Integrated Micro/Macro Approach for Laminate Composite Analysis: Applications to Turbine Blades

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An integrated micro/macro mechanical procedure for structural analysis of unidirectional metal matrix composites is proposed. The micromechanical analysis is performed with the composite cylinder assemblage model or the representative volume element approach. The macroscopic stress-strain relation is based on a modification of the vanishing fiber diameter theory and the concept of a smeared finite element. The fibers are considered to be linear elastic, and the matrix viscoplastic behavior is described by the Bodner and Partom model (Bodner, S. R., Review of Unified Elastic-Viscoplastic Theory, Unified Constitutive Equations for Plastic Deformation and Creep of Engineering Alloys, edited by A. Miller, Elsevier Science, New York, 1987, pp. 77-106). The overall composite behavior is assumed to be elastic-viscoplastic. Two types of material systems are used: SCS-6/Ti-15-3 and SCS-6/Tiβ21-S. Both sets of material systems exhibit isotropic and/or kinematic hardening under specific conditions of temperature and loading. The proposed methodology is validated with experimental and analytical results available in the literature. After the validation process, this methodology is applied to a three-dimensional finite element model of a [0/90] 2s SCS-6/Tiβ21-S turbine blade tip. Aerodynamic and centrifugal loading are considered to be acting at the same time. The turbine blade tip inelastic strain field is presented.