Dynamic penetration of cellular solids: Experimental investigation using Hopkinson bar and computed tomography

Šleichrt, Jan; Fíla, Tomáš; Koudelka, Petr; Adorna, Marcel; Falta, Jan; Zlámal, Petr; Glinz, Jonathan; Neühauserová, Michaela; Doktor, Tomáš; Mauko, Anja; Kytýř, Daniel; Vesenjak, Matej; Duarte, Isabel; Ren, Zoran; Jiroušek, Ondřej

doi:10.1016/j.msea.2020.140096

Cited by 28 publications

(13 citation statements)

References 78 publications

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“…A dynamic mechanical analyser applied constant rate-controlled compression to foam samples, with concurrent high-speed optical full-field strain measurement. Full-field strain measurement by digital image correlation (DIC) [70,[72][73][74] gives more accurate strain measurement than tracking discrete markers. This work has implications for the application of auxetic foam to soft-shell PPE, such as potential improvements to consistency in performance between certification tests and actual use.…”

Section: Introductionmentioning

confidence: 99%

Effect of Compressive Strain Rate on Auxetic Foam

et al. 2021

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Auxetic foams have previously been shown to have benefits including higher indentation resistance than their conventional counterparts, due to their negative Poisson’s ratio, making them better at resisting penetration by concentrated loads. The Poisson’s ratio and Young’s modulus of auxetic open cell foams have rarely been measured at the high compressive strain rates typical during impacts of energy absorbing material in sporting protective equipment. Auxetic closed cell foams are less common than their open cell counterparts, and only their quasi-static characteristics have been previously reported. It is, therefore, unclear how the Poisson’s ratio of auxetic foam, and associated benefits such as increased indentation resistance shown at low strain rates, would transfer to the high strain rates expected under impact. The aim of this study was to measure the effect of strain rate on the stiffness and Poisson’s ratio of auxetic and conventional foam. Auxetic open cell and closed cell polymer foams were fabricated, then compression tested to ~80% strain at applied rates up to 200 s−1, with Poisson’s ratios obtained from optical full-field strain mapping. Open cell foam quasi-static Poisson’s ratios ranged from −2.0 to 0.4, with a narrower range of −0.1 to 0.3 for closed cell foam. Poisson’s ratios of auxetic foams approximately halved in magnitude between the minimum and maximum strain rates. Open cell foam quasi-static Young’s moduli were between 0.02 and 0.09 MPa, whereas closed cell foams Young’s moduli were ~1 MPa, which is like foam in protective equipment. The Young’s moduli of the auxetic foams approximately doubled at the highest applied strain rate of 200 s−1.

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Section: Introductionmentioning

confidence: 99%

Effect of Compressive Strain Rate on Auxetic Foam

et al. 2021

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“…The SHPB apparatus has also been used to evaluate the influence of elevated and reduced temperatures on the deformation response of steel auxetic lattices [ 18 ]. Furthermore, we have used modified Hopkinson pressure bar devices to investigate the dynamic impact characteristics of lattice structures [ 19 ] and metal foam-based lightweight cellular solids [ 20 ], where the possibility to use ex situ X-ray tomography has also been demonstrated.…”

Section: Introductionmentioning

confidence: 99%

Strain Rate-Dependent Compressive Properties of Bulk Cylindrical 3D-Printed Samples from 316L Stainless Steel

et al. 2022

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The main aim of the study was to analyse the strain rate sensitivity of the compressive deformation response in bulk 3D-printed samples from 316L stainless steel according to the printing orientation. The laser powder bed fusion (LPBF) method of metal additive manufacturing was utilised for the production of the samples with three different printing orientations: 0∘, 45∘, and 90∘. The specimens were experimentally investigated during uni-axial quasi-static and dynamic loading. A split Hopkinson pressure bar (SHPB) apparatus was used for the dynamic experiments. The experiments were observed using a high-resolution (quasi-static loading) or a high-speed visible-light camera and a high-speed thermographic camera (dynamic loading) to allow for the quantitative and qualitative analysis of the deformation processes. Digital image correlation (DIC) software was used for the evaluation of displacement fields. To assess the deformation behaviour of the 3D-printed bulk samples and strain rate related properties, an analysis of the true stress–true strain diagrams from quasi-static and dynamic experiments as well as the thermograms captured during the dynamic loading was performed. The results revealed a strong strain rate effect on the mechanical response of the investigated material. Furthermore, a dependency of the strain-rate sensitivity on the printing orientation was identified.

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“…Due to their specific properties [ 11 , 12 ] and their versatile combinations with other filler materials, APM foam elements have a wide range of applications in layers of composite materials [ 13 , 14 ], in components for functional thermal conductivity [ 15 ], in components for absorbing impact energy [ 16 ] and vibrations [ 7 ] and inside hollow construction parts for their reinforcement against local wall buckling [ 5 , 17 , 18 ]. Using them as a filler material inside hollow components is especially advantageous, since they can easily fill even complex internal cavities of hollow components [ 19 ].…”

Section: Introductionmentioning

confidence: 99%

Analysis of Advanced Pore Morphology (APM) Foam Elements Using Compressive Testing and Time-Lapse Computed Microtomography

et al. 2021

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Advanced pore morphology (APM) foam elements are almost spherical foam elements with a solid outer shell and a porous internal structure mainly used in applications with compressive loading. To determine how the deformation of the internal structure and its changes during compression are related to its mechanical response, in-situ time-resolved X-ray computed microtomography experiments were performed, where the APM foam elements were 3D scanned during a loading procedure. Simultaneously applying mechanical loading and radiographical imaging enabled new insights into the deformation behaviour of the APM foam samples when the mechanical response was correlated with the internal deformation of the samples. It was found that the highest stiffness of the APM elements is reached before the appearance of the first shear band. After this point, the stiffness of the APM element reduces up to the point of the first self-contact between the internal pore walls, increasing the sample stiffness towards the densification region.

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Dynamic penetration of cellular solids: Experimental investigation using Hopkinson bar and computed tomography

Cited by 28 publications

References 78 publications

Effect of Compressive Strain Rate on Auxetic Foam

Effect of Compressive Strain Rate on Auxetic Foam

Strain Rate-Dependent Compressive Properties of Bulk Cylindrical 3D-Printed Samples from 316L Stainless Steel

Analysis of Advanced Pore Morphology (APM) Foam Elements Using Compressive Testing and Time-Lapse Computed Microtomography

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