Gregory Chagnon

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In-vivo characterization of soft tissue is a key step towards accurate biomechanical simulation enabling planning and intra-operative assisted surgery. This chapter presents the new version of LASTIC, a device measuring soft tissue deformations using a negative pressure. Its capabilities are compared with standard tensile tests on five samples with(More)
This paper reports on the development of a new network alteration theory to describe the Mullins e%ect. The stress-softening phenomenon that occurs in rubber-like materials during cyclic loading is analysed from a physical point of view. The Mullins e%ect is considered to be a consequence of the breakage of links inside the material. Both 8ller-matrix and(More)
In this paper, the static interaction forces between a medical needle and soft tissue during CT (Computerized Tomography) guided insertion are studied. More precisely a set of linearly independent elements describing the forces (a basis) is identified. This forms a generic basis from which any forces that act on a static needle (that is not fixed at its(More)
The present paper reports and rationalizes the use of Continuum Damage Mechanics (CDM) to with isotropic damage is considered. Since it is demonstrated that stress-softening is not strictly speaking a damage phenomenon, the limitations of the CDM approach are highlighted. Moreover, connections with two-network-based constitutive models proposed by other(More)
Many rubber like materials present a phenomenon known as Mullins effect. It is characterized by a difference of behavior between the first and second loadings and by a permanent set after a first loading. Moreover, this phenomenon induces anisotropy in an intially isotropic material. A new constitutive equation is proposed in this paper. It relies on the(More)
Drawing process of thin walled tubes used to fabricate catheters and stents for medical applications was studied. Medical use needs accurate dimensions and a smooth finish of the inner and outer surfaces. This paper deals with 316L stainless steel tubes which are manufactured by means of cold drawing with or without inner plug (mandrel drawing and hollow(More)
The present paper demonstrates that the Hart-Smith constitutive model and the more recent Arruda and Boyce eight chains and Gent constitutive models are closely related. The ability of these three models to predict both small and large strain responses of rubbers is highlighted and equations that relate their material parameters are established.(More)
LASTIC is a device estimating in vivo soft tissue elasticity. It uses negative pressure to deform the tissue surface and captures several deformation stages to trace the behavioral curve. Using Finite Element inverse analysis and a Neo Hookean constitutive law, the tissue’s Young modulus is evaluated. This paper compares LASTIC capabilities with standard(More)
Cold tube drawing is a metal forming process which enables to produce tubes with high dimensional precision. It consists in reducing tube dimensions by pulling it through a die. Tube outer diameter is calibrated by a die and the tube inner diameter and thickness are calibrated by a mandrel. One of the major concern of metal forming industry is the constant(More)
Architectured membranes can be developed in order to mimic living tissues. The main point is to generate anisotropic membranes that can endure large deformations. In this way, crenellated membranes are elaborated with a filled silicone rubber. The aim of this work is to develop a constitutive equation which describes the mechanical behavior of such(More)