A dynamic constitutive model for carbon nanotubes (CNTs) modified unidirectional fibre reinforced plastic laminates

A constitutive model is developed herein for carbon nanotubes (CNTs) modified unidirectional fibre reinforced plastic (FRP) laminates subjected to impact loading. In the model, intralaminar damage is described by continuum damage mechanics (CDM) model which is modified by introducing two parameters (namely, matrix correction factor (S) and residual strength factor (RSF)); interlaminar damage (delamination) is depicted by cohesive element damage model. In order to verify the model, numerical simulations are carried out on the response and failure of unidirectional FRP laminates with or without CNTs modification under both ballistic and low-speed impact. Furthermore, parametric study is performed on the influences of impact velocity. It is demonstrated that the present model predictions are in good agreement with available experimental data in terms of residual velocity, energy absorption, failure patterns and delamination. It is also demonstrated that, with the same impact energy, larger mass impact causes greater intralaminar damage whilst lower mass higher velocity ballistic impact leads to more interlaminar damage and less intralaminar damage.