Search results for "BIOMECHANICS"
showing 10 items of 281 documents
In Vitro Measurement of Strain Localization Preceding Dissection of the Aortic Wall Subjected to Radial Tension
2020
AbstractBackgroundAortic dissection (AD) is a common pathology and challenging clinical problem. A better understanding of the biomechanical effects preceding its initiation is essential for predicting adverse events on a patient-specific basis. Moreover, the predictability of patient-specific biomechanics-based computational models is hampered by uncertainty about boundary conditions and material properties.ObjectivePredisposition of thoracic aortic aneurysms (TAA) to ADs can be related to the degradation of biomechanically important constituents in the aortic wall of TAAs. The goal of the present study is to develop a new methodology to measure strain fields in aortic tissues subjected to…
Contribution to the development and the improvement of a digital model of the human body biofidelic HUByx by numerical methods for impact applications
2017
The study of human tolerance thresholds to impacts requires experiments on living or post mortem human subjects, which naturally raises ethical questions. To overcome these limitations, the development of numerical tools has led over the last few years to the implementation of numerical models more or less capable to accurately reproduce the mechanical behavior of the human body when subjected to various types of stresses. It is in this context that the numerical model HUByx (Hermaphrodite Biomechanics yx-model) has been developed within the research department COMM of the ICB lab at UTBM. This PhD work aims at validating and improving the biofidelity of the thoracic part of the HUByx model…
Instrumentation in sports biomechanics
2007
La biomecánica deportiv emplea una serie de herramientas y técnicas de instrumentación paara el análisis de las diferentes disciplinas físico-deportivas, así como también para el desarrollo de nuevos materiales y equipamiento deportivo. Sin embargo, estas herramientas empleadas actualmente, poseen su cuerpo de conocimientos teóricos en los conocidos como "precursores de la biomecánica". Aristóteles, Da Vinci, Galileo, Descartes, Borelli, Newton, etc... El documento, presenta diferentes técnicas instrumentales desarrolladas para evaluar y aportar información relevante en la ejecución físico-deportiva, así como contribuir en la disminución de la epidemiología deportiva. Entre las principales …
Validation of a subject specific 3-actuator torque-driven model in human vertical jumping.
2013
In this study, a forward dynamic subject specific 3-actuator torque-driven model of the human musculoskeletal system was created based on measurements of individual characteristics of a subject. Simulation results were compared with experimental vertical squat jumping with and without adding weights. By analyzing kinematic and kinetic experimental data at the instant of the toe-off for the same initial conditions, it was shown that a simple computer simulation using a suitable cost function could reproduce the real task performed by humans. This investigation is the first step in a wider project that will incorporate elastic components, and that will evaluate the advantages of the individua…
Optimization model predictions for postural coordination modes
2003
International audience; This paper examines the ability of the dynamic optimization model to predict changes between in-phase and anti-phase postural modes of coordination and to evaluate influence of two particular environmental and intentional constraints on postural strategy. The task studied was based on an experimental paradigm that consisted in tracking a target motion with the head. An original optimal procedure was developed for cyclic problems to calculate hip and ankle angular trajectories during postural sway with a minimum torque change criterion. Optimization results give a good description of the sudden bifurcation phase between in-phase and anti-phase postural coordination mo…
Self-efficacy and performance of the roundhouse kick in taekwondo
2014
[ES] El desarrollo de escalas de autoeficacia permite el análisis de las percepciones de los deportistas y el examen de la relación entre dichas percepciones y el rendimiento. El objetivo de este estudio fue (1) desarrollar una escala específica de autoeficacia para una tarea de taekwondo, la patada circular, y (2) analizar el rendimiento deportivo y su relación con los resultados de dos escalas de autoeficacia (específica y general) en función del género de los deportistas. En el estudio participaron 43 taekwondistas (33 hombres y 10 mujeres). Se administraron las escalas de autoeficacia Física (PSE) y Específica (RKSES). Los datos de rendimiento (fuerza de impacto y tiempo total de respue…
Utilidad de un nuevo sistema de cronometraje para proporcionar feedback inmediato a los nadadores
2007
El presente documento tiene dos objetivos, en primer lugar, describir un nuevo sistema de cronometraje que proporciona feedback en tiempo real y sin interferir en la ejecución del nadador y, en segundo lugar, comprobar su utilidad. El sistema consiste en una pantalla de leds, resistente al agua e instalada en el fondo de la piscina, conectada a una Unidad Central mediante una plataforma de contacto colocada en la pared donde se realiza el viraje. La pantalla de leds informa al nadador de los tiempos y número de vueltas e, incluso, puede presentar texto (consignas) escrito por el entrenador. Este sistema se puede conectar a un PC o una PDA, permitiendo registrar los tiempos para su posterior…
A 2D-FEM Model of Nonlinear Ultrasound Propagation in Trans-cranial MRgFUS Technique
2022
Magnetic Resonance guided Focused Ultrasound (MRgFUS) is a non-invasive technique based on the thermal ablation of a target using high intensity focused ultrasound. MRgFUS treatment applied to brain is challenging due to the skull presence that attenuates ultrasound, leading to heating effects in bone region. In this study, we simulate trans-cranial nonlinear ultrasound propagation considering the detailed structure of bone tissue. We developed a 2D Finite Element (FE) model that mimics the propagation of focused ultrasound through skin, skull and brain tissue. The skull is represented as a three-layered system with two cortical tables packing a layer of trabecular bone. We assume that the …
Original strain energy density functions for modeling of anisotropic soft biological tissue
2017
This thesis has focused on the construction of strain energy densities for describing the non-linear behavior of anisotropic materials such as biological soft tissues (ligaments, tendons, arterial walls, etc.) or fiber-reinforced rubbers. The densities we have proposed have been developed with the mathematical theory of invariant polynomials, particularly the Noether theorem and the Reynolds operator. Our work involved two types of anisotropic materials, the first with a single fiber family and the second with a four-fiber family. The concept of polyconvexity has also been studied because it is well known that it plays an important role for ensuring the existence of solutions. In the case o…
Contributions regarding 3D modelling of biomechanics of the foot
2021
Within this paper, a detailed study is elaborated regarding the human foot during both orthostatic and gait, the main goal being to develop 3D models which are very useful in the foot motion and loading state research. In order to elaborate the accurate 3D modelling of the human foot assembly, a thorough biomechanical study is done. Such a study was required due to the fact of the high anatomical complexity of the motions within the foot, taking into consideration the 26 bones and 33 joints consisting it. The research aims the CAD modelling of the biomechanics of the healthy subjects alongside with predisposed pathological conditions. The resulting models will have important utility in both…