Study on dynamic similarity of elastic shell during water entry

In the study of thin-walled wedge shells subjected to lateral water entry impact loads, similarity theory is employed to predict the behavior of the prototype by analyzing the dynamic response of the model. However, the traditional similarity law for structural impact fails to accurately describe the relationship between the dynamic responses of the model and the prototype, mainly due to the ignoring of the fluid-structure coupling effect and geometric distortion in the thickness direction. To address this limitation, this study employs dimensional analysis to derive the scaling factors for achieving structural similarity during water entry while considering the effects of fluid-structure coupling. Based on the analysis of the governing equations for thin-walled wedge shells under water entry impact loads, the scaling factor accounting for geometric distortion for water entry of wedge shells is determined. Numerical models are established to verify the applicability of the geometric distortion similarity model with different materials. The results demonstrate the effectiveness of the proposed similarity model, which significantly reduces the disparities in displacement peaks and energy between the scaled model and the prototype. In addition, experimental platforms are constructed to further verify the proposed similarity model by performing vertical water entry tests on thickness-distorted and material-distorted specimens.