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Duffy D, McCracken JM, Hebner TS, White TJ, Biggins JS. Lifting, Loading, and Buckling in Conical Shells. PHYSICAL REVIEW LETTERS 2023; 131:148202. [PMID: 37862652 DOI: 10.1103/physrevlett.131.148202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Accepted: 08/15/2023] [Indexed: 10/22/2023]
Abstract
Liquid crystal elastomer films that morph into cones are strikingly capable lifters. Thus motivated, we combine theory, numerics, and experiments to reexamine the load-bearing capacity of conical shells. We show that a cone squashed between frictionless surfaces buckles at a smaller load, even in scaling, than the classical Seide-Koiter result. Such buckling begins in a region of greatly amplified azimuthal compression generated in an outer boundary layer with oscillatory bend. Experimentally and numerically, buckling then grows subcritically over the full cone. We derive a new thin-limit formula for the critical load, ∝t^{5/2}, and validate it numerically. We also investigate deep postbuckling, finding further instabilities producing intricate states with multiple Pogorelov-type curved ridges arranged in concentric circles or Archimedean spirals. Finally, we investigate the forces exerted by such states, which limit lifting performance in active cones.
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Affiliation(s)
- Daniel Duffy
- Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ, United Kingdom
| | - Joselle M McCracken
- Department of Chemical and Biological Engineering, University of Colorado Boulder, 596 UCB, Boulder, Colorado 80309, USA
| | - Tayler S Hebner
- Department of Chemical and Biological Engineering, University of Colorado Boulder, 596 UCB, Boulder, Colorado 80309, USA
| | - Timothy J White
- Department of Chemical and Biological Engineering, University of Colorado Boulder, 596 UCB, Boulder, Colorado 80309, USA
| | - John S Biggins
- Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ, United Kingdom
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Cheng X, Fan Z, Yao S, Jin T, Lv Z, Lan Y, Bo R, Chen Y, Zhang F, Shen Z, Wan H, Huang Y, Zhang Y. Programming 3D curved mesosurfaces using microlattice designs. Science 2023; 379:1225-1232. [PMID: 36952411 DOI: 10.1126/science.adf3824] [Citation(s) in RCA: 28] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/25/2023]
Abstract
Cellular microstructures form naturally in many living organisms (e.g., flowers and leaves) to provide vital functions in synthesis, transport of nutrients, and regulation of growth. Although heterogeneous cellular microstructures are believed to play pivotal roles in their three-dimensional (3D) shape formation, programming 3D curved mesosurfaces with cellular designs remains elusive in man-made systems. We report a rational microlattice design that allows transformation of 2D films into programmable 3D curved mesosurfaces through mechanically guided assembly. Analytical modeling and a machine learning-based computational approach serve as the basis for shape programming and determine the heterogeneous 2D microlattice patterns required for target 3D curved surfaces. About 30 geometries are presented, including both regular and biological mesosurfaces. Demonstrations include a conformable cardiac electronic device, a stingray-like dual mode actuator, and a 3D electronic cell scaffold.
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Affiliation(s)
- Xu Cheng
- Applied Mechanics Laboratory, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, P.R. China
- Laboratory of Flexible Electronics Technology, Tsinghua University, Beijing 100084, P.R. China
| | - Zhichao Fan
- Applied Mechanics Laboratory, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, P.R. China
- Laboratory of Flexible Electronics Technology, Tsinghua University, Beijing 100084, P.R. China
- College of Mechanical and Vehicle Engineering, Hunan University, Changsha 410082, P.R. China
| | - Shenglian Yao
- School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, P.R. China
| | - Tianqi Jin
- Applied Mechanics Laboratory, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, P.R. China
- Laboratory of Flexible Electronics Technology, Tsinghua University, Beijing 100084, P.R. China
| | - Zengyao Lv
- Applied Mechanics Laboratory, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, P.R. China
- Laboratory of Flexible Electronics Technology, Tsinghua University, Beijing 100084, P.R. China
| | - Yu Lan
- Applied Mechanics Laboratory, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, P.R. China
- Laboratory of Flexible Electronics Technology, Tsinghua University, Beijing 100084, P.R. China
| | - Renheng Bo
- Applied Mechanics Laboratory, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, P.R. China
- Laboratory of Flexible Electronics Technology, Tsinghua University, Beijing 100084, P.R. China
| | - Yitong Chen
- Applied Mechanics Laboratory, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, P.R. China
- Department of Automation, Tsinghua University, Beijing 100084, P.R. China
| | - Fan Zhang
- Applied Mechanics Laboratory, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, P.R. China
- Laboratory of Flexible Electronics Technology, Tsinghua University, Beijing 100084, P.R. China
| | - Zhangming Shen
- Applied Mechanics Laboratory, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, P.R. China
- Laboratory of Flexible Electronics Technology, Tsinghua University, Beijing 100084, P.R. China
| | - Huanhuan Wan
- College of Mechanical and Vehicle Engineering, Hunan University, Changsha 410082, P.R. China
| | - Yonggang Huang
- Querrey Simpson Institute for Bioelectronics, Northwestern University, Evanston, IL 60208, USA
- Departments of Civil & Environmental Engineering, Mechanical Engineering, and Materials Science & Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Yihui Zhang
- Applied Mechanics Laboratory, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, P.R. China
- Laboratory of Flexible Electronics Technology, Tsinghua University, Beijing 100084, P.R. China
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Lange J, Bernitt E, Döbereiner HG. Biomechanical Aspects of Actin Bundle Dynamics. Front Cell Dev Biol 2020; 8:422. [PMID: 32582705 PMCID: PMC7296148 DOI: 10.3389/fcell.2020.00422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 05/06/2020] [Indexed: 12/03/2022] Open
Abstract
Lamellipodial and filopodial protrusions are two of the main aggregate types of filamentous actin in living cells. Even though filopodia are essential to a range of vital cell functions, the mechanisms leading to their formation are still debated. Filopodia are relatively stiff and rod-like structures that are embedded in the highly dynamic framework of the backward flowing meshwork of the lamellipodium. Phenomena such as lateral filopodia drift and collision events suggest that mechanical aspects play a significant role in filopodia dynamics. In this paper, we systematically analyze the interplay between the backward flow of actin in the lamellipodium and the drift velocity of actin bundles, that we identify to be filopodia, in a quantitative manner in cells of given morphology and controlled myosin activity. Moreover, we study mechanical aspects of fusion of actin bundles drifting laterally in the lamellipodium. We find that the dynamics of actin bundles drift and fusion can be captured in a mechanical framework, which leads to a model of actin bundles orientation.
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Affiliation(s)
- Julia Lange
- Institute of Biophysics, University of Bremen, Bremen, Germany
| | - Erik Bernitt
- Institute of Biophysics, University of Bremen, Bremen, Germany
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Mikkelsen A, Rozynek Z. Mechanical Properties of Particle Films on Curved Interfaces Probed through Electric Field-Induced Wrinkling of Particle Shells. ACS APPLIED MATERIALS & INTERFACES 2019; 11:29396-29407. [PMID: 31329414 DOI: 10.1021/acsami.9b08045] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Similar to the human skin, a monolayer of packed particles capillary bound to a liquid interface wrinkles when subjected to compressive stress. The induced wrinkles absorb the applied stress and do not disappear unless the stress is removed. Experimental and theoretical investigations of wrinkle formation typically concern flat particle monolayers subjected to uniaxial stress. In this work, we extend the results on wrinkling of particle-covered interfaces to the investigation of mechanical properties of particle films on a curved interface, that is, we study particle shells formed on droplets and subjected to hoop stress. Opposed to flat particle layers where liquid buoyancy alone acts as the effective stiffness, the mechanical properties of particle layers on small droplets are also affected by the surface curvature. We show here that this leads to formation of wrinkles with different characteristic wavelengths compared to those found at flat interfaces. Our experimental results also reveal that the wrinkle wavelength of particle shells is proportional to the square root of particle size and the size of the droplets on which the shells are formed. Wrinkling of particle layers composed of microparticles with diameters ranging from around 1-100 μm was induced using a novel approach combining electrodeformation and electrohydrodynamic flows. We demonstrate that our contactless approach for studying the mechanical properties of particle shells enables estimation of elasticity, particle film thickness, and bending stiffness of particle shells. The proposed approach is insensitive to both particle coverage and electric field strength. In addition, it enables manipulation of particle packing that is intimately linked with formation of wrinkling patterns. With a wide range of applications depending on accurate mechanical properties (e.g., drug-delivery capsules to self-healing materials), this work provides a valuable method to characterize the mechanical properties of shells and tailor their surface properties (i.e., permeability and roughness).
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Affiliation(s)
- A Mikkelsen
- Faculty of Physics , Adam Mickiewicz University , Uniwersytetu Poznańskiego 2 , Poznań 61-614 , Poland
| | - Z Rozynek
- Faculty of Physics , Adam Mickiewicz University , Uniwersytetu Poznańskiego 2 , Poznań 61-614 , Poland
- Harvard John A. Paulson School of Engineering and Applied Sciences , Harvard University , Cambridge , Massachusetts 02138 , United States
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