Paper number 469

A RATE DEPENDENT ANISOTROPIC DAMAGE MODEL FOR COMPOSITE MATERIALS AT ELEVATED TEMPRERATURES |

**George Z. Voyiadjis and Babur Deliktas**

*Department of Civil and Environmental EngineeringLouisiana State University, Baton Rouge, LA 70803, U.S.A.*

Summary |
A coupled incremental damage and plasticity theory for rate independent and rate dependent composite materials is introduced here.This allows damage to be path dependent either on the stress history or ther-modynamic force conjugate to damage. This is achieved through the use of an incremental damage tensor. Damage and inelastic deformations are incorporated in the proposed model that is used for the analysis of fiber-reinforced metal matrix composite materials. The damage is described kinematically in both the elastic and inelastic domains using the fourth order damage effect tensor which is a function of the second-order damage tensor. A physical interpretation of the second order damage tensor is given in this work which relates to the microcrack porosity within the unit cell. A three step split operator algorithm is used in this work to additively decompose the set of differential equations into the elastic, plastic and damage deformation. In order to test the validity of the model, a series of uniaxial test experiments are conducted for damage characterization of the metal matrix composite. The experiments and numerical simulations are conducted for laminate layups (90)8s and are tested under uniaxial tension. |

Keywords |
composites, anisotropy, damage, rate effects, elevated temperatures. |