Dynamic reconfiguration of magneto-elastic lattices

Schaeffer, Marshall; Ruzzene, Massimo

doi:10.1016/j.crme.2015.06.007

Cited by 10 publications

(5 citation statements)

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“…The magnetization pattern with attracting nearest neighbors is used to showcase the drastic changes in properties that can be achieved by reconfiguration. The reconfiguration considered is the transition to the re-entrant lattice (Figure 2c) as this is possibly the easiest way to reconfigure the magneto-elastic hexagonal lattice studied based on previous research by the authors Schaeffer and Ruzzene [1,20]. In contrast with the hexagonal patterns, the re-entrant lattice is anisotropic.…”

Section: Results: 2d Latticesmentioning

confidence: 99%

Homogenization of 1D and 2D magnetoelastic lattices

Schaeffer

Ruzzene

2015

EPJ Applied Metamaterials

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-This paper investigates the equivalent in-plane mechanical properties of one dimensional (1D) and two dimensional (2D), periodic magneto-elastic lattices. A lumped parameter model describes the lattices using magnetic dipole moments in combination with axial and torsional springs. The homogenization procedure is applied to systems linearized about stable configurations, which are identified by minimizing potential energy. Simple algebraic expressions are derived for the properties of 1D structures. Results for 1D lattices show that a variety of stiffness changes are possible through reconfiguration, and that magnetization can either stiffen or soften a structure. Results for 2D hexagonal and re-entrant lattices show that both reconfigurations and magnetization have drastic effects on the mechanical properties of lattice structures. Lattices can be stiffened or softened and the Poisson's ratio can be tuned. Furthermore for certain hexagonal lattices the sign of Poisson's ratio can change by varying the lattice magnetization. In some cases presented, analytical and numerically estimated equivalent properties are validated through numerical simulations that also illustrate the unique characteristics of the investigated configurations.

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Section: Results: 2d Latticesmentioning

confidence: 99%

Homogenization of 1D and 2D magnetoelastic lattices

Schaeffer

Ruzzene

2015

EPJ Applied Metamaterials

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“…Eximem-se, assim, os fenícios e púnicos de uma prática considerada modernamente uma aberração e transforma-se o molk em um rito iniciático não sangrento. Schaeffer (1956) teria sido o pioneiro da hipótese funerária. Em 1956, ele defendeu que os restos humanos encontrados no tofet de Cartago não eram vítimas de um sacrifício humano, infantil no caso, e sim mortos por causas naturais.…”

Section: A Interpretaçãounclassified

O papel de Cartago no debate acerca do sacrifício humano fenício-púnico

Kormikiari¹

2018

Rom

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A existência ou não do sacrifício humano, especificamente infantil, entre os povos fenício-púnicos é tema de acalorados debates acadêmicos há mais de um século. Recentemente, um conjunto significativo de revisões e novas abordagens físico-químicas da documentação cartaginesa reavivou a questão, que se viu, mais uma vez, no centro de réplicas e tréplicas internacionais. Estaremos diante de um tema que foge à nossa capacidade de análise imparcial? Este artigo pretende abordar os dados mais recentemente organizados em relação ao tema e as interpretações daí advindas. Neste contexto, o Norte da África destaca-se como espaço, até o momento, onde foram encontrados vestígios arqueológicos particularmente instigantes. Além do papel central que Cartago parece ter desempenhado, temos em solo norte-africano o único caso conhecido de “exportação” dessa prática ritual tão complexa. Referimo-nos ao santuário de El-Hofra, em Cirta (moderna Constantina, Argélia), área númida com posição estratégica na rede de trocas da região, visitada e habitada por gregos, latinos, cartagineses, além dos próprios berberes.

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“…[18][19][20][21] Yet, a common vision for elastomeric mechanical metamaterials is to mitigate impact, in which case high strain rates are induced. [23,24] These internal instabilities break the direct proportionality between micro-and macroscale behaviors. While there are inherent ties between shock absorption mechanisms and the elastic buckling of the beam constituents in such elastomeric metamaterials, [22] when composed into material systems the presence of buckling members gives rise to non-affine response at the microscale that ultimately governs macroscopic energy dissipation properties of the system.…”

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confidence: 99%

Illuminating Origins of Impact Energy Dissipation in Mechanical Metamaterials

2017

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Elastomeric mechanical metamaterials have revealed striking ability to attenuate shock loads at the macroscopic level. Reports suggest that this capability is associated with the reversible elastic buckling of internal beam constituents observed in quasistatic characterizations. Yet, the presence of buckling members induces non-affine response at the microscale, so that clear understanding of the exact energy dissipation mechanisms remains clouded. In this report, the authors examine a mechanical metamaterial that exhibits both micro-and macroscopic deformations under impact loads and devise an experimental method to visualize the resulting energy dissipation mechanisms. By illuminating the dynamic distribution of strain in the metamaterial, the authors uncover a rational way to program the macroscopic deformation and enhance impact mitigation properties. The results emphasize that mechanical metamaterials clearly integrate materials science and structural engineering, encouraging future interdisciplinary studies to capitalize on the opportunities.The blow of an impact can rapidly harm people and engineered systems. [1,2] This challenge has fueled development of resilient engineered material systems able to suppress the transmission of impact energy to the shielded body or structure. Recent attention has turned to buckling-based material system concepts, whereby elastic and/or plastic buckling structural members on a microscale level [3][4][5][6][7] are harnessed to absorb shock at the system level. Preferring the reusability of elastic buckling phenomena and the practicality of elastomers, classes of elastomeric mechanical metamaterials have been devised with internal cellular geometries that absorb elastic energy via reversible buckling events in periodic, microscale elastomeric beam constituents. [8][9][10][11][12] Under low frequency cycling of applied strain or stress, these new generations of cellular materials [13] are shown to exhibit exceptional elastic energy dissipation properties [14][15][16] due to a "reversible plasticity" effect [17] that has an analogy to energy management in cytoskeletal actin networks. [18][19][20][21] Yet, a common vision for elastomeric mechanical metamaterials is to mitigate impact, in which case high strain rates are induced. In this light, experimental evidence suggests these metamaterials are effective to dissipate sudden accelerations [9] and shocks, [11] although the exact energy mitigation mechanisms are unknown. While there are inherent ties between shock absorption mechanisms and the elastic buckling of the beam constituents in such elastomeric metamaterials, [22] when composed into material systems the presence of buckling members gives rise to non-affine response at the microscale that ultimately governs macroscopic energy dissipation properties of the system. [23,24] These internal instabilities break the direct proportionality between micro-and macroscale behaviors. [25] Although high-speed video has shed light on energy transfer and dissipation in similar problem...

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Dynamic reconfiguration of magneto-elastic lattices

Cited by 10 publications

References 21 publications

Homogenization of 1D and 2D magnetoelastic lattices

Homogenization of 1D and 2D magnetoelastic lattices

O papel de Cartago no debate acerca do sacrifício humano fenício-púnico

Illuminating Origins of Impact Energy Dissipation in Mechanical Metamaterials

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