1
|
Hörmann L, Cartus JJ, Hofmann OT. Impact of Static Distortion Waves on Superlubricity. ACS OMEGA 2023; 8:42457-42466. [PMID: 38024737 PMCID: PMC10652266 DOI: 10.1021/acsomega.3c05044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Accepted: 10/06/2023] [Indexed: 12/01/2023]
Abstract
Friction is a major source of energy loss in mechanical devices. This energy loss may be minimized by creating interfaces with extremely reduced friction, i.e., superlubricity. Conventional wisdom holds that incommensurate interface structures facilitate superlubricity. Accurately describing friction necessitates the precise modeling of the interface structure. This, in turn, requires the use of accurate first-principles electronic structure methods, especially when studying organic/metal interfaces, which are highly relevant due to their tunability and propensity to form incommensurate structures. However, the system size required to calculate incommensurate structures renders such calculations intractable. As a result, studies of incommensurate interfaces have been limited to very simple model systems or strongly simplified methodology. We overcome this limitation by developing a machine-learned interatomic potential that is able to determine energies and forces for structures containing thousands to tens of thousands of atoms with an accuracy comparable to conventional first-principles methods but at a fraction of the cost. Using this approach, we quantify the breakdown of superlubricity in incommensurate structures due to the formation of static distortion waves. Moreover, we extract design principles to engineer incommensurate interface systems where the formation of static distortion waves is suppressed, which facilitates low friction coefficients.
Collapse
Affiliation(s)
- Lukas Hörmann
- Institute of Solid State Physics, Graz University of Technology, Graz 8010, Austria
| | - Johannes J. Cartus
- Institute of Solid State Physics, Graz University of Technology, Graz 8010, Austria
| | - Oliver T. Hofmann
- Institute of Solid State Physics, Graz University of Technology, Graz 8010, Austria
| |
Collapse
|
2
|
Iwashita W, Matsukawa H, Otsuki M. Static friction coefficient depends on the external pressure and block shape due to precursor slip. Sci Rep 2023; 13:2511. [PMID: 36781981 PMCID: PMC9925803 DOI: 10.1038/s41598-023-29764-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 02/09/2023] [Indexed: 02/15/2023] Open
Abstract
Amontons' law states that the maximum static friction force on a solid object is proportional to the loading force and is independent of the apparent contact area. This law indicates that the static friction coefficient does not depend on the external pressure or object shape. Here, we numerically investigate the sliding motion of a 3D viscoelastic block on a rigid substrate using the finite element method (FEM). The macroscopic static friction coefficient decreases with an increase in the external pressure, length, or width of the object, which contradicts Amontons' law. Precursor slip occurs in the 2D interface between the block and substrate before bulk sliding. The decrease in the macroscopic static friction coefficient is scaled by the critical area of the precursor slip. A theoretical analysis of the simplified models reveals that bulk sliding results from the instability of the quasi-static precursor slip caused by velocity-weakening local friction. We also show that the critical slip area determines the macroscopic static friction coefficient, which explains the results of the FEM simulation.
Collapse
Affiliation(s)
- Wataru Iwashita
- Department of Mechanical Science and Bioengineering, Osaka University, Toyonaka, 560-8531, Japan.
| | - Hiroshi Matsukawa
- Department of Physical Sciences, Aoyama Gakuin University, Sagamihara, 252-5258, Japan
| | - Michio Otsuki
- Department of Mechanical Science and Bioengineering, Osaka University, Toyonaka, 560-8531, Japan
| |
Collapse
|
3
|
Kalousek V, Yoo AJ, Sheth SA, Janardhan V, Mamic J, Janardhan V. Cyclical aspiration using a novel mechanical thrombectomy device is associated with a high TICI 3 first pass effect in large-vessel strokes. J Neuroimaging 2021; 31:912-924. [PMID: 34101284 PMCID: PMC8519104 DOI: 10.1111/jon.12889] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 05/13/2021] [Accepted: 05/14/2021] [Indexed: 01/01/2023] Open
Abstract
Background and Purpose Complete reperfusion (TICI 3) after the first thrombectomy attempt or first pass effect (FPE) is associated with best clinical outcomes in large‐vessel occlusion (LVO) acute ischemic stroke. While endovascular therapy techniques have improved substantially, FPE remains low (24–30%), and new methods to improve reperfusion efficiency are needed. Methods In a prospective observational cohort study, 40 consecutive patients underwent cyclical aspiration thrombectomy using CLEARTM Aspiration System (Insera Therapeutics Inc., Dallas, TX). Primary outcome included FPE with complete/near‐complete reperfusion (TICI 2c/3 FPE). Secondary outcomes included early neurological improvement measured by the National Institute of Health Stroke Scale (NIHSS), safety outcomes, and functional outcomes using modified Rankin Scale (mRS). Outcomes were compared against published historical controls. Results Among 38 patients who met criteria for LVO, median age was 75 (range 31–96). FPE was high (TICI 3: 26/38 [68%], TICI 2c/3: 29/38 [76%]). Among anterior circulation strokes, core lab‐adjudicated FPE remained high (TICI 3: 17/29 [59%], TICI 2c/3: 20/29 [69%]), with excellent final successful revascularization results (Final TICI 3: 24/29 [83%], Final TICI 2c/3: 27/29 [93%]). FPE in the CLEAR‐1 cohort was significantly higher compared to FPE using existing devices (meta‐analysis) from historical controls (TICI 2c/3: 76% vs. 28%, p = 0.0001). High rates of early neurological improvement were observed (delta NIHSS≥4: 35/38 [92.1%]; delta NIHSS≥10: 27/38 [71%]). Similarly, high rates of good functional outcomes (mRS 0–2: 32/38 [84%]) and low mortality (2/38 [5%]) were observed. Conclusion Cyclical aspiration using the CLEARTM Aspiration System is safe, effective, and achieved a high TICI 3 FPE for large‐vessel strokes.
Collapse
Affiliation(s)
- Vladimir Kalousek
- Department of Radiology, Zagreb, Croatia.,University Hospital Center 'Sestre Milosrdnice', Zagreb, Croatia
| | - Albert J Yoo
- Texas Stroke Institute, Dallas-Fort Worth, Texas.,Medical City Plano, Medical City Healthcare, Plano, Texas, USA
| | - Sunil A Sheth
- Department of Neurology, UTHealth McGovern Medical School, Houston, Texas, USA
| | | | - Josip Mamic
- Department of Radiology, Zagreb, Croatia.,University Hospital Center 'Sestre Milosrdnice', Zagreb, Croatia
| | - Vallabh Janardhan
- Medical City Plano, Medical City Healthcare, Plano, Texas, USA.,Insera Therapeutics, Inc., Dallas, Texas, USA
| |
Collapse
|
4
|
Skondras-Giousios D, Karkalos NE, Markopoulos AP. Finite element simulation of friction and adhesion attributed contact of bio-inspired gecko-mimetic PDMS micro-flaps with SiO 2spherical surface. BIOINSPIRATION & BIOMIMETICS 2020; 15:066004. [PMID: 32480387 DOI: 10.1088/1748-3190/ab983e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2019] [Accepted: 06/01/2020] [Indexed: 06/11/2023]
Abstract
The remarkable tribological attributes of the gecko feet have grown much interest in the field of biomimetic tribology over the past two decades. It has been shown that the complexity of friction and adhesion phenomena made it difficult to transfer these exceptional properties into fully functional smart, dry, micro patterned adhesives. The latter, combined with the relative lack of literature on computational oriented studies on these phenomena, is the motive of the current work. Here, a 2D time-dependent finite element model of friction and adhesion attributed contact of polydimethysiloxane (PDMS) micro flaps with a smooth SiO2spherical surface is presented. The model is tested through simulations concerning changes in the disc curvature, the flap density, as well as different disc mounting heights, representing the effect of preload. Furthermore, the effect of tribological parameters of adhesion and friction coefficient is discussed. Finally, the effect of the use of two hyperelastic material models was examined.
Collapse
Affiliation(s)
- D Skondras-Giousios
- School of Mechanical Engineering, Laboratory of Manufacturing Technology, National Technical University of Athens, Heroon Polytechniou 9, 15780, Athens, Greece
| | - N E Karkalos
- School of Mechanical Engineering, Laboratory of Manufacturing Technology, National Technical University of Athens, Heroon Polytechniou 9, 15780, Athens, Greece
| | - A P Markopoulos
- School of Mechanical Engineering, Laboratory of Manufacturing Technology, National Technical University of Athens, Heroon Polytechniou 9, 15780, Athens, Greece
| |
Collapse
|
5
|
Multi-Scale Surface Texturing in Tribology—Current Knowledge and Future Perspectives. LUBRICANTS 2019. [DOI: 10.3390/lubricants7110095] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Surface texturing has been frequently used for tribological purposes in the last three decades due to its great potential to reduce friction and wear. Although biological systems advocate the use of hierarchical, multi-scale surface textures, most of the published experimental and numerical works have mainly addressed effects induced by single-scale surface textures. Therefore, it can be assumed that the potential of multi-scale surface texturing to further optimize friction and wear is underexplored. The aim of this review article is to shed some light on the current knowledge in the field of multi-scale surface textures applied to tribological systems from an experimental and numerical point of view. Initially, fabrication techniques with their respective advantages and disadvantages regarding the ability to create multi-scale surface textures are summarized. Afterwards, the existing state-of-the-art regarding experimental work performed to explore the potential, as well as the underlying effects of multi-scale textures under dry and lubricated conditions, is presented. Subsequently, numerical approaches to predict the behavior of multi-scale surface texturing under lubricated conditions are elucidated. Finally, the existing knowledge and hypotheses about the underlying driven mechanisms responsible for the improved tribological performance of multi-scale textures are summarized, and future trends in this research direction are emphasized.
Collapse
|
6
|
Arslanian RA, Marosfoi M, Caroff J, King RM, Raskett C, Puri AS, Gounis MJ, Chueh JY. Complete clot ingestion with cyclical ADAPT increases first-pass recanalization and reduces distal embolization. J Neurointerv Surg 2019; 11:931-936. [PMID: 30718384 DOI: 10.1136/neurintsurg-2018-014625] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 01/07/2019] [Accepted: 01/09/2019] [Indexed: 01/29/2023]
Abstract
BACKGROUND Evidence is mounting that first-pass complete recanalization during mechanical thrombectomy is associated with better clinical outcomes in patients presenting with an emergent large vessel occlusion. We hypothesize that aspiration achieving complete clot ingestion results in higher first-pass successful recanalization with quantitative reduction in distal emboli. METHODS A patient-specific cerebrovascular replica was connected to a flow loop. Occlusion of the middle cerebral artery was achieved with clot analogs. Independent variables were the diameter of the aspiration catheter (0.054-0.088in) and aspiration pattern (static versus cyclical). Outcome measures were the first-pass rates of complete clot ingestion, the extent of recanalization, and the particle-size distribution of distal emboli. RESULTS All aspiration catheters were successfully navigated to the occlusion. Complete clot ingestion during aspiration thrombectomy resulted in first-pass complete recanalization in every experiment, only achieved in 21% of experiments with partial ingestion (P<0.0001). Aspiration through the large bore 0.088in device resulted in the highest rates of complete clot ingestion (90%). Cyclical aspiration (18-29 inHg, 0.5 Hz) significantly increased the rate of complete clot ingestion (OR21 [1.6, 266]; P=0.04). In all experiments, complete clot ingestion resulted in fewer and smaller distal emboli. CONCLUSIONS Complete clot ingestion results in fewer distal emboli and the highest rates of first-pass complete recanalization. The rate of complete ingestion during aspiration thrombectomy is a function of both the inner diameter of the aspiration catheter and use of cyclical aspiration.
Collapse
Affiliation(s)
- Rose A Arslanian
- Department of Radiology, New England Center for Stroke Research, Division of Neuroimaging and Intervention, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Miklos Marosfoi
- Department of Radiology, New England Center for Stroke Research, Division of Neuroimaging and Intervention, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Jildaz Caroff
- Hôpital Beaujon, Department of Interventional Neuroradiology, Clichy, France
| | - Robert M King
- Department of Radiology, New England Center for Stroke Research, Division of Neuroimaging and Intervention, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Christopher Raskett
- Department of Radiology, New England Center for Stroke Research, Division of Neuroimaging and Intervention, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Ajit S Puri
- Department of Radiology, New England Center for Stroke Research, Division of Neuroimaging and Intervention, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Matthew J Gounis
- Department of Radiology, New England Center for Stroke Research, Division of Neuroimaging and Intervention, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Ju-Yu Chueh
- Department of Radiology, New England Center for Stroke Research, Division of Neuroimaging and Intervention, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| |
Collapse
|
7
|
Guarino R, Costagliola G, Bosia F, Pugno NM. Evidence of friction reduction in laterally graded materials. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2018; 9:2443-2456. [PMID: 30254839 PMCID: PMC6142729 DOI: 10.3762/bjnano.9.229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 08/22/2018] [Indexed: 06/08/2023]
Abstract
In many biological structures, optimized mechanical properties are obtained through complex structural organization involving multiple constituents, functional grading and hierarchical organization. In the case of biological surfaces, the possibility to modify the frictional and adhesive behaviour can also be achieved by exploiting a grading of the material properties. In this paper, we investigate this possibility by considering the frictional sliding of elastic surfaces in the presence of a spatial variation of the Young's modulus and the local friction coefficients. Using finite-element simulations and a two-dimensional spring-block model, we investigate how graded material properties affect the macroscopic frictional behaviour, in particular, static friction values and the transition from static to dynamic friction. The results suggest that the graded material properties can be exploited to reduce static friction with respect to the corresponding non-graded material and to tune it to desired values, opening possibilities for the design of bio-inspired surfaces with tailor-made tribological properties.
Collapse
Affiliation(s)
- Roberto Guarino
- Laboratory of Bio-Inspired & Graphene Nanomechanics, Department of Civil, Environmental and Mechanical Engineering, University of Trento, Via Mesiano 77, 38123 Trento, Italy
| | - Gianluca Costagliola
- Department of Physics and Nanostructured Interfaces and Surfaces Centre, University of Torino, Via Pietro Giuria 1, 10125 Torino, Italy
| | - Federico Bosia
- Department of Physics and Nanostructured Interfaces and Surfaces Centre, University of Torino, Via Pietro Giuria 1, 10125 Torino, Italy
| | - Nicola Maria Pugno
- Laboratory of Bio-Inspired & Graphene Nanomechanics, Department of Civil, Environmental and Mechanical Engineering, University of Trento, Via Mesiano 77, 38123 Trento, Italy
- Ket Lab, Edoardo Amaldi Foundation, Italian Space Agency, Via del Politecnico snc, 00133 Rome, Italy
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, E1-4NS London, United Kingdom
| |
Collapse
|
8
|
Avalanche precursors of failure in hierarchical fuse networks. Sci Rep 2018; 8:12090. [PMID: 30108308 PMCID: PMC6092438 DOI: 10.1038/s41598-018-30539-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Accepted: 07/13/2018] [Indexed: 11/30/2022] Open
Abstract
We study precursors of failure in hierarchical random fuse network models which can be considered as idealizations of hierarchical (bio)materials where fibrous assemblies are held together by multi-level (hierarchical) cross-links. When such structures are loaded towards failure, the patterns of precursory avalanche activity exhibit generic scale invariance: irrespective of load, precursor activity is characterized by power-law avalanche size distributions without apparent cut-off, with power-law exponents that decrease continuously with increasing load. This failure behavior and the ensuing super-rough crack morphology differ significantly from the findings in non-hierarchical structures.
Collapse
|
9
|
Brely L, Bosia F, Pugno NM. Emergence of the interplay between hierarchy and contact splitting in biological adhesion highlighted through a hierarchical shear lag model. SOFT MATTER 2018; 14:5509-5518. [PMID: 29923589 DOI: 10.1039/c8sm00507a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Contact unit size reduction is a widely studied mechanism as a means to improve adhesion in natural fibrillar systems, such as those observed in beetles or geckos. However, these animals also display complex structural features in the way the contact is subdivided in a hierarchical manner. Here, we study the influence of hierarchical fibrillar architectures on the load distribution over the contact elements of the adhesive system, and the corresponding delamination behaviour. We present an analytical model to derive the load distribution in a fibrillar system loaded in shear, including hierarchical splitting of contacts, i.e. a "hierarchical shear-lag" model that generalizes the well-known shear-lag model used in mechanics. The influence on the detachment process is investigated introducing a numerical procedure that allows the derivation of the maximum delamination force as a function of the considered geometry, including statistical variability of local adhesive energy. Our study suggests that contact splitting generates improved adhesion only in the ideal case of extremely compliant contacts. In real cases, to produce efficient adhesive performance, contact splitting needs to be coupled with hierarchical architectures to counterbalance high load concentrations resulting from contact unit size reduction, generating multiple delamination fronts and helping to avoid detrimental non-uniform load distributions. We show that these results can be summarized in a generalized adhesion scaling scheme for hierarchical structures, proving the beneficial effect of multiple hierarchical levels. The model can thus be used to predict the adhesive performance of hierarchical adhesive structures, as well as the mechanical behaviour of composite materials with hierarchical reinforcements.
Collapse
Affiliation(s)
- Lucas Brely
- Department of Physics and "Nanostructured Interfaces and Surfaces" Inter-Departmental Centre, Università di Torino, Via P. Giuria 1, 10125, Torino, Italy
| | | | | |
Collapse
|
10
|
Costagliola G, Bosia F, Pugno NM. Hierarchical Spring-Block Model for Multiscale Friction Problems. ACS Biomater Sci Eng 2017; 3:2845-2852. [PMID: 33418707 DOI: 10.1021/acsbiomaterials.6b00709] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
A primary issue in biomaterials science is to design materials with ad hoc properties, depending on the specific application. Among these properties, friction is recognized as a fundamental aspect characterizing materials for many practical purposes. Recently, new and unexpected frictional properties have been obtained by exploiting hierarchical multiscale structures, inspired by those observed in many biological systems. In order to understand the emergent frictional behavior of these materials at the macroscale, it is fundamental to investigate their hierarchical structure, spanning across different length scales. In this article, we introduce a statistical multiscale approach, based on a one-dimensional formulation of the spring-block model, in which friction is modeled at each hierarchical scale through the classical Amontons-Coulomb force with statistical dispersion on the friction coefficients of the microscopic components. By means of numerical simulations, we deduce the global statistical distributions of the elementary structure at micrometric scale and use them as input distributions for the simulations at the next scale levels. We thus study the influence of microscopic artificial patterning on macroscopic friction coefficients. We show that it is possible to tune the friction properties of a hierarchical surface and provide some insight on the mechanisms involved at different length scales.
Collapse
Affiliation(s)
- Gianluca Costagliola
- Department of Physics and Nanostructured Interfaces and Surfaces inter-departmental Center, University of Torino, Via Pietro Giuria 1, 10125, Torino, Italy
| | - Federico Bosia
- Department of Physics and Nanostructured Interfaces and Surfaces inter-departmental Center, University of Torino, Via Pietro Giuria 1, 10125, Torino, Italy
| | - Nicola M Pugno
- Laboratory of Bio-Inspired & Graphene Nanomechanics, Department of Civil, Environmental and Mechanical Engineering, University of Trento, Via Mesiano, 77, 38123 Trento, Italy.,School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, U.K.,Ket-Lab Italian Space Agency, Via del Politecnico snc, 00133 Rome, Italy
| |
Collapse
|