Analysis of uncertainty characteristics of early dynamic response of hull structure and system of underwater explosion

Abstract：The dynamic response of the hull structure of an underwater explosion can be divided into two distinct stages: the early and late stages. The early dynamic response produces structural damage that exhibits strong nonlinear and non-stationary characteristics. The changes in system parameters, initial conditions, and other factors can lead to bifurcation and mutation of the early dynamic response, resulting in an output that exhibits characteristics of uncertainty. This paper proposes a novel method for analyzing the nonlinear dynamic response of an underwater explosion hull structure and system. The method is based on phase space reconstruction technology, parabolic mapping, and symbolic dynamics theory. Its objective is to characterize the evolution of the early dynamic response and predict the test results in the neighborhood of system parameters. Initially, a scaled model is constructed based on a stiffened cylindrical shell structure. Tests are conducted under different impact factors to study the time-space evolution law of the nonlinear and non-stationary dynamic response of the underwater explosion hull structure under different impact loads. The uncertainty characteristics were characterized and described. Secondly, a series of tests were conducted on a cabin structure and floating impact platform model of a specific type of ship. These tests were designed to further analyze the uncertainty characteristics of the early dynamic response of the underwater explosion hull structure. The results of these tests prove the effectiveness and universality of the method. The results demonstrate that the nonlinear dynamic data analysis technology can characterize and describe the nonlinear and non-stationary dynamic response of a ship underwater explosion. Moreover, it can be employed to forecast the outcomes in the vicinity of system parameters.