Search results for "Finite element"

Numerical simulation of low temperature thermal conductance of corrugated nanofibers

2010

Impact of Aortic Stenosis on Myofiber Stress: Translational Application of Left Ventricle-Aortic Coupling Simulation

2020

The severity of aortic stenosis (AS) has traditionally been graded by measuring hemodynamic parameters of transvalvular pressure gradient, ejection jet velocity, or estimating valve orifice area. Recent research has highlighted limitations of these criteria at effectively grading AS in presence of left ventricle (LV) dysfunction. We hypothesized that simulations coupling the aorta and LV could provide meaningful insight into myocardial biomechanical derangements that accompany AS. A realistic finite element model of the human heart with a coupled lumped-parameter circulatory system was used to simulate AS. Finite element analysis was performed with Abaqus FEA. An anisotropic hyperelastic mo…

Intraoperative neural electrode for continuous monitoring of nerve function

2009

Nerve damage is still a major concern in all types of surgery and may result in permanent nerve injury. Real time nerve monitoring can reduce the risk of nerve lesions by continuous surveillance of nerve integrity. A stable proximal stimulation of the nerve and recording at the effector organ is essential and the electrodes should not significantly influence the surgical intervention.

Modeling the pelvic region for non-invasive pelvic intraoperative neuromonitoring

2016

Abstract Finite element analysis (FEA) of electric current distribution in the pelvis minor may help to assess the usability of non-invasive surface stimulation for continuous pelvic intraoperative neuromonitoring. FEA requires generation of quality volumetric tetrahedral mesh geometry. This study proposes the generation of a suitable mesh based on MRI data. The resulting volumetric mesh models the autonomous nerve structures at risk during total mesorectal excision. The model also contains the bone, cartilage, fat, skin, muscle tissues of the pelvic region, and a set of electrodes for surface stimulation. The model is ready for finite element analysis of the discrete Maxwell’s equations.

Modelling cardiac mechanics of left ventricular noncompaction

2020

Left ventricular noncompaction (LVNC) can be defined as a cardiomyopathy characterised by a pattern of prominent trabecular structure and deep intertrabecular recesses, that is thought to be caused by an arrest of normal endomyocardial morphogenesis. Using patient-specific computational modelling, we assessed the cardiac mechanics of five patients with LVNC and compared myocardial stress and pump performance to those of healthy controls. Findings shown that patients with LVNC have impaired left ventricular (LV) function, making it possible that the lack of fibre shortening of noncompacted layer can determine poor heart function. Pronounced end-systolic wall stress on left ventricular wall o…

Predicting stiffness and strength of birch pulp:Polylactic acid composites

2016

This paper studies failure of birch pulp–polylactic acid composites. Stiffness and strength are calculated using the theory of short fibre composites and the results are compared to experimental data. The results differed from the experimental values by 0–6%. With less aligned fibres the short fibre theory is not feasible. The performance of the 40 wt% birch pulp – polylactic acid composite is predicted with X-ray microtomography based finite element modelling, and the results are compared with experiments. Stiffness results differed from experiments by 1–17% . By adding into the models a third material phase representing the interface between the fibres and the matrix, the stress–strain c…

On the Finite Element Modeling of the Lumbar Spine: A Schematic Review

2023

Finite element modelling of the lumbar spine is a challenging problem. Lower back pain is among the most common pathologies in the global populations, owing to which the patient may need to undergo surgery. The latter may differ in nature and complexity because of spinal disease and patient contraindications (i.e., aging). Today, the understanding of spinal column biomechanics may lead to better comprehension of the disease progression as well as to the development of innovative therapeutic strategies. Better insight into the spine’s biomechanics would certainly guarantee an evolution of current device-based treatments. In this setting, the computational approach appears to be a remarkable …

On time-harmonic Maxwell equations with nonhomogeneous conductivities : Solvability and FE-approximation

1989

The solvability of time-harmonic Maxwell equations in the 3D-case with non­homogeneous conductivities is considered by adapting Sobolev space technique and variational formulation of the probJem in question. Moreover, a finite element approximation is presented in the 3D·case together with an error estimate in the energy norm. Some remarks are given to the 2D-problem arising from geophysics. peerReviewed

Durability of a 3D woven composite assisted by finite element multi-scale modelling

2012

International audience; The textile composite studied is a 3D woven composite. A unit cell is defined by using microscopic examinations of the microstructure. A multiscale approach assisted by the finite element method is performed in order to estimate the effective properties of the composite and then to access to local stress field. This approach allows the determination of the kind of load to which warp yarns are subjected. Moreover, detailed analysis of damaged model using different configurations of broken yarns are treated. The evolution of the stress concentration coefficient highlight the load transfers due to consecutive yarn breaks.

Influence of the Screw Positioning on the Stability of Locking Plate for Proximal Tibial Fractures: A Numerical Approach

2020

Tibial fractures are common injuries in people. The proper treatment of these fractures is important in order to recover complete mobility. The aim of this work was to investigate if screw positioning in plates for proximal tibial fractures can affect the stability of the system, and if it can consequently influence the patient healing time. In fact, a more stable construct could allow the reduction of the non-weight-bearing period and consequently speed up the healing process. For that purpose, virtual models of fractured bone/plate assemblies were created, and numerical simulations were performed to evaluate the reaction forces and the maximum value of the contact pressure at the screw/bo…