Dynamic deformation model of thin-walled ellipsoidal shells under impact loading

In order to study the deformation characteristics of thin-walled ellipsoidal shells under localized impact loading, experimental investigations and numerical simulations were conducted. The global deformation characteristics, central dent depth and dent boundary of the recovery ellipsoidal shell impacted by cylindrical projectiles at different velocities were obtained by projectile impact tests on a light gas gun apparatus and three-dimensional digital image correlation (DIC) technology for deformation process record. The simulation analysis focused on the effects of three different curvature radii on the depression depth and the lengths of the major and minor axes of the ellipsoidal shell. The primary dimensionless independent variables on which the dimensionless deformation characteristics depend were determined by means of dimensional analysis. The influence of less significant parameters was reduced through parameter sensitivity analysis. Under the condition of maintaining consistent scaling ratios for material properties, projectile dimensions, and shell thickness, specific response surface function expressions between dimensionless deformation characteristics vs. three curvature radii and velocity parameters were derived. A formula for predicting global deformation based on the depth of the depression and the depression boundary was proposed. The established expression can well describe the size effect and has a high prediction accuracy, and can provide reference for the design of impact load protection of large-sized curved thin shells in engineering.