International Journal of Computational Materials Science and Engineering

The shape and height of a natural balanced soil arch are two of the critical factors for the development of a sinkhole. The exposure of the natural balanced soil arch can be described as the initiation of the surface-collapse phase of the cover-collapse sinkhole in karst terrain. In this paper, by simplifying the natural balanced soil arch as a thin shell in a limit equilibrium state, a theoretical model is developed using the nonmoment theory of rotary shells with the shape and height of the natural balanced soil arch derived based on the Protodyakonov’s theory. First, the developed model is validated using a case study (a cover-collapse sinkhole occurred in Guizhou, China). It demonstrates that the shell theory used in this study can describe the equilibrium state of a natural balanced soil arch reasonably well. After model validation, a series of numerical simulations are then carried out to investigate the critical factors which govern the collapse of a sinkhole. The results show that buried depth serves as a compulsory condition for the formation of the natural balanced soil arch. Furthermore, it shows that a buried depth less than six times of the radius of a cave could result in the formation of a natural balanced soil arch in the cone surface.

The electronic structure and optical properties of ${\mathrm{\text{CaThO}}}_3$, ${\mathrm{\text{SrThO}}}_3$ and ${\mathrm{\text{BaThO}}}_3$ in cubic perovskite structure are calculated using a density functional theory with full-potential linearized augmented plane wave (FP-LAPW) method. In this study, we have used the approximations LDA, GGA and mBJ, with mBJ the best approximation to get the band gap energy. This study is conducted through five stages: (1) We have started by optimizing the lattice parameters to find the basic state of each component (2) We have calculated electronic properties such as density of state, band structure, charge density (3) and based on the band structure we have also calculated the optical properties as dielectric function, absorption coefficient, refractive index, reflectivity and optical conductivity to discuss the different transitions and the new peaks. The mechanical (4) and thermodynamic (5) behavior was discussed for the first time for ${\mathrm{\text{CaThO}}}_3$ and ${\mathrm{\text{BaThO}}}_3$ in the cubic phase, in terms of elastic constants, and their related parameters, such as Young’s modulus, shear modulus and Poisson’s ratio. Our results show that $X{\mathrm{\text{ThO}}}_3$ has a stable ductile trait that makes it effective for high temperature electronic applications. As a result, the various new peaks in the wide UV region due to the transition of electrons confirm the application of $X{\mathrm{\text{ThO}}}_3$($X=\mathrm{\text{Ca}}$, Sr and Ba) in the field of optoelectronic devices.

Recently, wavelet-based numerical methods have been newly developed in the areas of science and engineering. In this paper, we proposed a full-approximation scheme for the numerical solution of Burgers’ equation using biorthogonal wavelet filter coefficients as prolongation and restriction operators. The presented scheme gives higher accuracy in terms of higher convergence in less CPU time, which has been illustrated through the test problem.

In this study, reliable image-based meso-scale damage evolution simulation of concrete can be executed by considering its heterogeneous meso-components. Meso-scale damage evolution of concrete with different meso-components are simulated and analyzed here, which can be used to optimize seismic resistance of concrete. As a case study, seismic damage process of a reinforced concrete (RC) column with different meso-component parameters are simulated. From the simulation results, it can be seen that improvement of the properties of interfacial transition zone (ITZ) can significantly improve the seismic performance of RC columns. The established reliable damage evolution simulation of concrete can supply a useful numerical tool to study the method for improving seismic performance of RC column such as optimizing concrete’s meso-model parameters.

The critical damage for carbon fiber structures, which are being employed in aircraft structures, is known as delamination/crack. Fasteners are commonly installed to arrest the delamination by clamping the laminate together. Fasteners are installed in each corner of the delaminated zone to provide significant arrest capability, shifting the failure mode away from delamination under most conditions. The Finite Element Analysis (FEA) model is constructed to study the effectiveness of the fastener as crack arrest mechanism. The FEA results show that the fastener provides significant crack retardation capability in Mode-I condition.

An analytical model is developed for the delamination embedded between the skin and stiffener interface of the joint. The fasteners are modeled with spring elements. The analysis is solved with Virtual Crack Closure Technique (VCCT) approach. The primary objective of the current research work is to enhance the safety of bonded joint by providing arrest mechanisms.

This paper investigates the orthotropic properties of Fused Deposition Modeling (FDM)-printed Acrylonitrile Styrene Acrylate (ASA) material with different raster configurations. The elastic properties were determined using a non-destructive ultrasonic technique. This technique allows us to deduce the orthotropic elastic constants from the material density and the velocities of the longitudinal and shear waves propagating through the material along different directions. Tensile tests were performed in addition to ultrasonic tests to obtain the yield properties of the ASA material and to validate the elastic constants determined by the ultrasonic tests, which have shown very close correspondence. Finally, numerical verification was performed by comparing the experimental results of the three-point and four-point bending tests with the finite element simulation results which have as input the material properties from the ultrasonic testing. The simulation results have shown excellent agreement with the experimental results, implying that the material properties obtained from the ultrasonic testing were highly accurate comparing to the actual orthotropic elastic properties of the 3D-printed ASA material.