Multilevel hierarchy in bi-material lattices with high specific stiffness and unbounded thermal expansion

Xu, Hang; Farag, A. M.; Pasini, Damiano

doi:10.1016/j.actamat.2017.05.059

Cited by 77 publications

(37 citation statements)

References 33 publications

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“…Ashby plot of the thermal expansion coefficients versus the filling ratio for the representative mechanical metamaterials reported previously [ 3–7,9–12,54,56,60,61,63,66,70 ] and kirigami‐inspired 2D hierarchical designs proposed in the current work. i) Reproduced with permission.…”

Section: Figurementioning

confidence: 92%

“…Ashby plot of the thermal expansion coefficients of natural materials, [ 11,64 ] NTE materials, [ 50,52,72–77 ] representative mechanical metamaterials reported previously (i.e., planar lattice structures, [ 3–5,11,54,56,60,61,63,66 ] topology optimized structures, [ 9,10 ] and chiral metamaterials [ 6,7,12 ] ), and kirigami‐inspired 2D hierarchical designs proposed in the previous [ 70 ] and current work. i) Reproduced with permission.…”

Section: Figurementioning

confidence: 99%

Section: Figurementioning

confidence: 99%

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Designing Mechanical Metamaterials with Kirigami‐Inspired, Hierarchical Constructions for Giant Positive and Negative Thermal Expansion

Guo

et al. 2020

Advanced Materials

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Advanced mechanical metamaterials with unusual thermal expansion properties represent an area of growing interest, due to their promising potential for use in a broad range of areas. In spite of previous work on metamaterials with large or ultralow coefficient of thermal expansion (CTE), achieving a broad range of CTE values with access to large thermally induced dimensional changes in structures with high filling ratios remains a key challenge. Here, design concepts and fabrication strategies for a kirigami‐inspired class of 2D hierarchical metamaterials that can effectively convert the thermal mismatch between two closely packed constituent materials into giant levels of biaxial/uniaxial thermal expansion/shrinkage are presented. At large filling ratios (>50%), these systems offer not only unprecedented negative and positive biaxial CTE (i.e., −5950 and 10 710 ppm K−1), but also large biaxial thermal expansion properties (e.g., > 21% for 20 K temperature increase). Theoretical modeling of thermal deformations provides a clear understanding of the microstructure–property relationships and serves as a basis for design choices for desired CTE values. An Ashby plot of the CTE versus density serves as a quantitative comparison of the hierarchical metamaterials presented here to previously reported systems, indicating the capability for substantially enlarging the accessible range of CTE.

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Section: Figurementioning

confidence: 92%

Section: Figurementioning

confidence: 99%

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Designing Mechanical Metamaterials with Kirigami‐Inspired, Hierarchical Constructions for Giant Positive and Negative Thermal Expansion

Guo

et al. 2020

Advanced Materials

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“…Another approach is to change the base materials, here hardwood and silicone rubber, as well as the aspect ratio of BB, here quite large ( l / h = 9). For example, a change of silicone rubber, the core material, with a solid of higher elasatic modulus yet distinct CTE, such as polytetrafluoroethylene (PTFE) 64 , and the selection of less slender BB can contribute to compensate the low stiffness observed in our proof-of-concepts. A third option to enhance stiffens in the deformed state is to envision an interlocking strategy that autonomously locks the material phenotype.…”

Section: Outlook and Conclusionmentioning

confidence: 99%

Encoding kirigami bi-materials to morph on target in response to temperature

Liu

Qiao

et al. 2019

Sci Rep

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Shape morphing in response to an environmental stimulus, such as temperature, light, and chemical cues, is currently pursued in synthetic analogs for manifold applications in engineering, architecture, and beyond. Existing strategies mostly resort to active, namely smart or field responsive, materials, which undergo a change of their physical properties when subjected to an external stimulus. Their ability for shape morphing is intrinsic to the atomic/molecular structure as well as the mechanochemical interactions of their constituents. Programming shape changes with active materials require manipulation of their composition through chemical synthesis. Here, we demonstrate that a pair of off-the-shelf passive solids, such as wood and silicone rubber, can be topologically arranged in a kirigami bi-material to shape-morph on target in response to a temperature stimulus. A coherent framework is introduced to enable the optimal orchestration of bi-material units that can engage temperature to collectively deploy into a geometrically rich set of periodic and aperiodic shapes that can shape-match a predefined target. The results highlight reversible morphing by mechanics and geometry, thus contributing to relax the dependence of current strategies on material chemistry and fabrication.

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“…Thus, its range of CTE is very narrow, considering the CTEs of the available materials and assembly process. Fortunately, a promising approach employs the hierarchical structure to achieve large NTE [3,41,42]. The hierarchical structure uses small scale bi-material lattices to replace the elements in the origin lattice.…”

Section: Introductionmentioning

confidence: 99%

Bi-Material Negative Thermal Expansion Inverted Trapezoid Lattice based on A Composite Rod

et al. 2019

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Negative thermal expansion (NTE) lattices are widely used in aerospace engineering where the structures experience large temperature variation. However, the available range of NTE of the current lattices is quite narrow, which severely limits their engineering application. In this paper, we report an inverted trapezoid lattice (ITL) with large NTE. The NTE of the ITL is 2.6 times that of a typical triangular lattice with the same height and hypotenuse angle. Theoretically, with a pin-jointed assumption, the ITL can improve the NTE by order of magnitude if the length ratio of the composite rod is changed. In the presented ITL, a composite rod is utilized as the base of the ITL. The composite rod has large inner NTE. The inverted trapezoid structure converts the inner NTE to the vertical direction contraction and obtains an extra NTE. Finite element simulations and experimental verification by interferometric measurement were conducted to verify the large thermal expansion of the ITL.

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Multilevel hierarchy in bi-material lattices with high specific stiffness and unbounded thermal expansion

Cited by 77 publications

References 33 publications

Designing Mechanical Metamaterials with Kirigami‐Inspired, Hierarchical Constructions for Giant Positive and Negative Thermal Expansion

Designing Mechanical Metamaterials with Kirigami‐Inspired, Hierarchical Constructions for Giant Positive and Negative Thermal Expansion

Encoding kirigami bi-materials to morph on target in response to temperature

Bi-Material Negative Thermal Expansion Inverted Trapezoid Lattice based on A Composite Rod

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