An integrated methodology and formulations for micro/macro modeling and analysis of metal matrix composites.

摘要

Composites are attractive for engineering applications due to their light weight and high strength. Of the various types of composites, Metal Matrix Composites (MMC) are of interest here because of their ability to withstand very high temperatures. Hence, these composites are an excellent candidate for aircraft and aerospace structural components where elevated temperatures are frequently encountered. Routine testing/analysis of complex composite geometries such as those encountered in aircraft structures are cost-prohibitive and/or impractical, especially in hostile temperature environments. Therefore, there is a need for the development of effective computational methods and modeling/analysis techniques involving linear/nonlinear material behavior for analyzing such structural geometries.; An integrated micro/macromechanics procedure for the stress analysis of unidirectional MMC's is proposed. The micromechanical analysis is used to obtain the effective elastic moduli via the Composite Cylinder Assemblage model (CCA) or the Representative Unit Cell approach (RUC). On the other hand, for the macroscopic analysis, the macromechanical stress-strain relation is based on a modification of the so-called Vanishing Fiber Diameter theory (VFD). The fibers are considered to be linear elastic. The matrix viscoplastic behavior is described by either the Bodner and Partom or the Power Law models. The proposed integrated methodology allows the use of: (i) a physically realistic constitutive model; (ii) a macromechanical stress-strain formulation via the VFD theory; (iii) an elastic-viscoplastic constitutive material behavior; (iv) a smeared finite element procedure; and (v) efficient numerical algorithms for analyzing the behavior of composite structures. The proposed developments are validated with available experimental and analytical results for simple geometries whenever feasible, and an application to a realistic practical problem is also demonstrated.