Effect of core density on the low-velocity impact response of foam-based sandwich composites

Feng, Dianshi; Aymerich, Francesco

doi:10.1016/j.compstruct.2020.112040

Cited by 51 publications

(36 citation statements)

References 24 publications

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“…They summed up that the core density and the core thickness influence the impact resistance of sandwich structures, and the maximum force rises with increasing foam density. Similar conclusions were described in [ 32 ], in which the authors concluded that the foam core density significantly affects the structural response to a low velocity impact. The damage area in the tested samples decreases with increasing core density and simultaneously influences the enhancement in maximum force and energy absorption.…”

Section: Introductionsupporting

confidence: 89%

“…The difference in the amount of energy absorbed by laminates is a result of the initiation process and propagation of the damage in the foam instead of metal or composite layers. Foam core is damaged by crushing and shearing, which results in delamination at the foam–composite interface and foam failure [ 26 , 27 , 30 , 32 ]. Furthermore, based on the absorbed energy and impact energy, the coefficient of restitution (COR) was determined, which enables the assessment of material failure mode at different impact energies [ 46 , 47 ]:

where:

—impact energy,

—energy absorbed by laminates…”

Section: Resultsmentioning

confidence: 99%

“…Foam sandwich laminates have different failure mechanisms depending on the impact energy value. The main failure modes include matrix cracking, delaminations, foam crushing, or face-core debonding and perforation [27,32,38]. Failure in sandwich panels is sensitive to the main constituents of the skins and the core, the adhesives used, the skin ply sequences and other factors [29].…”

Section: Introductionmentioning

confidence: 99%

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Experimental Investigation on the Low Velocity Impact Response of Fibre Foam Metal Laminates

et al. 2021

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The combination of fibre metal laminates (FML) and sandwich structures can significantly increase the performance under impact of FMLs. The goal of this work was to create a material that will combine the superior properties of FMLs and foam sandwich structures in terms of the impact resistance and simultaneously have lower density and fewer disadvantages related to the manufacturing. An extensive impact testing campaign has been done using conventional fibre metal laminates (carbon- and glass-based) and in the proposed fibre foam metal laminates to assess and compare their behaviour. The main difference was observed in the energy absorption mechanisms. The dominant failure mechanism for fibre foam laminates is the formation of delaminations and matrix cracks while in the conventional fibre metal laminate the main failure mode is fibre cracking due to high local stress concentrations. The reduction in the fibre cracking leads to a better after-impact resistance of this type of structure improving the safety of the structures manufactured with these materials.

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Section: Introductionsupporting

confidence: 89%

where:

—impact energy,

—energy absorbed by laminates…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Experimental Investigation on the Low Velocity Impact Response of Fibre Foam Metal Laminates

et al. 2021

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“…Crush-able foam models are typically applied to represent the inelastic behaviour of the foam core. Several investigations based on this modelling framework have been reported in the literature for the simulation of low-velocity impact damage in foam cored sandwich composite plates [11,13,15,[26][27][28][29][30][31]. The predictions of these studies generally show a good agreement with experimental data in terms of structural behaviour as well as damage features and extent.…”

Section: Introductionmentioning

confidence: 85%

“…Various studies have been, for example, conducted to examine the influence of the foam density on the structural response and on the damage mechanisms of sandwich composites subjected to impact. It is generally acknowledged that the resistance to impact damage is improved by increasing the stiffness and the strength of the core, with specimens with lower density foam core exhibiting lower threshold energy for damage initiation and more extensive damage areas than specimens with higher density cores [8][9][10][11]. The gain in damage resistance of composite sandwiches observed with increasing foam density can be attributed to the improved support provided by denser and stiffer foam cores to the impacted skin.…”

Section: Introductionmentioning

confidence: 99%

A Numerical and Experimental Investigation into the Impact Response of Sandwich Composites under Different Boundary Conditions

2022

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The paper reports the results of an experimental and numerical investigation into the effect of the support conditions on the low velocity impact behaviour of sandwich composite panels. Significant differences are observed experimentally between the structural and damage responses to impact of small-span and large-span sandwich panels. In particular, impact events on large-span panels generate lower peak forces, larger displacements and smaller damage sizes in comparison to small-span panels subjected to the same impact energy. The experimental results are employed to validate the capability of a finite element (FE) tool to simulate the impact behaviour of the sandwich panels for the different boundary conditions. The comparison of FE and experimental results shows that the model provides a good prediction of the structural response as well as of the extent and mechanisms of impact damage for both small-span and large-span lengths, thus demonstrating the potential of the FE tool for verification and design of sandwich components in real engineering applications.

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Damage analysis of Nomex honeycomb sandwich structures using image processing and artificial intelligence approaches

Demirci,

Saritas

2023

Polymer Composites

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In this study, a method was developed to detect impact damage and determine the damage propagation in increasing and repetitive impacts. The effect of nanographene additives on the propagation of delamination damage in the top face layer of a sandwich structure was investigated using the developed method. In addition, the effects of nanographene on visible (VID) or barely visible damage (BVID) formation were investigated, and the stiffness of the sandwich structures was evaluated. An ultrasonic C‐scan nondestructive testing was used to visualize the damage, and the numerical values of the damaged areas of the sandwich structures at different energy levels were determined using an image processing method. The obtained values were used in artificial neural network (ANN) training to estimate the impact energy at which the structural integrity of the sandwich structures was disrupted. It was observed that the nanographene additive was effective in maintaining rigidity of the sandwich structures and therefore, slowed the delamination damage progression in increasing and repeated impacts. The damage areas of the neat sandwich structures (NSS) and graphene nanoplatelets doped sandwich structures (GSS) structures at the first impact 5j energy level was 1004 and 811 mm2, respectively. At the first impact, 20% less damage occurred in the GNP‐doped sandwich structures. The increasing and repetitive last impact energies at the end of the neural network training were 5j + 35j in NSS and 5j + 50j in GSS. The method allows for a detailed examination of the damage progression of sandwich structures under increasing and repeated impact loads.Highlights Low‐velocity impact tests of Nomex honeycomb sandwich structures were performed. Damage formation and propagation in sandwich structures were investigated. The non‐destructive test C‐scan method was used to determine BVID. The damaged areas were determined using an image processing method. The damage areas were estimated using artificial neural networks.

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Effect of core density on the low-velocity impact response of foam-based sandwich composites

Cited by 51 publications

References 24 publications

Experimental Investigation on the Low Velocity Impact Response of Fibre Foam Metal Laminates

Experimental Investigation on the Low Velocity Impact Response of Fibre Foam Metal Laminates

A Numerical and Experimental Investigation into the Impact Response of Sandwich Composites under Different Boundary Conditions

Damage analysis of Nomex honeycomb sandwich structures using image processing and artificial intelligence approaches

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