Ductile Metal Elastic-plastic Damage Model Research And Application

Based on previous steel structure engineering accident, can be summed up, civilengineering structures in use for a long time will suffer from damage, damage case thestructure resistance decrease, it could lead to engineering accident eventually, causesignificant casualties and property losses. Thus material damage to the destruction ofthe structure is very serious, it is meaningful to study ductile metal damage model.In this paper, based on the elastoplastic and damage theory, derived the elastic andplastic damage of ductile metals of equation, using the finite element analysis method,was carried out on a common steel fram with the calculation and analysis. Study theunder great strain, the influence of damage on steel. Analysis of the steel frame underthe load, when to produce damage, damage evolution and produce damage, materialphysical relationship problems such as how to change.The main work from the following four aspects:1. Based on the existing elastic-plastic, material collection and analysis, choose asuitable for steel elastic-plasticity constitutive model. On the basis of the existingconstitutive model, based on the continuum damage mechanics theory, gives the steelelastoplastic damage evolution model to establish the basic steps and the selectingprinciple of damage variable, the elastoplastic damage evolution equation is deduced.2. Adopt J.Lemaitred strain equivalence principle, The selected damage evolutionequation and ductility of the metal in no damage state of material hardening modelcoupling, ductile metal elastoplastic damage constitutive model is given. Based onFORTRAN language, follow the ABAQUS user subroutine UMAT writing requirement, the ductility of metal damage model into a subroutine of ABAQUS.3. In this paper, the definition of the plastic damage model, is a "triaxial stressrelying on" model, the damage model has two characteristics: first, the change of thevalue of damage evolution, in addition to the relationship with the change of theequivalent plastic strain, also related to hydrostatic pressure. Second: the damage modeland the hydrostatic pressure, the plastic strain coupling.4. With a single cell, multiple cells demonstrate the effectiveness of a subroutine tocalculate respectively, the results were compared with uniaxial tensile experiment,verify the rationality of the subroutine. Steel frame finite element model is establishedand the static load, get the damage effect on the properties of steel. From the resultshows that under the condition of without considering damage, namely in the real stressand strain space, steel mechanics performance is: the stress has been increased with theincrease of strain, it obviously does not accord with the objective facts. As a result, theplastic stage of the analysis of steel structure, the damage to its influence must beconsidered. Defined in this paper, the damage model is applied to the structure, theresult shows that material stress-strain curve after elastic, softening the decline,strengthening the paragraphs. The production of plastic deformation, will accelerate theproduction of damage and so on structure design, should avoid some parts first enteredthe plastic stage, or you will make the structure of local damage first. Defined in thispaper, the damage model is applied to the material in the whole process of the finiteelement analysis, can provide some reference for engineering design.