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Barney CW, Berezvai S, Chau AL, Kwon Y, Pitenis AA, McMeeking RM, Valentine MT, Helgeson ME. Experimental observation of near-wall effects during the puncture of soft solids. SOFT MATTER 2024; 20:3806-3813. [PMID: 38646972 DOI: 10.1039/d3sm01216f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
Performing conventional mechanical characterization techniques on soft materials can be challenging due to issues such as limited sample volumes and clamping difficulties. Deep indentation and puncture is a promising alternative as it is an information-rich measurement with the potential to be performed in a high-throughput manner. Despite its promise, the method lacks standardized protocols, and open questions remain about its possible limitations. Addressing these shortcomings is vital to ensure consistent methodology, measurements, and interpretation across samples and labs. To fill this gap, we examine the role of finite sample dimensions (and by extension, volume) on measured forces to determine the sample geometry needed to perform and unambiguously interpret puncture tests. Through measurements of puncture on a well-characterized elastomer using systematically varied sample dimensions, we show that the apparent mechanical response of a material is in fact sensitive to near-wall effects, and that additional properties, such as the sliding friction coefficient, can only be extracted in the larger dimension case where such effects are negligible.
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Affiliation(s)
- Christopher W Barney
- Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA.
- Department of Mechanical Engineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA.
| | - Szabolcs Berezvai
- Department of Applied Mechanics, Faculty of Mechanical Engineering, Budapest University of Technology and Economics, Müegyetem rkp. 3., H-1111 Budapest, Hungary
| | - Allison L Chau
- Materials Department, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Younghoon Kwon
- Department of Mechanical Engineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA.
| | - Angela A Pitenis
- Materials Department, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Robert M McMeeking
- Department of Mechanical Engineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA.
- Materials Department, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Megan T Valentine
- Department of Mechanical Engineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA.
| | - Matthew E Helgeson
- Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA.
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Püffel F, Walthaus OK, Kang V, Labonte D. Biomechanics of cutting: sharpness, wear sensitivity and the scaling of cutting forces in leaf-cutter ant mandibles. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220547. [PMID: 37839449 PMCID: PMC10577030 DOI: 10.1098/rstb.2022.0547] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Accepted: 06/01/2023] [Indexed: 10/17/2023] Open
Abstract
Herbivores large and small need to mechanically process plant tissue. Their ability to do so is determined by two forces: the maximum force they can generate, and the minimum force required to fracture the plant tissue. The ratio of these forces determines the relative mechanical effort; how this ratio varies with animal size is challenging to predict. We measured the forces required to cut thin polymer sheets with mandibles from leaf-cutter ant workers which vary by more than one order of magnitude in body mass. Cutting forces were independent of mandible size, but differed by a factor of two between pristine and worn mandibles. Mandibular wear is thus likely a more important determinant of cutting force than mandible size. We rationalize this finding with a biomechanical analysis, which suggests that pristine mandibles are ideally 'sharp'-cutting forces are close to a theoretical minimum, which is independent of tool size and shape, and instead solely depends on the geometric and mechanical properties of the cut tissue. The increase of cutting force due to mandibular wear may be particularly problematic for small ants, which generate lower absolute bite forces, and thus require a larger fraction of their maximum bite force to cut the same plant. This article is part of the theme issue 'Food processing and nutritional assimilation in animals'.
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Affiliation(s)
- Frederik Püffel
- Department of Bioengineering, Imperial College London, London SW7 2AZ, UK
| | - O. K. Walthaus
- Department of Bioengineering, Imperial College London, London SW7 2AZ, UK
| | - Victor Kang
- Department of Bioengineering, Imperial College London, London SW7 2AZ, UK
| | - David Labonte
- Department of Bioengineering, Imperial College London, London SW7 2AZ, UK
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Aghababaei R, Malekan M, Budzik M. Cutting Depth Dictates the Transition from Continuous to Segmented Chip Formation. PHYSICAL REVIEW LETTERS 2021; 127:235502. [PMID: 34936770 DOI: 10.1103/physrevlett.127.235502] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Accepted: 10/20/2021] [Indexed: 06/14/2023]
Abstract
The process of material cutting emerges from a series of nonlinear phenomena including frictional contact, plastic deformation, and fracture. While cutting dominated by shear deformation is of interest to achieve a smooth material removal and a high-quality surface finish, the fracture-induced chip breaking is of equal importance to prevent the formation of long chips. Here we show that discrepant observations and predictions of these two distinct cutting mechanisms can be reconciled into a unified framework. A simple analytical model is developed to predict the mechanism of chip formation in a homogeneous medium as a function of work piece intrinsic material properties, tool geometry, and the process parameters. The model reveals the existence of a critical depth of cut, below which the chip formation is gradually progressed by plastic deformation in the shear plane, and above which chips break off by abrupt crack propagation. The models' prediction is validated by systematic in situ orthogonal cutting experiments and literature data for a wide range of materials over multiple length scales.
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Affiliation(s)
- Ramin Aghababaei
- Department of Mechanical and Production Engineering, Aarhus University, 8000 Aarhus C, Denmark
- Centre for Integrated Materials Research (iMAT), Aarhus University, 8000 Aarhus C, Denmark
| | - Mohammad Malekan
- Department of Mechanical and Production Engineering, Aarhus University, 8000 Aarhus C, Denmark
- SDU Mechatronics, Department of Mechanical and Electrical Engineering, University of Southern Denmark, 6400 Sønderborg, Denmark
| | - Michal Budzik
- Department of Mechanical and Production Engineering, Aarhus University, 8000 Aarhus C, Denmark
- Centre for Integrated Materials Research (iMAT), Aarhus University, 8000 Aarhus C, Denmark
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Duncan TT, Sarapas JM, Defante AP, Beers KL, Chan EP. Cutting to measure the elasticity and fracture of soft gels. SOFT MATTER 2020; 16:8826-8831. [PMID: 33026040 DOI: 10.1039/d0sm01174f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The fracture properties of very soft and/or brittle materials are challenging to measure directly due to the limitations of existing fracture testing methods. To address this issue, we introduce a razorblade-initiated fracture test (RIFT) to measure the mechanical properties related to fracture for soft polymeric gels. We use RIFT to quantify the elasticity, crack initiation energy, and the fracture energy of gellan hydrogels as a function of gellan concentration. Additionally, we use RIFT to study the role of friction in quantifying the fracture properties for poly(styrene-b-ethylene butadiene-b-styrene) gels as a function of test velocity. This new method provides a simple and efficient means to quantify the fracture properties of soft materials.
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Affiliation(s)
- Teresa T Duncan
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
| | - Joel M Sarapas
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
| | - Adrian P Defante
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
| | - Kathryn L Beers
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
| | - Edwin P Chan
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
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Toughening and stiffening of starch food extrudates through the addition of cellulose fibres and minerals. Food Hydrocoll 2018. [DOI: 10.1016/j.foodhyd.2018.06.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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