Investigation on the compressive properties of auxetic foams under different loading rates

Nazari, Zahra; Ahmadi, Hamed; Liaghat, Gholamhossein; Vahid, Samireh

doi:10.1002/pen.25959

Cited by 6 publications

(5 citation statements)

References 14 publications

(14 reference statements)

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“…In addition, all structures were sheet based as prior studies have shown that they have better potential for energy absorption applications. [23,32] The three TPMS structures chosen in this study are the Gyroid, Fischer-Koch S, and PMY which are represented by Equation ( 1), (2), and (3), respectively, where x, y, z represent the Cartesian coordinates ranging from 0 to 2π, and c represents the contour. The unit cells of these TPMS structures are shown in Figure 2.…”

Section: Tpms Structure Developmentmentioning

confidence: 99%

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3D‐printed and foamed triply periodic minimal surface lattice structures for energy absorption applications

Weber

Sundarram

2023

Polymer Engineering & Sci

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Structures currently used for energy absorption include foams, composites, and honeycombs. Recent studies have indicated the potential of triply periodic minimal surfaces (TPMS) for energy absorption applications as well as weight reduction. This study presents three TPMS lattice structures, namely the Gyroid, Fischer‐Koch S, and PMY, which are fabricated in uniform and graded densities. These structures, created in the MSLattice software are 3D printed using polylactic acid. Subsequently, the 3D‐printed structures undergo a gas foaming process to investigate benefits of higher porosity on energy absorption. The structures are then characterized for porosity, compressive properties, energy absorption, and thermal properties. The results show that the uniform and graded density structures have similar energy absorption values as long as the structures have a similar average density with the PMY structure exhibiting the highest energy absorption value, both in unfoamed and foamed conditions, respectively. The foaming process increased the porosity by 50% but did not improve the energy absorption characteristics of any of the structures with the foamed PMY structures exhibiting the least deviation compared to the unfoamed samples. These foamed TPMS structures are suitable for applications in the automotive and aerospace industry that demand lightweight structures for energy absorption.

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Section: Tpms Structure Developmentmentioning

confidence: 99%

“…Current structures that are used in the engineering industry for energy absorption include foams, [1,2] honeycomb, [3,4] and composites. [5,6] All of these structures are cellular materials offering improved specific properties compared to bulk materials owing to their higher surface area.…”

mentioning

confidence: 99%

3D‐printed and foamed triply periodic minimal surface lattice structures for energy absorption applications

Weber

Sundarram

2023

Polymer Engineering & Sci

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“…With increasing number of re-entrant cells, the absorbed energy in quasi-static compression tests was shown to improve. [20] Polyethylene (PE) foam was also used as raw materials to convert into auxetic foams. Duncan et al reported on the preparation of auxetic foams via steam (water vapor) treatment, [21] and a pressure-vessel method (vacuum).…”

Section: Introductionmentioning

confidence: 99%

“…With increasing number of re‐entrant cells, the absorbed energy in quasi‐static compression tests was shown to improve. [ 20 ]…”

Section: Introductionmentioning

confidence: 99%

“…The main idea to produce auxetic foams from conventional ones is to convert the standard foam structure (honeycomb/polyhedral-shaped cells) into a re-entrant cellular structure. [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] To this end, different treatments were proposed including mechanical, thermal, physical, and chemical methods, which can be performed alone or in combination. These processes involved volumetric compression, heating beyond the polymer's softening temperature and cooling while remaining under compression.…”

Section: Introductionmentioning

confidence: 99%

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Conversion of polystyrene foams into auxetic metamaterials

Chen

Rodrigue

2023

Polymer Engineering & Sci

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Auxetic foams have gained popularity within the research community because of their enhanced properties, such as low density combined with high relative stiffness, toughness, and damping properties. Low density polystyrene (PS) foams are commonly used in the packaging industry, but have a short service life and generate a high volume of waste (white pollution). This is why their recycling and valorizing is necessary and imperative. The objective of this work is to present a simple and environmentally friendly process combining low pressure (vacuum) and mechanical compression to convert recycled PS foams (15 kg/m 3 ) into low density foams (50-63 kg/m 3 ) having negative tensile and compressive Poisson's ratios (NPR). The effect of processing conditions (vacuum level, temperature, mechanical pressure, and time) were studied. Based on the optimized conditions, the tensile Poisson's ratio of the resulting auxetic foams reached À0.65 for the Y direction (width) and À0.74 for the Z direction (thickness) when stretching in the X direction (length). On the other hand, the minimum compressive Poisson's ratios were À0.32 for the Y direction and À0.28 for the Z direction. The foam structure was characterized via morphological analysis to determine the changes after treatment. Finally, tensile and compressive properties (Young's modulus, strain energy, energy dissipation, and damping capacity) are also discussed. It was observed that the mechanical properties of the resulting auxetic foams were improved compared to the original PS foam (PS-O) in terms of resilience and strength. For example, the elongation at break of auxetic foams (31%-62%) were much higher compared to PS-O (7%). These auxetic foams can be used in several applications, such as sports and military protective equipment.

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Programmable multi-layered auxetic mechanisms

Karunanidhi,

Sobczyk,

Wiesenhütter

et al. 2023

J Mater Sci

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The present work investigates programmable auxetic surfaces and how they can be enabled to achieve a general surface shape upon external control. To actively generate target geometries from an initial geometry, a process of non-uniform expansion or contraction as well as an alteration of local curvatures are necessary. This implies the alignment of a multiplicity of control factors. The present work suggests that auxetic mechanisms hold a high potential to achieve and simplify such alignments. As a key principle for achieving defined target forms and the required shape transitions, the study identifies the modification of the local scaling factor and the Gaussian curvature of plane surfaces. Within this work, such active surfaces are created utilizing multi-layered auxetic tessellations. To control the scaling factor and the curvature of the resulting structure, we propose different multi-layered auxetic structures comprising rotational actuators. These concepts are demonstrated for the example of kagome tessellations but can easily be transferred to other auxetic tessellations.

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Investigation on the compressive properties of auxetic foams under different loading rates

Cited by 6 publications

References 14 publications

3D‐printed and foamed triply periodic minimal surface lattice structures for energy absorption applications

3D‐printed and foamed triply periodic minimal surface lattice structures for energy absorption applications

Conversion of polystyrene foams into auxetic metamaterials

Programmable multi-layered auxetic mechanisms

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