Magnetization dynamics of elastically strained nanostructures studied by coupled micromagnetic-mechanical simulations

Elastically strained ferromagnetic objects have been studied by coupled micromagnetic-mechanical numerical simulations. Both temporal evolution of the magnetization and modal frequency analysis of ferromagnetic thin films and arrays of nanostructures are presented. For this purpose, we have numerically coupled the micromagnetic equations (including magnetoelastic effects) to the ones of solid mechanics by including periodic boundary conditions. Our approach has been evaluated first on an elastically strained thin film and validated by performing in situ ferromagnetic resonance experiments. We have undertaken simulations on nanostructured arrays (modulated arrays of nanowires) and show that the heterogeneity of the strain fields and magnetic mode profiles of those strained nanostructures induce significative disparities in the magnetic mode energies, allowing applications to be foreseen where one could control in a differentiated way the spin-wave energies as a function of the applied elastic strains

The effect of the process on mechanical properties of polylactic acid - date palm leaf fibers composite films produced by extrusion blowing

Biocomposite films prepared with melt compounding and film blowing have become a new trend in plastic research to deliver more eco-friendly packages. Polylactic acid (PLA) was melt compounded with minimally processed date palm leaf fiber (DPLF) and converted into films by blown film extrusion. The compounding was done in order to enhance the film mechanical properties in one hand, and to decrease the film production cost in the other hand. In this present study, a reference PLA film and films with 1%, 2%, and 5% of DPLF (weight %) were produced with different process parameters. The spatial variations in films thickness and lay flat width indicate that the addition of DPLF up to 2% enhances the bubble stability for the tested process parameters. However, the composite with 5% DPLF shows nearly the same processability window as the neat PLA. The structural and mechanical characterizations of films suggest a reinforcing effect of the PLA matrix up to 2% of fiber (with an optimum at 1%). Larger DPLF loading leads to depressed and more anisotropic mechanical properties, related to an increased density of defects at the fiber-PLA fragile interface and to a DPLF-induced enhanced PLA thermal degradation and amorphous phase orientatio

Modélisation de fissures elliptiques internes par hybridation de fonctions de poids

Une méthode améliorant le calcul des facteurs d'intensité de contrainte par hybridation de deux fonctions de poids est présentée et appliquée aux cas de fissures elliptiques internes sous différents chargements. L'hybridation consiste à utiliser l'une ou l'autre des deux fonctions dans la zone de la fissure où la fonction est la plus efficace. La délimitation des deux zones est faite après optimisation du rapport des axes et du rayon de courbure de la fissure. Lors de l'optimisation on cherche à atténuer l'effet des singularités présentes dans les fonctions de poids et à mieux prendre en compte l'influence de la courbure de l'ellips

Computation of stress intensity factor in cracked plates under bending in static and fatigue by a hybrid method

A hybrid weight-function technique is presented. It consists of dividing an elliptical crack into two zones, then using the appropriate weight function in the area where it is more efficient. The proportion between zones is determined by optimizing two crack parameters (axis ratio and curvature radius). Stress intensity factors for plates containing elliptical and semi-elliptical cracks are hence computed by a self developed computer code. Static and fatigue loadings of bending are considered. The results found by the present approach are in good correlation with the analytical solutions (when vailable) as well as with those of other researcher

Comment on “Ultralow magnetostrictive flexible ferromagnetic nanowires” by G. Muscas, P. E. Jönsson, I. G. Serrano, Ö. Vallin, and M. V. Kamalakar, Nanoscale , 2021, 13 , 6043–6052

International audienceA strain field ( ε xx ) in Ti/Co/Al nanowires on the PEN substrate subjected to uniaxial stress. The applied stress perpendicular to the nanowire length leads to very low strain in nanowires (about 30 times lower than the macroscopic strain)

Supersonic flutter study of porous 2D curved panels reinforced with graphene platelets using an accurate shear deformable finite element procedure

International audienc

Fatigue growth of embedded elliptical cracks using paris-type law in a hybrid weight function approach

A hybrid weight function method (HWFM), improving the calculation of the stress intensity factor (SIF) in mode I, has recently been proposed and validated in the static case [B.K. Hachi, S. Rechak, M. Haboussi, M. Taghite, Modélisation des fissures elliptiques internes par hybridation de fonctions de poids, C. R. Mecanique 334 (2006) 83–90]. In the present Note, the hybridization approach is presented for the fatigue crack growth prediction of embedded elliptical crack in infinite bodies. Hence, Paris’s law of crack propagation is incorporated into the developed hybridization-based computer code, along with two degrees of freedom technique for managing the crack evolution and the cracked structure fatigue life. Simulations of the evolution of elliptical cracks (in infinite bodies) of different configurations (ellipse axes ratio, maximum crack advance) corresponding to fatigue and brittle fracture have been conducted. Comparisons with other numerical methods such as the classical weight function method (WFM) or the extended finite element methods (X-FEM) show the pertinence of the HWFM in the treatment of an aspect of fatigue cracking problem

Analysis of elliptical cracks in static and in fatigue by hybridization of green’s functions

A hybrid weight function technique is presented. It consists of dividing an elliptical crack into two zones, then using the appropriate weight function in the area where it is more efficient. The proportion between zones is determined by optimizing two crack parameters (axis ratio and curvature radius). Stress intensity factors are hence computed by a self developed computer code. Static and fatigue loadings are considered. The results found by the present approach are in good correlation with the analytical and experimental solutions (when available) as well as with those obtained numerically by other researcher

Improvement of a four-implant retained bridge for totally edentulous patients

36th Congress of the Society-of-Biomechanics, Besancon, FRANCE, AUG 31-SEP 02, 2011International audienc