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Peres J.,Aix - Marseille University | Thollon L.,Aix - Marseille University | Delotte J.,University of Nice Sophia Antipolis | Tillier Y.,MINES ParisTech | And 3 more authors.
Computer Methods in Biomechanics and Biomedical Engineering | Year: 2014

Trauma during pregnancy especially occurring during car crashes leads to many foetal losses. Numerical modelling is widely used in car occupant safety issue and injury mechanisms analysis and is particularly adapted to the pregnant woman. Material modelling of the gravid uterus tissues is crucial for injury risk evaluation especially for the abruption placentae which is widely assumed as the leading cause of foetal loss. Experimental studies on placenta behaviour in tension are reported in the literature, but none in compression to the authors' knowledge. This lack of data is addressed in this study. To complement the already available experimental literature data on the placenta mechanical behaviour and characterise it in a compression loading condition, 80 indentation tests on fresh placentae are presented. Hyperelastic like mean experimental stress versus strain and corridors are exposed. The results of the experimental placenta indentations compared with the tensile literature results tend to show a quasi-symmetrical behaviour of the tissue. An inverse analysis using simple finite element models has permitted to propose parameters for an Ogden material model for the placenta which exhibits a realistic behaviour in both tension and compression. © 2012 Taylor & Francis. Source

Hambli R.,Prisme Institute | Benhamou C.-L.,French Institute of Health and Medical Research | Jennane R.,Prisme Institute | Lespessailles E.,French Institute of Health and Medical Research | And 5 more authors.
IRBM | Year: 2013

The purpose of this work was to develop a combined remodeling-to-fracture finite element model allowing for the combined simulation of human proximal femur remodeling under a given boundary conditions followed by the simulation of its fracture behaviour under quasi-static load. The combination of remodeling and fracture simulation into one unified model consists in considering that the femur properties resulting from the remodeling simulation correspond to the initial state for the fracture prediction. The remodeling model is based on a coupled strain and fatigue damage stimulus approach. The fracture model is based on continuum damage mechanics in order to predict the progressive fracturing process, which allows to predict the fracture pattern and the complete force-displacement curve under quasi-static load. To investigate the potential of the proposed unified remodeling-to-fracture model, we performed remodeling simulations on a 3D proximal femur model for a duration of 365 days followed by a side fall fracture simulation reproducing. © 2013 Published by Elsevier Masson SAS. Source

Sansalone V.,CNRS Multiscale Modelling and Simulation Laboratory | Naili S.,CNRS Multiscale Modelling and Simulation Laboratory | Bousson V.,University Paris Diderot | Bergot C.,University Paris Diderot | And 5 more authors.
Journal of Biomechanics | Year: 2010

Cortical bone is a multiscale composite material. Its elastic properties are anisotropic and heterogeneous across its cross-section, due to endosteal bone resorption which might affect bone strength. The aim of this paper was to describe a homogenization method leading to the estimation of the variation of the elastic coefficients across the bone cross-section and along the bone longitudinal axis. The method uses the spatial variations of bone porosity and of the degree of mineralization of the bone matrix (DMB) obtained from the analysis of 3-D synchrotron micro-computed tomography images. For all three scales considered (the foam (100. nm), the ultrastructure (5 γm) and the mesoscale (500 γm)), the elastic coefficients were determined using the Eshelby's inclusion problem. DMB values were used at the scale of the foam. Collagen was introduced at the scale of the ultrastructure and bone porosity was introduced at the mesoscale. The pores were considered as parallel cylinders oriented along the bone axis. Each elastic coefficient was computed for different regions of interest, allowing an estimation of its variations across the bone cross-section and along the bone longitudinal axis. The method was applied to a human femoral neck bone specimen, which is a site of osteoporotic fracture. The computed elastic coefficients for cortical bone were in good agreement with experimental results, but some discrepancies were obtained in the endosteal part (trabecular bone). These results highlight the importance of accounting for the heterogeneity of cortical bone properties across bone cross-section and along bone longitudinal axis. © 2010 Elsevier Ltd. Source

Agency: Cordis | Branch: FP7 | Program: CP-FP | Phase: GC-SST.2010.7-5. | Award Amount: 3.88M | Year: 2011

ECOSHELL is concerned with the development of optimal structural solutions for superlight electric vehicles (category L6 and L7e), decreasing its environmental footprint and using an innovative bio-composite material for the vehicle body. Traditionally this category of urban vehicles has been relatively expensive and lacking of sufficient security measures compared to a classic vehicle (category m1 n1), thus less attractive for popular use. However, a body car lighter than 100Kg can allow the electric vehicles to have acceptable performances at an affordable price, due to lower power of the engine and lower energy consummation. This project aims at handling the first two major draw backs (production cost and safety) while further improving the associated environmental advantages via the application of innovative biodegradable materials for the vehicle body . ECOSHELL partners will work at the same time on: - The material: finding the best material for such application : natural fibber, resin and glue - The structural parts: defining the optimum geometry and architecture of the body and the optimum shape of the different parts - The vehicle: defining the optimum shape and architecture. The work will be carried out throw three subprojects: - Manufacturing: Manufacturing the material, manufacturing and assembling the parts of the body and assembling the car. - Live cycle: Finding materials whose properties are in accordance with the vehicle live cycle, defining the parts of the body responding to the constraints of the vehicle live cycle and defining the vehicle, testing it against torsion, flexion and crash. - End of live : defining the end of live for the material, the structural parts, and the car (disassembly ) ECOSHELL stands out clearly as an innovative project compared to most currently related activities which are mostly concerned with the improvement of production and weight of small size vehicles.

Salin D.,CADLM | Salin D.,Aix - Marseille University | Arnoux P.-J.,Aix - Marseille University | Kayvantash K.,CADLM | Behr M.,Aix - Marseille University
Computer Methods in Biomechanics and Biomedical Engineering | Year: 2016

In the field of biomechanics, the offer of models which are more and more realistic requires to integrate a physiological response, in particular, the controlled muscle bracing and the reflexes. The following work aims to suggest a unique methodology which couples together a sensory and motor loop with a finite element model. Our method is applied to the study of the oscillation of the elbow in the case of a biceps brachial stretch reflex. The results obtained are promising in the purpose of the development of reactive human body models. © 2016 Informa UK Limited, trading as Taylor & Francis Group Source

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