FE Analysis of Ship Structures Under Blast Loads

Abstract

Naval vessels and Submarines structures in their fighting role are susceptible to Underwater shock generated due to explosion of torpedoes, mines, depth charges etc. The damage inflicted by Non-Contact Underwater explosion consists of direct shock wave damage of hull, whipping damage of keel and mechanical damage to onboard equipment and associated systems. Hence in order to design a shock resistant structure or to know the shock withstandibility of the same, it is important to simulate these structures and loads and then subsequently analyze the same to predict the response (as performing experiments would be expensive). The Underwater explosion analysis of large structures like ships could be considered as one of the most complicated numerical analysis. The most important steps of these analyses are, the accurate load calculation and then the solution process. Loads can be calculated using published empirical formulas, which are complicated if calculated for a large structure. Also the application of load time history for large structure is a tedious job. To solve the complications related to load calculation and application, an in-house software named IRUNDEX, was developed, which, not only calculates the complex loading at all panels comprising the ship structure, but could also apply the loads (using ANSYS Macro) within minutes, thus saving considerable percentage of time taken for the analysis. It could be recognized that underwater shock simulation and analysis should form an important criterion to verify the design of any Naval Vessel or structure susceptible to explosions. This present work illustrates the use of the FE Software ANSYS, backed up with the in-house developed software, for Underwater Explosion analysis of structures.