Pressure-impulse diagram with multiple failure modes of one-way reinforced concrete slab under blast loading using SDOF method

Two loosely coupled single degree of freedom (SDOF) systems were used to model the flexural and direct shear responses of one-way reinforced concrete slabs subjected to explosive loading. Blast test results show that the SDOF systems are accurate in predicting the failure mode of the slab under blast loads by incorporating the effects of the strain rate effect caused by rapid load application. Based on different damage criteria, pressure-impulse (P-I) diagrams of the two failure modes were analyzed with the SDOF systems. The effects of span length, concrete strength, and reinforcement ratio of the slab on the P-I diagram were also investigated. Results indicate that a slab tends to fail in direct shear mode when it is of a smaller span length and tends to fail in flexure mode when it is of a larger span length. With the increase of the concrete strength or reinforced ratio, both the flexure and shear capacity increase. Based on numerical results, a simplified method and a semi analytical equation for deriving the P-I diagram are proposed for different failure modes and damage levels.

AN ISOBAR-ISOTHERMAL PHASE DIAGRAM OF THE Nd-Fe-B SYSTEM AT ATMOSPHERIC PRESSURE AND 1000℃

An isothermal section of Nd-Fe-B system at 1000℃ and the phase equilibrium relationship in Fe-Nd and Nd-B binary systems were investigated with diffusion couple by means of metallographic observation, electron microprobe analysis and X-ray diffraction.It was shown that there are three stable ternary com- pounds,Nd_2Fe_(14)B,Nd_2Fe_7B_6 and Nd_9Fe_3B_8 in Nd-Fe-B system at 1000℃.None of these phases has solu- bility,that is,they are exactly stoichiometric phases.On the other hand,there exist rather wide two-phase regions between Nd_2Fe_7B_6 and liquid as well as between Nd_9Fe_3B_8 and liquid.It was identified that there is no NdFe_2 compound in the system under atmospheric pressure.

Pressure-Induced Metallization and Electrical Phase Diagram for Polycrystalline CaB_6 under High Pressure and Low Temperature

The electrical properties of polycrystaltine CaB6 are revealed by in-situ resistance measurements under high pressure and low temperature. Due to the existence of grain boundaries, polycrystalline CaB6 behaves with semiconducting transport properties, which is different from the semimetallic CaB6 single crystals. The temperaturedependent resistance measurement results show that before the structural phase transition at 12.3 GPa the high pressure first induces the metallization at 6.5 GPa for CAB6. Moreover, the phase diagram for CaB6 is drawn based on the investigated electric conducting properties and at least three different conducting phases are found even at moderate high pressure and low temperature, indicating that the electric nature of CaB6 is very sensitive to the environment.

Evolution of superconductivity and charge order in pressurized RbV_(3)Sb_(5)

The kagome metals AV_(3)Sb_(5)(A=K,Rb,Cs)under ambient pressure exhibit an unusual charge order,from which superconductivity emerges.In this work,by applying hydrostatic pressure using a liquid pressure medium and carrying out electrical resistance measurements for RbV_(3)Sb_(5),we find that the charge order becomes suppressed under a modest pressure pc(1.4 GPa<pc<1.6 GPa),while the superconducting transition temperature Tc is maximized.Tc is then gradually weakened with further increase of pressure and reaches a minimum around 14.3 GPa,before exhibiting another{maximum}around 22.8 GPa,signifying the presence of a second superconducting dome.Distinct normal state resistance anomalies are found to be associated with the second superconducting dome,similar to KV_(3)Sb_(5).Our findings point to qualitatively similar temperature-pressure phase diagrams in KV_(3)Sb_(5) and RbV_(3)Sb_(5),{and suggest a close link}between the second superconducting dome and the high-pressure resistance anomalies.