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The extensive consumption of fossil fuels and other energy resources worldwide necessitates the exploration of alternative energy sources. Thermoelectric power generation is one of the most prominent technologies to convert heat energy into electrical energy. Numerous researchers have devoted significant efforts to enhancing the efficiency of thermoelectric technology through the synthesis of nanomaterials using various methodologies. Among these methods, high-pressure synthesis emerges as one of the most efficient techniques for synthesizing thermoelectric materials. In this study, we fabricated skutterudite-type thermoelectric materials of LaxCo4Sb12 by using a high-pressure synthesis method with a high filling rate, where the actual filling fraction can increase up to x = 0.28, exceeding the theoretical filling limit at ambient pressure. As a result, LaxCo4Sb12 shows a significantly lower lattice thermal conductivity value of 1.3 W/mK which is much lower value than for CoSb3. The results clearly demonstrate that the high-pressure synthesis method is a promising tool for enhancing the performance of thermoelectric materials. [ABSTRACT FROM AUTHOR]

In this study, the effects of print parameters on the mechanical properties of additively manufactured metallic parts were investigated using a tensile test. The 17-4 PH stainless steel specimens with two print parameters, including infill density and pattern orientation, were fabricated by additive manufacturing (AM) using the bound metal deposition (BMD) technique. The mechanical properties considered in this study are the Young's modulus and ultimate tensile strength. The results demonstrate that the pattern orientations do not affect the Young's modulus of the infill specimen with the triangular pattern. In contrast, the ultimate strength significantly varies depending on the pattern orientations, where the samples with the pattern orientation of zero degrees yield the best ultimate strength. In fact, the mechanical properties of infill specimens increase with their infill density. However, when operating cost and time are considered, an index for estimating performance and sustainability is consequently established. The relationship between the normalized ultimate strength of an infill specimen and the relative density is defined as the weight efficiency. The index for assessing a sustainable product is characterized by the weight efficiency versus sustainable parameter(s). The index can help end users select an appropriate infill density for AM products by considering the operating cost and time. Different cost models, including material-only costs, direct costs, and total costs, can be included in the index model to assess a sustainable product in a particular cost context. [ABSTRACT FROM AUTHOR]

In this study, the effective out-of-plane rigidities of several 2D lattices, consisting of Euler beams, with different common unit cell topologies are investigated. The effective out-of-plane rigidities per weight density of these lattices, normalized by those of the full solid plates with the same material and thickness, are determined. The effective out-of-plane rigidities are computed by the homogenization method based on equivalent strain energy and the Kirchhoff plate theory. Particularly, the homogenization-related equations, including the equivalent strain energy equation itself, are not taken from their corresponding equations for 3D solids, but are derived directly using the Kirchhoff plate equations. Moreover, the exact forms, having some dimensionless factors, of the effective material constants for 2D-lattice plates are analytically derived. By using exact curve fitting, these exact forms, in most cases, yield the closed forms of the effective material constants. Finally, the efficiency of the considered unit cell topologies, in terms of the normalized effective rigidities per weight density of their resulting lattices, is discussed. [ABSTRACT FROM AUTHOR]

In this study, the effective elastic constants of several 2D and 3D frame-like periodic cellular solids with different unit-cell topologies are analytically derived using the homogenization method based on equivalent strain energy. The analytical expressions of strain energy of a unit cell under different strain modes are determined using a generic symbolic object-oriented finite element (FE) program written in MATLAB. The obtained analytical expressions of the strain energy are then used to symbolically compute the effective elastic constants that include Young's moduli, Poisson's ratios, and shear moduli. The obtained analytical effective elastic constants are numerically verified using results from an ordinary numerical FE program. The obtained closed-form effective elastic constants are also compared with some existing solutions from the literature. This study demonstrates that symbolic computation platforms can be properly used to provide efficient methodologies for finding useful analytical solutions of mechanical problems. Without the symbolic object-oriented FE program in this study, elaborate and tedious analytical analysis has to be manually performed for each different unit cell. The symbolic object-oriented FE program provides analytical analysis of unit cells that is accurate and fast. The object-oriented programming technique allows the symbolic FE program in this study to be efficiently implemented. [ABSTRACT FROM AUTHOR]

This study presents the exact forms of the effective elastic constants of arbitrary frame-like periodic cellular solids that can be modeled accurately using Euler beams. The forms are derived analytically by using the homogenization method based on equivalent strain energy. In the derivation, the cross sections of all struts in a frame-like periodic cellular solid with an arbitrary topology are set to be the same and are also set to have the same moment of inertia in all directions. The exact forms of the effective elastic constants are obtained in terms of some dimensionless factors, the characteristic length and volume of the unit cell, the area and moment of inertia of the struts, and Young's modulus of the base material. The dimensionless factors are dependent on the topology of the solid. In general, these factors can be functions of the area and moment of inertia of the struts. However, for numerous practical topologies, the factors are constant. In these cases, the obtained forms can be used as exact parametric forms. The constant factors for frame-like periodic cellular solids with a particular topology can be determined by exact curve fitting using numerical finite element results with different areas and moments of inertia of the struts. If exact fitting cannot be achieved beyond the fitting data, it follows that, for the topology being considered, some of the factors are not constant and the results of the curve fitting should not be used. To check the validity of the proposed exact forms of the effective elastic constants, they are used with several topologies of 2D and 3D frame-like periodic cellular solids. The obtained effective elastic constants are compared with exact solutions from elaborate symbolic finite element computations and/or the literature. When all dimensionless factors in the proposed exact forms are constant, the effective elastic constants obtained in this study are found to be exactly the same as the exact solutions. [ABSTRACT FROM AUTHOR]