Numerical Simulation Of Fracture Behavior For Shape Memory Alloy

With the super elasticity and shape memory effect, shape memory alloy makes theresearch of the fracture mechanics behavior become complicated. It is still no one can explaininternal and external influence mechanism of shape memory alloy, in order to meet the needsof the safety design, prevent fracture failure accidents and improve the mechanical propertiesof SMA, It has realistic significance to check defect component which may have possiblehidden danger, the special part with stress concentration condition, forecast componentfracture fatigue damage life and so on. Contents are as follows:Introduce the characteristics of martensitic transformation and thermoelastic martensitictransformation judgement basis, the shape memory alloy phase change belongs to thethermoelastic martensitic transformation. By making martensite transformation or martensitepreferred orientation to achieve deformation of the shape memory alloy, this paper introducesthe mechanism of shape memory effect and superelasticity about stress and strain.By using ANSYS SMA unit material model library model of shape memory alloy tosolve plate center crack problem of2D and3D and inclined crack on the numericalsimulation, solving shape memory alloy crack front equivalent stress, and appropriateselection variables discussed the crack front equivalent stress under different conditions andthe relationship of the internal variables. By changing the loading of the load size and loadingway, and discussing the relationship of the crack front maximum normal stress value, themaximum equivalent total strain, martensite volume fraction. Applied load size, crack frontmaximum normal stress value, the maximum equivalent total strain and martensite volumefraction showed a positive correlation.By changing the shape memory alloy plate width and crack size ratio, research thechange of shape memory alloy crack front equivalent stress. The value of b/a is bigger whilethe crack front equivalent stress is smaller. When b/a≥14, with the increase of the value ofb/a，the crack front equivalent stress change tends to be gentle, so infinite plate model cansolve this limited width plate problem approximatively，where b/a≥14.