International Journal of Computational Materials Science and Engineering

In fiber-reinforced composites, fibers are randomly positioned during the manufacturing process. Most of the theoretical studies assume regular arrangement of fibers in matrix that permits the use of representative volume element (RVE) for prediction of mechanical properties. Theoretical methods established in the literature for random fiber composites are complex and approximate. A simple approach is established in this work to accurately predict the transverse thermal conductivity of unidirectional random fiber-reinforced composites using the principle of electrical analogy (EA). In this study, circular fiber is transformed into an equivalent square fiber that facilitates the application of EA, and predicted the transverse thermal conductivity of random fiber composites. The conductivity of equivalent square fiber is evaluated by back-track approach using an equivalent thermal system. Python code is developed to generate the random location of fibers in the composite. The results obtained in this way are verified and found to be in good agreement with benchmark results over a wide range of fiber composites with varying conductivity ratios, fiber volume fraction, and randomness.

This paper aims to evaluate the performance of steel slag in improving the properties of concrete by using different homogenization models and finite element simulations. The free vibration of functionally graded (FG) concrete beams reinforced with steel slag is investigated by using the Euler–Bernoulli and Timoshenko beam theories. It has been assumed that the modulus of elasticity and the density change in the thickness direction according to the power law. The equations governing the free vibration are resolved in an exact way for Euler–Bernoulli theory and by using ANSYS software for Timoshenko theory. Then, a parametric study is carried out in order to analyze the influence of volume fraction and distribution of steel slag, beam slenderness ratio and shear on the dynamic behavior of FG beams. The results demonstrate the significant effect of the studied parameters on the vibration of concrete beams reinforced with steel slag.

The linear and nonlinear optical (NLO) properties of 3,5-dinitrobenzoic acid and some benzamide derivatives are determined using density functional theory. The B3LYP levels with a $6-311+G(d,p)$ basis are used to geometrically optimize 3,5-dinitrobenzoic acid with benzamide derivatives (DBBZM, DB1BZM, DB2BZM, DB3BZM, and DB4BZM). The low energy gap value indicates the possibility of intramolecular charge transfer. These calculations clearly show that the studied molecules can be used as attractive future NLO materials. Their first-order hyperpolarizability is found to be in the [$3.479\times 10^{-30}$, $12.843\times 10^{-30}$ esu] range, indicating that they have significant NLO properties. Furthermore, the RDG, AIM, NBO analyses, the MEP, and gap energy are calculated. The presence of intermoleculars O–H$\cdots$O and N–H$\cdots$O is confirmed by a topological feature at the bond critical point, determined by AIM theory and NBO analyses. All of these calculations have been performed in gas phase as well as cyclohexane, toluene, and water solvents in order to demonstrate solvent effect on molecular structure and NLO properties. In a final step, a molecular docking study was performed to understand the structure–activity relationship.

This paper proposes novel unit cells that can be arranged periodically constructing disparate auxetic metamaterials with negative Poisson’s ratio for engineering applications. The two-dimensional auxetic unit cells are designed utilizing the mathematical model of the modified Solid Isotropic Material with Penalization (SIMP) topological optimization method with the objective of maximizing the magnitude of the negative Poisson’s ratio. The deformation mechanisms of the auxetic structures are controlled effectively by straight and oblique struts attached at rotation joints since the optimum designs are a combination of chiral and re-entrant unit cells. Three structures with optimum auxetic designs are chosen to verify the modified SIMP method using numerical simulation. Additionally, the energy absorption and vibration mitigation of auxetic metamaterials have been extensively studied. The results showed a significant impact of negative Poisson’s ratio on the considered dynamic properties of the auxetic structures.

Foundations can be subjected to dynamic or seismic loads depending on their applications and the site being constructed in. The researchers concentrated their works on investigating the reasons of the significant damage of piles during seismic excitation. Based on the findings of laboratory experiments and other numerical analyses, such failures were referred to as the kinematic impact of the earthquake on piles since they were associated with discontinuities in the subsoil because of sudden changes in soil stiffness. The current work investigates the seismic response of closed-end (CE) pipe pile using three-dimensional finite element analysis, including the impact of the scaling-up model, acceleration-time history of the ground motion, and ground conditions. The numerical model is developed using a variety of scaling rules and the outputs of the available laboratory tests. The current results showed that the saturated sand models have larger pile deformation factors than dry sand models. Pile frictional resistance was evaluated numerically, and the entire findings were evaluated against the earlier work. Mainly, the frictional resistance around the pile shaft was lower than that at the pile tip, and the frictional resistance factor on the soil surface of dry soil models was larger than that of saturated soil models. Owing to the acceleration amplifications, the pile and soil suffered cycles of compression and tension stresses. A hysteresis loop is broader and flatter on the x-axis as the shear strain increases serve to identify the shear stress–strain plane behavior. The main outputs of the scaled models were normalized to provide a deep insight of model to prototype scaling effects.

The aim of this work is to analyze the dynamic behavior of axially loaded Timoshenko flexible shafts with cantilevered overhung disk based on the differential transformation analysis. The equations of motion are derived using Hamilton’s principle. The set of the latter consists of four coupled partial differential equations, which can be reduced to a set of two coupled equations by using a complex transformation to further improve the computational effort. An efficient mathematical recursive technique called the differential transformation method (DTM) is then used to solve the differential equations of motion. The natural frequencies of the shaft are obtained, the influence of intrinsic and extrinsic parameters on the natural frequencies is investigated, and the results are compared to those found in the literature. The results reflect the high accuracy and precision of the DTM. The novelty of the work is the application of the DTM to determine the frequency characteristics and the stability of an axially loaded overhung rotor’s free vibration analysis. These results show that the current analysis is accurate and offers an effective approach that is relatively simple and more direct regarding previous modal analyses.