Finite element analysis of elastic–plastic and fracture behavior in functionally graded materials (FGMs)

Abstract

The effect of material property variation on ductility and fracture strain in functionally graded materials (FGMs) is investigated using the finite element method (FEM) and the Gurson–Tvergaard–Needleman (GTN) model, which is strain-controlled for void nucleating. The material properties of FGMs in the tensile tests are assumed to be represented by a power-law distribution in the thickness direction. A gradation index (n) assigns the material property distribution. The lower and upper surfaces are pure hard (n = ∞) and pure soft (n = 0) materials, respectively, in the simulations. The ductility and fracture strain changes with varying gradation index. The development of stress triaxiality slows down in FGMs, and the total void volume fraction is reduced. The analysis is performed for five values of n, and the results are discussed numerically. The aim of this study is to help the researchers for better design and fabrication of FGMs. The necking strain in FGMs is calculated and it is found that it increases when the rate of hardening in the effective stress–strain curve increases. Lastly, it can be concluded that gradation index has significant effect on the elastic–plastic and fracture behavior of the functional graded (FG) specimen.