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Tourlonias M.,CNRS Textile Mechanics and Physics Laboratory | Bueno M.-A.,CNRS Textile Mechanics and Physics Laboratory | Poquillon D.,Inter - University Research and Engineering Center on Materials
Composites Part A: Applied Science and Manufacturing | Year: 2017

The aim of this study conducted on carbon tows and single fibres is to highlight some friction behaviours to help better understand the friction mechanisms that occur during the manufacture of carbon composites. These mechanisms are responsible for damage that reduces the specifications and lifetime of mechanical parts. An experiment has been developed in order to rub together two carbon tows, or two single carbon fibres (with a diameter down to 5 µm), at an angle of 90°. The influences of friction velocity, normal load, and type of carbon fibre have been studied. For both tows and fibres the friction follows the Coulomb's law because there is no influence of the velocity and the normal load in the tested range. The rearrangement of fibres within the tow has been shown to be fundamental. For the single fibre, the role of the Young's modulus and the sizing treatment is important. © 2017 Elsevier Ltd

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.,University of Valenciennes and Hainaut‑Cambresis | 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.

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.

Bueno M.A.,CNRS Textile Mechanics and Physics Laboratory | Bocquet R.,CNRS Textile Mechanics and Physics Laboratory | Tourlonias M.,CNRS Textile Mechanics and Physics Laboratory | Rossi R.M.,Empa - Swiss Federal Laboratories for Materials Science and Technology | Derler S.,Empa - Swiss Federal Laboratories for Materials Science and Technology
Wear | Year: 2013

The surfaces of fibrous materials like textiles are characterised by emergent superficial fibres forming hairiness. Hairiness is an important factor for the frictional and tactile properties of fabrics. In this study, we investigated the friction mechanisms of hairy fabrics by sliding probes with varying geometry over the textile surfaces. The total friction between a hairy fabric and a cuboid-shaped slider is given by two main contributions-one due to the contact of hairs with the front of the slider and the other one resulting from the hairiness underneath the slider. By changing the slider geometry, the relative importance of these two contributions can be systematically varied, so that conclusions about adhesion and deformation mechanisms involved in the friction of hairy fabrics can be drawn. For a given slider area and a given normal load, the force underneath the slider was found to be independent of the slider width while the force in front of the slider increased linearly with the slider width. The major contribution of the force underneath the slider is highlighted. This force is influenced by the material and surface roughness of the slider, indicating that adhesion mechanisms play a significant role in the friction. © 2013 Elsevier B.V.

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.

Basit A.,CNRS Textile Mechanics and Physics Laboratory | L'Hostis G.,CNRS Textile Mechanics and Physics Laboratory | Durand B.,CNRS Textile Mechanics and Physics Laboratory
Materials Letters | Year: 2012

In this work, the multi shape memory effect is studied for two types of thermal active epoxy polymer composites. One of them is called the controlled behavior of composite material (CBCM) which has already been tested as an unsymmetrical active composite and the other one is the conventional symmetrical composite. The shape memory of these composites characterized by the value of the initial fixity is obtained through one-step programming cycle. During this cycle, the composites are heated to the fixity temperature above their thermal glass transition temperature. During the recovery step, by providing different lower recovery temperatures than the fixity temperature, the properties of multi-step positions are obtained. For a certain recovery temperature, the ability to conserve the corresponding positions is investigated for several cycles. For CBCM, contrary to symmetric composite, the coupling between its shape memory property and unsymmetrical constitution leads to a two-way bending actuator with two opposite positions. © 2012 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.

Khoffi F.,CNRS Textile Mechanics and Physics Laboratory | Heim F.,CNRS Textile Mechanics and Physics Laboratory
Journal of the Mechanical Behavior of Biomedical Materials | Year: 2015

Transcatheter aortic valve implantation (TAVI) has become today an increasingly attractive procedure to relieve patients from aortic valve disease. However, the procedure requires crimping biological tissue within a metallic stent for low diameter catheter insertion purpose. This step induces specific stress in the leaflets especially when the crimping diameter is small. One concern about crimping is the potential degradations undergone by the biological tissue, which may limit the durability of the valve once implanted. The purpose of the present work is to study the effect of low diameter crimping on the mechanical performances of pericardium valve prototypes. The prototypes were compressed to a diameter of 1. mm within braided stents for 20. min. SEM observations performed on crimped material show that crimped leaflets undergo degradations characterized by apparent surface defects. Moreover mechanical extension tests were performed on pericardium strips before and after crimping. The strips (15. mm long, 5. mm wide) were taken from both crimped and native leaflets considering 2 different valve diameters, 19 and 21. mm. In order to prevent the premature drying of the pericardium tissue during the procedure, the biological tissue was kept in contact with a formaldehyde solution. Results show that the ultimate strength value decreases nearly by up to 50%. The modifications observed in the material may jeopardize the long term durability of the device. However, further tests are necessary with a larger amount of samples to confirm these early results. © 2015 Elsevier Ltd.

Tourlonias M.,CNRS Textile Mechanics and Physics Laboratory | Bueno M.-A.,CNRS Textile Mechanics and Physics Laboratory
Composites Part A: Applied Science and Manufacturing | Year: 2016

Nowadays many mechanical composite parts are reinforced by carbon weaving material. During the weaving process some damage to the carbon yarns appears that decreases the final mechanical properties of the part. This study focused on the friction interactions that occurred between warp yarns. A specific kinematic experiment has been done in order to simulate the weaving movement of these yarns, which induces friction. By varying experimental parameters, initial normal load, oscillation frequency and oscillation angle, it is possible to understand their influence on friction phenomena and fibre damage. The energies induced during friction have also been studied. The results obtained show that the coefficient of friction decreases with the increase of normal load, but is not influenced by the oscillation frequency. Yarn wear, i.e. filament breaks, appears beyond a certain normal load. The friction energy increases with normal load and oscillating angle but does not depend on oscillation frequency. © 2015 Elsevier Ltd.