TY - JOUR
T1 - Uniaxial stretch-release of rubber-plastic bilayers
T2 - Strain-dependent transition to stable helices, rolls, saddles, and tubes
AU - Ramachandran, Rahul G.
AU - de Cortie, Jonah
AU - Maiti, Spandan
AU - Deseri, Luca
AU - Velankar, Sachin S.
N1 - Funding Information:
L.D. gratefully acknowledges the partial support of the following grants: (i) The Italian MIUR with the “Departments of Excellence” Grant L. 232/2016 , (ii) BOHME, FET EU grant No. 86317 , (iii) PRIN 2017 20177TTP3S , (iv) FET Proactive (Neurofibres) grant No. 732344 . L.D. also acknowledges the participation to the NIH, United States R56-HL142743-01 grant.
Funding Information:
This research was supported by the grant NSF-CMMI 1636064, NSF-2036164 and NSF-CMMI-1561789. We are grateful to Dr. Steven Abramowitch for the use of his tensile testing equipment. L.D. gratefully acknowledges the partial support of the following grants: (i) The Italian MIUR with the ?Departments of Excellence? Grant L. 232/2016, (ii) BOHME, FET EU grant No. 86317, (iii) PRIN2017 20177TTP3S, (iv) FET Proactive (Neurofibres) grant No. 732344. L.D. also acknowledges the participation to the NIH, United StatesR56-HL142743-01 grant.
Publisher Copyright:
© 2021 Elsevier Ltd
PY - 2021/10
Y1 - 2021/10
N2 - Polymeric plastics deform irreversibly (i.e., inelastically) whereas rubbers deform reversibly, i.e., elastically. Thus, uniaxially stretching a rubber-plastic bilayer composite beyond its yield point can create an elastic strain mismatch between the two layers. Upon release, the bilayer may then bend out-of-plane. We quantify the mechanics of such stretch-release-induced shape changes in rectangular specimens of rubber-plastic bilayers. We show a remarkable dependence of the final shape upon the stretch applied prior to release. At small stretch, all bilayers bend into arch or roll shapes with the plastic on the convex face. At large stretch, the bilayers bend into half-tubes with the plastic, now heavily-wrinkled, becoming the concave face. Thus, the sign and direction of the curvature both flip as applied stretch increases. Between these two extremes, saddle shapes appear which have characteristics of both arches as well as half-tubes. Sufficiently narrow samples show different behavior: they transition from arches to helices as stretch increases. All these shapes are mono-stable. We document numerous ways in which the mechanics of rubber-plastic bilayers differs from that of fully-elastic bilayers. Most importantly, yielding of the plastic layer during the shape change strongly affects the mechanics of the elastic–plastic bilayers, and yielding accompanied by plastic wrinkling has an especially large effect. A strain energy model illustrates how the shape change is dictated by the change in the ratio of elastic strain mismatch in the two directions due to the formation of wrinkles at the rubber-plastic interface.
AB - Polymeric plastics deform irreversibly (i.e., inelastically) whereas rubbers deform reversibly, i.e., elastically. Thus, uniaxially stretching a rubber-plastic bilayer composite beyond its yield point can create an elastic strain mismatch between the two layers. Upon release, the bilayer may then bend out-of-plane. We quantify the mechanics of such stretch-release-induced shape changes in rectangular specimens of rubber-plastic bilayers. We show a remarkable dependence of the final shape upon the stretch applied prior to release. At small stretch, all bilayers bend into arch or roll shapes with the plastic on the convex face. At large stretch, the bilayers bend into half-tubes with the plastic, now heavily-wrinkled, becoming the concave face. Thus, the sign and direction of the curvature both flip as applied stretch increases. Between these two extremes, saddle shapes appear which have characteristics of both arches as well as half-tubes. Sufficiently narrow samples show different behavior: they transition from arches to helices as stretch increases. All these shapes are mono-stable. We document numerous ways in which the mechanics of rubber-plastic bilayers differs from that of fully-elastic bilayers. Most importantly, yielding of the plastic layer during the shape change strongly affects the mechanics of the elastic–plastic bilayers, and yielding accompanied by plastic wrinkling has an especially large effect. A strain energy model illustrates how the shape change is dictated by the change in the ratio of elastic strain mismatch in the two directions due to the formation of wrinkles at the rubber-plastic interface.
KW - Bilayer
KW - Composites
KW - Plasticity
KW - Shape change
KW - Strain mismatch
KW - Wrinkling
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U2 - 10.1016/j.eml.2021.101384
DO - 10.1016/j.eml.2021.101384
M3 - Article
AN - SCOPUS:85109889170
VL - 48
JO - Extreme Mechanics Letters
JF - Extreme Mechanics Letters
SN - 2352-4316
M1 - 101384
ER -