UC Santa Barbara

Fiber-reinforced ceramic matrix composites (CMCs) exhibit high strengths at high temperatures, making them attractive for use in turbine engines. The present work explores the inelastic deformation response of two 0°/90° oxide CMCs with a focus on strains in pin-loaded specimens in the vicinity of contact points. An existing phenomenological elastic-plastic model is adapted to describe the behavior of the oxide CMCs. The model is calibrated using a new procedure involving data from uniaxial tension tests in 0°/90°, 15°/75°, and ±45° orientations as well as Iosipescu shear tests in the 0°/90° orientation. The model is assessed by comparing the evolving strain fields in pin-loaded specimens obtained experimentally (using digital image correlation) with those computed by finite element analysis (using the calibrated constitutive model). The inelastic constitutive law provides a more accurate representation of local strain fields than those obtained assuming purely elastic behavior.