A multi-stage material model calibration procedure for enhancing numerical solution fidelity in the case of impact loading of composites

Abstract

The numerical prediction of impact-induced damage to composite materials and the subsequent residual strength under compression loading continue to be a challenging task. The current study proposes a calibration routine for optimizing the set of material model parameters prior to the virtual simulation of impact tests, which also simplifies the process of parameter determination. The calibration algorithm is based on the comparison of the numerical force-strain or force-displacement curves with the corresponding experimental ones to get the optimal input data, and it includes basic quasi-static material characterization tests. For the sake of simplicity, the calibration process was divided into two parts. The first part includes the in-plane loading tests (tension 0° & 90°, compression 0° & 90°, shear and open-hole tension) for calibration of orthotropic damage material model; whereas the second one consists of the mode I and mode II interlaminar fracture tests as well as the short beam shear test, and it mainly targets to the adjustment of cohesive model parameters. Given the optimal set of parameters of material models, low and high velocity impact simulations at the energy level of 30 J were carried-out to LS-DYNA software and compared with experiments. The percentage difference between numerical and experimental delamination area, after the calibration enablement, reduced from 77% and 60% to 10% and 25% for low- and high-velocity impact, respectively. Afterwards, the damaged specimens were experimentally and virtually tested to compression loading. In terms of maximum compressive load, the computational error is close to 1% for both impact conditions.