Dynamic Response of Viscoelastic Solids Described by Implicit Constitutive Theories
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The aim of this work is to study the impact response of multilayered polymers using a thermodynamically consistent framework. Rather than integral type viscoelastic model, the approach here is based on the idea of two inter penetrating networks, one is permanent and other is transient together with the rate equations for the time evolution of the transient network. The primary hypothesis is that, it is possible to use a two network theory to capture the essential features of a impact response of multilayered polymers and solve the resulting boundary value problem using finite volume scheme. We first study the impact of layered polymer plate involving small deformation using a thermodynamic framework. The constitutive equations are nonlinear even though the strains are small. Six different protocols involving PU and PC, namely pure PC, pure PU, bilayer(PU/PC and PC/PU) and trilayer(PU/PC/PU and PC/PU/PC) were considered to evaluate the performance of the layering sequence based on the kinetic energy transferred on the wall. The interfaces are assumed to be fully bonded. The material parameters for the model was obtained from the experimental creep data from the literature. The layering of polymers improved the performance of plate depending upon the type of layering sequence. In the one and two dimensional study carried out, the performance was best when a compliant layer is placed between two stiff layers. Whereas, when a stiff layer was placed between two less compliant layer, the performance was worse than bilayer. Finally, a thermodynamically consistent finite deformation model was used to evaluate the impact performance of layered plate involving large deformation. A full scale three dimensional impact analysis was carried out with the thermal phenomena suppressed. Similar to the small deformation study, six different protocols were considered. The material parameters were obtained from the experimental data from the literature involving strain values above 50%. The overall performance was similar to what has been observed in the small strain model.
Ponnalagu, Alagappan (2015). Dynamic Response of Viscoelastic Solids Described by Implicit Constitutive Theories. Doctoral dissertation, Texas A & M University. Available electronically from