Calculation of the local critical state taking into account the deterioration and the residual stresses

Jinescu, Valeriu V.; Nicolof, Vali-Ifigenia; Chelu, Angela

doi:10.56958/jesi.2017.2.3.9

Cited by 5 publications

(2 citation statements)

References 7 publications

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“…Impact models are usually run at one of the following levels: Macro, with the target being one body, made of a single equivalent material, used especially for metallic shields [ 41 ]; Meso, implying the layers as a continuous body with equivalent properties determined experimentally [ 27 ] and paying attention to modeling the bonding between them, being applied the cohesive zone model [ 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 ], as the designer wanted to have the thickness of the entire panel as small as possible; in this group, we can include fabrics modeled with yarns. This model is difficult to calibrate, taking into account the statistical response of such a multitude of bodies; Micro, when analyzing the behavior of a bundle of fibers under impact [ 50 , 51 ]; the big differences between dimensions of the fiber cross section and the projectile dimensions influence the model behavior.…”

Section: Results Of the Simulationmentioning

confidence: 99%

“…Meso, implying the layers as a continuous body with equivalent properties determined experimentally [ 27 ] and paying attention to modeling the bonding between them, being applied the cohesive zone model [ 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 ], as the designer wanted to have the thickness of the entire panel as small as possible; in this group, we can include fabrics modeled with yarns. This model is difficult to calibrate, taking into account the statistical response of such a multitude of bodies;…”

Section: Results Of the Simulationmentioning

confidence: 99%

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Ballistic Response of a Glass Fiber Composite for Two Levels of Threat

et al. 2023

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This paper presents the behavior of composite panels based on glass fiber unidirectional fabrics and a bi-component epoxy resin under ballistic impacts that characterize two threat levels: FB2 and FB3, according to EN 1523:2004. The tested panels had characteristics kept in narrow ranges: thickness 18.26 ± 0.22 mm, mass ratio fabrics/panel 0.788 ± 0.015, surface density 27.51 ± 0.26 kg/m2. After testing the panels, the failure mechanisms of the panel were evidenced by scanning electron microscopy and photographs. Here the authors present a finite-element model at meso scale that was used for evaluating if the composite, initially tested at level FB2 (9 mm FMJ, v0 = 375 m/s), could withstand the higher level of impact, FB3 (projectile type .357 Magnum and impact velocity of v0 = 433 m/s). Simulation was performed in Explicit Dynamics (Ansys), keeping the same target but changing the projectile for the two different levels of threat. The results of the simulation were encouraging for making tests at level FB3, indicating the importance of alternating actual tests with simulations in order to achieve better protection with reduced surface weight. The simulation illustrated differences in impact duration and number of layers broken on the panel for each level. Validation of the model was based on the number of broken layers and the dimension of the delamination zone between the last two layers. Scanning electron microscopy was used for identifying failure mechanisms at the micro and meso scale. We found that damage to the composite was intensively dependent on impact velocity, this being quantitatively evaluated using the number of layers broken, the effect of delamination on separating layers and the deformation of the last layer.

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Section: Results Of the Simulationmentioning

confidence: 99%

Section: Results Of the Simulationmentioning

confidence: 99%

Ballistic Response of a Glass Fiber Composite for Two Levels of Threat

et al. 2023

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Simulation of the Behavior of 32-Layer Composite Plate for Ballistic Protection

et al. 2022

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This paper presents experimental results and a failure analysis of a composite for ballistic protection. The stratified plate is manufactured at laboratory scale, after a technology designed by the authors. The plates were tested for level FB2, taking into account the standard SR EN 1522:2004 (Windows, doors, shutters and blinds. Bullet resistance. Requirements and classification) and SR EN 1523:2004 (Windows, doors, shutters and blinds. Bullet resistance. Test method) and the results point out that this plate could face more dangerous threats. In order to evaluate the behavior of the plate under the impact characterizing a higher level of threat, the authors uses a FE model and simulated the system bullet – plate for different impact velocities.

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Non-propogation crack criteria and fracture criteria in the case of mixed-mode fracture, taking into account the deterioration

Jinescu¹

2021

JESI

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The paper develops in the case of mixed-mode fracture: criteria of nonpropagation crack and fracture criteria, for mechanical structures, taking into account the deterioration, namely general relations for the superposition of loadings corresponding to the three fracture modes. It refers to the concepts of stress intensity factor, crack tip opening displacement and J-integral; new fracture criteria taking into account the deterioration, the rate of loading and the scattering of the material characteristics were established. The relations obtained have been compared and verified against experimental data and empirical relations reported in literature. The numerical example allows one to comprehend the practical use of the established relations.

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Calculation of the local critical state taking into account the deterioration and the residual stresses

Cited by 5 publications

References 7 publications

Ballistic Response of a Glass Fiber Composite for Two Levels of Threat

Ballistic Response of a Glass Fiber Composite for Two Levels of Threat

Simulation of the Behavior of 32-Layer Composite Plate for Ballistic Protection

Non-propogation crack criteria and fracture criteria in the case of mixed-mode fracture, taking into account the deterioration

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