Research On The Response Prediction Method Of Double-layer Bulkhead Under Penetration Loads

In the modern sea battle, warship will face high speed fragment penetration damage caused by the explosion of anti-ship missile, in which the transverse bulkhead structure is the main anti-penetration protection structure. It is related to the safety of the main parts such as warship's ammunition and supply tank. As a new type of bulkhead, the double-layer bulkhead structure has been gradually adopted by modern ships because of its excellent anti penetration performance. Conducting research on numerical prediction to double-layer bulkhead about anti-penetration, and putting forward a quick and easy, accurate and reliable prediction method for double-layer bulkhead has important and military value to ensure the safety and normal use of the warship, and to improve the vitality and fighting capacity of the warship as well.This paper mainly studies the response prediction method of double-layer bulkhead structure under high speed fragment penetration loads. At first, it studied the theory of penetration and numerical simulation method, and compared the numerical results with the formula results to verify the reliability of the numerical method; By software MSC/DYTRAN, process of fragment penetrating corrugated sandwich double bulkhead structure was studied by numerical simulation, and the dynamic response process of penetration was analyzed. On the basis of the study, the sensitivity of different penetration loading parameters to the penetration response was studied. Through theoretical analysis and numerical simulation, the formula of fragment penetrating single-layer target was modified, so that residual velocity and energy absorption of fragment penetrating double bulkhead was obtained. Respectively from different initial velocity and mass of fragment through numerical simulation, the fitness between numerical and predicted results was compared, thus to verify the reliability of the response prediction method.The main research work of this paper is as follows:(1) Research on penetration theory and numerical simulation method. In this paper, the classification and failure mode of projectile target and the model of classical penetration theory were summarized, and the basic theory and analysis methods of the numerical method based on MSC/DYTRAN software were introduced as well. Finally, taking fragment penetrating single target plate as an example, the residual velocity of fragment under different initial velocity was obtained by numerical simulation, and was compared with the results of empirical formulas, the feasibility of the numerical method was verified.(2) Sensitivity analysis of penetration load parameters. On the basis of simulation results of high speed fragment penetrating double corrugated sandwich bulkhead structure, Taking the fragment shape, initial velocity, angle of attack, quality and yield stress parameters as the research target, the sensitivity of fragment penetrating double bulkhead results in these different penetration load parameters was studied, and ultimately selected which was more typical of and response to the penetration effect of load parameter of large, and laid the foundation for the research of the follow-up response prediction method.(3) Study on the dynamic response prediction for double-layer bulkhead structure under penetration loads. Numerical simulation on process of fragment penetrating target plate of single unit, and according the numerical calculation results to statistics the fragment penetrating target diameter and target board plugging block thickness, so as to establish a fragment pier rough and target plate washing than the diameter of the fragment and the relation between the target plate thickness changes; Based on fragment penetrating target plate after single residual velocity and energy absorption formula, modifying the formula with numerical results, the fragment penetrating double bulkhead structure after the residual velocity and energy absorption prediction formula of bulkhead was put forward.(4) Verification of the prediction method for fragment penetrating double-layer bulkhead. Respectively from different velocity and mass of fragment, taking residual velocity and bulkhead structure energy absorption as the research target, the forecast formula calculation results and the numerical simulation of alignment was compared to verify the reliability of proposed response prediction method.