" Sample cutting is an important minimally invasive medical procedure. Currently there are several types of medical devices used to cut a distal biological sample, for example, a video endoscope and TurboHawk Plaque Excision Systems. Directional Atherectomy (DA) with the TurboHawk Plaque Excision Systems is a catheter-based, minimally invasive treatment method for peripheral arterial disease (PAD). During a procedure, a catheter is directed toward an area of plaque buildup to remove the plaque from the body, restoring blood flow (Covidien, 2013). Endoscopy is an important procedure used in the medical field to study and diagnose different parts of a body without the need to undergo a major surgery. The major devices are a video endoscope with a flexible or rigid insertion tube and endoscopic therapy devices. Arrays of the devices, through the instrument channel in the insertion tube of endoscopes, to perform a variety of functions are offered. The biological sample cut is one of the important endoscopic therapies. Both of Directional Atherectomy and endoscopy procedures require a power transmission from the proximal tip of device to the distal end, where the cutter is located, for cutting a sample. However, the working length is up to meters, and the diameter of the devices is in millimeter scale in the minimally invasive surgery. Thus enough power transmitting to the distal end of the device for the biological sample cutting is crucial. This research presents the effort toward the investigation of the potential power mechanisms from the proximal tip to the cutter at the distal end of the device for rapid rotational cutting motion to improve the cutting efficiency and accuracy. In this thesis, the potential powering mechanisms including fluid, electrical, and torque coils are investigated. Since the transmission power is used for a rotational cutting action, and the cutting geometry has influence on the cutting power, thus this research also focuses on the analysis of the cutting geometry for the rotational sample cutting. The Hertz contact theory and von Mises yield criterion are used to find the influence of tool geometry on the material removing process, as well as Abaqus, a commercial FEM software, is used for the finite element analysis. Fiber-reinforced composite structures are the main characteristic of the representative biological sample, and their mechanical behavior is strongly influenced by the concentration and structural arrangement of constitute such as collagen and elastin. Researches show that the biological sample, for example, a soft biological sample, has hyperelastic properties and behave anisotropically, and there are a few publications about the plastic properties and cutting mechanics. Thus a linear elastic and linear plastic material model is defined for the finite element analysis of material removal. The analytical results and finite element results both show that as the tool rake angle increases or the tool angle decreases, the magnitude of cutting force decreases. A preliminary representative sample cutting experiment was conducted, and standard cutters with different cutting geometries were tested in order to find the characteristic of the biological sample cutting and the influence of tool geometry on the required cutting power. The experiments reveal the same conclusions as the analytical and finite element results. "

Les composites utilisés dans l'industrie aéronautique sont hétérogènes. Ils sont composés d'une matrice polymère souple et ductile et d'un renfort dur et fragile. Les différentes phases ainsi que l'anisotropie du matériau peuvent rendre l'usinage de ces matières, difficile. Deux problèmes majeurs peuvent être rencontrés lors de l'usinage : garder l'intégrité de la matière usinée et réduire l'usure de l'outil de coupe. Les niveaux de qualité demandés dans le secteur aéronautique imposent une coupe sans défaut, ces derniers pouvant entrainer une altération ultérieure de la pièce. Les principaux défauts rencontrés sont : le délaminage des plis, la surchauffe de la résine, les plis non coupés francs ou l'écaillage. / Aeronautic composites are inhomogeneous and most often consist in two distinctly phases. The reinforcement fibres are relatively hard and brittle whereas the matrix is soft and ductile. The anisotropy causes some severe challenges when machining composites. People in the field often experience a trade-off between two main problems ; on one hand, keeping the composite parts integrity and quality, and on the other hand, reducing the wear of the cutting tools. The quality level required in aeronautic applications imposes a high quality cut of machined parts. Common defects that may occur during machining of these materials are delamination, overheat of the resin, uncut fibres, and fibre pull-out.

Le micro-fraisage (diamètre fraise < 1 mm) permet l’usinage précis de structures en 3D, à des dimensions micrométriques, dans desmatériaux d’ingénierie, se plaçant aux frontières de deux mondes : d’une part, le fraisage traditionnel appelé « fraisage macro » et d’autre part,la micro-fabrication et ses techniques dites de « salle blanche ».L'étude innovante porte sur le micro-fraisage d’aciers inoxydables 316L avec des micro-fraises cylindriques en carbure de tungstèneavec un équipement industriel (machine outil commercialisée et non optimisée) permet d’accentuer les nombreuses difficultés technologiquesliées à la mise en oeuvre du micro-fraisage et d’effectuer directement un transfert de compétences vers l’industrie. L’acier 316L(biocompatible, réputé de difficilement usinable) n’a jamais été étudié en micro-fraisage.L’étude aborde, au travers de neufs ratios caractéristiques du micro-fraisage, les problématiques de choix de moyens et de méthodespour caractériser la technique du micro-fraisage.Après analyses des paramètres de l’étude et des caractérisations des usinages, la définition géométrique optimale d’une micro-fraiseinnovante est proposée. Sa tenue en service est validée par des tests en usinage dans l’acier 316L, répondant ainsi, à une problématique decoupe négative à basse vitesse de coupe avec des effets d’échelle du matériau.Une originalité de l’étude est d’aborder l’effet de la population inclusionnaire visant à améliorer l’usinabilité. En comparant lesrésultats obtenus par micro-fraisage de 2 nuances d’acier 316L, la population inclusionnaire de l’acier 316L n’est pas identifiée comme unfacteur améliorant l’usinabilité à l’échelle de la coupe micro. / The micro-milling ( tool diameter < 1 mm) target the precise machining of 3D structures to micrometric dimensions, in engineeringmaterials, to be placed at the borders of two worlds : the one hand , the traditional milling called "macro milling" and other hand, the microfabricationand its so-called "clean room" techniques.The innovative study focuses on the micro-milling of 316L steel with carbide micro end mills with industrial equipment (machine toolmarketed unoptimized) can caricature the many technological challenges related to the implementation of the micro-milling and make a directtransfer of skills to the industry. 316L steel (biocompatible, reputed difficult to machine) has never been studied in micro-milling.The study looks at ratios through new features of the micro-milling, the problems of choice of means and methods to characterizemicro-milling.After analysis study parameters and machined parts, the optimal geometric definition of an innovative micro end mill is proposed.Service behavior is validated by testing machining in 316L steel, responding to a question of negative cutting with low cutting speeds andscale effects of the material.An originality of the study is to address the effect of the inclusion population to improve machinability. Comparing the resultsobtained by micro-milling two 316L steel grade, the inclusion population of 316L steel is not identified as a factor improving themachinability cutting at micro scale.