Deformation Field in Diametrically Loaded Soft Cylinders

Abstract

Deformation fields at the surface of diametrically squeezed shallow cylinders in the large deformation regime are measured experimentally and numerically for different material behaviour in the large deformation regime. By means of a digital image correlation method optimized for large displacements, strain fields are measured and compared with finite element simulations. Assuming a neo-Hookean behaviour for cylinders made of rubber silicone, the strain field is found to be in quantitative agreement with non-linear finite element simulations up to the highest deformations reached in our experiments (15%). For materials that follow an elastoplastic constitutive law, agreement is lost after few percents of deformation and location of the strain field differences are identified up to strains as high as 30%. Strain field evolution is also measured for solid foam cylinders up to 60% of global deformation strain. This method that can be applied to a broad variety of materials, even in the occurrence of large deformations, provides a way to study quantitatively local features of the mechanical contact.

Soft-grain compression: Beyond the jamming point

“…As shown in fig. 10a and b, in agreement with what is observed for a single particle [50] (see the inset of fig.6a) , C is homogeneously equals to 1 at the beginning of the compression and then rapidly decreases both in the center and very close to the edges of the particles. On the contrary, in between, few millimeters away from the edges, the von Mises strain increases and can even reach values higher than 1 in this area where the shear strain is dominant.…”

“…Set-up One of the most challenging point when dealing with experimental study of highly strained granular matter is to make quantitative measurements at the grain scale for the whole packing. To overcome this challenge, we used the novel set-up already presented in Vu et al [50] and shown in fig. 1a.…”

Numerical simulations of the compaction of assemblies of rubberlike particles: A quantitative comparison with experiments

“…Uniaxial compressions of bidisperse assemblies of elastic rubberlike particles were carried out with the experimental setup introduced in the previous works [13,14] for studying the compression of a single particle. It consists of a compression device placed on a horizontal flatbed scanner as shown in Fig.…”

“…These surfaces are coated with a shiny thin glitter layer (glitter mean size of 20 μm), consisting of a random and homogeneous pattern on the bottom of the particles with a high black-and-white contrast. This pattern is used to get the displacement field of each particle by means of a digital image correlation (DIC) algorithm introduced in previous works [13,14] in which the deformations of a unique particle were investigated. In order to apply this algorithm to the case of an assembly of particles, the positions of the particles are first tracked step by step, and the rigid body motion of each particle is determined and withdrawn before the application of the DIC algorithm.…”

“…The constitutive law of the silicone rubber used for the particles is known to follow the isotropic neo-Hookean model [14,16,17], whose strain energy density function is…”