29 research outputs found

    L’hypertrophie de la prostate et la rĂ©tention aiguĂ« d’urine : vers un stent urĂ©tral Ă  base de bio-matĂ©riaux NiTi et silicone

    No full text
    Acute urinary retention is the major complication of benign prostatic hyperplasia. Today, the first line treatment consists in emergency catheterization, which often leads to urinary infection. This thesis aimed at developing an innovative nitinol based stent as a alternative treatment for acute urinary retention. Using a combination of NiTi wires and tubes, this stent is given two distinct shape memories during heating. The stent components are mostly loaded under pure bending during the stent activation. A pure bending apparatus allowing large deformations on slender specimens was thus designed. This device gave access to the NiTi wires and tubes behaviour under pure bending, and also provided information about localization phenomena during pure bending experiment. A numerical method able to identify the shear-stress shear-strain function from experimental pure torsion tests, and the stress strain function under compressive load from experimental uni-axial tensile and pure bending tests was also eveloped. This method was applied using afore-obtained numerical results to identify the NiTi wires and tubes behaviour under uni-axial compressive load.La rĂ©tention aiguĂ« d’urine est la complication la plus grave de l’hyperplasie bĂ©nigne de la prostate. Elle est aujourd’hui traitĂ©e en urgence par cathĂ©tĂ©risation, ce qui expose le patient Ă  un important risque infectieux. Dans le cadre de cette thĂšse, un stent urĂ©tral innovant a Ă©tĂ© dĂ©veloppĂ© afin de remplacer la cathĂ©tĂ©risation. Ce stent utilise des Ă©chantillons filiformes d’alliage Ă  mĂ©moire de forme Nickel-Titane, lui confĂ©rant deux mĂ©moires deforme distinctes au chauffage, et permettant ainsi une pose et une ablation simplifiĂ©es. Afin de convenablement dimensionner les Ă©lĂ©ments constitutifs de ce stent, un dispositif permettant la rĂ©alisation d’essais de flexion pure Ă  haute dĂ©formation sur des Ă©chantillons de gĂ©omĂ©trie filiforme a Ă©tĂ© conçu. Ce dispositif a permis la caractĂ©risation de fils et tubes de NiTi en flexion pure, ainsi que l’étude du phĂ©nomĂšne de localisation qui est survenue lors de ces essais. Une mĂ©thode numĂ©rique permettant l’identification des lois de comportement matĂ©riau Ă  partir d’essais expĂ©rimentaux Ă  champ de contrainte non uniforme a Ă©tĂ© dĂ©veloppĂ©e. Cette mĂ©thode a notamment permis d’identifier le comportement en compression uni-axiale de fils et tubes de NiTi, Ă  partir de rĂ©sultats expĂ©rimentaux obtenus en flexion pure et en traction uni-axiale

    LUTS in case of BPH : a NiTi-Silicone based uretral stent as a solution

    No full text
    La rétention aiguë d'urine est la complication la plus grave de l'hyperplasie bénigne de la prostate. Elle est aujourd'hui traitée en urgence par cathétérisation, ce qui expose le patient à un important risque infectieux. Dans le cadre de cette thÚse, un stent urétral innovant a été développé afin de remplacer la cathétérisation. Ce stent utilise des échantillons filiformes d'alliage à mémoire de forme Nickel-Titane, lui conférant deux mémoires de forme distinctes au chauffage, et permettant ainsi une pose et une ablation simplifiées.Afin de convenablement dimensionner les éléments constitutifs de ce stent, un dispositif permettant la réalisation d'essais de flexion pure à haute déformation sur des échantillons de géométrie filiforme a été conçu. Ce dispositif a permis la caractérisation de fils et tubes de NiTi en flexion pure, ainsi que l'étude du phénomÚne de localisation qui est survenue lors de ces essais.Une méthode numérique permettant l'identification des lois de comportement matériau à partir d'essais expérimentaux à champ de contrainte non uniforme a été développée. Cette méthode a notamment permis d'identifier le comportement en compression uni-axiale de fils et tubes de NiTi, à partir de résultats expérimentaux obtenus en flexion pure et en traction uni-axiale.Acute urinary retention is the major complication of benign prostatic hyperplasia. Today, the first line treatment consists in emergency catheterization, which often leads to urinary infection. This thesis aimed at developing an innovative nitinol based stent as a alternative treatment for acute urinary retention. Using a combination of NiTi wires and tubes, this stent is given two distinct shape memories during heating.The stent components are mostly loaded under pure bending during the stent activation. A pure bending apparatus allowing large deformations on slender specimens was thus designed. This device gave access to the NiTi wires and tubes behaviour under pure bending, and also provided information about localization phenomena during pure bending experiment.A numerical method able to identify the shear-stress shear-strain function from experimental pure torsion tests, and the stress strain function under compressive load from experimental uni-axial tensile and pure bending tests was also developed. This method was applied using afore-obtained numerical results to identify the NiTi wires and tubes behaviour under uni-axial compressive load

    L’hypertrophie de la prostate et la rĂ©tention aiguĂ« d’urine : vers un stent urĂ©tral Ă  base de bio-matĂ©riaux NiTi et silicone

    No full text
    Acute urinary retention is the major complication of benign prostatic hyperplasia. Today, the first line treatment consists in emergency catheterization, which often leads to urinary infection. This thesis aimed at developing an innovative nitinol based stent as a alternative treatment for acute urinary retention. Using a combination of NiTi wires and tubes, this stent is given two distinct shape memories during heating. The stent components are mostly loaded under pure bending during the stent activation. A pure bending apparatus allowing large deformations on slender specimens was thus designed. This device gave access to the NiTi wires and tubes behaviour under pure bending, and also provided information about localization phenomena during pure bending experiment. A numerical method able to identify the shear-stress shear-strain function from experimental pure torsion tests, and the stress strain function under compressive load from experimental uni-axial tensile and pure bending tests was also eveloped. This method was applied using afore-obtained numerical results to identify the NiTi wires and tubes behaviour under uni-axial compressive load.La rĂ©tention aiguĂ« d’urine est la complication la plus grave de l’hyperplasie bĂ©nigne de la prostate. Elle est aujourd’hui traitĂ©e en urgence par cathĂ©tĂ©risation, ce qui expose le patient Ă  un important risque infectieux. Dans le cadre de cette thĂšse, un stent urĂ©tral innovant a Ă©tĂ© dĂ©veloppĂ© afin de remplacer la cathĂ©tĂ©risation. Ce stent utilise des Ă©chantillons filiformes d’alliage Ă  mĂ©moire de forme Nickel-Titane, lui confĂ©rant deux mĂ©moires deforme distinctes au chauffage, et permettant ainsi une pose et une ablation simplifiĂ©es. Afin de convenablement dimensionner les Ă©lĂ©ments constitutifs de ce stent, un dispositif permettant la rĂ©alisation d’essais de flexion pure Ă  haute dĂ©formation sur des Ă©chantillons de gĂ©omĂ©trie filiforme a Ă©tĂ© conçu. Ce dispositif a permis la caractĂ©risation de fils et tubes de NiTi en flexion pure, ainsi que l’étude du phĂ©nomĂšne de localisation qui est survenue lors de ces essais. Une mĂ©thode numĂ©rique permettant l’identification des lois de comportement matĂ©riau Ă  partir d’essais expĂ©rimentaux Ă  champ de contrainte non uniforme a Ă©tĂ© dĂ©veloppĂ©e. Cette mĂ©thode a notamment permis d’identifier le comportement en compression uni-axiale de fils et tubes de NiTi, Ă  partir de rĂ©sultats expĂ©rimentaux obtenus en flexion pure et en traction uni-axiale

    L'hypertrophie de la prostate et la rétention aiguë d'urine : vers un stent urétral à base de bio-matériaux NiTi et silicone

    No full text
    Acute urinary retention is the major complication of benign prostatic hyperplasia. Today, the first line treatment consists in emergency catheterization, which often leads to urinary infection. This thesis aimed at developing an innovative nitinol based stent as a alternative treatment for acute urinary retention. Using a combination of NiTi wires and tubes, this stent is given two distinct shape memories during heating.The stent components are mostly loaded under pure bending during the stent activation. A pure bending apparatus allowing large deformations on slender specimens was thus designed. This device gave access to the NiTi wires and tubes behaviour under pure bending, and also provided information about localization phenomena during pure bending experiment.A numerical method able to identify the shear-stress shear-strain function from experimental pure torsion tests, and the stress strain function under compressive load from experimental uni-axial tensile and pure bending tests was also developed. This method was applied using afore-obtained numerical results to identify the NiTi wires and tubes behaviour under uni-axial compressive load.La rétention aiguë d'urine est la complication la plus grave de l'hyperplasie bénigne de la prostate. Elle est aujourd'hui traitée en urgence par cathétérisation, ce qui expose le patient à un important risque infectieux. Dans le cadre de cette thÚse, un stent urétral innovant a été développé afin de remplacer la cathétérisation. Ce stent utilise des échantillons filiformes d'alliage à mémoire de forme Nickel-Titane, lui conférant deux mémoires de forme distinctes au chauffage, et permettant ainsi une pose et une ablation simplifiées.Afin de convenablement dimensionner les éléments constitutifs de ce stent, un dispositif permettant la réalisation d'essais de flexion pure à haute déformation sur des échantillons de géométrie filiforme a été conçu. Ce dispositif a permis la caractérisation de fils et tubes de NiTi en flexion pure, ainsi que l'étude du phénomÚne de localisation qui est survenue lors de ces essais.Une méthode numérique permettant l'identification des lois de comportement matériau à partir d'essais expérimentaux à champ de contrainte non uniforme a été développée. Cette méthode a notamment permis d'identifier le comportement en compression uni-axiale de fils et tubes de NiTi, à partir de résultats expérimentaux obtenus en flexion pure et en traction uni-axiale

    A method to determine the shear and compressive stress-strain curves from torsion and bending tests of thin wires

    No full text
    International audienceSome materials are provided as wire or other slender geometries and are commonly used as mechanical parts, especially in medical applications. If slender geometries are well adapted to quasi-static tensile tests, such geometries cannot be properly tested under shear and compressive loads. The shear and compressive stress-strain curves nevertheless remain of major interest to engineers and designers. This paper proves and illustrates that material shear and compressive stress-strain curves can eciently be extracted from torsion and bending tests on thin wires, even in noisy situations. The method is rst presented to analyze torsion tests. This method is then developed and adapted to extract the material compressive stress-strain curve from both pure bending and uni-axial tensile tests

    METHOD TO EXTRACT STRESS-STRAIN FUNCTIONS FROM PURE TORSION OR PURE BENDING EXPERIMENTAL TESTS

    No full text
    International audienceA mathematical methodology has been developed to extract stress-strain relations from pure torsion tests. This method has also been developed to extract the compression stress-strain relation from uniaxial and pure bending experimental tests. The extraction method has been experimentally tested on pure copper wire specimens; the extracted stress-strain relations proved to be fully satisfactory, validating thus the proposed method
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