Bogdan Szturomski

Research on biomimetic underwater vehicles for underwater ISR

Autonomous Biomimetic Underwater Vehicles BUVs driven by an undulating propulsion are a new branch in an area of an underwater robotics. They imitate both the construction and kinematics of a motion of underwater living organisms, e.g. fishes. Such vehicles have several features crucial from the point of view of military applications, e.g. larger secrecy and potential range of operation. The paper presents results of the research on BUVs carried out within two (Polish and EDA) projects both led by Polish Naval Academy. At the beginning, the initial efforts in building Polish BUV called CyberFish are included. Then, selected results of the tests of subsystems, e.g. navigational and 3D model of BUV built within national project are described. Next, the initial research achieved in the international project are showed. At the end, the schedule of the research planned to carry out within both projects is inserted. The paper is mainly focused on the hardware development of the BUVs.

Dynamic Characteristics of High Quality Steel in Johnson-Cook’s Model for Fast Processes Simulation in CAE Programs

The paper presents the dynamic behavior of gain for higher quality steel (armor) for the numerical simulation of fast processes, implemented in programs CAE, determined on the basis of results obtained from tensile tests of round samples conducted on the MTS testing machine type and rotary hammer, in terms of strain rate from 0,0001 to 500 s-1 in tabular and equation JC. Posted simulation results armor penetration high quality steel bullet caliber 12,7 mm compared with experimental results.

Analysis of the State of Stress in the Hull of the Ship Kormoran II Loaded with Non-Contact Mine Explosion

In this paper an analysis of the stress state of the hull of the ship Kormoran II loaded by non-contact mine explosion were performed. An empirical description of the pressure wave from the non-contact TNT explosion loads reported by authors such as RH Cole T. L. Geers and K.S. Hunter was used. The way of modeling the pressure wave using the acoustic medium implemented CAE programs was shown. The paper presents the results of pressure distribution on the hull of the ship Kormoran II at selected time points from TNT explosion under the keel of the ship. The paper presents detailed results of the stress state in the selected nodes, for example on the frame of main motor construction.

Designing Diagnosis of the Ship's Hull Strenght

The paper presents problems of modeling the ships hull loaded by the shock wave associated with non-contact underwater explosion. These problems are mainly due to the rapidness of the phenomena and the need of taking into consideration that processes go on at the border of different centers (water medium-ships hull-air). The article presents analysis for describing the parameters of shock wave as well as preliminary results of virtual tests of the steel hull subjected to an impulse load.

Impact Modeling of Underwater Explosion

Ship shock tests have been conducted for shock qualification of hull integrity and proper operation systems and subsystems. The ship shock trial identifies design and construction and it also validates shock hardening criteria. The main problem is that ship shock trials are costly. Numerical modeling and simulation, using FEM, may provide information to look into the details of fluid model, dynamic characteristics of ship hull and its internal component. The ship shock modeling and simulation has been performed and the predicted results were compared with ship shock test data made into sea trials. The preliminary studies of shock analysis approach are presented and the important parameters are discussed

Simulating the Impact of Exposure to Corrosive Medium on Cracking Initiation in AW7020M Alloy Specimens

An influence of depth of the pits resulting from exposure to corrosive medium on the initiation of stress corrosion cracking process of AW 7020M (Rm=430MPa) alloy has been presented in the paper. The samples were subjected to several weeks of exposure to the solution simulating seawater, which resulted in uniform surface corrosion with the pits of depth from 30 to 100 μm. These samples were then subjected to a tensile test to determine their new properties (after the exposure). The tests have shown that the initiation of neck and cracking spot do not always coincide with the location of pits. The aim of this study was to estimate the minimum depth of pitting under the assumed shape, resulting in the initiation of cracking during the tensile test, using numerical simulations with the CAE software. The paper presents simulation results for the samples made of AW-7020 alloy of 3.75 mm thickness.