Modeling Study on Failure Behavior of Quenched Hot Forming Boron Steel Considering Damage
Quenched hot-forming steel has high strength and poor toughness.The hot-forming deformation damage aggravates the fracture failure of the quenched material,and further resulting in the overestimation of the in-service crashworthiness of parts,and safety hazards and other puzzles.Taking the hardened boron steel quenched at 600℃ as the object,effects of the high temperature pre-strain on the mechanical properties and failure behaviors were studied in deep.It was found that the distinct ductile-brittle transition occurs due to the higher the pre-strain,the lower strength and elongation.Five kinds of stress triaxiality sub-samples were further designed,and their fracture failure strains were measured by DIC system.Combined with the finite element inverse optimization method,the failure hyperbola and GISSMO damage failure model of the quenched boron steel under four pre-strains were obtained.Furthermore,the axial crush test of the hardened hat-shaped structure was developed to investigate effects of considering forming damage and introducing failure model on the prediction accuracy of structural crash performance.Results shows that the only introducing the GISSMO failure model can better predict the failure behavior of quenched parts,whereas the predicted values are overestimated.In comparison,the co-simulation coupled with hot forming pre-strain history and corresponding failure model can improve the predictive accuracy effectively,and the best predictive result on crashworthiness of quenched boron-steel structures can be obtained.
hot forming quenched boron-steelGISSMOdamagefailure modeling
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