Reduction in stress concentration around a pair of circular holes with functionally graded material layer

The stress concentration in an infinite panel having a pair of circular holes surrounded by a functionally graded material layer subjected to different load conditions using the extended finite element method is numerically analysed. Young's modulus of the functionally graded material layer varies with a power law function, in the direction normal to the holes. To model the material properties and the hole boundary, a level set function is used. The relation of stress concentration factor with functionally graded material layer parameters (i.e. power law index, thickness of layer) and hole geometry parameters (i.e. normalised distance between holes, hole radius ratio) is discussed, and it is observed that the functionally graded material layer around the pair of circular holes results in a significant reduction in stress concentration. It is concluded that the proper selection of power law index and thickness of the functionally graded material layer helps in reducing the stress concentration factor to a great extent.