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Giljean S.,CNRS Textile Mechanics and Physics Laboratory | Bigerelle M.,University of Valenciennes and HainautCambresis | Anselme K.,CNRS Mulhouse Institute of Materials Science
Scanning | Year: 2014

Summary In this study, two series of 11 samples of TiAl6V4 titanium alloy and 316L stainless steel have been polished in an isotropic manner at different levels in order to quantify the influence of biomaterial roughness on cell behavior. Topography was measured by a tactile profilometer and a multiscale analysis has been carried out. Human osteoblasts have been cultured on those samples. It appears that roughness has no reproducible effect on the cell behavior except an influence on cell orientation on the wider grooves. As a conclusion, biomaterial surface damage, in the roughness range between R a = 0.01 and 0.1 μm, has no influence on cell-adhesion mechanisms when roughness is isotropic and groove width is inferior to a critical value. SCANNING 36:2-10, 2014. © 2012 Wiley Periodicals, Inc. © Wiley Periodicals, Inc.

Gassmann V.,University of Strasbourg | Gassmann V.,Oklahoma State University | Knittel D.,University of Strasbourg | Pagilla P.R.,CNRS Textile Mechanics and Physics Laboratory | Bueno M.-A.,Oklahoma State University
IEEE Transactions on Control Systems Technology | Year: 2012

Flexible materials such as textiles, papers, polymers, and metals are transported on rollers during their processing. Maintaining web tension in the entire processing line under changing web speed is a key factor in achieving good final product quality. Many industrial applications use dancer position feedback to indirectly regulate tension. Although widely used in the industry, pendulum dancers (rotational motion of the dancer roller) have received very little attention in the literature compared to linear ones (translational motion). The lack of clearly identified controllers synthesis methods can thus be noticed, as industry typically uses hand-tuned decentralized PI controllers. An improved alternative based on $H \infty methods is proposed in this paper to provide a systematic framework. The focus in this study is the unwind section of a processing line that contains a pendulum dancer (PD). The nonlinear and linear phenomenological models of the unwind section containing the PD are discussed first. The position controller based on dancer position feedback is synthesized using the standard $H \infty approach with mixed sensitivity. Because of the high order of the controllers synthesized with this approach, techniques to generate reduced-order controllers are used to calculate a fixed-order controller resembling standard industrial practice. The performance of the proposed controllers is demonstrated by carrying out experiments on a large experimental web handling platform containing four driven rollers, many idle rollers, and a PD in the unwind section. To the best of our knowledge, these are the first published results of successful application of an $H \infty controller to a real plant containing a PD. © 2006 IEEE.

Giljean S.,CNRS Textile Mechanics and Physics Laboratory | Bigerelle M.,CNRS Roberval Laboratory (Mechanical Research Unit) | Anselme K.,CNRS Mulhouse Institute of Materials Science | Haidara H.,CNRS Mulhouse Institute of Materials Science
Applied Surface Science | Year: 2011

The relationship between wettability and roughness has been studied on micro-roughened titanium surface after different cleaning procedures. Whereas most studies addressing (super)-hydrophobic behaviors have so far dealt with the wetting of low surface energy and textured substrates in air environment, we here report on a totally novel system and configuration involving the wetting of highly hydrophilic, textured metallic materials in liquid alkane medium, the so-called two liquid phase method. Roughness characterization showed that substrates were isotropic (2D), at a lengthscale much smaller than the size of the drop, with a heterogeneous (vertical) distribution of peaks and valleys. Depending on whether the alkane that initially penetrates and resides in the pores is displaced or not by the water drop (as for air pockets in air environment), we show that different wetting regimes may appear, depending on the cleaning procedure. To our knowledge, this is the first systematic study dealing with the interplay between surface roughness, the wetting behavior and in particular the (super)-hydrophilicity of high surface energy substrates, in non water miscible liquid environments. Whenever competitive processes of liquid/liquid displacement are involved at such high surface energy and textured substrates, such as titanium implant in bone tissue, these results may contribute understanding and predicting their wetting behavior. © 2011 Elsevier B.V. All rights reserved.

Heim F.,CNRS Textile Mechanics and Physics Laboratory
The Journal of heart valve disease | Year: 2013

Percutaneous aortic valve implantation has become an alternative technique to surgical valve replacement in patients at high risk for open-chest surgery. Biological valve tissue is, however, a fragile material when folded for small-diameter catheter insertion purposes. Textile polyester is a less fragile material, and could be an alternative replacement for the valve leaflets. The dynamic performances obtained in vitro with a valve prosthesis made from textile have proven in previous studies to be satisfactory. However, as textile is a porous material the interaction processes between the fabric leaflet surfaces and living tissues remain unknown. The study aim was to discuss the fabric design criteria which are best suited to clinical application. An appropriate design provided strength, limited porosity and low bulk to the fabric, which was particularly suited for small-diameter catheter insertion purposes. The in-vivo behavior of a non-coated polyester textile valve prototype was then studied in the mitral position in a sheep model. The results showed that limited tissue ingrowth occurred, and Ca deposits tended to stiffen the fabric leaflets after a two-month implantation period, which was not compatible with the survival of the animal. The initial results obtained with this non-coated polyester textile valve confirmed that this revolutionary fabric is worthy of further investigation.

Henry P.,CNRS Textile Mechanics and Physics Laboratory | Pac M.-J.,CNRS Textile Mechanics and Physics Laboratory | Rousselot C.,University of Franche Comte | Tuilier M.-H.,CNRS Textile Mechanics and Physics Laboratory
Surface and Coatings Technology | Year: 2013

Microtribology experiments were carried out on a set of protective nanostructured Ti1-xAlxN (0≤x≤1) coatings, deposited by radio frequency magnetron reactive sputtering onto steel substrates and Si(100). Tests were carried out at room temperature using low applied loads and sliding velocities to prevent from surface oxidation. The surfaces were in contact against alumina to avoid the sticking of the counterpart, using a ball-on-disc reciprocating tribometer. Thus, these conditions allow the determination of the wear behaviour of the nitride layer itself. Film wear mechanisms were investigated from the evolutions of the friction coefficient and scanning electron microscopy observations. Moreover, two different models were used to characterise the coating according to x Al content: calculations of film fracture toughness KIC from microindentation tests and crack propagation resistance CPRs from scratch experiments. By X-ray diffraction, growth directions of the crystallised domains of the nanostructured films are analysed. Combining the results obtained from the different mechanical tests, the film damages caused by friction stresses are presented as a function of composition and micro-and nanostructure of the films, which play a crucial role in the functionality of coatings. The amount of wear debris generated by friction is directly linked to the coating crack initiation resistance. The nature of wear debris, i.e. ductile or brittle, acting as a third body, has a major influence on the evolution of the thin film damage.Al-rich films promote a preferred [001] crystallographic hcp orientation which has a large impact on the resistance to crack initiation and then the amount of debris generated by friction. Ti-rich coatings show better tribological properties due to a higher toughness and a higher elastic modulus. For Ti0.50Al0.50N, abrasive wear debris are generated after several friction cycles, leading to the progressive destruction of the coating. The main direction of Ti-rich films is along the fcc [100] axis, though some [111] crystallised domains grow in Ti0.62Al0.38N and Ti0.50Al0.50N. The former film which has less volume of [111] crystallised domains shows more satisfactory wear behaviour than Ti0.50Al0.50N. © 2013 Elsevier B.V.

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