A functionally graded particulate composite: Preparation, measurements andfailure analysis

A functionally graded composite is prepared and the spatial gradation of Yo ung's modulus in the functionally graded material (FGM) is measured. Elasti c modulus gradients occur over length scales suitable for experimental mech anics investigations using optical interferometry. Crack tip fields are map ped in the FGM under quasi-static loading conditions with cracks oriented p erpendicular to the direction of the elastic gradient and near the interfac e of the graded and the homogeneous portions of three-point-bending specime ns. The optical measurements are used to extract fracture parameters based on the prevailing understanding of the crack tip behavior in FGMs. The resu lts are also compared with finite element computations which incorporate me asured elastic properties of the FGM. The advantage of using FGM interlayer as opposed to piecewise homogeneous joints is demonstrated through crack i nitiation tests. (C) 1998 Acta Metallurgica Inc. Published by Elsevier Scie nce Lid. All rights reserved.