Search results for " mechanics."
showing 10 items of 5002 documents
Prédiction de cycle et stratégie de gestion énergétique basée sur une méthode d’optimisation globale
2017
International audience; La nécessité de prédire le cycle de conduite d’un automobiliste afin d’améliorer sa gestion énergétique et ainsi réduire la consommation de carburant a été démontré (Debert, Quigley). Dès lors, il serait aisé d’appliquer une méthode d’optimisation globale, telle que la Programmation Dynamique (DP en anglais), pour obtenir la stratégie optimale. Cette méthode est déjà utilisée dans de nombreuses applications (Sciarretta), mais au quotidien nombreux sont les facteurs environnants qui peuvent perturber les conditions de circulation (météo, travaux, accidents....) et impacter le cycle de conduite. Il est donc nécessaire d’élaborer une stratégie adaptative en temps réel. …
A few remarks about the computer implementation and the verification of some hyperelastic constitutive laws and an illustration with the mechanical r…
2022
In this short technical note, we are interested in the constitutive equations used to model macroscopically the mechanical function of soft tissues under mechanical loading. Soft tissues have the ability to undergo large elastic reversible deformations under quasi-static loading and are usually modelled using hyperelastic constitutive laws. Several constitutive equations have been defined in the literature by means of strain components or strain invariants isotropic hyperelastic models. This short technical note recalls how to derive the weak form for hyperelasticity equations, and how this weak form can be linearized. It also presents a semi-analytical solution for a simplified geometry re…
Modelling an Improved NOL Ring Test Using a Reduced Volume Method for the Characterisation of Composite Cylinders
2019
International audience
YETI: YET another Iga code
2023
YETI is a library offering an implementation of IsoGeometric Analysis based on NURBS and B-Splines. It is published under the GNU Lesser General Public Licence and comes in the form of a Python library allowing the user to enter the input data of a NURBS arametrization (as a text file inspired from Abaqus input files syntax). Stiffness and mass matrices and right hand side vector are computed to form linear systems for solving mechanical or thermal problems. Solid or Kirchhoff-Love shell elements are available.In the context of shape optimization, a NURBS parametrization can be set up with design variables based on control points position. YETI can compute the analytical sensitivities [1] o…
The Numerical Challenges in Multiphysical Modeling of Laser Welding with ALE
2018
International audience
Modélisation numérique de structures composites réparées par collage de patchs externes en traction
2014
National audience; Request PDF on ResearchGate \textbar On Dec 30, 2014, Lingling Peng and others published Modélisation numérique de structures composites réparées par collage de patchs externes en traction
Analyse numérique de structures sandwichs viscoélastiques et modèle à dérivées fractionnaires
2019
The work deals with the free vibration problem of sandwich structures with a viscoelastic core. Zener model with fractional derivatives with four parameters is used to describe the viscoelastic behaviour. The fractional law is implemented in a numerical tool based on the Ritz method and a variable kinematics approach which is particularly adapted for sandwich plate modelling, the Sublaminate Generalized Unified Formulation (SGUF). The non-linear eigenvalue problem that arises from the frequency dependence of the viscoelastic properties is solved using an iterative algorithm. The approach is validated on several examples consisting of viscoelastic sandwich beam and plate structures, includin…
Excitons in few-layer hexagonal boron nitride: Davydov splitting and surface localization
2018
Hexagonal boron nitride (hBN) has been attracting great attention because of its strong excitonic effects. Taking into account few-layer systems, we investigate theoretically the effects of the number of layers on quasiparticle energies, absorption spectra, and excitonic states, placing particular focus on the Davydov splitting of the lowest bound excitons. We describe how the inter-layer interaction as well as the variation in electronic screening as a function of layer number $N$ affects the electronic and optical properties. Using both \textit{ab initio} simulations and a tight-binding model for an effective Hamiltonian describing the excitons, we characterize in detail the symmetry of t…
Pull-off adhesion of hybrid glass-steel adhesive joints in salt fog environment
2016
The aim of this paper was to evaluate the durability behaviour of glass/steel adhesive joints exposed to salt fog environmental conditions for ten weeks, according to ASTM B117 standard. To this scope, pull-off mechanical tests were carried out in order to evaluate the performances evolution and damage phenomena of the adhesive joints during the ageing exposition. Two different types of adhesives were compared (i.e. epoxy and polyurethane ones). Moreover, the effects of the glass surface condition and the presence of a basalt mat layer within the adhesive thickness were evaluated. The mechanical performances were related with the occurred failure mechanisms. Epoxy-based joints showed higher…
The bending triad of the quasi-spherical top molecule SO2F2 in the 550 cm(-1) region
2006
International audience; The analysis of the v(3)/v(7)/v(9) bending triad of SO2F2 has been recently performed with the Watson's Hamiltonian up to octic terms employing 79 rovibrational parameters but including only the first order Coriolis interaction terms, fixed to ab initio values [H. Burger, J. Demaison, F. Hegelund, L. Margules, I. Merke, J. Mol. Struct. 612 (2002) 133-141]. Since SO2F2 is a quasi-spherical top, it can also be considered as derived from the SO42- sulfate ion. We have thus developed a new tensorial formalism in the O(3) > Td > C2v group chain [M. Rotger, V. Boudon, M. Loete, J. Mol. Spectrosc. 216 (2002) 297-307]. This approach allows a systematic development of rovibra…