Le tolérancement inertiel, une autre façon d'intégrer l'aspect combinatoire dans les processus assemblés

International audienceNous proposons dans cette communication de remplacer la façon traditionnelle de tolérancer les caractéristiques mécaniques (Bipoint [min - Max]) par une nouvelle façon totalement originale : le tolérancement inertiel. Le principe consiste à tolérancer l'inertie des écarts par rapport à la cible. En tolérancement inertiel l'écart maximal par rapport à la cible n'est pas figé, il dépend du nombre de pièces que l'on réalise Cette nouvelle façon de tolérancer offre de très nombreux avantages sur le tolérancement classique, notamment dans les cas de mélanges de lots, de tolérancement de produits assemblés, de définition de la conformité... Couplé avec le nouvel indicateur de capabilité Cpi, ce tolérancement permet de réaliser le meilleur compromis entre la qualité des produits assemblés et le coût de production

Interaction between the fission yeast nim1/cdr1 protein kinase and a dynamin-related protein

AbstractThe nim1/cdr1 protein kinase is required for an efficient adaptation of cell cycle parameters to changes in nutritional conditions. We have isolated msp1, a new fission yeast member of the dynamin-related large GTPase family, in a two-hybrid screen designed to identify proteins interacting with the nim1 kinase. Msp1 has been shown to be essential for the maintenance of mtDNA and hence for the inheritance of functional mitochondria. We present evidence indicating that nim1 and msp1 proteins physically interact both in vitro and in vivo in fission yeast. These interactions occur through the amino-terminal catalytic domain of nim1 and the carboxy-terminal putative regulatory domain of msp1. These results provide new evidence for the existence of a connection between mitochondrial function and the cell cycle machinery

Impact damage evolution under fatigue loading by InfraRed Thermography on composite structures

This study deals with cumulative damage and its evolution in already impact damage composite structure. In order to follow the growing damage and to compare it with cumulative model, tests are monitored with an InfraRed thermography system. A carbon-epoxy composite is first low-energy impacted and then fatigued under tension-compression loading. This study also enables a very fast analysis of predicting the damage evolution coupling InfraRed Thermography as NDT method and InfraRed thermography as a following system

Fatigue behaviour of impacted composite structures

The aim of this study was to compare the mechanical behavior of different impact-damaged composite materials. Three composite materials were realized using the Liquid Resin Infusion process (LRI) accord- ing to three different cycles of polymerization. Thus the temperature of the glass transition of the resin was controlled and the influence of this parameter was then determined. In accordance with the aeronautical use of composite materials, the plates were subjected to Barely Visible Impact Damage (BVID). Two experimental methods were developed to ensure that impact condi- tions were respected. The first method, using the numerical digitalization of surfaces made it possible to reconstruct the defect. Thus the residual indentation could be measured. This indentation had to be lower than 0.3 mm. The second method, using passive infrared thermography, enabled the thermal cartography on the surface to be determined. The size of the damage area was then obtained. Through the use of these two methods, the best cycle of polymerization was determined and fatigue tests were carried out to estimate the evolution of the defect. For this purpose and in compliance with impact and fatigue testing standards, a new and adapted sample was imagined (FAI sample). The fatigue testing conditions were determined to avoid buckling effects and to limit the rise of the temperature of the sample. An experimental method using infrared thermography was then developed to follow the size evolution of the defect. This real time evolution was then compared to the loss of rigidity of the sample

The detection of aeronautical defects in-situ on composite structures using Non Destructive Testing

A study of three Non Destructive Testing methods (Ultrasonic Testing, InfraRed Thermography and Speckle Shearing Interferometry, known as Shearography) was carried out on different specific types of composite specimens having a variety of defects. The aim of this study is to evaluate the efficiency of these NDT methods in the detection of in-situ defects resulting from Barely Visible Impact Damages (BVID) or in-service damages to complex surfaces such as wings or rods. The size and position of all the defects were determined by GVI (General Visual Inspection): GVI being the reference. The evaluation of the three NDT techniques enabled conclusions to be drawn regarding defect detection and size. The first part of the study deals with determining and measuring defects. It appears that only the ultrasonic method enables the depth of a defect to be determined. In the second part of the study, the results obtained by the three NDT methods are compared. Finally, the feasibility and the time taken to set up the experimental protocol are analyzed. The study shows that all the defects were revealed by, at least, one of the three NDT methods. Nevertheless it appears that InfraRed Thermography and Shearography produced results very quickly (in about 10 s) compared to Ultrasonic Testing

The Purcell Three-link swimmer: some geometric and numerical aspects related to periodic optimal controls

International audienceThe maximum principle combined with numerical methods is a powerful tool to compute solutions for optimal control problems. This approach turns out to be extremely useful in applications, including solving problems which require establishing periodic trajectories for Hamiltonian systems, optimizing the production of photobioreactors over a one-day period, finding the best periodic controls for locomotion models (e.g. walking, flying and swimming). In this article we investigate some geometric and numerical aspects related to optimal control problems for the so-called Purcell Three-link swimmer [20], in which the cost to minimize represents the energy consumed by the swimmer. More precisely, employing the maximum principle and shooting methods we derive optimal trajectories and controls, which have particular periodic features. Moreover, invoking a linearization procedure of the control system along a reference extremal, we estimate the conjugate points, which play a crucial role for the second order optimality conditions. We also show how, making use of techniques imported by the sub-Riemannian geometry, the nilpotent approximation of the system provides a model which is integrable, obtaining explicit expressions in terms of elliptic functions. This approximation allows to compute optimal periodic controls for small deformations of the body, allowing the swimmer to move minimizing its energy. Numerical simulations are presented using Hampath and Bocop codes

Rhizosphere microbial community in intercropped durum wheat and faba bean as affected by phosphorus fertilizer history

The experiment was conducted in the long term P fertilizer trial of INRA research centre at Auzeville(43.5oN, 1.43oE) in south western France. The three P regimes corresponded to fertilizer levels applied since1968: P0 (no fertilization), P1 (fertilization rate to balance the mean annual P removal by crops) and P4(fertilization rate representing three-­‐ to four-­‐fold that of P1). Durum wheat and faba bean were grown aloneor as durum wheat/faba bean intercrops in this field trial. Their rhizospheres were collected at the faba beanflowering stage, as well as the corresponding bulk soils. Soil DNA and RNA were extracted in these varioussamples and qPCR was used to assess the number of gene copies of fungi, bacteria, as well as several bacterialphyla (Actinobacteria, α-­‐Proteobacteria and Firmicutes (strongly dominated with P-­‐cycling taxa)) and betapropeller phytase (BPP)

Les facteurs anthropiques de la dégradation des mangroves d’Angondjé, Okala et Mikolongo au nord du Grand Libreville

Dans la partie Nord du Grand Libreville, les quartiers Angondjé, Okala et Mikolongo connaissent une croissance démographique accompagnée d’une extension urbaine soutenue, et ayant des impacts sur les zones humides à mangroves. Considérée comme un danger écologique, la dégradation des mangroves dans ces milieux est due principalement aux activités anthropiques socio-économiques. Dans ces forêts à mangroves, les activités et les aménagements exercent des pressions humaines. La méthode de collecte des données et autres informations a fait appel respectivement, d’une part, sur le terrain à un guide d’observation directe et de caractérisation des activités socio-économiques, des prises de vues et l’utilisation d’un GPS et, d’autre part, la consultation des rapports divers et des documents cartographiques. Les données recueillies montrent que les activités tels que le bâti, le maraîchage, la pêche, la chasse et les manifestations de la pollution sont les facteurs de dégradation et déforestation des mangroves. Cette anthropisation problématique des milieux humides à mangroves se déroule dans un contexte d’étalement urbain favorisé par une urbanisation non maîtrisée, dans le nord du Grand Libreville.   In the northern part of Greater Libreville, the Angondjé, Okala and Mikolongo districts are experiencing demographic growth accompanied by sustained urban expansion, and having impacts on wetlands with mangroves. Considered an ecological hazard, the degradation of mangroves in these environments is mainly due to anthropogenic socio-economic activities. In these mangrove forests, activities and developments exert human pressures. The method of collecting data and other information called respectively, on the one hand, on the ground for a guide of direct observation and characterization of socio-economic activities, shots and the use of a GPS and, on the other hand, the consultation of various reports and cartographic documents. The data collected show that activities such as construction, market gardening, fishing, hunting and manifestations of pollution are the factors of degradation and deforestation of mangroves. This problematic anthropization of wetlands with mangroves takes place in a context of urban sprawl favored by uncontrolled urbanization, in the north of Greater Libreville

High-speed digital image correlation: application to bi-axial fatigue

To study the behavior of a carbon fiber reinforced plastic laminate under a bi-axial stress state, a new type of cruciform specimen has been developed. This specimen is loaded bi-axially under static and cyclic fatigue loadings. The experiments are monitored simultaneously using Digital Image Correlation with two High-speed cameras, and infrared thermography. A comparison between the measurements and finite elements model is used to validate the design of the sample