International Journal of Computational Materials Science and Engineering

To explore the applications of functionally graded materials (FGMs) in dynamic structures, structural kinematics based health monitoring technique becomes an important problem. Depending upon the displacements in three dimensions, the health of the material to withstand dynamic loads is inferred in this paper, which is based on the net compressive and tensile displacements that each structural degree of freedom takes. These net displacements at each finite element node predicts damage zones of the FGM where the material is likely to fail due to a vibration response which is categorized according to loading condition. The damage zone prediction of a dynamically active FGMs plate have been accomplished using Reddy's higher-order theory. The constituent material properties are assumed to vary in the thickness direction according to the power-law behavior. The proposed C⁰ finite element model (FEM) is applied to get net tensile and compressive displacement distributions across the structures. A plate made of Aluminum/Ziconia is considered to illustrate the concept of structural kinematics-based health monitoring aspects of FGMs.

In the present work, we focus on computational investigations of the Reynolds number effect and the wall heat transfer on the performance of axial compressor during its miniaturization. The NASA stage 35 compressor is selected as the configuration in this study and computational fluid dynamics (CFD) is used to carry out the miniaturization process and simulations. We perform parameter studies on the effect of Reynolds number and wall thermal conditions. Our results indicate a decrease of efficiency, if the compressor is miniaturized based on its original geometry due to the increase of viscous effects. The increased heat transfer through wall has only a small effect and will actually benefit compressor performance based on our study.

It is vitally important to ensure the safety of brittle materials. Therefore, it is essential to deeply understand the interaction of the material's microstructure and crack propagation. In this study, we constructed a multi-phase-field crack model which can express crack propagation in polycrystal. To evaluate the basic characteristics of the developed model, we performed two-dimensional crack propagation simulations in a bicrystal where a crack enters an inclined grain boundary by changing the ratio of the grain boundary energy to the crack surface energy. As a result, it is confirmed that the model can reasonably determine the crack path, depending on those conditions. Furthermore, by performing crack propagation simulations in a polycrystal, it is concluded that the model can properly express transgranular and intergranular cracks.

Energy harvesting is one of the emerging applications of piezoelectric materials. In order to replace conventional lead-based materials with lead-free materials, it is important to evaluate their performance for such applications. In the present study, finite element method-based simulation shows mean power density produced from (K_0.475Na_0.475Li_0.05)(Nb_0.92Ta_0.05Sb_0.03)O₃ add with 0.4 wt.% CeO₂ and 0.4 wt.% MnO₂ (KNLNTS) bimorph is 96.64% of lead zirconate titanate (Pb [Zr_xTi_1-x] O₃) (PZT) ceramics. Load resistance (R), length of proof mass (L_m) and thickness of host layer (t_h) are optimized (using genetic algorithm) for maximum power density and tuning the operating frequency range which is near to natural frequency of the structure. The lead-free piezoelectric material KNLNTS has comparable results to that of PZT for piezoelectric energy harvester in the ambient frequency range of 90 Hz to 110 Hz. Results show that KNLNTS ceramics can be potentially used in energy harvesting devices.

In this paper, we develop a theoretical model for quantitative analysis of temperature-dependent heat capacity calculation of the magnetoresistance compounds RMnO₃ (R = La, Nd). The results on heat capacity obtained by us are in good agreement with the measured values. An effective interionic interaction potential (EIoIP) with the long-range Coulomb, van der Waals (vdW) interaction and short-range repulsive interaction up to second neighbor ions within the Hafemeister and Flygare approach was formulated to estimate the Debye and Einstein temperature and was found to be consistent with the available experimental data. In addition, the properties studied are the cohesive energy, molecular force constant, Restrahlen frequency and Gruneisen parameter. After characterizing thermal properties, a systematic investigation of elastic behavior has been undertaken and it has been found that the elastic moduli are decreasing continuously with increasing temperature.

The tensile and shear mechanical properties of nanotwinned copper with embedded defects have been investigated by using molecular dynamics simulations. Simulation results show that the stress concentration at the tips of crack-like defects dominates the first partial dislocation nucleation at the onset of plastic deformation, the joint action of twin boundaries and dislocations controls the yield stress at the earlier plastic deformation stage and the dislocation/twin boundary–dislocation interactions determine the plastic flow stage. Furthermore, it is found that the yield stress decreases nonlinearly with the increase of the crack length, while it decreases almost linearly with the increase of the temperature.