Information from fold shapes

Hudleston, Peter J.; Lan, Labao

doi:10.1016/0191-8141(93)90124-s

Cited by 102 publications

(22 citation statements)

References 41 publications

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“…These so-called primary ridges continue to develop for about two more months. 24,25 On a completely different length scale, in geology, hierarchical folding patterns resembling wrinkles 26,27 are also well known, albeit still not completely understood. Table 1 summarizes a few selected examples of wrinkling; in all cases wrinkles form when a compressive force acts on a rigid skin that rests on a softer foundation.…”

Section: Beyond the Human Skinmentioning

confidence: 99%

Soft matter with hard skin: From skin wrinkles to templating and material characterization

2006

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The English-language dictionary defines wrinkles as ''small furrows, ridges, or creases on a normally smooth surface, caused by crumpling, folding, or shrinking''. In this paper we review the scientific aspects of wrinkling and the related phenomenon of buckling. Specifically, we discuss how and why wrinkles/buckles form in various materials. We also describe several examples from everyday life, which demonstrate that wrinkling or buckling is indeed a commonplace phenomenon that spans a multitude of length scales. We will emphasize that wrinkling is not always a frustrating feature (e.g., wrinkles in human skin), as it can help to assemble new structures, understand important physical phenomena, and even assist in characterizing chief material properties.

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Section: Beyond the Human Skinmentioning

confidence: 99%

Soft matter with hard skin: From skin wrinkles to templating and material characterization

2006

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“…Indeed, even the dermal ridges in our fi ngerprints are thought to arise from the relative growth between the two layers in the fetus 17 and thus may be explained in terms of the above ideas 18 . On a completely different length scale, in geology, these hierarchical folding patterns 19,20 are also well known but remain poorly understood; although our experiments and theoretical model are strictly relevant only for the simplest reversible elastic deformations, their essentially geometrical underpinnings suggest a mechanism for how irreversible hierarchical folds might arise in geology.…”

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confidence: 99%

Nested self-similar wrinkling patterns in skins

et al. 2005

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. Here we show that model elastomeric artifi cial skins wrinkle in a hierarchical pattern consisting of self-similar buckles extending over fi ve orders of magnitude in length scale, ranging from a few nanometres to a few millimetres. We provide a mechanism for the formation of this hierarchical wrinkling pattern, and quantify our experimental fi ndings with both computations and a simple scaling theory. Th is allows us to harness the substrates for applications. In particular, we show how to use the multigeneration-wrinkled substrate for separating particles based on their size, while simultaneously forming linear chains of monodisperse particles.Wrinkling, buckling and other mechanical instabilities have been typically treated as a nuisance to be avoided rather than an exquisite pattern to be exploited. Although this view is changing with the growing understanding of how ubiquitous these phenomena are 9 , the utilization of wrinkling in applications has been hampered by the absence of a detailed understanding of the phenomena, as well as the ability to control it experimentally. Here we focus on the tunable hierarchical wrinkling of model stiff elastomeric artifi cial skins supported on a soft base. These wrinkles are fabricated by uniaxially stretching poly(dimethyl siloxane) (PDMS) network sheets (thickness ∼0.5 mm, Young modulus ∼1 MPa) 10 in a custom-designed stretching apparatus 11 and exposing them to ultraviolet/ozone (UVO) radiation for extended periods of time (30-60 minutes). Previous studies established that the UVO treatment of PDMS converts the fi rst ∼5 nm of the PDMS surface into a stiff 'skin' 12 , whose density is approximately a half of that of silica 13 . Optical microscopy and scanning force microscopy (SFM) experiments confi rm that the surfaces are originally fl at in the presence of strain.After the UVO treatment, the strain is removed from the specimen and, the skin buckles perpendicularly to the direction of the strain. The buckle morphology depends on the strain removal rate. Specifically, stretched and UVO-modified specimens released at a fast rate (strain removed abruptly)

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“…However, as discussed by Hudleston and Lan [53], there is no unique correlation relating fold shapes and strain patterns, folding mechanisms and rock properties.…”

Section: Finite Strain Pattern In Transpressive Foldsmentioning

confidence: 99%

“…However, the precise shape of a folded layer does not allow the state of strain to be established at each point in the fold [17,50,51,52,53] and the geometry of the fold profiles alone cannot therefore be used to distinguish between different folding mechanisms. Indeed, as is well known, different mechanisms can produce parallel folds according to the nature of the deforming rock mass and the physical conditions imposed on it.…”

Section: Classical Folding Mechanisms Producing Parallel Foldsmentioning

confidence: 99%

Heterogeneous strain behaviour in competent layers during folding in transpressive regimes

Dias

Ribeiro

2008

Geodinamica Acta

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The understanding of folding processes in transpression is crucial in structural geology. However, the study of folding in multilayers where adjacent strata exhibit high competence contrast is impossible if the observations are only restricted to geometrical features. Nevertheless, using detailed three dimensional finite strain analyses it is possible to constrain the solutions. Strain data from the deformed northern Portugal Ordovician quartzites show that folding mechanisms in transpression are highly variable. For the more deformed materials found, not only in the short limbs, but also in the thinner layers of the long limbs, the strain ellipsoids orientations can be explained by a combination of flexural shear (related to the folding process) and sinistral wrench component parallel to the bedding plane (a pervasive regime in the southern branch of the Ibero-Armorican Arc). In the thicker layers of the long limbs, orthogonal flexure seems to be the dominant mechanism. Concerning the strain ellipsoid shape, the constrictional forms predominate mainly in the long limbs. Strain partitioning in transpressive regimes is important at the mesoscopic fold scale, especially in asymmetric folds. In the more deformed short limb, the data indicate that transpression tends to be always an active mechanism, while in the long limb the regional wrench component it's often less important.

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Information from fold shapes

Cited by 102 publications

References 41 publications

Soft matter with hard skin: From skin wrinkles to templating and material characterization

Soft matter with hard skin: From skin wrinkles to templating and material characterization

Nested self-similar wrinkling patterns in skins

Heterogeneous strain behaviour in competent layers during folding in transpressive regimes

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