scholarly journals Finite Element Analysis of Normal Pressure Hydrocephalus: Influence of CSF Content and Anisotropy in Permeability

2010 ◽  
Vol 7 (3) ◽  
pp. 187-197 ◽  
Author(s):  
K. Shahim ◽  
J.-M. Drezet ◽  
J.-F. Molinari ◽  
R. Sinkus ◽  
S. Momjian
Keyword(s):  
Finite Element ◽  
Normal Pressure Hydrocephalus ◽  
Diffusion Tensor ◽  
Great Influence ◽  
Normal Pressure ◽  
Element Model ◽  
Brain Parenchyma ◽  
Element Analysis ◽  
Cerebral Disease ◽  
The Brain

Hydrocephalus is a cerebral disease where brain ventricles enlarge and compress the brain parenchyma towards the skull leading to symptoms like dementia, walking disorder and incontinence. The origin of normal pressure hydrocephalus is still obscure. In order to study this disease, a finite element model is built using the geometries of the ventricles and the skull measured by magnetic resonance imaging. The brain parenchyma is modelled as a porous medium fully saturated with cerebrospinal fluid (CSF) using Biot's theory of consolidation (1941). Owing to the existence of bundles of axons, the brain parenchyma shows locally anisotropic behaviour. Indeed, permeability is higher along the fibre tracts in the white matter region. In contrast, grey matter is isotropic. Diffusion tensor imaging is used to establish the local CSF content and the fibre tracts direction together with the associated local frame where the permeability coefficients are given by dedicated formulas. The present study shows that both inhomogeneous CSF content and anisotropy in permeability have a great influence on the CSF flow pattern through the parenchyma under an imposed pressure gradient between the ventricles and the subarachnoid spaces.

scholarly journals Finite element analysis for normal pressure hydrocephalus: The effects of the integration of sulci

2015 ◽  
Vol 24 (1) ◽  
pp. 235-244 ◽  
Author(s):  
Hakseung Kim ◽  
Dae-Hyeon Park ◽  
Seong Yi ◽  
Eun-Jin Jeong ◽  
Byung C. Yoon ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Normal Pressure Hydrocephalus ◽  
Normal Pressure ◽  
Element Analysis

Modelling Normal Pressure Hydrocephalus as a ‘Two-Hit’ Disease Using Multiple-Network Poroelastic Theory

2010 ◽  
Author(s):  
Brett Tully ◽  
Yiannis Ventikos
Keyword(s):  
Normal Pressure Hydrocephalus ◽  
Normal Pressure ◽  
Brain Parenchyma ◽  
Strongly Correlated ◽  
Clinical Markers ◽  
Cerebral Diseases ◽  
Spatio Temporal ◽  
Multiple Network ◽  
Poroelastic Theory ◽  
The Brain

The evolution of many cerebral diseases such as Alzheimer’s and Parkinson’s Disease, Hydrocephalus, Cerebral Oedema, Stroke, and Tumour are strongly correlated to a change in the transport properties of fluid in the brain. This research proposes a novel application of Multiple-Network Poroelastic Theory (MPET) to investigate cerebral hydrodynamics through a detailed investigation of multiscalar, spatio-temporal transport of fluid between the cerebral blood, cerebrospinal fluid (CSF) and brain parenchyma. Specifically, MPET is used to interrogate the clinical markers of Normal Pressure Hydrocephalus (NPH).

Finite Element Analysis and Lightweight Design of Crusher Flywheel

2014 ◽  
Vol 684 ◽  
pp. 297-302 ◽  
Author(s):  
Chun Lan Yang ◽  
Da Ming Huang ◽  
Fa Long Cheng
Keyword(s):  
Finite Element ◽  
Parametric Design ◽  
Weak Link ◽  
Lightweight Design ◽  
Great Influence ◽  
Element Model ◽  
Structural Features ◽  
Element Analysis ◽  
Jaw Crusher ◽  
Crushing Force

Traditional jaw crusher has the problems of unreasonable structure, heavy weight, low utilization of material and high cost. This paper chooses the flywheel which has great influence on the total weight as the research object. Finite element method are used to anlysis stress and displacement distribution under the action of maximum crushing force. It shows weak link and surplus position of primary structure. Use the parametric design language APDL to establish and analyze finite element model, based on crusher structural features. Make lightweight design meeting the demands of intensity, stiffness and moment of inertia. The result indicates that modified flywheel is less than the original one by 5%, makes structure more reasonable and stress distribution more even.

scholarly journals Finite Element Analysis of Shield Pipe Structure and Stress Cone Position of 10kV Cable Intermediate Joint

2019 ◽  
Vol 81 ◽  
pp. 01020
Author(s):  
Bo-yu Shang ◽  
Rui-ming Fang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Electric Field ◽  
Electric Field Distribution ◽  
Great Influence ◽  
Element Model ◽  
Optimum Shape ◽  
Element Analysis ◽  
Xlpe Cable ◽  
The Finite Element Model

The shielding tube and stress cone of the intermediate joint of XLPE cable accessory make the potential distribution along the insulation surface linearized to optimize the electric field and. By establishing the finite element model of the intermediate joint of 10kV cable accessory, the electric field distribution of different structure shielding tube and stress cone in different position of the joint is simulated and analyzed. The results show that the structure of shield tube and the position of stress cone are also a parameter characteristic which can not be ignored in the design, and they have a great influence on the distribution of the field strength of the intermediate joint. On the basis of finite element analysis, the optimum shape of shield tube and the best position of stress cone are obtained by comparing and analyzing the variation law of electric field intensity.

Influence of Central Buckle on Dynamic Behavior of Long-Span Suspension Bridge with Deck-Truss Composite Stiffening Girder

2013 ◽  
Vol 838-841 ◽  
pp. 1096-1101 ◽  
Author(s):  
Feng Jiang Qin ◽  
Jin Di ◽  
Jie Dai ◽  
Guang Ling Li
Keyword(s):  
Finite Element ◽  
Large Scale ◽  
Great Influence ◽  
Suspension Bridge ◽  
Element Model ◽  
Vibration Modes ◽  
Element Analysis ◽  
Long Span ◽  
Main Cable ◽  
Central Buckle

A 3-D finite element model for Yueyang Dongting Lake bridge was established with a large scale general finite element analysis software, and the subspace iteration method was adopted to analyze the natural vibration characteristics of the bridge, meanwhile, the influences of settings different types of central buckles at the mid-span of the main spans between the main cables and girder on the dynamic behaviors of the long-span suspension bridge with deck-truss composite stiffening girder were studied. The results show that compared with only setting short hanger cable at mid-span, the the whole rigidity of suspension bridge is raised and the natural frequencies increase by the setting central buckle, but various types of vibration modes are affected in different extents; among all of these vibration modes, the antisymmetric vibration and Longitudinal floating of stiffening girder are most obviously affected. The stiffness of central buckle has a great influence on the vibration of main cable, while compared with only setting short hanger cable, the vibration of main cable increases 7.32% while setting the rigid central buckle. The conclusions of this paper provide theoretical basis for the using of central buckle in long-span suspension bridge.

Modal Analysis of Boring and Milling Machine

2011 ◽  
Vol 105-107 ◽  
pp. 204-207
Author(s):  
Jian Dong Shang ◽  
Jun Qi Guo ◽  
Dong Fang Hu
Keyword(s):  
Finite Element ◽  
Modal Analysis ◽  
Dynamic Performance ◽  
Three Dimensional ◽  
Great Influence ◽  
Element Model ◽  
Mode Shapes ◽  
Machining Accuracy ◽  
Element Analysis ◽  
Modes Of Processing

The vibration is a high-precision machine tool components in the design of the major issues, facing its precision has a great influence, so column parts of its modal analysis is necessary. Creating three-dimensional finite element model of the column, using finite element analysis software ANSYS modal analysis of the column, which can reached the first five natural frequencies and mode shapes. Column Part of our understanding of dynamic performance and improve the machining accuracy is helpful. Modal analysis method is the dynamic performance of the column on the main approach, which mainly is to determine the vibration characteristics of the column that is the natural frequency and vibration mode, which we can determine the modes of processing accuracy, and thus the relevant parts of the machine column can be optimized so that it meet the requirements.

Influence of Bolt Joint on Dynamic Characteristic of Linear Rolling Guide

2013 ◽  
Vol 307 ◽  
pp. 182-185
Author(s):  
Xiao Peng Li ◽  
Ya Min Liang ◽  
Hao Tian Yang ◽  
Xing Ju ◽  
Guang Hui Zhao
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Theoretical Result ◽  
Finite Element Model ◽  
Dynamic Characteristic ◽  
Great Influence ◽  
Element Model ◽  
Joint Surface ◽  
Element Analysis ◽  
Rolling Guide

Bolt joint has an important influence on the dynamic characteristic of guide rail. Linear rolling guide is chosen as the research object in this paper. Firstly, the dynamic model of the linear rolling guide joint surface is established and its natural frequency is figured out. Then we use ANSYS to make finite element analysis of guide on whether the bolt joint is considered or not. Finally, the validity of finite element model is verified through modal test. By comparing the results of the two kinds of finite element analysis with the theoretical result, we can conclude that the finite element model considering the bolts joint is closer to the theoretical result. So the bolt joint has a great influence on the dynamic characteristics of linear rolling guide. This paper provides the theoretical guide for the research on the bolt joint.

FINITE ELEMENT ANALYSIS OF THE DYNAMIC BEHAVIOR OF ALUMINUM HONEYCOMBS

2014 ◽  
Vol 11 (supp01) ◽  
pp. 1344001 ◽  
Author(s):  
SHANQING XU ◽  
DONG RUAN ◽  
JOHN H. BEYNON
Keyword(s):  
Finite Element ◽  
Strain Rate ◽  
Great Influence ◽  
Element Model ◽  
Edge Length ◽  
Deformation Pattern ◽  
Element Analysis ◽  
Plateau Stress ◽  
Velocity Impact ◽  
Aluminum Honeycomb

In this paper, a finite element model was built using ANSYS/LS-DYNA to study the effect of strain rate on the dynamic out-of-plane plateau stress of aluminum honeycombs under constant velocity impact. The strain rates vary from 102 to 104 s-1. It has been found that the t/l ratio (wall thickness to edge length ratio) and strain rate have great influence on deformation pattern and plateau stress. The effect of strain rate on the plateau stress under high velocity impact was found to be different from that under low strain rate compression. The threshold impact velocity is approximately 100 m/s for the aluminum honeycomb studied.

scholarly journals Normal pressure hydrocephalus - active and passive pathogenic mechanisms

2013 ◽  
Vol 20 (3) ◽  
pp. 241-247
Author(s):  
St.M. Iencean ◽  
Al. Tascu ◽  
A.St. Iencean ◽  
I. Poeata ◽  
M.R. Gorgan
Keyword(s):  
Normal Pressure Hydrocephalus ◽  
Normal Pressure ◽  
Brain Parenchyma ◽  
Long Term Results ◽  
Communicating Hydrocephalus ◽  
Ventricular Wall ◽  
Short Term ◽  
Clinical Triad ◽  
The Brain

Abstract Normal pressure hydrocephalus (NPH) is characterized by normal CSF pressure, less than 18 cm H2O, classical clinical triad: gait disturbance, dementia and incontinence in patients with communicating hydrocephalus on CT or MRI. We analyzed retrospectively the NPH hospitalized patients in three neurosurgical departments between July 2007 and December 2012. Only the cases who met all diagnostic criteria were selected for this study. There were 47 selected cases of patients with NPH, including 24 patients with secondary NPH and 23 patients with idiopathic NPH. Ventriculo-peritoneal shunt was performed in all 24 patients with secondary NPH and at 11 patients with IdNPH. The short-term and long-term results were good and very good for cases of secondary NPH and good in 60% and poor in 40% in cases of IdNPH. The MR imaging showed the absence of CSF passage through the ventricular wall and the ventricular wall in cases of IdNPH with poor results after shunting: ependyma and glia limitans interna represents a fluid - parenchymal barrier between the brain parenchyma and the ventricles as a glialependymal barrier. We can consider that secondary NPH and some cases of idiopathic NPH with repeated small increases of ICP, with transependymal migration of CSF and hydrocephalus causing clinical triad because of the open glial-ependymal barrier, as an Active Normal Pressure Hydrocephalus and the shunt has good results. Other cases of IdNPH have not increases of intracranial pressure, no transependymal migration of CSF and there are periventricular deep lesions, without brain atrophy, causing clinical triad, as a passive hydrocephalus, it is a Passive Normal Pressure Hydrocephalus.

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