The effects of different volume fraction distribution and micromechanics homogenization schemes on the mechanical behavior of FGM pressurized pipes

Abstract

Functionally Graded Materials are characterized by a smooth and gradual microstructural composition along one or more of its dimensions. Problems related to the existence of interfaces such as debonding and delaminations, which are commonplace in laminated composites, are mitigated in such materials. FGMs are manufactured by varying the volume fraction of its constituents throughout its thickness, in order to tailor the final mechanical properties. Micromechanics homogenization schemes have been successfully employed on the study of these materials to obtain a description of the constitutive laws that describe the macroscopic state of stress and strain as a function of the microstructural composition. Such methods can be either analytical or numerical, but both approaches take into account the influence of the several phases or inclusions on the overall behavior of a representative volume element (RVE). The analysis of the differences among various homogenization schemes, different volume fraction profiles, as well as the influence of the inclusion geometry on the overall behavior of the FGM thick cylinder was carried out in the present work. The composite chosen for the analysis was Al-SiC and the comparisons were made in terms of stress and strain profiles along the wall of a pressurized hollow cylinder with varying SiC profiles. User subroutines (UMAT) were developed in Abaqus in which different homogenization schemes were implemented and analyzed. The results found showed the importance of the accurately describing the volume fraction distribution as well as the impact of the different homogenization schemes on the overall mechanical behavior of the material.