Thermo-hydro-mechanical viscoplastic constitutive model for polyester strap reinforcement long-term response

Abstract

Polymeric materials have been shown to be rate-dependent materials, that is, their response will vary depending on the conditions to which they are subjected. The present work details the formulation, validation and implementation of a viscoplastic constitutive model with stress, strain, temperature, and relative humidity dependencies aimed to simulate the long-term response of polymeric materials, particularly that of polyester. The model is capable of predicting primary and secondary creep, often observed in geosynthetic materials. Both creep mechanisms can be modelled independently if needed. For calibration, a wide data-set of polyester strap reinforcement creep measurements was used. The validation process was done using parameters for load-, product-, and material-specific scenarios. Load- and product-specific scenarios showed suitable agreement between simulated and measured data. The coupled capabilities of the model are shown via variable temperature and relative humidity boundary conditions. Due to lack of data, temperature and relative humidity dependencies represent idealized scenarios. Simulations of stress-relaxation response for constant rate of strain scenarios are also provided. The proposed formulation is aimed at modelling the mechanical response of reinforced soil structures while accounting for the effect of in-air or in-soil conditions to which reinforcement materials can be exposed to throughout the structure’s life-cycle.