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1
Content available Novel energy-absorbing auxetic sandwich panel with detached corrugated aluminium layers
Al-Rifaie Hasan
Vibrations in Physical Systems
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2023
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Vol. 34, nr 2
art. no. 2023215
EN
Sandwich panels have the potential to serve as plastically deforming sacrificial structures that can absorb blast or impact energies. Auxetic sandwich panels with welded or bolted corrugated layers have, as far as the author is aware, had their blast behaviour thoroughly addressed in the literature. Therefore, the objective of this numerical analysis was to create a novel, low-cost, simple-to-build graded sandwich panel with detached corrugated layers that may be employed as a multi-purpose sacrificial protective structure against a wide range of blast threats. The suggested sandwich panel has overall dimensions of 330x330x150mm and is made of six detached aluminium (AL6063-T4) layers enclosed in a steel (Weldox 460E) frame. With different stepwise plate thicknesses of 0.4, 0.8, and 1.2mm for each pair of layers, the six layers all have the same re-entrant auxetic geometry. Utilising the Abaqus/Explicit solver, the numerical analysis was carried out. A wide variety of blast intensities (4, 7, 11, 13, and 16 MPa peak reflected over-pressures) were tested on the suggested auxetic sandwich panel, and the results showed uniform progressive collapse, a superior decrease in reaction forces, and greater energy dissipation compared to comparable non-auxetic topologies. The innovative sandwich panel design has potential uses for both military and civic structures that need to be protected.
2
Content available Numerical analysis of an auxetic anti-tetrachiral sandwich panel subjected to steady-state harmonic base motion
Michalski Jakub, Stręk Tomasz
Vibrations in Physical Systems
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2022
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Vol. 33, nr 3
art. no. 2022323
EN
In this paper, the authors show the results of numerical simulations representing the test of an aluminum sandwich panel with an auxetic anti-tetrachiral core on an exciter. Steady-state vibration analyses utilizing modal superposition (linear dynamics) were performed. The bottom of the panel had all the degrees of freedom constrained and excitation in form of base acceleration in the vertical direction was applied. The obtained results were in form of contour plots of selected output variables in the frequency domain. In addition, curves showing the variation of acceleration, velocity and displacement of a selected representative point in frequency were generated. The results were compared with those obtained for the panel with a non-auxetic core, in the form of a standard hexagonal honeycomb. It was found that the auxetic panel is not superior in the whole range of frequencies but a workflow useful in the design of sandwich panels for operating conditions involving vibrations was developed.
3
Content available The vibrations induced by fluid flow in plates with different Poisson’s ratios
Burlaga Bartłomiej, Stręk Tomasz
Vibrations in Physical Systems
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2020
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Vol. 31, nr 3
art. no. 2020301
EN
A fluid interacts with every solid object that is submerged in its flow. In this paper, the dynamic instability of elastic solid is modeled and analyzed based on the benchmark model. It is caused by a continuous stream of vortices (known as von Kármán vortex street). In the presented approach, prerequisites are calculated to meet the necessary conditions for this phenomenon to occur. The main objective of this study is to determine the influence of different Poisson ratios on the intensity of a solid body’s deflection. In the first part, governing equations are presented. The following part describes the model domain as well as assumed parameters with chosen values explanation. The third part presents simulation specific information - mesh and applied options. The conclusion and possible real-life applications are preceded by obtained results.
4
Content available Numerical analysis of the lower limb prosthesis subjected to various load conditions
Kowalczyk Milena, Jopek Hubert
Vibrations in Physical Systems
|
2020
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Vol. 31, nr 3
art. no. 2020309
EN
This article presents the simulation of a prosthetic socket with an auxetic structure under typical loading cases. The designed model of prosthetic socket is dedicated to patients who have undergone transfemoral amputation and consists of four elements, among which can be distinguished an inner lining, a shock absorbing element, component with a honeycomb re-entrant structure, which has a negative Poisson's ratio an outer shell. The prosthetic socket was analysed by means of the finite element method. The simulations were used to evaluate the strength of the design and to check whether it is possible to avoid a problem of changing the circumference of the patient's stump, thanks to the use of an auxetic structure in the socket.
5
Content available remote Smart Cellular Systems with Pressure Dependent Poisson’s Ratios
Attard D., Cauchi R., Gatt R., Grima-Cornish J. N., Grima J. N.
Computational Methods in Science and Technology
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2020
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Vol. 26, No. 2
37--45
EN
The Poisson’s ratio behaviour of cellular systems which change their internal features when subjected to pressure change to become a “re-entrant” or “non-re-entrant” honeycomb was investigated. It was shown, through finite elements simulations, that these changes in geometry permit the systems to exhibit a wide range of Poisson’s ratios, the magnitude and sign of which can be controlled through the external pressure. Auxetic behaviour was also shown to be obtainable at specific pressures with the right combination of design and materials.
6
Content available remote Compressive Property of an Auxetic-Knitted Composite Tube Under Quasi-Static Loading
Boakye Andrews, Raji Rafui King, Ma Pibo, Cong Honglian
Autex Research Journal
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2020
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Vol. 20, no. 2
101--109
EN
This research investigates the compressive property of a novel composite based on a weft-knitted auxetic tube subjected to a quasi-static compression test. In order to maximize the influence of the fiber content on the compression test, a Kevlar yarn was used in knitting the tubular samples using three different auxetic arrow-head structures (i.e. 4 × 4, 6 × 6 and 8 × 8 structure). A quasi-static compression test was conducted under two different impact loading speeds (i.e. 5 mm/min and 15 mm/min loading speed). The results indicate that the energy absorption (EA) property of the auxetic composite is highly influenced by the auxeticity of the knitted tubular fabric.
7
Content available Vibration properties of auxetic beam
Matuszewska A., Stręk T.
Vibrations in Physical Systems
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2018
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Vol. 29
art. no. 2018031
EN
This study presents vibration analysis for a beam with an auxetic cross-section. In order to verify damping properties of auxetic materials, the numerical results were compared with classical H-beam which has basic geometry. The response of analyzed models was considered with taking into account the Rayleigh damping of the internal material structure. Performed calculations comprise deformation of the certain beam, selected points displacement and vibration transmission loss coefficient. The analysis was carried out by means of Finite Element Method using Comsol Multiphysics software.
8
Content available Forced response of plate with viscoelastic auxetic dampers
Stręk T.
Vibrations in Physical Systems
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2018
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Vol. 29
art. no. 2018003
EN
The example studies a forced response of plate with viscoelastic auxetic damper located at the free end of the plate. Damping elements consist of the cover layer and layer of viscoelastic material with positive or negative Poisson's ratio. Viscoelastic materials are often used for reduction of vibration (seismic or wind induced vibrations in building structures or other structures). The common feature is that the frequency of the forced vibrations is low. Calculations are made using finite element method with Comsol Multiphysics software.
9
Content available Simulations of the properties of elongated hexagonal dodecahedron systems
Grima J. N., Caruana-Gauci R., Attard D., Gatt R.
TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk
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2014
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Vol. 18, No 2
117--135
EN
This study considers a 3D basic unit-cell proposed for auxetic and non-au xetic foams namely the elongated hexagonal dodecahedron deforming through changes in angle b etween its ligaments (idealised hinging model). This structure was studied in detail for the potential of exhibiting negative Poisson’s ratio and/or negative compressibility b y means of a method based on standard force-field molecular modelling technique, termed as Empiri cal Modelling Using Dummy Atoms ( EMUDA ). The mechanical properties obtained from this method were then compared to a previously published analytical model of this structure [Grima J N, CaruanaGauci R, Attard D, and Gatt R 2012, Proc. Roy. Soc. A 468 3121], and found to be in good agreement with each other. The results showed that this system can ex hibit zero Poisson’s ratios in one of its planes and positive or negative Poisson’s ratios in other plan es, depending on the geometry of the model. It was also shown that under certain conditions, ne gative linear and/or area compressibility was also exhibited.
10
Content available remote Workings of auxetic nano-materials
Yao Y. T., Uzun M., Patel I.
Journal of Achievements in Materials and Manufacturing Engineering
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2011
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Vol. 49, nr 2
585--593
EN
The human mind is consistently interested in new materials having unique properties. Recently, a relatively new field is being investigated which exhibits a negative Poisson’s ratio (NPR), and consequently are termed auxetic materials. Design/methodology/approach: One of the main reason for interest in auxetic materials is due to the possibility of enhanced mechanical properties such as shear modulus, plane strain fracture toughness and indentation resistance compared to non auxetic material. Findings: Auxetic materials were described concerning their classification, characteristic, properties and potential applications. Research limitations/implications: The paper is an overview the modelling structure and deformation mechanisms of auxetic nano-materials. Originality/value: The paper shows the possibilities of auxetic materials application resulting from their mechanical properties.
11
Content available remote Propagation of solitary waves in rod made of material with negative Poisson’s ratio
Kołat P.
Vibrations in Physical Systems
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2008
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Vol. 23
195--198
EN
It is found the propagation of longitudinal solitary waves in an elastic rod made of material with negative Poisson’s ratio. It is used the difference scheme to solve the non-linear partial differential equation.
12
Content available remote Negative Poisson's ratios from rotating rectangles
Grima J. N., Alderson A., Evans K. E.
Computational Methods in Science and Technology
|
2004
|
Vol. 10, nr 2
137-145
EN
Materials with a negative Poisson's ratio exhibit the unexpected property of becoming fatter when stretched and narrower when compressed. This counter-intuitive behaviour is known as 'auxetic behaviour' and imparts many beneficial effects on the material’s macroscopic properties. This paper discusses the potential of systems composed of rigid rectangles connected together through flexib1e hinges at their vertices. It will be shown that, on application of uniaxial loads, these rigid rectangles will rotate with respect to each other to form, in some cases, a more open structure hence giving rise to a negative Poisson's ratio.
13
On static and dynamic design criteria of sandwich plate structures with a negative Poisson's ratio core
Scarpa F., Tomlinson G.
Applied Mechanics and Engineering
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2000
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Vol. 5, no 1
207-222
EN
In this paper the static and dynamic performances of sandwich structures with in-plane negative Poisson's ratio core are investigated from an analytical point of view. The cellular material theory is applied to calculate the orthotropic mechanical properties of re-entrant cell honeycomb cores, which shows negative Poisson's ratio values. This special geometrical layout of the cells allows higher out-of-plane shear modulus, compared to the one of regular honeycombs. The laminate orthotropic plate theory with shear correction factors is applied in order to describe the static and dynamic behaviour of symmetric sandwich plates with different core to sheet thickness ratios. Comparisons are made with analogous structures with regular honeycomb. The maximum deflections due to uniform pressure and buckling loads are enhanced, while the natural frequencies show a slight enhancing for some parameters of the cells.
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