Modelling and Prediction of Stress Relaxation for Thermal Bonded Nonwoven Geotextiles

Stress relaxation experiments were performed on three types of thermal bonded nonwoven geotextiles in this study to model and predict their stress relaxation behaviors. Four mechanical models, including the standard linear solid mechanics model, Eyring’s model, the modified two-Maxwell-unit model and the modified three-Maxwell-unit model were used to predict stress values for 600 h based on 3 and 90 h experimental relaxation data. Results indicated that Eyring’s model and the modified three-Maxwell-unit model fitted the experimental results better than the other two. Estimation using modified three-Maxwell-unit model seemed to construct an upper bound while that using Eyring’s model form a lower bound for the corresponding experimental data. In addition, predicted curves were much closer to the experimental curve when equations of the two models were built with the 90 h experimental data than those data of 3 h. Thus, the prediction capability of the two models can be substantially improved by employing the data with longer time. In summary, the combination of the modified three-Maxwell-unit model and Eyring’s model can well forcast the range of actual stress during stress relaxation experiments with the longer term experimental data.