Prediction of ship bulkhead deflection under internal explosion

Abstract Internal explosions within ship compartments pose a severe threat to structural integrity. To investigate the plastic dynamic response of ship bulkheads under such loading, this study presents a comprehensive approach integrating experimental testing, numerical simulation, and theoretical derivation. First, a numerical model for shock wave propagation in a confined cabin was established to characterize the complex load distribution. Based on the simulation results, fitting formulas for reflected shock wave overpressure in different bulkhead regions were derived. Subsequently, a simplified theoretical model for predicting plastic deformation was developed based on the principle of energy conservation and the momentum theorem. By utilizing impulse equivalence and constructing a deflection shape function, the plastic dissipation energy—including the bending of plastic hinge lines and in-plane membrane stretching—was analytically solved. To validate the proposed theoretical model, cabin explosion tests using 80 g TNT charges were conducted. The results indicate that the theoretical predictions align well with the experimental measurements, with a relative error of approximately 13.8%. This demonstrates that the proposed method provides a rapid and effective tool for predicting the plastic deformation of bulkheads under internal blast loading, offering a practical alternative to time-consuming numerical simulations.