The paper presents a method of the numerical modelling of micro-stresses in carbonised austenitic cast steel being developed during rapid cooling due to differences in the values of thermal expansion coefficients for this material phases -carbides and austenitic matrix. Micro-stresses are indicated as the main cause of crack initiation in the tooling elements of carburising furnaces being mainly made of austenitic cast steel. A calculation model of carbonised and thermally fatigued austenitic cast steel was developed based on the microstructure images obtained using light microscopy techniques and the phase composition evaluated with the X-ray diffraction method. The values of the stress tensor components and the reduced stress in the complex models of test material structure were determined numerically by the finite element method. The effort analysis was performed and the areas where development of cracks is to be expected were identified, which was experimentally confirmed.
In order to increase security of the country in the field of new materials and technologies and research methods were developed, patented and implemented: austenitic steel X02CrNiMoMnN21-16-5-4 with electrodes for welding of steel and high-strength bainitic steel 10GHMBA-E620T. The author developed a theoretical and technological basis for the design of marine constructional-ballistic shields, which has implemented a pilot scale and technical support. In addition, he developed an original method for testing ballistic shields and unified position to the research, which studied and co-patented.
In this work, the author presents experimental verification of numerical simulation of projectile impact on constructional shields. The experimental tests were performed at a unified test stand to investigate ballistic resistance of materials in field conditions. The stand was developed at the Polish Naval Academy in Gdynia, and then patented. The design of this test stand was based on construction of a ballistic pendulum, fitted to measure: impact force, turn angle of the ballistic pendulum χ, impact velocity and residual velocity of the projectile. All the measurement data were transmitted to a digital oscilloscope and a personal computer. The ballistic velocity of the shield of V BL[R] -defined according to Recht's and Ipson's method, was compared with V BL [Z] and V BL[Z1] -determined according to the author's method. Verification of numerically simulated ballistic velocity VRO versus the before-mentioned velocity was carried out at the 10GHMBA-E620T steel shields impacted by 12.7 mm type B-32 projectiles. The introduced method can be used for determining ballistic thickness h BL and ballistic velocity V BL for both homogeneous plates as well as multi-layered constructional shields. NomenclatureE BL -ballistic energy absorbed by the shield and the projectile, m BL V 2 BL /2, [kg m 2 s −2 ], E p -kinetic energy of the projectile impact, m p V 2 p /2, [kg m 2 s −2 ], h BL -ballistic thickness, [m], I -impulse of force transmitted to the dynamometer of the ballistic pendulum, [Ns], J -polar moment of inertia, [kgm 2 ], l -radius of rotation, [m], Brought to you by | West Virginia University Authenticated Download Date | 7/21/15 4:36 AM 546 ZDZISŁAW ZATORSKI M ew -equivalent mass of the pendulum, [kg], m BL -equivalent ballistic mass, [kg], m ri -residual mass of i-th projectile and shield fragment, [kg], m ri ·V ri · cos φ i -residual momentum of the i-th fragment in the shot direction, [kgms −1 ], m p -initial mass of the projectile, [kg], m sp , m st -residual masses of the projectile and the shield which are remaining in the shield, [kg], m r p , m rt -residual masses of the projectile and the shield which are running away from the shield, [kg], V BL -ballistic velocity of the shield, V r = 0, [ms −1 ], V BL[RI] -ballistic velocity of the shield according to Recht's and Ipson's method, [ms −1 ], V BL[Z,Z1] -ballistic velocity of the shield according to author's method, [ms −1 ], V p -impact velocity, [ms −1 ], V r -residual velocity, [ms −1 ], V w -velocity of the pendulum, [ms −1 ], ω w -angular velocity of the ballistic pendulum, [s −1 ], χ -turn angle of the ballistic pendulum, A, B -experimental constants.
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