Ab Initio Micromechanics Based Multiscale Model of Woven Ceramic Matrix Composites

Abstract

Multiscale models play a key role in capturing the inelastic response of woven carbon fiber reinforced ceramic matrix composites. Due to the mismatch in the thermal properties between the constituents of plain weave carbon fiber/silicon carbide composites, microcracks are present in the as-produced composite. Capturing the initial damage state of the composite requires the development of a multiscale thermoelastic constitutive damage model. The developed model is used to simulate the elastic and damage behavior of a plain weave C/SiC composite system under thermal and mechanical loads. It is shown to accurately predict the composite behavior and serves as a valuable tool in investigating the physics of damage initiation and progression and the evolution in effective composite elastic moduli as a result of temperature changes and damage. Nomenclature = coefficient of thermal expansion C = elastic stiffness tensor  = increment in coefficient of thermal expansion  eq = increment in equivalent strain e eq  = increment in equivalent elastic strain K 0 = increment in undamaged bulk modulus K = increment in instantaneous bulk modulus  = increment in damage variable  eq = increment in equivalent stress T = increment in temperature T = increment in change in temperature T = relative temperature change  = total strain tensor  = rate of change in strain tensor  eq / H = equivalent/hydrostatic strain 1 Graduate Research Associate, School of Engineering of Matter, Transport and Energy, Student Member, Luke.Borkowski@asu.edu 2 Professor, School of Engineering of Matter, Transport and Energy, AIAA Fellow Downloaded by ROKETSAN MISSLES INC. on February 8, 2015 | http://arc.aiaa.org | e eq  = equivalent/hydrostatic elastic strain  T = thermal strain tensor  = damage scalar f = damage potential  = damage variable (1-) I 1 = first invariant of the stress/strain tensor K 0 = undamaged bulk modulus K = instantaneous bulk modulus  = Poisson's ratio n = damage normalized secant modulus  = stress tensor  axial = fiber axial strength  axial = fiber transverse shear strength  crit / dam = critical hydrostatic stress value  eq / H = equivalent/hydrostatic stress T = temperature

Multiscale Modeling of Advanced Materials for Damage Prediction and Structural Health Monitoring

“…In plain weave carbon fiber/silicon carbide (C/SiC) composites, for example, when microcracks form in the as-produced parts due to the mismatch in thermal properties between constituents, a multiscale thermoelastic framework can be used to capture the as-received damage state of these composites. In this research, a micromechanics-based multiscale model coupled with a thermoelastic progressive damage constitutive law is developed to simulate the elastic and damage behavior of a plain weave C/SiC composite system under thermal and mechanical loading conditions (Borkowski and Chattopadhyay, 2013;Borkowski and Chattopadhyay, 2015). …”