Pseudo inverse approach for cold forging processes and its comparison with adaptive incremental approach

La simulation numérique des procédés de mise en forme fortement non-linéaire nécessite souvent des méthodes numériques performantes. Les couts de calcul qui sont souvent important rende difficile l'utilisation d'un outil de simulation numérique dans une boucle d'optimisation. Nous proposons dans ce papier de simuler un procédé 2D axisymétrique de forgeage d'une roue en utilisant une approche pseudo-inverse et une approche MEF adaptive incrémentale. Ces deux approches seront ensuite comparées en termes de temps de calcul et prédictibilité sur la forme des bruts de forge

Un modèle analytique d'homogénéisation 3D complet pour les plaques composites orthotropes de type carton ondulé

La modélisation des plaques composites en carton ondulé est fastidieuse et couteuse en temps CPU. On propose un modèle d'homogénéisation analytique 3D complet en 2 étapes. A la première étape, on détermine les rigidités globales d'une plaque homogène équivalente. A la deuxième étape, on retransforme la plaque homogénéisée en un solide orthotrope composé de plusieurs couches et on identifie les paramètres des matériaux à partir de ces rigidités globales pour prendre en compte le comportement élasto-plastique suivant l'épaisseur. Le modèle est validé à l'aide du logiciel Abaqus

Finite Element Thermal Simulations for the Design of Mold Conformal Heating Channels Manufactured by 3D Printing Sand Casting for Molding of EPDM Rubber

This paper presents an application of Additive Manufacturing (AM) technology that is suitable for manufacturing molding tools with conformal heating channels to increase productivity for EPDM rubber molding. The design and the manufacturing of a molding tool by combining 3D sand printing and casting processes was analyzed. A simplified finite element thermal analysis was used to optimize the EPDM molding cycle time of an automotive hood seal. The simulation results showed that by using a mold with conformal heating channels manufactured by 3D printing sand casting, the cycle time process of EPDM can be reduced by 41.5%

MODELISATION NUMERIQUE 3D VOLUMIQUE DU REMPLISSAGE DES MOULES D'INJECTION

REIMS-BU Sciences (514542101) / SudocSudocFranceF

Buckling and free vibration analysis of laminated composite plates using an efficient and simple higher order shear deformation theory

In this paper, the buckling and free vibration analysis of laminated composite plates using an efficient and simple higher order shear deformation theory are examined by using a refined shear deformation theory. This theory is based on the assumption that the transverse displacements consist of bending and shear components where the bending components do not contribute to shear forces, and likewise, the shear components do not contribute to bending moments. The most interesting feature of this theory is that it allows for parabolic distributions of transverse shear stresses across the plate thickness and satisfies the conditions of zero shear stresses at the top and bottom surfaces of the plate without using shear correction factors. The number of independent unknowns in the present theory is four, as against five in other shear deformation theories. In this analysis, the equations of motion for simply supported thick laminated rectangular plates are derived and obtained through the use of Hamilton’s principle. The closed-form solutions of anti-symmetric cross-ply and angle- ply laminates are obtained using Navier solution. Numerical results of the present study are compared with three-dimensional elasticity solutions and results of the first-order and the other higher-order theories reported in the literature. It can be concluded that the proposed theory is accurate and simple in solving the buckling and free vibration behaviors of laminated composite plates

A Displacement Based Analytical Model to Determine Residual Stress Components in a Finite Elastic Thin Plate with Hole-Drilling Method

International audienceIn order to measure the residual stress components in an elastic thin plate, the hole-drilling strain-gage method has been used. This method enables to determine the relation between the magnitudes and directions of the principal stresses and the strain relaxation about the hole. In the existing analytical models based on stress field, the formulations associated with the hole-drilling method are based on the assumption of an infinite plate, this may cause some errors for a finite plate and it’s difficult to validate these solutions by FE methods. Furthermore, in the composite, the displacement field is continuous but the stress field is not necessarily continuous, the displacement field based method has to be used. In the present paper an analyt-ical model based on a displacement field described by a function with coefficients to determine for a finite round thin plate is presented. The coefficients used in the displacement field are independent on the three residual stress components, and they are determined by minimization of the internal strain energy during the hole-drilling process. Once the coefficients in the dis-placement field are determined, three strains measured in three radial directions are utilized to determine the three residual stress components. The proposed analytical model can be also adapted to infinite plate by assuming that the diameter of the round plate tends to infinite

Analytical Homogenization for Honeycomb Sandwich Plates with Skin and Height Effects

International audienceNumerical modeling of honeycomb sandwich plates is too tedious and time consuming. The analytical homogenization enables to obtain an equivalent homogeneous solid and its elastic stiffness. In this paper, the skin effect is considered for the in-plane shear and torsion problems, in which the two skins are relatively rigid. Homogenization models using trigonometric function series and energy method is proposed to study the influence of the honeycomb height on these moduli. The comparison between our H-model and Abaqus 3D modeling has shown very good agreement

Whole-Body Cryostimulation: New Insights in Thermo-Aeraulic Fields inside Chambers

(1) Background: This article presents a study that aims to provide a precise understanding of the temperature distribution within a whole-body cryostimulation (WBC) chamber, whether it is empty or occupied by one or several individuals; (2) Methods: The study employs a mixed numerical and experimental approach, utilizing simplified computational fluid dynamics (CFD) simulations and experimental analysis; (3) Results: The results reveal a non-negligible temperature difference between the setpoint and actual temperature in the middle of the cryochamber. Furthermore, it is shown that the presence of individuals inside the chamber results in both an average temperature rise and a more heterogeneous thermal behavior associated with the number of individuals present. As the number of occupants in the cryochamber increases, the magnitude of the thermal gradient (up to 10 °C) and temperature heterogeneity (up to 13%) also increase; (4) Conclusions: The results suggest that when the cryotherapy chamber is occupied by three people, it becomes necessary to extend the duration of cold exposure to obtain a dose/effect ratio and analgesic threshold equivalent to those obtained when only one person is present. The findings of this study emphasize the need for further research to establish temperature guidelines and standardize measurement methods for effective WBC treatment

Spent Coffee Grounds as Building Material for Non-Load-Bearing Structures

The gradual development of government policies for ecological transition in the modern construction sector leads researchers to explore new alternative and low environmental impact materials with a particular focus on bio-sourced materials. In this perspective, the mechanical, thermal insulation, and the sound absorption performances of a spent coffee grounds/potato starch bio-based composite were analyzed for potential application in buildings. Based on thermal conductivity and diffusivity tests, the coffee grounds waste biocomposite was characterized as an insulating material comparable with conventional thermal insulation materials of plant origin. Acoustical tests revealed absorption coefficients in the same range as other conventional materials used in building acoustical comfort. This bio-sourced material presented a sufficient compressive mechanical behavior for non-load-bearing structures and a sufficient mechanical capacity to be shaped into building bricks. Mechanical, thermal, and acoustic performances depend on the moisture environment. The groundwork was laid for an initial reflection on how this composite would behave in two opposite climates: the continental climate of Reims in France and the tropical climate of Belém in Brazil