Abstract in English:

Abstract An easier and more efficient method is proposed for evaluating the ultimate strength of ship structures under fire conditions. Based on the Ideal Structural Unit Method (ISUM) and experiments from reference literature, a stress and strain equation for stiffened plates under fire conditions, as well as Fire ISUM, are proposed. To verify the effectiveness of the Fire ISUM method, 48 sets of FEA simulations incorporating the Fire ISUM were used to calculate the ultimate strength of different cabin fire positions and temperatures. The results showed that both the simulation and Fire ISUM were able to evaluate the high temperature ultimate strength. However, the Fire ISUM method does not account for initial imperfections due to the use of ideal high-temperature stress-strain curves. As a result, simulation results are lower than those obtained with the Fire ISUM, with a maximum error of 5.24%. To study the influence mechanism of ultimate strength of ship under high temperature conditions, the ultimate strength attenuation factor “IUR” was defined. Simulation results show that the ultimate strength attenuation of different cabins is not only related to the high-temperature width but also to the distance between the deck and the neutral axis. In actual fire rescue processes, when a deck of the same area is subjected to high temperatures, the further the deck is from the neutral axis, the more important its protection.

Abstract in English:

Abstract The penetration and reaming performance of a toroidal explosively formed projectile (TEFP) warhead with a charge diameter (D) of 56 mm was investigated when it was used to penetrate Q235 steel targets that were 10 mm thick at different stand-off distances (h). Thought the experimental and numerical result, the formation and penetration mechanisms of TEFP was revealed, and the differences between the radial and axial velocities in various portions of the TEFP were the primary causes of the TEFP expansion and rupture. When the TEFP tail has not completely ruptured and detached (h < 2.14D), TEFP has a strong penetration ability, resulting in TEFP perforating the target plate. The perforation process included three phases: pit opening, plastic hole expansion, and shear-block formation; these phases had average energy consumption ratios of 26.0%, 56.8%, and 17.2%, respectively. Finally, a method of evaluating the perforation and reaming capability of the TEFP was developed and used to identify the optimal stand-off distance, h0 = 1.96D, which produced a penetration hole with a diameter of 1.875D.