Bulletin of the American Physical Society
APS March Meeting 2018
Monday–Friday, March 5–9, 2018; Los Angeles, California
Session B53: Mechanics of Networks II
11:15 AM–2:15 PM,
Monday, March 5, 2018
LACC Room: 513
Sponsoring Units: GSOFT GSNP DPOLY
Abstract: B53.00014 : Origins of the Poynting effect in elastic networks*
1:51 PM–2:03 PM
Poynting observed that some elastic networks expand when sheared, while others contract. We study the origins of this nonlinear effect in random spring networks, a minimal model for biopolymer gels, foams, and other mechanical networks. We show theoretically and verify numerically that the sign of the Poynting effect is predicted by the microscopic Grüneisen parameter, which measures how stretching the system shifts its eigenfrequencies. Spring networks contract under shear (a negative Poynting effect) because their eigenfrequencies shift upwards. We find that the amplitude of the Poynting effect is sensitive to the network's preparation protocol, and it diverges at the isostatic point. Finally, we illustrate correlations between the Poynting effect and the manner in which a network stiffens under strain.
*This work was funded by the Netherlands Organization for Scientific Research (NWO).
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