◽  
Vol 809-810 ◽  
pp. 859-864
Author(s):  
Dănuţ Zahariea

In this paper, the finite element analysis for stress/deformation/modes of vibration for the centrifugal fan impeller with constant thickness backward-curved blades using CATIA software will be presented. The principal steps of the finite element analysis procedure using CATIA/Generative Structural Analysis environment will be presented: creating the 3D model; configuring the mesh; applying the restraints; applying the loads; running the numerical static analysis and the numerical frequency analysis; interpreting the results and observing the modes of vibration correlating with the impeller mode shape. This procedure will be used for 4 different centrifugal fan impellers according with the 4 blade design methods and the results will be comparatively analyzed. For each design method, two materials will be used: steel with density of 7860 kg/m3 and aluminium with density of 2710 kg/m3. Two important results have been obtained after the structural analysis: under the working conditions considered for the analysis, all 4 blade design methods leads to impellers with very good mechanical behaviour; any frequency of the main modes of vibrations for all blade design methods and for both materials is not in phase with the impeller speed, thus the possibility of resonance being eliminated.


2007 ◽  
Vol 23 ◽  
pp. 229-232
Author(s):  
Liliana Sandu ◽  
Nicolae Faur ◽  
Cristina Bortun ◽  
Sorin Porojan

Several studies evaluated the removable partial dentures by the finite element analysis, but none of them evaluated thermal stresses. The purpose of the study was to explore the influence of thermal oral changes induced by hot/cold liquids and food on the circumferential cast clasps of removable partial dentures. A 3-dimensional finite element method was used to explore the temperature distribution, thermal stress and the influence of thermal changes on stresses and displacements of circumferential clasps during functions. Thermal variations induce stresses in dental clasps, high temperatures having a more aggressive effect than lower one. Cold liquids and food induce high stresses in the retentive clasp arms while hot ones in the occlusal rests of the clasps and for the back action clasp also in the minor connector. The study suggests the importance of consFigureidering thermal variations for stress analyses of the cast clasps.


2014 ◽  
Vol 11 (4) ◽  
pp. 65-69
Author(s):  
Patil Tushar Vishwas ◽  
◽  
Supale Jayant P ◽  
Vinaay Patil

2003 ◽  
Vol 15 (02) ◽  
pp. 82-85 ◽  
Author(s):  
SHYH-CHOUR HUANG ◽  
CHANG-FENG TSAI

This paper presents results from using a 3-dimensional finite element model to assess the stress distribution in the bone, in the implant and in the abutment as a function of the implant's diameter and length. Increasing implant diameter and length increases the stability of the implant system. By using a finite element analysis, we show that implant length does not decrease the stress distribution of either the implant or the bone. Alternatively, however implant diameter increases reduce the stresses. For the latter case, the contact area between implant and bone is increased thus the stress concentration effect is decreased. Also, with increased implant diameter the bone loss is decreased and as a consequence the success rate is improved.


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