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71.
Antoine Le Duigou Jean-Marc Deux Peter Davies Christophe Baley 《Applied Composite Materials》2012,19(3-4):363-378
In the present paper the environmental impact of biocomposites and bio-sandwich materials production are evaluated, using simplified Life Cycle Analysis (LCA) following the procedure recommended in the ISO 14044 standard. The materials are dimensioned and evaluated by comparing with reference materials, glass mat reinforced unsatured polyester and glass mat/unsatured polyester/balsa sandwich. The results indicate that bio-sandwich materials are very attractive in terms environmental impact. However further improvements in biocomposite and bio-sandwich mechanical strength are necessary if they are to be used in transport application compared to glass/polyester and glass/polyester/balsa sandwich. 相似文献
72.
A priori checking inconsistencies among strategic constraints for assembly plan generation 总被引:1,自引:1,他引:0
Christophe Perrard Eric Bonjour 《The International Journal of Advanced Manufacturing Technology》2012,63(5-8):817-838
This paper is related to the field of assembly plan generation. It describes a new approach to a priori check the consistency of an assembly strategy that is given by the assembly system designers before running an assembly plan generation algorithm. The aim of this work is to improve the assembly plan designer’s efficiency by reducing the research space while proving the existence of acceptable solutions. The assembly strategy combined with the product’s model implies a set of constraints on the assembly processes. The proposed method determines whether the given assembly strategy produces possible assembly processes. In case of inconsistencies among the strategic constraints, the method will help the designer to identify the contradictory constraints. The set of constraints can be expressed by a Boolean equation. First we present the key concepts and models related to the product, processes, and added values in the field of assembly plan generation. Second we define existing strategic constraints, and propose three new ones and a classification of strategic assembly constraints. The originality of the proposed method consists in defining an elementary strategic constraint that is used to describe every other constraint. The proposed method leads to model an assembly strategy by a single Boolean equation that is used to check the inconsistencies. An industrial case study is provided to highlight and to demonstrate the interests of this approach. 相似文献
73.
74.
In high-speed rolling element bearings, the drag forces can be prominent and it is demonstrated in this investigation that the classical models may not be appropriate for correctly estimating this power loss contribution. A modification of the models is thus proposed, including the usual drag forces formulation relying upon the drag coefficient to be evaluated from a numerical computational fluid dynamics (CFD) approach. A three-dimensional approach that considers both the rings and the cylinder ends seems the only adequate approach to be used because a two-dimensional approach predicts a drag coefficient value that is too low. When using the former computed drag coefficient for the evaluation of the total power losses, high values of oil volume fraction must be employed to recover the measured power losses. 相似文献
75.
Joseph R. Carazzone Christophe L. Martin Zachary C. Cordero 《Journal of the American Ceramic Society》2020,103(9):4754-4773
Cracking during sintering is a common problem in powder processing and is usually caused by constraint that prevents the sintering material from shrinking in one or more directions. Different factors influence sintering-induced cracking, including temperature schedule, packing density, and specimen geometry. Here we use the discrete element method to directly observe the stress distribution and sinter-cracking behavior in edge notched panels sintered under a uniaxial restraint. This geometry allows an easy comparison with traditional fracture mechanics parameters, facilitating analysis of sinter-cracking behavior. We find that cracking caused by self-stress during sintering resembles the growth of creep cracks in fully dense materials. By deriving the constrained densification rate from the appropriate constitutive equations, we discover that linear shrinkage transverse to the loading axis is accelerated by a contribution from the effective Poisson's ratio of a sintering solid. Simulation of different notch geometries and initial relative densities reveals conditions that favor densification and minimize crack growth, alluding to design methods for avoiding cracking in actual sintering processes. We combine the far-field stress and crack length to compute the net section stress, finding that it characterizes the stress profile between the notches and correlates with the sinter-crack growth rate, demonstrating its potential to quantitatively describe sinter-cracking. 相似文献
76.
Rositi Hugo Appadoo Owen Kevin Mestre Daniel Valarier Sylvie Ombret Marie-Claire Gadea-Deschamps Émilie Barret-Grimault Christine Lohou Christophe 《Multimedia Tools and Applications》2021,80(2):1945-1967
Multimedia Tools and Applications - Microsoft has recently released a mixed reality headset called HoloLens. This semi-transparent visor headset allows the user who wears it to view the projection... 相似文献
77.
78.
Optimization campaigns, which are being launched more and more often, require the execution of many parametric studies which
can make the approach very costly in terms of computation time. Here, in order to reduce these computation times, we undertake
to develop a multiparametric strategy using the LATIN method along with Proper Generalized Decomposition. This approach is
compared to other common strategies, especially those based on POD. 相似文献
79.
Brahim Bchir Souhail Besbes Romdhane Karoui Michel Paquot Hamadi Attia Christophe Blecker 《Food and Bioprocess Technology》2012,5(3):999-1009
Pomegranate seeds were osmodehydrated using date juice added with sucrose (final °Brix, 55) as immersion solution. The kinetics
of osmotic dehydration showed that the most significant changes of mass transfer took place during the first 20 min of the
process, regardless of date juice varieties. During this time, seed water loss and solid gain were estimated to be ∼39% and
∼6%, respectively. After 20 min of the process, the percentage of water loss and solid gain varied slightly and ranged on
average close to ∼40% and ∼9%, respectively. During osmotic dehydration, there was a leaching of natural solutes from seeds
into the solution, which is quantitatively not negligible, and might have an important impact on the sensorial and nutritional
value of seeds and date juices. Both scanning electron microscopy and texture (compression) analysis revealed that osmotic
dehydration process induced modifications of seed texture and cell structure. Sucrose was found to be the essential element
which influences the texture of seed and the viscosity of date juice. Additionally, natural sugar present in date juice permits
substituting 35% of the total quantity of sucrose added to the osmotic solution. 相似文献
80.
Experimental Data Highlighting the Role of Surface Fracture Energy in Quasi-Static Confined Comminution 总被引:1,自引:0,他引:1
Carlos Ovalle Christophe Dano Pierre-Yves Hicher 《International Journal of Fracture》2013,182(1):123-130
Since the pioneering work of Griffith, Linear Elastic Fracture Mechanics has been widely experimentally validated and successfully developed in solid mechanics modeling. However, recent theoretical models applying the energy balance found in Griffith theory specifically for quasi-static confined comminution have until now not been systematically confronted to experiments. In this study, we analyze data of compression tests on crushable sand, where grain breakage has been triggered by flooding the initially dry material at constant stresses. We consider a partition of the dissipation between surface fracture energy and the rearrangement of fragments and grains surrounding crushed particles. Our results show that the role of the surface fracture energy is stressdependent and that its influence becomes less significant at high stresses. 相似文献