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arXiv · 2507.15014

A rediscovery of stiff pentmodes. A comment on "High bulk modulus pentamodes: the three-dimensional metal water"

Graeme W. Milton
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Abstract

We bring attention to the fact that the claim of Brambilla et.al. [Extreme Mechanics Letters 74 (2025) 102267; arXiv:2406.14502] of discovering a novel design for pentamode materials is incorrect. Back in 2016 Briane, Harutyunyan and myself [Mathematics and Mechanics of Complex Systems 5 (2016) 41--94; arXiv:1606.03305] designed a class of stiff pentamodes, that include the high bulk modulus pentamodes of Brambilla et.al. Our design generalized to three-dimensions, and to full anisotropy, the main aspects of a two-dimensional construction of Sigmund [Journal of the Mechanics and Physics of Solids 48 (2000) 397--428]. It is emphasized that the in depth analysis of Brambilla et.al. goes well beyond our brief treatment.

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Graeme W. Milton. 2025-07-20. A rediscovery of stiff pentmodes. A comment on "High bulk modulus pentamodes: the three-dimensional metal water". https://arxiv.org/abs/2507.15014

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