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In this paper, we studied the container-content interaction between a high-density polyethylene-based packaging (HDPE) and amyl acetate solution considered as diffusing agent. We were specifically interested in the impact of sorption and diffusion phenomena on the mechanical properties of HDPE bottles under static conditions at different stages of physical aging. Several uniaxial tests were realized on samples cut from bottles and structural tests were performed on bottles. The analysis of such various experimental results highlighted the Fickian nature of the diffusion phenomenon and the decrease of the compression strength of the bottles with the preconditioning time. We have also focused on the modelling of the mechanical behavior of HDPE taking into account the mass transfer induced by the diffusion phenomenon. Elastic-viscoplastic model was proposed and implemented in the finite element code ABAQUS. The parameters of this model were identified from tensile tests by solving an optimization problem. The identified models have been validated by numerical simulation of top-load compression of HDPE bottles. The obtained numerical results are in a good agreement with experimental measurements. [ABSTRACT FROM AUTHOR]

This article presents an efficient pseudo-inverse approach for the damage prediction in cold forging process simulation. Pseudo-inverse approach combines the advantages of the fast inverse approach and accurate incremental approaches. Some intermediate configurations are created geometrically and corrected mechanically to well describe the deformation path. The formulation of an axi-symmetrical element based on pseudo-inverse approach is presented. A strain-based damage model is introduced in the flow theory of plasticity. A direct scalar integration algorithm of plasticity-damage is developed, leading to a fast and robust algorithm for large strain increments. The cold forging processes of two axi-symmetrical parts are simulated to validate pseudo-inverse approach by the incremental approach ABAQUS/Explicit. Pseudo-inverse approach gives very good results, but uses much less CPU time. [ABSTRACT FROM PUBLISHER]

Abstract: This paper presents a new simplified method called “Pseudo Inverse Approach” (PIA) for the axi-symmetrical cold forging modeling. The PIA keeps the advantages of the Inverse Approach (very fast) but gives good stress estimation by taking into account the loading history. Some intermediate configurations are created by using a free surface method to consider the deformation paths without contact treatment. A new direct algorithm of plasticity is developed leading to a fast and robust plastic integration procedure for very large strain increments. The PIA results are compared to those obtained by using ABAQUS software to show the efficiency and limitations of the PIA. [Copyright &y& Elsevier]

This paper presents experimental and numerical studies of drop tests of corrugated cardboard packaging containing different foam cushions. An efficient homogenization model for the corrugated card- board has been developed. In our homogenized model, the corrugated cardboard is represented by a 2D plate. Instead of using a local constitutive law (relating the strains to the stresses) at each material point, the homogenization gives the global rigidities (relating the generalized strains to the resultant forces) for the equivalent homogeneous plate. This model was implemented into the FE software ABAQUS. The foam behaviour was experimentally determined and modelled using a crushable foam model of ABAQUS. The packages are tested in free fall from a given height on a rigid floor. The deceleration of the packed product was recorded using a triarial accelerometer. The numerical results obtained using the FE simulation with the homogenized model agree well with the experimental results. We have also shown that the contribution of the corrugated cardboard box to the shock response could not be neglected in the design of cushioning package. [ABSTRACT FROM AUTHOR]

Cette Note présente un nouvel algorithme efficace pour effectuer l'intégration plastique et calculer les contraintes dues aux grandes déformations pour des matériaux obéissant au critère anisotrope de Hill. L'algorithme d'intégration plastique classique comme la ‹ Méthode du Retour Radial › est largement utilisé pour l'analyse non linéaire des structures et la simulation des procédés de mise en forme des matériaux, mais il nécessite une résolution itérative et peut avoir des problèmes de convergence. Un nouvel algorithme direct, basé sur une méthode scalaire, est développé permettant d'obtenir directement le multiplicateur plastique sans résolution itérative, ainsi le temps de calcul est largement diminué et les problèmes numériques sont évités. Pour citer cet article : I. Titeux et al., C. R. Mecanique 332 (2004). [Copyright 2004 Elsevier]