Papers by Keyword: Molecular Chain Network Theory

Abstract: New finite element homogenization model with nonaffine constitutive equation of rubber is developed to study the deformation behavior of silica-filled rubber under monotonic and cyclic deformation. The obtained results clarified the effect of the volume fraction of the silica coupling agent and the networklike structure connecting the silica particles on essential physical enhancement mechanisms of deformation resistance and hysteresis loss for silica-filled rubber. The finding suggests that the material characteristics of silica-filled rubber are much more controllable than those of carbon-black-filled rubber.

Abstract: To clarify the essential deformation characteristics of silica-filled rubber, we construct the finite element homogenization models of silica-filled rubber with newly proposed nonaffine molecular chain network model of rubber. These models can reflect the generation of complicated inter-fillers connecting phases where the characteristics of rubber are intricately changed depending on the volume fraction of silica coupling agent and relative size of particles and their location. The results obtained clarified the essential physical enhancement mechanisms of deformation resistance and hysteresis loss for rubber filled with silica with different distribution patterns under diffrent rate of deformation. The volume fraction of coupling agent essentially affects the deformation behavior of silica filled rubber which suggests the high controlability of the material characteristics of silica filled rubber as compared with carbon black filled rubber.

Abstract: A constitutive equation of rubber is derived by employing a nonaffine molecular chain network model for an elastic deformation behavior and the reptation theory for a viscoelastic deformation behavior. The results reveal the roles of the individual springs and dashpot, and the strain rate dependence of materials in the monotonic and cyclic deformation behaviors, particularly softening and hysteresis loss, that is, the Mullins effect, occurring in stress-stretch curves under cyclic deformation processes of carbon black filled rubber..

Abstract: In this study, we employ the two-dimensional homogenization model based on molecular chain network theory to investigate the micro- to macroscopic mechanical behavior of plastic foam under macroscopic uniform compression. A parametric study is performed to quantify the effect of a characteristic value of matrix, distribution and initial volume fraction of voids, and the macroscopic triaxiality of loading condition on the deformation behavior of the foam. The results suggest that the onset of localized shear band at the ligament between voids together with the microscopic buckling of the ligament leads to the macroscopic yield of the foam. The initial modulus and the macroscopic yield stress of the foam have no dependence on the characteristic value of matrix. Furthermore, as the microscopic buckling of the ligament is promoted in case of high initial volume fraction of voids and high triaxiality loading condition, the macroscopic yield point appears at early deformation stage. After the macroscopic yield, macroscopic strain hardening appears in the macroscopic response and a remarkable strain hardening is shown in case of high initial volume fraction of voids and high triaxiality loading condition due to the considerable increase of the density of the foam in these cases.

Abstract: The constitutive equation of rubber is derived by employing a nonaffine molecular chain network model for an elastic deformation behavior and the reptation theory for a viscoelastic deformation behavior. The results reveal the roles of the individual springs and dashpot, and the strain rate dependence of materials and disentanglement of molecular chains in the monotonic and cyclic deformation behaviors, particularly softening and hysteresis loss, that is, the Mullins effect, occurring in stress-stretch curves under cyclic deformation processes.