Thermomechanical nonlocal models in continuum damage mechanics
Conference
·
OSTI ID:175165
- Universitb di Roma (Italy)
A general framework aimed at describing the thermomechanical nonlocal behaviour of microcracked bodies in strain softening conditions is introduced in this paper. The microcrack state is described by means of a field on the body which is identified by an application which takes values in a finite-dimensional, connected, differentiable manifold. This field, the {open_quotes}structure{close_quotes}, together with the associated displacement field, are the mechanical descriptors of the body. In this {open_quotes}structured continuum{close_quotes} scheme, the equations of evolution of the microcrack state have a clearer physical meaning with regard to the rearrangement of the internal structure of the body than in the {open_quotes}internal variable{close_quotes} approach. Certain mathematical complications of the latter scheme can also be avoided. On the other hand, at least at the present state of the models, it is still necessary to resort to the classical internal variable scheme in many instances (e.g. chemical ageing). Nonlocal effects to be taken into account are (1) the long range interactions of the microcracks with one another, related to the high scattering effects of the elastic waves, and (2) the interactions of the strain fields induced in the body by the opening of the microcracks themselves. It is usual, in damage models, to introduce nonlocality into the constitutive equations by means of an integral (nonlocal) representation of the damage variables: this approach appears simpler than the nonlocal representation of all state variables and is physically more plausible for materials in which nonlocal constitutive effects of the undamaged state are negligible. However, in actual fact, nonlocality is related with the very phenomenon of damage, not only with the nonlocal constitutive nature of the damage variables. Therefore, in the present paper, nonlocal effects are introduced into the balance equation by means of the Edelen`s localisation residuals.
- OSTI ID:
- 175165
- Report Number(s):
- CONF-950686--
- Country of Publication:
- United States
- Language:
- English
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