Laurent Orgéas

Publications (59) View all

• Source

  Available from: Christian Geindreau

  Article: Severe Bending of Two Aortic Stent-Grafts: An Experimental and Numerical Mechanical Analysis.

  Nicolas Demanget, Pierre Latil, Laurent Orgéas, Pierre Badel, Stéphane Avril, Christian Geindreau, Jean-Noël Albertini, Jean-Pierre Favre
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  ABSTRACT: Stent-grafts (SGs) are commonly used for treating abdominal aortic aneurysms (AAAs) and numerical models tend to be developed for predicting the biomechanical behavior of these devices. However, due to the complexity of SGs, it is important to validate the models. In this work, a validation of the numerical model developed in Demanget et al. (J. Mech. Behav. Biomed. Mater. 5:272-282, 2012) is presented. Two commercially available SGs were subjected to severe bending tests and their 3D geometries in undeformed and bent configurations were imaged from X-ray microtomography. Dedicated image processing subroutines were used in order to extract the stent centerlines from the 3D images. These skeletons in the undeformed configurations were used to set up SG numerical models that are subjected to the boundary conditions measured experimentally. Skeletons of imaged and deformed stents were then quantitatively compared to the numerical simulations. A good agreement is found between experiments and simulations. This validation offers promising perspectives to implementing the numerical models in a computer-aided tool and simulating the endovascular treatments.
  Annals of biomedical engineering 07/2012; · 2.41 Impact Factor
• Source

  Available from: Laurent Orgéas

  Article: Severe Bending of Two Aortic Stent-Grafts: an Experimental and Numerical Mechanical Analysis

  Nicolas Demanget, Pierre Latil, Laurent Orgéas, Pierre Badel, Stéphane Avril, Christian Geindreau, Jean-Noël Albertini, Jean-Pierre Favre
  [show abstract] [hide abstract]
  ABSTRACT: Stent grafts (SGs) are commonly used for treating abdominal aortic aneurysms (AAAs) and numerical models tend to be developed for predicting the biomechanical behavior of these devices. However, due to the complexity of SGs, it is important to validate the models. In this work, a validation of the numerical model developed in Demanget et al. (J. Mech. Behav. Biomed. Mater. 5:272-282, 2012) is presented. Two commercially available SGs were subjected to severe bending tests and their 3D geometries in undeformed and bent configurations were imaged from X-ray microtomography. Dedicated image processing subroutines were used in order to extract the stent centerlines from the 3D images. These skeletons in the undeformed configurations were used to set up SG numerical models that are subjected to the boundary conditions measured experimentally. Skeletons of imaged and deformed stents were then quantitatively compared to the numerical simulations. A good agreement is found between experiments and simulations. This validation offers promising perspectives to implementing the numerical models in a computer-aided tool and simulating the endovascular treatments.
  Annals of Biomedical Engineering 07/2012; · 2.37 Impact Factor
• Source

  Available from: Laurent Orgéas

  Article: Towards the simulation of mould filling with polymer composites reinforced with mineral fillers and short fibres

  Olivier Guiraud, Pierre J. J. Dumont, Laurent Orgéas, Jean-Pierre Vassal, Thai-Hung Le, Denis Favier
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  ABSTRACT: Bulk Moulding Compounds (BMC’s) are short fibre reinforced polymer composites that behave, during their forming, as concentrated fibre suspensions. Their suspending fluid is also a concentrated granular suspension made up of the polymer filled with mineral fillers. In this work, a method is proposed to model their flow. Firstly, the rheology of an industrial BMC was analysed by performing two types of mechanical tests, i.e. lubricated simple and plane strain compression experiments. Experimental results underline the roles of the current strain, the strain rate as well as the mechanical loading on the rheology of the BMC. Secondly, a 3D tensorial rheological model is proposed to reproduce the simple and plane strain compression experiments. Then this model is implemented into a Finite Element code dedicated to the simulation of compression moulding. Simulation results are finally compared with experiments achieved with rather complex flow situations. KeywordsPolymer composites-Fibre suspension-Granular system-Rheometry-Process simulation-Compression moulding-Bulk Moulding Compounds (BMC)
  International Journal of Material Forming 04/2012; 3:1313-1326.
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  Available from: Laurent Orgéas

  Article: Processing, characterisation and rheology of transparent concentrated fibre-bundle suspensions

  Pierre Dumont, Jean-Pierre Vassal, Laurent Orgéas, Véronique Michaud, Denis Favier, Jan-Anders E. Månson
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  ABSTRACT: Highly concentrated planar fibre-bundle suspensions with a transparent PMMA matrix were processed with various initial bundle contents and orientations. They were submitted to simple compression and plane strain compression deformation modes. First rheological measurements are presented. They highlight the role of the bundle content and orientation on recorded stress levels. The transparent matrix allows the observation of fibrous microstructures before and after compressions: The in-plane deformation of bundles (flattening and bending) as well as the evolution of their orientation are analysed and discussed.
  Rheologica Acta 04/2012; 46(5):639-651. · 2.03 Impact Factor
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  Available from: Laurent Orgéas

  Article: Separation of the polymer matrix and the fibrous reinforcement during compression moulding of Glass Mat Thermoplastics (GMT)

  Laurent Orgéas, Pierre J. J. Dumont, Véronique Michaud, Denis Favier
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  ABSTRACT: Homogeneous plane strain compression tests were performed on standard industrial GMT composites using a channel mould at 200°C. A charring and weighting technique was used to determine the fibre concentration after the compression experiments. Experimental results emphasise the influences of the initial length of samples, the compression elongation and axial strain rate on the fibre-matrix separation phenomenon.
  International Journal of Material Forming 04/2012; 1:929-932.