Micromechanical approach to viscoelastic stress analysis of a pin-loaded hole in unidirectional laminated PMC

Abstract

This paper aims to investigate the effect of viscoelastic behavior of polymer matrix of unidirectional fiber-reinforced laminated composite on stress distribution around the pin-loaded hole under tensile loading. The Laplace transform is used to prevent the integral form of matrix governing stress-strain relation. Applying a micromechanical model, all equilibrium equations for the fibers are written analytically in the Laplace domain. The numerical algorithm of Gaver–Stehfest is implemented, and the governing equations were solved at any given time to extract the concerned results in the time domain. The obtained results are validated against the Finite Element Method results obtained through ANSYS software. Moreover, a comparison of the results of this study at the time equal zero with elastic solutions of other references showed a good agreement. The results revealed that in the long term, the maximum tensile load in the intact fiber around the pinhole was enlarged and the tensile load in fibers far from the pinhole slightly was decreased. Moreover, the location of the maximum axial load that had occurred on pinhole edges was moved slightly toward the center over time.

The Study Influence Analysis of the Mathematical Model Choice for Describing Polymer Behavior

“…There is a certain variety of descriptions for the viscoelastic-plastic behavior of a material; in particular, there are such models as the cooperative-viscoplasticity theory based on overstress (VBO) model [16], combining a nonlinear viscoelastic model with a viscoplastic model using the von Mises yield criterion [12,24,[50][51][52], etc. However, in the present work, gamma-modified PTFE is considered.…”