10.5061/DRYAD.JJ0KJ
Labonte, David
University of Cambridge
Williams, John A.
University of Cambridge
Federle, Walter
University of Cambridge
Data from: Surface contact and design of fibrillar ‘friction pads’ in
stick insects (Carausius morosus): mechanisms for large friction
coefficients and negligible adhesion.
Dryad
dataset
2015
hairs
Contact Area
Carausius morosus
Stick insects
2015-01-17T00:00:00Z
2015-01-17T00:00:00Z
en
https://doi.org/10.1098/rsif.2014.0034
18116 bytes
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CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
Many stick insects and mantophasmids possess tarsal ‘heel pads’
(euplantulae) covered by arrays of conical, micrometre-sized hairs
(acanthae). These pads are used mainly under compression; they respond to
load with increasing shear resistance, and show negligible adhesion.
Reflected-light microscopy in stick insects (Carausius morosus) revealed
that the contact area of ‘heel pads’ changes with normal load on three
hierarchical levels. First, loading brought larger areas of the convex
pads into contact. Second, loading increased the density of acanthae in
contact. Third, higher loads changed the shape of individual hair contacts
gradually from circular (tip contact) to elongated (side contact). The
resulting increase in real contact area can explain the load dependence of
friction, indicating a constant shear stress between acanthae and
substrate. As the euplantula contact area is negligible for small loads
(similar to hard materials), but increases sharply with load (resembling
soft materials), these pads show high friction coefficients despite little
adhesion. This property appears essential for the pads’ use in locomotion.
Several morphological characteristics of hairy friction pads are in
apparent contrast to hairy pads used for adhesion, highlighting key
adaptations for both pad types. Our results are relevant for the design of
fibrillar structures with high friction coefficients but small adhesion.
Labonte2014_FrictionThis file contains measurements of peak friction
forces generated by isolated "heel" pads of Indian stick
insects, meausred at three different normal loads
(n=10).Labonte2014_AcanthaeAspectRatioThis file contains data on the
relationship between aspect ratio and contact area of individual acanthae
"tiny, hair-like outgrowths), found on the "heel" pads of
Indian stick insects.Labonte2014_AcanthaeContactAreaThis file contains
data on the projected contact area, hair contact density and contact area
of individual hairs for "heel" pads of Indian stick insects,
measured at five different normal loads (n=10 per normal load).