Comparative Analyse Of Response On Steel And Composite Ships Under Water Explosion

When naval warship is executing the task, it is inevitable that it will be impactfracture confronted with non-contact explosion. When non-contact explosions act on thehull, the hull structures and the ship borne equipment will be sabotaged in large scale.Therefore, to enhance the vitality and battle effectiveness of the warship, it is a must tomake research on the response of warships under non-contact explosions. Theenvironment that minesweepers work put forward harsh requests on the materialbuilding it. These requests include antimagnetic and well performance under explosionsshocks. Most common used materials building minesweepers are low-magnetic steeland glass fiber reinforced plastic (GFRP).The driving source of the response of hull structure and equipment under explosionshocks are under water explosions (UNDEX). Accurate description of the UNDEX isthe foundation of the research on response of warship under shocks. Firstly, based onextensive reading of literature at home and abroad, this paper studied on theories ofUNDEX shock wave. A finite model of dynamite explode in unlimited water was builtin MSC.PATRAN, and numerical calculation was executed in MSC.DYTRAN, atransient dynamics software. Through this emulation, the pressure of the UNDEX andchanging law of shock wave was obtained. The emulation coincides well with theempirical formula. Then, a rectangle model was built to research on the response of itunder UNDEX, and the results of the emulation coincide well with the experimentcarried by K.Ramajeyathilagam and C.P.Vendhan, too.Secondly, a finite model of GFRP warship was built, and the response underUNDEX was analyzed. When shock wave transfers to the warship, the displacementresponse increases rapidly and then tends to be steady. For the ship hull plate, thebiggest displacement part appears between the second and the third deck, the fourth andthe fifth bulkhead, the fifth and the sixth bulkhead. The acceleration response tends tobe high frequency, and under shock wave, the acceleration of some nodes can be5000m/s2. The observation nodes were checked by E.M.Wu failure criterion. The resultsshow that none of these nodes fail under this shock wave defined in this paper. After that, two steel warship models, which had the same surface yet differ fromthe weights, were built. Comparative analysis of behavior of shock resistance was madebetween steel and GFRP warships. The results demonstrates that GFRP warship behavebetter than the two steel ones in this paper under UNDEX.This paper also made a comparison between the responses under UNDEX of mildsteel and low-magnetic steel. Because of higher sensibility to strain rate, the dynamicyield stress of mild steel improves significantly. Thus, structure of mild steel can bearmore shock load. Moreover, this paper made a research on influence of material modelsettings and strain rate effect on the emulation result. The strain rate effect and theparameters of strain rate have a great influence on the emulation result.