Fabrication and Characterization of New Functional Graded Material Based on Ti, Ta, and Zr by Powder Metallurgy Method

In view of the aging population and various diseases worldwide, the demand for implants has been rapidly increasing. Despite the efforts of doctors, engineers, and medical companies, the fabrication of and procedures associated with implants have not yet been perfected. Therefore, a high percentage of premature implantations has been observed. The main problem with metal implants is the mechanical mismatch between human bone and the implant material. Zirconium/titanium-based materials with graded porosity and composition were prepared by powder metallurgy. The whole samples are comprised of three zones, with a radial gradient in the phase composition, microstructure, and pore structure. The samples were prepared by a three-step powder metallurgy method. The microstructure and properties were observed to change gradually with the distance from the center of the sample. The x-ray diffraction analysis and microstructure observation confirmed the formation of diffusive connections between the particular areas. Additionally, the mechanical properties of the obtained materials were checked, with respect to the distance from the center of the sample. An analysis of the corrosion properties of the obtained materials was also carried out.

A control volume finite element method for the thermoelastic problem in functional graded material with one relaxation time

In this paper, a new direct vertex-centred finite volume method (CV-FEM) has been developed for the thermoelastic problem in functional graded material (FGM) based on Lord-Shulman theory. The heat conduction equation in Lord-Shulman theory is modified by considering the product term of spatial gradient of relaxation time and the heat flux rate, and it makes the present method more accurate to capture characteristics of a thermoelastic wave in inhomogeneous and FGM compared with previous methods. Some benchmark examples are used to demonstrate the capability of the present method for hyperbolic heat conduction and thermoelastic coupled problems. The effects of the ‘product-term’ on the wave propagation are studied by a heat conduction problem in inhomogeneous material and a thermoelastic problem in FGM. The FGM results show that its effect on the thermoelastic response is significant even for a linear variation of material properties.

Torsion of a growing prismatic bar with triangular cross-section made of a functional-graded material

В работе рассматривается задача о кручении растущего стержня треугольного сечения, изготовленного из вязкоупругого стареющего функционально-градиентного материала, с интегральными краевыми условиями на торцах. Изучается процесс непрерывного наращивания под действием крутящего момента. Предлагаются методы решения поставленных краевых задач путем приведения задач теории наращивания к задачам теории упругости с внутренним параметром. Приводятся формулы расшифровки для восстановления истинных параметров напряженно-деформированного состояния. Исследуется распределение интенсивности касательных напряжений на различных стадиях процесса наращивания. Приводятся расчеты задачи кручения призматического стержня с сечением в форме правильного треугольника. The paper considers the problem of torsion of a growing triangular cross-section bar made of a viscoelastic aging functionally-graded material with integral boundary conditions at the ends. The process of continuous growth under the influence of torque is studied. Methods for solving the set boundary value problems by reducing the problems of the growth theory to the problems of the theory of elasticity with an internal parameter are proposed. Deciphering formulas are given to restore the true parameters of the stress-strain state. The distribution of the shear stress intensity at different stages of the growth process is investigated. Calculations of the problem of torsion of a prismatic bar with a cross-section in the form of a regular triangle are presented.