Mechanical response of packings of nonspherical particles: A case study of two-dimensional packings of circulo-lines

• Authors: Jerry Zhang, Yale University; Kyle VanderWerf, Yale University; Chengling Li, Emory University; Shiyun Zhang, Yale University; Mark D Shattuck, The City College of New York; Corey S O'Hern, Yale University
• Journal Title: PHYSICAL REVIEW E
• Volume: Volume 104, Number 1
• Publisher: AMER PHYSICAL SOC | 2021-07-27, Pages 014901-014901
• Type of Work: Article | Post-print: After Peer Review
• Publisher DOI: http://doi.org/10.1103/PhysRevE.104.014901
• Subjects: Engineering, Mechanical; Physics, General
• Keywords: Science & Technology; Physical Sciences; Physics, Fluids & Plasmas; Physics, Mathematical; Physics; STRESS

Abstract

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, (G(P))∼Pβ, with β∼0.5, over a wide range of pressure. For packings of circulo-lines, we also find robust power-law scaling of (G(P)) over the same range of pressure for aspect ratios Râ 1.2. However, the power-law scaling exponent β∼0.8-0.9 is much larger than that for jammed disk packings. To understand the origin of this behavior, we decompose (G) into separate contributions from geometrical families, Gf, and from changes in the interparticle contact network, Gr, such that (G)=(Gf)+(Gr). 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 (Gf) 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 (G(P)).