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Evolution of tenacity in mixed mode fracture - volumetric approach

Zebri O., El Minor H., Bendarma A.

Mechanics and Mechanical Engineering

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2018

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Vol. 22, nr 4

931--938

EN

In fracture mechanics most interest is focused on stress intensity factors, which describe the singular stress field ahead of a crack tip and govern fracture of a specimen when a critical stress intensity factor is reached. In this paper, stress intensity factors which represents fracture toughness of material, caused by a notch in a volumetric approach has been examined, taking into account the specific conditions of loading by examining various U-notched circular ring specimens, with various geometries and boundary conditions, under a mixed mode I+II. The bend specimens are computed by finite element method (FEM) and the local stress distribution was calculated by the Abaqus/CAE. The results are assessed to determine the evolution of the stress intensity factor of different notches and loading distances from the root of notch. This study shows that the tenacity is not intrinsic to the material for all different geometries notches.

2

Protocol to define material behaviour and failure strain level at low and high strain rates based on a compression test

Jankowiak T., Rusinek A., Bendarma A.

Journal of Theoretical and Applied Mechanics

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2018

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Vol. 56 nr 2

471--481

EN

Compression test is frequently used to define material behaviour. However, this test may be depending on different effects, for example friction, specimen inertia or local stress triaxiality. For this reason, a new design is proposed to analyse the previous effects and to try to minimize it on quantities measured as macroscopic stress and strain. To have a complete understanding, numerical simulations have been performed using finite element method (Abaqus/Standard and Abaqus/Explicit). It allows one to define the macroscopic behaviour and to have an access to the local values not accessible during experiments for a better understanding of the experimental measurements.

3

Experimental and numerical analysis of aluminum alloy AW5005 behavior subjected to tension and perforation under dynamic loading

Bendarma A., Jankowiak T., Łodygowski T., Rusinek A., Klósak M.

Journal of Theoretical and Applied Mechanics

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2017

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Vol. 55 nr 4

1219--1233

EN

The paper describes mechanical behavior of aluminum alloy AW5005 (EN AW5005) under impact loading. The work is focused on tensile tests and the process of perforation of aluminum alloy AW5005 sheets. Experimental, analytical and numerical investigations are carried out to analyse in details the perforation process. Based on these approaches, ballistic properties of the structure impacted by a conical nose shape projectile are studied. Different failure criteria are discussed, coupling numerical and experimental analyses for a wide range of strain rates. Optimization method functions are used to identify the parameters of the failure criteria. Finally, good correlation is obtained between the numerical and experimental results for both tension and perforation tests.