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Caractérisation et modélisation du comportement d'un polymère semi cristallin au crash

Abstract : Polymer materials are increasingly being used in the automotive sector, particularly for absorbing impact energy. A model for semi-crystalline polymers at room temperature is proposed. This model describes the four steps of polymer behaviour: the viscoelasticity is described by a Young’s modulus sensitive to the strain rate, the plastic elastic transition by a Drucker-Prager plastic criterion in order to take hydrostatic pressure into account, the viscoplasticity is described by a modified G’sell model with non associative plastic flow and the failure criterion is based on the stress triaxiality ratio evolution. All these models are implemented in the Pamcrash® finite elements code for shell elements. Identification of behaviour model parameters is done using tensile and compression tests at different strain rates (10-3 s-1 - 50 s-1). The experimental setup is also has a video camera to make deformation field measurements by digital image correlation. From these measurements, an innovative method (SEĖ method) has been developed to establish the law of material behaviour. An experimental approach is performed through tensile notched tests and Arcan tests to determine the shape of the failure criterion in relation to the initial ratio triaxiality stress. The fracture strain is defined as a function of the strain rate. Comparing the numerical results on simple tests and industrial structures with the experimental results highlights the improvements brought by this new model when simulating the behaviour of polymer materials over a wide range of strain rates.
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Submitted on : Monday, December 14, 2020 - 9:55:50 AM
Last modification on : Tuesday, November 23, 2021 - 9:44:54 AM
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  • HAL Id : tel-03060835, version 1


Alban Fabrice Epée. Caractérisation et modélisation du comportement d'un polymère semi cristallin au crash. Génie mécanique [physics.class-ph]. Université de Valenciennes et du Hainaut-Cambrésis, 2009. Français. ⟨NNT : 2009VALE0028⟩. ⟨tel-03060835⟩



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