Prediction techniques for the scaled models made of different materials under impact loading

Predicting the impact response of the full-size structure by scaled models is of great importance in practice. The traditional similarity relationships will not be satisfied when the material of scaled models differs from that of the prototype. A dynamic similarity method is proposed to predict the dynamic behavior of the full-size structure under impact loading, where the strain hardening and the strain rate effects of different materials are both considered. In this work, we firstly develop the loss function to quantify the flow yield stress difference between the scaled model and the prototype during the impact, further demonstrating that the optimal velocity scaling factor can be obtained when the total difference is minimum. A simple and practical material selection criterion is also proposed to guide the selection of the most suitable alternative material for the scaled model. Two impacted structures are verified numerically, the results show that scaled models made of different materials produce small errors in both time and space fields of collision force and displacement when the proposed loss function approach is used to predict the prototype response. It is also confirmed that the proposed material selection criteria can foresee the scaled model made of which material can achieve higher prediction accuracy.