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Mulla T, Pellenq RJM, Ulm FJ. Fluctuation-based fracture mechanics of heterogeneous materials. Phys Rev E 2022; 106:065003. [PMID: 36671134 DOI: 10.1103/physreve.106.065003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Accepted: 11/27/2022] [Indexed: 06/17/2023]
Abstract
We present results of a hybrid analytical-simulation investigation of the fracture resistance of heterogeneous materials. We show that bond-energy fluctuations sampled by Monte Carlo simulations in the semigrand canonical ensemble provide a means to rationalize the complexity of heterogeneous fracture processes, encompassing probability and percolation theories of fracture. For a number of random and textured model materials, we derive upper and lower bounds of fracture resistance and link bond fracture fluctuations to statistical descriptors of heterogeneity, such as two-point correlation functions, to identify the origin of toughening mechanisms. This includes a shift from short- to long-range interactions of bond fracture processes in random systems to the transition from critical to subcritical bond fracture percolation in textured materials and the activation of toughness reserves at compliant interfaces. Induced by elastic mismatch, they connect to a number of disparate experimental observations, including toughening of brittle solids by deformable polymers or organics in, e.g., gas shale, nacre; stress-induced transformational toughening in ceramics; and toughening of sparse elastic networks in hydrogels, to name a few.
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Affiliation(s)
- T Mulla
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - R J-M Pellenq
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- MIT-CNRS-AMU Joint Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Department of Physics, Georgetown University, Washington, DC, USA
| | - F-J Ulm
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- MIT-CNRS-AMU Joint Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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Tan X, Martínez JAI, Ulliac G, Wang B, Wu L, Moughames J, Raschetti M, Laude V, Kadic M. Single-Step-Lithography Micro-Stepper Based on Frictional Contact and Chiral Metamaterial. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2202128. [PMID: 35708218 DOI: 10.1002/smll.202202128] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 05/21/2022] [Indexed: 06/15/2023]
Abstract
Stepper motors and actuators are among the main constituents of control motion devices. They are complex multibody systems with rather large overall volume due to their multifunctional parts and elaborate technological assembly processes. Miniaturization of individual parts is still posing assembly problems. In this paper, a single-step lithography process to fabricate a micro-stepper engine with an accurate micrometric rotation axis and an overall sub-millimeter size is demonstrated. The device is based on the frictional contacts and chiral metamaterials to get rid of the dependence on the accuracy of parts. The functional aspects of fabricated samples are discussed for many rotation cycles and for different frictional surfaces.
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Affiliation(s)
- Xiaojun Tan
- Institut FEMTO-ST, CNRS UMR 6174, University Bourgogne Franche-Comté, Besançon, 25000, France
- National Key Laboratory of Science and Technology on Advanced Composites in Special Environments, Harbin Institute of Technology, Harbin, 150001, P. R. China
| | | | - Gwenn Ulliac
- Institut FEMTO-ST, CNRS UMR 6174, University Bourgogne Franche-Comté, Besançon, 25000, France
| | - Bing Wang
- National Key Laboratory of Science and Technology on Advanced Composites in Special Environments, Harbin Institute of Technology, Harbin, 150001, P. R. China
| | - Linzhi Wu
- National Key Laboratory of Science and Technology on Advanced Composites in Special Environments, Harbin Institute of Technology, Harbin, 150001, P. R. China
| | - Johnny Moughames
- Institut FEMTO-ST, CNRS UMR 6174, University Bourgogne Franche-Comté, Besançon, 25000, France
| | - Marina Raschetti
- Institut FEMTO-ST, CNRS UMR 6174, University Bourgogne Franche-Comté, Besançon, 25000, France
| | - Vincent Laude
- Institut FEMTO-ST, CNRS UMR 6174, University Bourgogne Franche-Comté, Besançon, 25000, France
| | - Muamer Kadic
- Institut FEMTO-ST, CNRS UMR 6174, University Bourgogne Franche-Comté, Besançon, 25000, France
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Felix LC, Galvao DS. Guided fractures in graphene mechanical diode-like structures. Phys Chem Chem Phys 2022; 24:13905-13910. [PMID: 35621060 DOI: 10.1039/d2cp01207c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The concept of a diode is usually applied to electronic and thermal devices but very rarely for mechanical ones. A recently proposed fracture rectification effect in polymer-based structures with triangular void defects has motivated us to test these ideas at the nanoscale using graphene membranes. Using fully-atomistic reactive molecular dynamics simulations we showed that robust rectification-like effects exist. The fracture can be 'guided' to more easily propagate along one specific direction than its opposite. We also observed that there is an optimal value for the spacing between each void for the rectification effect.
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Affiliation(s)
- Levi C Felix
- Applied Physics Department, 'Gleb Wataghin' Institute of Physics, State University of Campinas, Campinas, SP, 13083-970, Brazil. .,Center for Computing in Engineering & Sciences, State University of Campinas, Campinas, SP, 13083-970, Brazil
| | - Douglas S Galvao
- Applied Physics Department, 'Gleb Wataghin' Institute of Physics, State University of Campinas, Campinas, SP, 13083-970, Brazil. .,Center for Computing in Engineering & Sciences, State University of Campinas, Campinas, SP, 13083-970, Brazil
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