Research On Ductile Damage Models Of Structural Steel

Structural steel is multiphase material in which there are some nonmetal extraments. The cavity will generate around these nonmetal extraments and second-phase particles. With deformation these cavities will growth and join while the structural steel has damaged. Ductile damage is always the focus of research because it has great effects on materials. There are many researches work discuss macro-models and micro-models of ductile damage. This paper has established three kinds of ductile damage models from physical and geometry angle respectively.The first is rate constitutive model under finite deformation. This way is microscopic property-based phenomenological theory. In this model, ductile damage is physical defects which embodied in the damdge constitutive equation. The innovation first is geometrical non-linear is taken into account in the model. In the paper yielding condition is presented in initial configuration and updated configuration respectively. Second innovation is the coupling effect of hardening and damage has been taken into account. This model follows the thermodynamics and the state variable and the internal variable meet the orthogonal principle.The second is ductile damage incompatible model of structural steel. This model take account the incompatible with a view of ductile damage essential- geometry defect. In this model, quasi-plastic strain is defined from continuous damage virable and micro-damage theory respectively, to describe the deterioration of mechanical performance of structural steel. This model is a new way to discuss the ductile damage from the geometry, and it extends the elastic-plastic model remarkably.The last is ductile damage geometry- topology model of structural steel. This model has established differential manifold of ductile damage with view of geometry, and discussed the mechanical state of structural steel in the manifold. In this model, damage is described with the curvature and a physical non-linear problem is taken into physical linear and the curve of space. ductile damage geometry- topology model has unified form and can be extended to discuss more complex defects.