International Journal of Computational Materials Science and Engineering

In this study, nonlinear post-buckling and free vibration analysis of shape memory polymer sandwich composite (SMPSC) under dynamic temperature variation is performed. For the analysis, simplified Co continuity based on higher-order shear deformation theory (HSDT) has been adopted to perform finite element analysis (FEA). Numerical solutions are obtained by iterative Newton–Raphson method considering Von-Karman nonlinear kinematics. Material properties of SMPSC, with Shape Memory Polymer (SMP) as matrix and carbon fiber as reinforcements, have been calculated by theory of volume averaging. The effect of dynamic temperature variation and axial variable inplane loadings (AVIL) on SMPC and SMPSC has been evaluated for various parameters such as beam thickness ratio, layer variation, boundary conditions (BCs), position of core, thickness of core in sandwich structures for the first time. Apart from these, this study also clearly reveals the difference in magnitude of buckling and free vibration parameters between the shape memory polymer composites (SMPC) and SMPSC, before and after glass transition region of material.

Ab initio density functional calculations of the structural, optoelectronic, thermoelectric and thermodynamic properties of ZnO codoped with tin and fluorine with possible application as Transparent Conductive Oxides (TCO’s), are reported in this work. This study shows that incorporation of Sn and F into the ZnO matrix converts it to a degenerate semiconductor. The calculated optical absorption coefficients show that the four compounds ZnO, Sn:ZnO, F:ZnO and Sn:F:ZnO have transparent properties in the visible range. At 900K, the Seebeck coefficient of Sn:F:ZnO is greatly improved with respect to the undoped ZnO. A maximum electrical conductivity value of $3.75\times 10^{19}$S cm${}^{-1}$s${}^{-1}$ is predicted for Sn-doped ZnO. ZT increases with temperature to a maximum value of 0.13 at 900K for tin and fluorine codoped ZnO.

To protect the structural part of the rocket nozzle, an insulation liner is provided at its inner surface. Charring ablators are used for this purpose. The thickness of the insulation liner is one of the major design considerations of the nozzle. In the present analysis, an attempt has been made to predict thermal erosion (ablation) in the insulation liner through numerical studied CFD and FEA. The problem is modeled in ANSYS software. Fluid flow analysis is performed using the fluent module that works on the finite volume method, and the transient thermal module is used for the thermal analysis that works on the finite element method. Appropriate mesh convergence, residual convergence, and time step convergence exercises are made and the numerical results are verified with the analytical solution wherever possible. The possibility of reduction of thermal load due to the presence of char in ablator liner is considered and the thermal resistance in the region exposed to melting point temperature is altered to permit the propagation of thermal loads to the current pyrolysis front at any instant. The concept of this work is useful in the prediction of thermal ablation in rocket nozzles and in selecting the required thickness of the insulation layer.

This research paper focuses on the objective of developing a quadrature for evaluating the element stiffness matrix for the four-node quadrilateral element in finite element analysis (FEA). The proposed integration scheme is defined as an element edge method (EEM), which mimics the Gauss numerical integration scheme. This integration scheme consists of five sampling points and weights where four integration point locations are at the edges and one is at the center of the quadrilateral element. The proposed quadrature scheme has been tested using various benchmarked problems designed by various researchers to study the convergence of the results, accuracy of results, and stability of values.

This paper studies the effect of atoms number $(N)$ of bulk Ag: $N=2916$ atoms (Ag${}_{2916}$), 4000 atoms (Ag${}_{4000}$), 5324 atoms (Ag${}_{5324})$, 6912 atoms (Ag${}_{6912})$ at temperature $T=300$K, 400K, 500K, 600K, 700K, 800K, 900K, 1000K on bulk Ag${}_{5324}$ and annealing time $t$ = 200 ps on the structure and phase transition of Ag bulk by Molecular Dynamics (MD) method with Sutton–Chen (SC) pair interaction potential, periodic boundary conditions. The structural results are analyzed through the Radial Distribution Function (RDF), the total energy of the system ($E_{tot})$, the size $(l)$, the phase transition (determined by the relationship between $E_{tot}$ and $T$), and combined with the Common Neighbors Analysis (CNA) method. The obtained results show that the first peak’s position ($r)$ of the RDF has negligible change value, $r=2.78$Å, which is completely consistent with the experimental results. For bulk Ag, there are always four types of structure: FCC, HCP, BCC, Amor and glass transition temperature $T_g=500$K. When decreasing the temperature, bulk Ag changes from liquid state to crystalline state, when increasing the annealing time at $T_g=500$K, bulk Ag changes from amorphous phase to crystalline phase state, leading to the increase of FCC, HCP, BCC structures and the decrease of Amor structure. The obtained results will be used as guide for future experiments.

The aim of this paper is to establish the homogenization approach that eliminates the difficulties encountered by the conventional numerical methods in analyzing thermal behavior of the multi-material component systems with minimum computational resources. Analysis of problems with intricacies or larger domains can be made simpler through finite element assisted homogenization approach. In this paper, applicability of homogenization approach is verified by considering two cases (i) composite with voids and (ii) composite with fibers distributed randomly. Fiber randomness case is investigated by Digital Image-Based (DIB) modeling technique in association with MATLAB’S image processing module. Also effect of transverse fiber crack on the effective thermal conductivity of the composite is studied. Results of homogenization approach compared with micro-mechanics approach yielded maximum percentage deviation of 1.72% for voids case and 1.49% for fiber randomness case.