Saturated impulse and application of saturation equivalent method in cabin explosion

  Objectives  For the ship structures subjected to pulse loading such as explosion or slamming, research on the "saturated impulse" phenomenon shows that designing hull structures with maximum loading amplitude and total impulse is unreasonable. Hence, exploring the application of saturated impulse in engineering is necessary.

  Methods  The concept and development of the saturation phenomenon are first summarized. Then, taking a cabin internal explosion as a typical example, the loading curve and structural response characteristics are analyzed by FEM. Following that, the complex blast loadings are equivalent to the rectangular pressure pulse loadings of the saturated equivalent method, and the response of structures under the equivalent loadings are calculated by theoretical and numerical methods.

  Results   The results show that the saturated impulse phenomenon exists in a wide array of cabin explosions due to the existence of quasi-static overpressure. In practical engineering problems, the explosion loading will produce large plastic deformation (usually more than 10 times the plate thickness), with an error of less than 10% between the analysis results and the numerical simulation results, by using the equivalent method based on saturated impulse.

  Conclusions  By studying the cabin internal explosion saturation phenomenon, the results of the plastic dynamic response of the structure can be given more accurately, and repeated complex nonlinear numerical calculations can be reduced in structural optimization, so as to carry out the anti-impact design of the hull structure more effectively.