Skip to Main content Skip to Navigation
Theses

Modélisation de l'endommagement dynamique avec prise en compte de l'effet de forme des cavités

Abstract : The ductile fracture mechanism involves three stages: void nucleation, void growth and void coalescence. Under dynamic loading conditions, void growth is strongly affected by microinertia effects resulting from the local acceleration of the matrix material in the vicinity of the void. Several works devoted to quasi-static conditions also show that void shape has a strong impact on the behavior of porous ductile materials. However, there exist only few works considering the combined effect of these two contributions. In the present work, we propose an original, multi-scale constitutive model of porous materials, taking into account void shape and micro-inertia effects. In a first step, a representative volume element defined by two confocal prolate spheroids is used to represent the porous material. The matrix behavior is assumed to be rigid-viscoplastic. Based on the work of Molinari and Mercier (2001), the macroscopic stress is the sum of a static and a dynamic part. The static contribution is described by the Gologanu et al. model (1997). The dynamic stress is derived by choosing the trial velocity field proposed by Gologanu et al. (1993). With the present modeling, a link is established between the macroscopic dynamic stress, on the one hand and, the macroscopic strain rate tensor and its time derivative on the other hand. To validate the proposed model, finite element computations have been performed for different void geometries and void volume fractions. The influence of micro-inertia on the macroscopic flow surface is analyzed and a good agreement between modeling and simulations is observed. In a second step, a representative volume element defined by two confocal oblate spheroids is used to represent the porous material. For this configuration, the static contribution is also described by using the Gologanu et al. model (1997), while the derivation of the dynamic stress is based on the trial velocity field proposed by Gologanu et al. (1994). As for the prolate case, a good agreement is retrieved between model predictions and results of finite element computations. The spherical void configuration is investigated as the limit case for the oblate and prolate models. The continuity between the two models is established. Finally, the proposed models are combined to investigate the porosity and void shape evolutions in a porous solid under dynamic loadings. A parametric study has been performed by varying the stress triaxiality, the initial void shape and the loading rate. Significant void shape variations are observed for low triaxiality loadings. With the present modeling, the void can evolve from prolate to oblate shapes (and the reverse). Model predictions are compared to finite element computations
Document type :
Theses
File URL :
http://docnum.univ-lorraine.fr/prive/DDOC_T_2014_0195_SARTORI.pdf
Complete list of metadata

https://hal.univ-lorraine.fr/tel-01751136
Contributor : Thèses Ul <>
Submitted on : Thursday, March 29, 2018 - 1:07:37 PM
Last modification on : Friday, February 26, 2021 - 2:48:03 PM

Identifiers

  • HAL Id : tel-01751136, version 1

Citation

Cédric Sartori. Modélisation de l'endommagement dynamique avec prise en compte de l'effet de forme des cavités. Autre. Université de Lorraine, 2014. Français. ⟨NNT : 2014LORR0195⟩. ⟨tel-01751136⟩

Share

Metrics

Record views

32