FGM Model Research Articles

Development of cementless metal-backed acetabular cup prosthesis using functionally graded material

Metal backing has become widely used in acetaular cup design. A stiff backing for a polyethylene liner was initially believed to be mechanically favorable. Yet, recent studies of the load transfer around acetabular cups have shown that a stiff backing in fact generates higher stress peaks around the acetabular rim than full polyethylene cups, while reduces the stresses transferred at the central part of acetabulum causing stress shielding at the dome of acetabulum. To overcome these two problems, the aim of this study is to improve the design of cementless metal-backed acetabular cup using the two-dimensional functionally graded material concept through a finite element analysis and the optimization techniques. It is found that the optimal 2-D FGM model has three bioactive materials of hydroxyapatite, Bioglass and collagen. This optimal material reduces the stress shielding at the dome of acetabulum by 40% and 37% compared with stainless steel and titanium metal backing shell, respectively. However, using 2-D FGM model reduces the maximum interface shear stress in bone by 31% compared to titanium metal backing shell.

Stochastic simulation of non-Gaussian/non-stationary properties in a functionally graded plate

Composites with a graded profile between two distinct phases, titled functionally graded materials (FGM’s), have been proposed for a variety of applications. Many current numerical models of FGM’s overlook the inherent randomness observed in actual specimens, which arises due to the complexity and difficulty in tailoring the gradients to exact specifications during manufacturing processes. The effect of random variations, in both the component volume fractions and the porosity, on the response of a functionally graded metal/ceramic plate subjected to constant thermal boundary conditions is investigated in this work. These random variations are introduced into the FGM model via stochastic simulation. Of interest is the fact that the volume fraction and the porosity are both non-Gaussian and non-stationary. The non-stationarity is present due to the fact that the non-Gaussian probability density function describing both properties changes with location. Sample simulations are performed using a translation mapping from a stationary, standard Gaussian process to a non-stationary, non-Gaussian process. The results are used to quantify the effects of variations in the micromechanical configuration on the temperature, thermal stresses and safety factor within a functionally graded plate.

Consequences of departure from independence in two component systems when component life times depend through fgm model

The bounds for error in modelling system reliability and for the absolute error in modelling system life times are obtained for two-component series, parallel and stand by redundant systems, considering dependency of component life times through FGM model.