We investigate the mechanical response of jammed packings of circulo-lines in two spatial dimensions, interacting via purely repulsive, linear spring forces, as a function of pressure $P$ during athermal, quasistatic isotropic compression. The surface of a circulo-line is defined as the collection of points that is equidistant to a line; circulo-lines are composed of a rectangular central shaft with two semicircular end caps. Prior work has shown that the ensemble-averaged shear modulus for jammed disk packings scales as a power law, $\langle G\left(P\right)\rangle \sim P^{\beta }$, with $\beta \sim 0.5$, over a wide range of pressure. For packings of circulo-lines, we also find robust power-law scaling of $\langle G\left(P\right)\rangle$ over the same range of pressure for aspect ratios $\mathcal{R}\gtrsim 1.2$. However, the power-law scaling exponent $\beta \sim 0.8$–0.9 is much larger than that for jammed disk packings. To understand the origin of this behavior, we decompose $\langle G\rangle$ into separate contributions from geometrical families, $G_f$, and from changes in the interparticle contact network, $G_r$, such that $\langle G\rangle =\langle G_f\rangle +\langle G_r\rangle$. We show that the shear modulus for low-pressure geometrical families for jammed packings of circulo-lines can both increase and decrease with pressure, whereas the shear modulus for low-pressure geometrical families for jammed disk packings only decreases with pressure. For this reason, the geometrical family contribution $\langle G_f\rangle$ is much larger for jammed packings of circulo-lines than for jammed disk packings at finite pressure, causing the increase in the power-law scaling exponent for $\langle G\left(P\right)\rangle$.

• Received 24 May 2021
• Accepted 6 July 2021

DOI:https://doi.org/10.1103/PhysRevE.104.014901