Virtual design of electrospun-like gelatin scaffolds: The effect of three-dimensional fibre orientation on elasticity behaviour

Remarkable mechanical performance of biological tissues is explained by a hierarchical fibrous structure. Designing materials that have similar properties is challenging because of the need to assess complex deformation mechanisms. In order to shed more light on architectural possibilities of biopolymer fibrous networks, we propose a numerical study that relates the fibre arrangement to the elastic modulus of a gelatin scaffold obtained using electrospinning. The adopted approach is based on the virtual designing of scaffolds using all possible combinations of Euler angles that define fibre orientations including preferable alignment. The generated networks are converted into a finite element model and the predicted elastic behaviour is examined. Predictions show that the fibre alignment achieved experimentally in biopolymer fibrous networks is for most of the fibres exhibiting an orthotropic behaviour. Some particular combinations of Euler angles allow transverse isotropic architectures while only limited cases are isotropic. A large sensitivity of Young's moduli to Euler angles is achieved describing multiple scenarios of independent anisotropic behaviours. An anisotropy ratio of the elastic behaviour is suggested based on a suitable combination of elastic moduli. Such a ratio exhibits a wide variation depending on individual and coupled effects of Euler angles. The finite element model predicts 2D, 3D and 4D maps representing all possible configurations of fibre alignment and their consequences on elastic behaviour. The predicted fibre orientation representing the observed anisotropic behaviour of electrospun gelatin networks demonstrates unbalanced contributions of in-plane and out-of plane fibres for a large range of processing conditions

Virtual design of electrospun-like gelatin scaffolds: the effect of three-dimensional fibre orientation on elasticity behaviour

International audienceRemarkable mechanical performance of biological tissues is explained by a hierarchical fibrous structure. Designing materials that have similar properties is challenging because of the need to assess complex deformation mechanisms. In order to shed more light on architectural possibilities of biopolymer fibrous networks, we propose a numerical study that relates the fibre arrangement to the elastic modulus of a gelatin scaffold obtained using electrospinning. The adopted approach is based on the virtual designing of scaffolds using all possible combinations of Euler angles that define fibre orientations including preferable alignment. The generated networks are converted into a finite element model and the predicted elastic behaviour is examined. Predictions show that the fibre alignment achieved experimentally in biopolymer fibrous networks is for most of the fibres exhibiting an orthotropic behaviour. Some particular combinations of Euler angles allow transverse isotropic architectures while only limited cases are isotropic. A large sensitivity of Young's moduli to Euler angles is achieved describing multiple scenarios of independent anisotropic behaviours. An anisotropy ratio of the elastic behaviour is suggested based on a suitable combination of elastic moduli. Such a ratio exhibits a wide variation depending on individual and coupled effects of Euler angles. The finite element model predicts 2D, 3D and 4D maps representing all possible configurations of fibre alignment and their consequences on elastic behaviour. The predicted fibre orientation representing the observed anisotropic behaviour of electrospun gelatin networks demonstrates unbalanced contributions of in-plane and out-of plane fibres for a large range of processing conditions

Neural computation analysis of alumina-titania wear resistance coating

Pin-on-disc tests were performed on alumina–13 wt.% titania coatings obtained under several APS conditions. Friction coefficient data were analysed using artificial neural network. This permitted to predict parameter ranges for which good wear resistance is possible when varying each of the process parameters individually with respect to a reference condition. In this case, results suggest that large parameter ranges did not permit to obtain a significant friction coefficient variation which was mainly between 0.51 and 0.61. In addition, injection parameters and total plasma gas flow rate were the control factors

Amplification des effets des explosions sous l'effet du rayonnement thermique

National audienceLes explosions de poussières affectent tout le tissu industriel avec souvent, des conséquences désastreuses. De nombreux progrès ont été accomplis lors de ces dernières décennies dans la compréhension et la modélisation de ce type d'explosion en démontrant par exemple les similitudes qu'il peut y avoir avec les explosions de gaz. Mais on s'interroge sur le comportement des fines poussières métalliques capables d'engendrer des explosions extrêmement puissantes. L'objectif du projet RADIAN, soutenu par la région Picardie, est de découvrir la raison de la violence de ces explosions. Dans cette communication, on propose d'identifier à l'aide de quelques observations expérimentales l'importance potentielle du rayonnement thermique dans les processus de propagation des flammes dans des nuages d'air et de particules d'aluminium et d'imaginer, à l'aide de modèles théoriques quel pourrait être le comportement d'une flamme dominée par le rayonnement thermique. L'incidence de la taille des particules est discutée. On montre en particulier que des régimes d'explosion atypiques sont possibles contre lesquels les moyens de protection habituels pourraient bien être inopérants

Viscoelasticity properties of biopolymer composite materials determined using finite element calculation and nanoindentation

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