Propaedeutical to a better understanding of the mechanics of cables, with potential applications in material science and biology, tensile tests were performed on two-ply yarns made of rubber rods, manufactured by transforming the twist on two adjacent straight rods into tortuosity for the resulting double-helix shape. Modeling of the yarn as a pair of Kirchhoff rods in reciprocal contact, fails to provide results in agreement with experiments, especially when the helix slope angle alpha tends to pi/4, representing the geometric limit for material interpenetration. This discrepancy could not be justified by considering the viscosity of the rods, their cross-sectional distortion, or cohesive/frictional contact. Our contribution starts from the experimental observation that the rods are in an eigenstress state already in the reference balanced configuration. This is characterized by a high twist, dictated by the ratio between torsional and bending rod stiffness, which increases as alpha decreases, growing unboundedly as alpha -> pi/4. Experiments confirm that twisting can significantly increase the tensile stiffness of straight rubber rods, in agreement with non-linear elasticity theory. Tensile tests on the yarns can be reproduced excellently only if the twist-induced stiffening is considered.
Experimental assessment of the eigenstress state in two-ply yarns and its effect on tensile properties / Boni, Claudio; Muratore, Vincenzo Andrea; Royer-Carfagni, Gianni. - In: JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS. - ISSN 0022-5096. - 187:(2024). [10.1016/j.jmps.2024.105613]
Experimental assessment of the eigenstress state in two-ply yarns and its effect on tensile properties
Boni, Claudio;Muratore, Vincenzo Andrea;Royer-Carfagni, Gianni
2024-01-01
Abstract
Propaedeutical to a better understanding of the mechanics of cables, with potential applications in material science and biology, tensile tests were performed on two-ply yarns made of rubber rods, manufactured by transforming the twist on two adjacent straight rods into tortuosity for the resulting double-helix shape. Modeling of the yarn as a pair of Kirchhoff rods in reciprocal contact, fails to provide results in agreement with experiments, especially when the helix slope angle alpha tends to pi/4, representing the geometric limit for material interpenetration. This discrepancy could not be justified by considering the viscosity of the rods, their cross-sectional distortion, or cohesive/frictional contact. Our contribution starts from the experimental observation that the rods are in an eigenstress state already in the reference balanced configuration. This is characterized by a high twist, dictated by the ratio between torsional and bending rod stiffness, which increases as alpha decreases, growing unboundedly as alpha -> pi/4. Experiments confirm that twisting can significantly increase the tensile stiffness of straight rubber rods, in agreement with non-linear elasticity theory. Tensile tests on the yarns can be reproduced excellently only if the twist-induced stiffening is considered.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.