International Journal of Computational Materials Science and Engineering

To further understand the seismic performance of reinforced concrete (RC) frame-shear wall structures, a 1/8 model structure is scaled from a main factory structure with seven stories and seven bays. The model with four-stories and two-bays was pseudo-dynamically tested under six earthquake actions whose peak ground accelerations (PGA) vary from 50gal to 400gal. The damage process and failure patterns were investigated. Furthermore, nonlinear dynamic analysis (NDA) and capacity spectrum method (CSM) were adopted to evaluate the seismic behavior of the model structure. The top displacement curve, story drift curve and distribution of hinges were obtained and discussed. It is shown that the model structure had the characteristics of beam-hinge failure mechanism. The two methods can be used to evaluate the seismic behavior of RC frame-shear wall structures well. What’s more, the NDA can be somewhat replaced by CSM for the seismic performance evaluation of RC structures.

To solve the problem of coal-rock damage during cutting coal and rock by diamond saw blade — the LS-DYNA diamond saw blade — coal and rock finite element model is established. According to the fracture mechanism of brittle materials, by studying a single diamond saw blade with different cutting speeds and revolution speeds along with double diamond saw blades with different spacing, cutting speeds and cutting speeds of coal-rock damage, axial force and force change, the numerical simulation resultant demonstrated the axial force, cutting force and rock damage decrease significantly with an increase in rotational speed. The force and damage increase with an increase in the cutting speed and a decrease in the distance of the diamond saw blade. The axial force linearly increases with rotational speed and cutting speed. The cutting force exponentially decreases with increasing rotational speed, and it increases with increasing feeding speed. The forces decrease linearly with the increasing distance of the diamond saw blades. The damage degree of rock increases as the distance and rotational speed increase, and it decreases as the cutting speed increases.

Using first-principle calculations within the framework of density functional theory (DFT), the full-potential linearized augmented plane-wave (FP-LAPW) method have been performed to investigate structural, electronic and magnetic properties of the Ca₂MnMoO₆ double perovskite. Different spin configurations (ferromagnetic (FM), ferrimagnetic (FiM), and anti-ferromagnetic AFM1, and AFM2) within both generalized gradient approximation (GGA) and $\mathrm{\text{GGA}}+U$ (Hubbard Coulomb onsite correction) were considered. The value of the Hubbard−Coulomb $U$ parameter was varied in the range of $1-4$eV. The ground state is found to be AFM and insulating with the AFM1 state which is the most favorable. In the AFM1 spin configuration, Ca₂MnMoO₆ compound has a semiconductor nature, with the fully spin-polarized valence and conduction bands in the same spin channel. Within the $\mathrm{\text{GGA}}+U$ approximation, the FM phase has a half-metallic character with a net magnetic moment of $5.0{\mu }_{\mathrm{\text{B}}}$ while in the anti-ferromagnetic phase it has an insulating character with zero net magnetic moment which was found at $U\ge 2$eV. We found that in the AFM phase within the GGA approximation, a metallic character is obtained for Ca₂MnMoO₆ and also for $U=1$eV. In particular, for Hubbard $U$ of 3.6eV, a small energy gap of 0.20eV is observed. The main features shown by the density of states curves motivate further experimental exploration in the double perovskite Ca₂MnMoO₆ for spintronic applications.

We report here a tight-binding theoretical study of anti-ferromagnetism in graphene taking electron hopping up to third nearest neighbors. The graphene on substrate introduces inequivalence in the two sublattices of the honeycomb lattice. The on-site Coulomb interactions at two sublattices of graphene are treated within mean-field approximation and the electron occupancies at two sublattices include spin moments in opposite directions giving rise to anti-ferromagnetism in graphene. The AFM sublattice magnetizations are calculated by using Zubarev’s Green’s function technique and computed self-consistently for different ranges of Coulomb potential, substrate-induced gap and impurity concentrations. It is observed that $A$-site magnetization is suppressed by $A$-site impurity concentration, while $B$-site magnetization remains unaffected. Similar effect has been observed at $B$-site when doped with pentavalent dopant, while $A$-site magnetization remains unaffected. Furthermore, substrate-induced AFM gap has also been observed at different ranges of temperature.

First-principles calculation is carried out to study adsorption of potassium (K) on phosphorene, a single layer of black phosphorus (BP). Interesting adsorption distance dependent electronic properties were found for the K adsorption on phosphorene surface, which is different from that for the K adsorption on a few-layer black phosphorus. While the bandgap of few-layer BP decreases monotonically as K approaches its surface and a Dirac point emerges, that of phosphorene decreases first and then increases, remaining open at any separation between K and phosphorene. This abnormal behavior is a result of weaker Stark effect and charge localization in phosphorene.

Soft matter with hyperelastic behavior may be harnessed for novel applications. However, it is not achievable if the mechanical behaviors of soft matter are not well understood. At present, various traditional extensometers have been used to measure the engineering strain of materials to determine the mechanical properties. The basic assumption of extensometers is that the strain is assumed to be uniform over the gage length. However, this assumption does not hold good in case of experimental specimens having significant nonuniform strain distribution, for example, tensile tests on notched specimens or materials that undergo localized deformations. Hence, it is imperative to adopt a new method which enables us to capture the actual strain field on the surface of a material. Digital image correlation (DIC) technique is an adequate approach that has been widely used in many fields of science and engineering. In this paper, we have presented a mapping algorithm for hyperelastic materials, translating the strain field provided by DIC to the stress field based on continuum mechanics. It overcomes the limitation of extensometers and captures the real stress field for such materials. This method will not only improve the measuring accuracy of stress and strain fields in current experiments, but also greatly promote the study of the localized characteristic for nonlinear and inhomogeneous materials.