A continuum approach to brittle and fatigue damage : theory and numerical procedures

A unified continuum approach to brittle and fatigue damage is presented. A scalar variable is used to represent the damage state. General forms of the constitutive equations are established on a thermodynamic basis. Specific evolution laws are postulated and used to illustrate the capacity of the model. The governing equations are solved numerically. The computational effort is reduced by the application of an adaptive stepsize selection procedure for the integration of the rate equations and by uncoupling the constitutive equations. The response of a plate with an induced crack subjected to periodic loading is studied

The Mechanical Behaviour of Continuous Media with stochastic damage

A model to describe the damage state of materials is developed within the framework of Continuum Damage Mechanics. The damage variable is considered as a random variable. To predict the damage state in a body, knowledge of its intrinsic damage distribution is required. After dividing the body into a number of elementary cells, the intrinsic damage distribution can be determined utilizing statistics of extremes. Fitting this distribution to experimental data the best-fit model parameters in the intrinsic damage distribution are obtained. The model is applied to fatigue damage evolution in brittle elastic material