A functionally graded particulate composite: Preparation, measurements and failure analysis

A functionally graded composite is prepared and the spatial gradation of Young's modulus in the functionally graded material (FGM) is measured. Elastic modulus gradients occur over length scales suitable for experimental mechanics investigations using optical interferometry. Crack tip fields are mapped in the FGM under quasi-static loading conditions with cracks oriented perpendicular to the direction of the elastic gradient and near the interface of the graded and the homogeneous portions of three-point-bending specimens. The optical measurements are used to extract fracture parameters based on the prevailing understanding of the crack tip behavior in FGMs. The results are also compared with finite element computations which incorporate measured elastic properties of the FGM. The advantage of using FGM interlayer as opposed to piecewise homogeneous joints is demonstrated through crack initiation tests. (C) 1998 Acta Metallurgica Inc. Published by Elsevier Science Lid. All rights reserved.