Functionally Graded Materials for Yield Suppression at Stress Concentrators

Vapor-deposition techniques are emerging as an economical and flexible way of fabricating multiphase materials with spatially varying architectures. The aim of this work is to design architectures that exploit the concept of functional grading. We consider two basic problems; the first is the computation of the response of an infinite plate with a circular hole to a remote symmetric radial load, and the second is the computation of the response of an infinite matrix to a uniform temperature change when the matrix is perfectly bonded to an infinitely long, rigid, circularly cylindrical fiber with a zero coefficient of thermal expansion. For each configuration the variation of the material properties with position is determined so that the body yields everywhere at the same load, and we compute how this variation can be effected through variation of the distribution of two phases. We show that for each configuration the load required to initiate yielding can be doubled if the material is engineered properly.