3D FEM model to simulate Brownian motion inside trabecular tissue from human femoral head

Author(s):  
Fabiano Bini ◽  
Andrada Pica ◽  
Simone Novelli ◽  
Raffaella Pecci ◽  
Rossella Bedini ◽  
...  
2016 ◽  
Vol 6 (1) ◽  
pp. 7-15
Author(s):  
Daniela Mihaela Boca ◽  
A. Faur ◽  
A. Boca

Abstract This study aims to presents the importance of end constrains, boundary conditions and position of the applied forces regarding the design of precast/prestressed concrete box girders. The study is based on a destructive test which was performed on a 37.1 m span single-cell prestressed concrete box girder. The scope of the test was to certify the usage of such girders for the new Transylvania motorway bridges. The test is numerically reproduced through a full 3D FEM model implemented in SAP2000. The influence of the end diaphragms is considered by analysing the beam’s behaviour to six loading conditions: one of which is replicating the loadings during the test, while the others are conceived as real vertical and horizontally loading scenarios. The results obtained for the girders with and without end constrains are compared. The performances of both design solutions in the presence of prestressing are highlighted where applicable. It is considered that the results of this study may provide very important data if considering that Romania has an urgent need to realize a modern and an adequate transport infrastructure.


2012 ◽  
Vol 226-228 ◽  
pp. 13-16
Author(s):  
Xin Wang ◽  
Shao Ze Luo

In order to study the flow-induced vibration of the spillway tunnel working gate of one reservoir, hydraulic model test with scale 1:20 was conducted to obtain the dynamic pressure characteristics on the working gate. Experiment modal analysis method was employed to identify the structure dynamic characteristics through the 1:10 working gate mode test. The 3D FEM model of the gate was built to simulate the vibration response of the structure. The research showed the low order modal frequencies of the working gate were not fully breaking away from the high energy zone of the dynamic water, which would induce severe vibration. The vibration response of the gate became the biggest when it was operating at 0.5 partial opening.


2016 ◽  
Vol 13 (5) ◽  
pp. 652-664 ◽  
Author(s):  
Jesús Fernández Ruiz ◽  
Pedro Alves Costa ◽  
Rui Calçada ◽  
Luis E. Medina Rodríguez ◽  
Aires Colaço

Author(s):  
F. J. Tallavo ◽  
M. D. Pandey ◽  
M. Jyrkama ◽  
N. C. Christodoulou ◽  
G. A. Bickel ◽  
...  

A key element of the fuel channel life cycle management in CANDU® nuclear reactors is to prevent contact between the pressure tube (PT) and the calandria tube (CT) in a fuel channel. By preventing PT-CT contact, the development of hydride blisters and delayed hydride cracking of the PT can be avoided. The PT-CT contact is a result of in-reactor deformation due to irradiation induced creep of the fuel channel assembly. Excessive sagging of the PT can also interfere with the free passage of the fuel bundles when the channel is refueled. Contact of the CT with reactor control mechanisms located horizontally between the fuel channels can result from excessive sag of the CT. The prediction of dimensional changes due to in-reactor creep and the time of PT-CT contact is calculated using finite element modeling of the fuel channel with appropriate creep constitutive laws describing PT and CT deformation. The three-dimensional nature of creep deformation of fuel channels can be approximated by a one-dimensional finite element model (1D-FEM), which is a computationally tractable problem. However, the simplifications of a 1D-FEM model come at the expense of loss of prediction accuracy. This paper compares creep deformation analysis of fuel channels using 1D-FEM and 3D-FEM models. The comparison is based on PT and CT sag profiles as well as on PT-CT gap at different time intervals during service of the fuel channel. Results from the comparative analysis show that the 1D-FEM model predicts greater values of PT-CT gap. The difference in gap predicted between both FEM models increases rapidly when the minimum gap is located in the outlet span. At 250,000 equivalent full power hours, the 1D-FEM model overestimate the gap by 1.12 mm with respect to the 3D-FEM model.


Author(s):  
Tatsuo Nishiuchi

To clarify the effects of seismic response of concrete gravity dams under large earthquake, finite element method (FEM) analyses were carried out. In analyses, the height of dam and material properties of concrete and basement rock are same. The 2-dimensional (2D) and the 3-dimensional (3D) FEM model were made and used in earthquake response analyses. The contraction joints between dam block are concerned in 3D non-linear FEM analysis. In the case of same height of dam, the numerical results of damage states and placements in dam are different between 2D FEM model and 3D FEM model, due to the effect of difference in vibration mode of dam. In the 2D FEM model, the damage of top in cross-section becomes remarkable. In the 3D FEM model, the damage of attachment between dam body and basement rock at high-elevation becomes remarkable. The damage of 3D FEM model is smaller than that of 2D FEM model for the same acceleration level of earthquake. The influence of seismic response on contraction joints of 3D non-linear FEM dam model is smaller, which is as same as that of 3D linear FEM dam model. From the above results, the 2D FEM model gives a conservative assessment compared to the 3D FEM model.


2017 ◽  
Vol 4 (3) ◽  
pp. 17-00152-17-00152 ◽  
Author(s):  
Shohei ONITSUKA ◽  
Yoshihiro GOTO ◽  
Tadashi IIJIMA ◽  
Naoki OJIMA

2015 ◽  
Vol 137 (6) ◽  
Author(s):  
Hitoshi Nakamura ◽  
Wenwei Gu ◽  
Seiichi Tajima ◽  
Osamu Hazama

This paper describes the structure and application of a software system that automates the fatigue initiation and crack propagation analysis based on finite element method (FEM). The system automatically performs necessary procedures to track propagation history of cracks: insertion of a crack and updating of three-dimensional (3D) finite element mesh in accordance with the crack propagation. The system is equipped with a function to automatically perform fatigue analyses using the stress–strain histories at nodes of a 3D FEM model. Some analyses for several examples were carried out for validation. The important example is the surface crack propagation in steel pipes with residual stress.


2018 ◽  
Vol 7 (4.24) ◽  
pp. 148
Author(s):  
Bharath Kumar Narukullapati ◽  
T K Bhattacharya ◽  
ANaveen Reddy ◽  
Srikanth Gollapudi

The electromagnetic field calculation for a floating aluminum disc is difficult to calculate since the equation involved does not produce a closed solution. The numerical, analytical, semi-analytical techniques that are already developed to find these magnetic fields have no proper mathematical formulation when the disc is disturbed from its coaxial position. The stabilization of disc is going to be effected when the disc moves away from its coaxial position due to a change in inductance between the disc and coils, due to change in magnetic flux linkage, etc. In this paper, a 2D FEM model is developed to determine the magnetic fields on a floatingaluminum disc when it is moved away from its coaxial position. The 3D FEM model developed is simulated in both COMSOL-Multiphysics and ANSYS-Electronics. The results obtained by simulation are compared, for accuracy, with the numerical solution developed earlier using Finite Difference method (FDM) and also discussed.


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