Impact properties of uniaxially thermoformed auxetic foams

Zhang, Qicheng; Scarpa, Fabrizio; Barton, David A. W.; Zhu, Yunpeng; Lang, Zi-Qiang; Zhang, Dayi; Peng, Hua-Xin

doi:10.1016/j.ijimpeng.2022.104176

Cited by 26 publications

(14 citation statements)

References 55 publications

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“…The converted auxetic foams are anisotropic, with significant difference in terms of mechanics along the thermoforming directions d 1 and transverse directions d 2 and d 3 , due to the specific uniaxial thermoforming manufacturing procedure adopted [9,25,26]. Therefore, two types of specimens are cut from the thermoformed foam blocks with different r c values for the 3-point bending tests, all with same size of 120 9 20 9 10 mm (Fig.…”

Section: The Uniaxially Thermoformed Auxetic Foammentioning

confidence: 99%

“…When loaded along the thermoforming direction d 1 , the Poisson's ratio m 12 and m 13 are all close to 0. More detailed results about the mechanics and deformations of the thermoformed auxetic foams are provided in [9,25,26].…”

Section: The Uniaxially Thermoformed Auxetic Foammentioning

confidence: 99%

“…2). The force signal measured by the dynamic force sensor includes two components: the inertial force of the middle holder ðM þ 17=35m f Þ € yðtÞ and the force of the foam beam F f ðy t ð Þ; z t ð Þ; tÞ, as shown in (9). The acceleration and the inertial force can be derived from the measured displacement signal in the time domain.…”

Section: Modified Normalized Bouc-wen Model For the Concentrated Para...mentioning

confidence: 99%

“…negative Poisson's ratio) open-cell polyurethane (PU) foams have been developed and evaluated by many research groups [3]. Due to the counter-intuitive auxetic deformation and the properties of the PU material, auxetic foams show interesting mechanical properties, such as indentation resistance [4], synclastic behaviour [5], compliant shear [6,7], improved impact [8,9] and vibration [10] energy absorption. Auxetic foams therefore possess a significant potential for applications like apparel/personal protective equipment [8,11,12], cushioning [13,14], noise reduction [15,16], smart materials and sensors [17,18].…”

Section: Introductionmentioning

confidence: 99%

“…Some of the authors of this work have recently simplified the complex triaxially thermoforming manufacturing process into a uniaxial one via the use of an open mould. This production procedure provides a relatively low manufacturing cost and excellent auxetic performance [9,25,26], which makes it suitable for scaling-up manufacturing purposes.…”

Section: Introductionmentioning

confidence: 99%

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Hysteretic behaviour of uniaxially thermoformed auxetic foams under 3-point bending low-frequency vibration

Zhang

Scarpa

et al. 2022

Nonlinear Dyn

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The work describes experiments and models related to auxetic (negative Poisson’s ratio) foams subjected to low-frequency and variable amplitude 3-point bending loading. A custom 3-point bending vibration test rig is designed and used to perform the dynamic test of auxetic PU foam beams within low-frequency range (1–20 Hz) and 5 different displacement amplitudes. The auxetic foams tested in this work are manufactured using a simplified and relatively low-cost uniaxially thermoforming compression technique, which leads to the production of foams with transverse isotropic characteristics. Auxetic foam beam samples with two different cutting orientations and different thermoforming compression ratios rc (20–80%) are tested and compared, also with the use of theoretical Euler–Bernoulli-based and finite element models. The dynamic modulus of the foams increases with rc, ranging between 0.5 and 5 MPa, while the dynamic loss factor is marginally affected by the compression ratio, with overall values between 0.2 and 0.3. The auxetic PU foam has a noticeable amplitude-dependent stiffness and loss factors, while the dynamic modulus increases but slightly decreases with the frequency. The dynamic modulus is also 20–40% larger than the quasi-static one, while the dynamic and static loss factors are quite close. A modified Bouc–Wen model is also further developed to capture the amplitude and frequency-dependent properties of the conventional and auxetic foams with different volumetric compression ratios. The model shows a good agreement with the experimental results.

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Section: The Uniaxially Thermoformed Auxetic Foammentioning

confidence: 99%

Section: The Uniaxially Thermoformed Auxetic Foammentioning

confidence: 99%

Section: Modified Normalized Bouc-wen Model For the Concentrated Para...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Hysteretic behaviour of uniaxially thermoformed auxetic foams under 3-point bending low-frequency vibration

Zhang

Scarpa

et al. 2022

Nonlinear Dyn

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Auxetic Two‐Phase Chevron Mechanical Metamaterial

Xu,

Nash,

Batwa

et al. 2024

Adv Eng Mater

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This investigation explores novel two‐phase chevron mechanical metamaterials that exhibit auxetic properties. Unlike traditional foam‐like cellular or porous auxetic materials, these designs are composed of chevron patterned layers embedded in anisotropic matrix. This innovation design allows for auxeticity in two orthogonal in‐plane directions (bi‐auxeticity) or in all in‐plane directions (complete auxeticity), providing not only a general strategy but also detailed guidelines for designing non‐porous auxetic mechanical metamaterials with tunable auxetic behaviors. One goal of this work is to explore the mechanical behavior, specifically effective stiffness and Poisson's ratio, of these new designs and to identify the design space for auxetic behavior using numerical and experimental methods. Systematic finite element (FE) simulations are conducted using ABAQUS and Python scripts to quantify effective stiffness and Poisson's ratio within a small strain range. To validate the numerical predictions, three representative designs are selected and fabricated via multi‐material polymer jetting. Uniaxial tension experiments are conducted on these specimens. Design spaces for non‐auxeticity, partial‐auxeticity, and complete auxeticity are identified through an integrated numerical approach. Theoretical criteria for determining the completeness of auxeticity are proposed and verified via FE simulations.

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Investigating the Effect of Relative Humidity on the Mechanics and Dynamics of Open‐Cell Polyurethane Auxetic Foams

Williams

Zhang

Kergariou

et al. 2022

Physica Status Solidi (b)

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This work describes a series of investigations carried out on sets of pristine and auxetic (negative Poisson's ratio (NPR)) open‐cell polyurethane foams subjected to relative humidity (RH) conditioning ranging from 9% to 92% at room temperature. The foams have been produced using a uniaxially thermoforming process. Pristine and auxetic foams have then been subjected to quasi‐static compressive cyclic loading (with maximum strains of 10% and 80%, respectively), as well as vibration transmissibility tests with base accelerations up to 2.29 g. Increasing levels of RH do not seem to statistically affect the moduli and PRs of foams subjected to lower maximum strains, however, especially the auxetic foams at higher compressive deformations show a decrease in the stiffness with the increase of the RH. The vibration tests show an increasing trend of the dynamic modulus of the foams with the increase of the RH. The results indicate the complexity of the interaction between foam architecture and absorption/desorption mechanisms occurring inside these porous auxetic materials.

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Impact properties of uniaxially thermoformed auxetic foams

Cited by 26 publications

References 55 publications

Hysteretic behaviour of uniaxially thermoformed auxetic foams under 3-point bending low-frequency vibration

Hysteretic behaviour of uniaxially thermoformed auxetic foams under 3-point bending low-frequency vibration

Auxetic Two‐Phase Chevron Mechanical Metamaterial

Investigating the Effect of Relative Humidity on the Mechanics and Dynamics of Open‐Cell Polyurethane Auxetic Foams

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