Research On Structural Types And Dynamic Response Of Ship Bulkhead Subjected To The Penetration Of High-speed Fragments

In the sea battles of today’s world, ship was attacked mainly. Semi-Armor-Piercing anti-ship missiles can penetrate the side grillage easily and explode in the cabin, generating shock waves and high-speed fragments, which can cause destructive damage to the ship. Bulkhead structure is the main protective structure of the ship because of its outstanding location, whose shock resistance ability is very important to the ship’s life. Therefore, it is necessary to study the bulkhead structure’s dynamic response and protective property under the penetration of high-speed fragment, which has vital engineering meaning to improve the ship’s shock resistance ability and life and also provide reference for the new bulkhead structure optimization design.Based on the penetration theory of fragment on target, penetration of high-speed fragment caused by explosion of anti-ship missile in cargo on bulkhead structure was studied using transient dynamics software. Based on the simplified model of anti-ship missile, formation of high-speed fragment and its properties were numerical simulated firstly, and compared with empirical formula. Therefore, penetration load cases were obtained. Then finite element technique of the penetration of fragment on bulkhead structure was established. Also, failure feature, dynamic response and energy absorption of bulkhead structure under different load cases were researched. The effect of load and structure parameters on dynamic response results were analyzed. In the end, some types of double-layer bulkhead structures were designed based on the traditional single-layer bulkhead structure, whose anti-penetration performance were compared. A better type of double-layer bulkhead structure was obtained preliminarily.The main research contents are listed as follows:(1)Penetration theory was stated, including the classification of penetration features and penetration principle of thin target, which is also fit for moderate thickness target. The theory provides a theory foundation for the numerical simulation of penetration process.(2)The process of anti-ship missile exploding in the cabin was numerical simulated using software MSC.DYTRAN. Movement characteristics, shapes, and mass distribution of fragment were studied and then penetration load cases were established.(3) Finite element technique of the penetration of fragment on bulkhead structure was studied. Modeling method of penetration model and the simplification process were discussed including the determination of penetration point and mesh size of the bulkhead structure.(4)Dynamic responses of fragment and bulkhead structure under different penetration loads and structure parameters were analyzed.The different penetration load cases include the penetration velocity, shape, penetration angle and mass of fragment. Structure parameter is thickness of the bulkhead plate. Failure mode, damage region, deformation, velocity, acceleration, stress, strain and energy absorption of bulkhead structure and the residual property of fragment were studied systematically.(5)Based on the traditional single-layer bulkhead structure, I-shaped, V-shaped X-shaped, and Y-shaped double-layer bulkhead structures were designed preliminarily. Dynamic response of the four types of bulkhead structures under the penetration of faragment were researched and were compared with that of single-layer bulkhead structure, mainly comparing the residual velocity of fragment and energy absorption of bulkhead structure.A better type of bulkhead structure was obtained through the comparison.