Measurement of Coronary Lumen Area Using an Impedance Catheter: Finite Element Model and in Vitro Validation

2004 ◽  
Vol 32 (12) ◽  
pp. 1642-1653 ◽  
Author(s):  
Ghassan S. Kassab ◽  
Eugen R. Lontis ◽  
Hans Gregersen
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Lumen Area

Impact of spinal rod stiffness on porcine lumbar biomechanics: Finite element model validation and parametric study

2017 ◽  
Vol 231 (12) ◽  
pp. 1071-1080
Author(s):  
Martin Brummund ◽  
Vladimir Brailovski ◽  
Yvan Petit ◽  
Yann Facchinello ◽  
Jean-Marc Mac-Thiong
Keyword(s):  
Finite Element ◽  
Lumbar Spine ◽  
Finite Element Model ◽  
Three Dimensional ◽  
Variable Stiffness ◽  
Transverse Process ◽  
Threshold Value ◽  
Element Model ◽  
Three Dimensional Finite Element

A three-dimensional finite element model of the porcine lumbar spine (L1–L6) was used to assess the effect of spinal rod stiffness on lumbar biomechanics. The model was validated through a comparison with in vitro measurements performed on six porcine spine specimens. The validation metrics employed included intervertebral rotations and the nucleus pressure in the first instrumented intervertebral disc. The numerical results obtained suggest that rod stiffness values as low as 0.1 GPa are required to reduce the mobility gradient between the adjacent and instrumented segments and the nucleus pressures across the porcine lumbar spine significantly. Stiffness variations above this threshold value have no significant effect on spine biomechanics. For such low-stiffness rods, intervertebral rotations in the instrumented zone must be monitored closely in order to guarantee solid fusion. Looking ahead, the proposed model will serve to examine the transverse process hooks and variable stiffness rods in order to further smooth the transition between the adjacent and instrumented segments, while preserving the stability of the instrumented zone, which is needed for fusion.

scholarly journals Effects of Bone Young’s Modulus on Finite Element Analysis in the Lateral Ankle Biomechanics

2013 ◽  
Vol 10 (4) ◽  
pp. 189-195 ◽  
Author(s):  
W. X. Niu ◽  
L. J. Wang ◽  
T. N. Feng ◽  
C. H. Jiang ◽  
Y. B. Fan ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Finite Element Model ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Computational Simulation ◽  
Element Model ◽  
Surface Strain ◽  
Element Analysis

Finite element analysis (FEA) is a powerful tool in biomechanics. The mechanical properties of biological tissue used in FEA modeling are mainly from experimental data, which vary greatly and are sometimes uncertain. The purpose of this study was to research how Young’s modulus affects the computations of a foot-ankle FEA model. A computer simulation and an in-vitro experiment were carried out to investigate the effects of incremental Young’s modulus of bone on the stress and strain outcomes in the computational simulation. A precise 3-dimensional finite element model was constructed based on an in-vitro specimen of human foot and ankle. Young’s moduli were assigned as four levels of 7.3, 14.6, 21.9 and 29.2 GPa respectively. The proximal tibia and fibula were completely limited to six degrees of freedom, and the ankle was loaded to inversion 10° and 20° through the calcaneus. Six cadaveric foot-ankle specimens were loaded as same as the finite element model, and strain was measured at two positions of the distal fibula. The bone stress was less affected by assignment of Young’s modulus. With increasing of Young’s modulus, the bone strain decreased linearly. Young’s modulus of 29.2 GPa was advisable to get the satisfactory surface strain results. In the future study, more ideal model should be constructed to represent the nonlinearity, anisotropy and inhomogeneity, as the same time to provide reasonable outputs of the interested parameters.

Experimental Validation of a Finite Element Model of an Osteoporotic Human Femoral Bone Using Strain Gauge Measurement

2014 ◽  
Vol 658 ◽  
pp. 513-519
Author(s):  
Ioana Alexandra Takacs ◽  
Mircea Cristian Dudescu ◽  
Mihail Hărdău ◽  
Adrian Ioan Botean
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Strain Gauge ◽  
Computer Aided Design ◽  
Experimental Validation ◽  
Element Model ◽  
Femoral Bone ◽  
Vitro Analysis ◽  
Gauge Measurement

The complications of fractures caused by osteoporosis have a mortality rate of 15-20 % in elderly people, leading to severe physical disability and long term home care [1]. Although currently, the technology that allows us to prevent osteoporosis and fractures caused by this disease exists, the statistics are concerning and can be considered basis for further research regarding this pathology of the bone tissue. This paper aims to address this issue form an engineering perspective by achieving experimental validation of a finite element model of an osteoporotic human femoral bone using strain gauge measurement for an in vitro analysis. A Computer Aided Design (CAD) model based on a CT of a human femoral bone was then used in a numerical analysis. The material constants used are taken from the literature and have been validated experimentally by strain gauge technique.

In Vitro and finite-element model investigation of the conductance technique for measurement of aortic segmental volume

1996 ◽  
Vol 24 (6) ◽  
pp. 675-684 ◽  
Author(s):  
Douglas A. Hettrick ◽  
Joseph H. Battocletti ◽  
James J. Ackmann ◽  
John H. Linehan ◽  
David C. Warltier
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Model Investigation ◽  
Conductance Technique

scholarly journals The Simulation of Muscles Forces Increases the Stresses in Lumbar Fixation Implants with Respect to Pure Moment Loading

2021 ◽  
Vol 9 ◽  
Author(s):  
Matteo Panico ◽  
Tito Bassani ◽  
Tomaso Maria Tobia Villa ◽  
Fabio Galbusera
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Pedicle Screws ◽  
Element Model ◽  
Loading Conditions ◽  
Lateral Bending ◽  
Flexion Extension ◽  
Pure Moment ◽  
The Finite Element Model

Simplified loading conditions such as pure moments are frequently used to compare different instrumentation techniques to treat spine disorders. The purpose of this study was to determine if the use of realistic loading conditions such as muscle forces can alter the stresses in the implants with respect to pure moment loading. A musculoskeletal model and a finite element model sharing the same anatomy were built and validated against in vitro data, and coupled in order to drive the finite element model with muscle forces calculated by the musculoskeletal one for a prescribed motion. Intact conditions as well as a L1-L5 posterior fixation with pedicle screws and rods were simulated in flexion-extension and lateral bending. The hardware stresses calculated with the finite element model with instrumentation under simplified and realistic loading conditions were compared. The ROM under simplified loading conditions showed good agreement with in vitro data. As expected, the ROMs between the two types of loading conditions showed relatively small differences. Realistic loading conditions increased the stresses in the pedicle screws and in the posterior rods with respect to simplified loading conditions; an increase of hardware stresses up to 40 MPa in extension for the posterior rods and 57 MPa in flexion for the pedicle screws were observed with respect to simplified loading conditions. This conclusion can be critical for the literature since it means that previous models which used pure moments may have underestimated the stresses in the implants in flexion-extension and in lateral bending.

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