Digital Repository, ECF14, Cracow 2002

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Prediction of Ductile Fracture of High-Rate Loaded Steel Structures

Last modified: 2013-02-10


The prediction of damage subsequent to internal explosions has been asubject of interest for many years now. In order to be able to analyse the deformation andfailure behaviour by numerical methods, experiments have been performed on steel platematerial to derive the deformation and fracture behaviour. These experiments areperformed for varying deformation rates to account for the influence of the strain rate inactual high-rate loaded structures. The flow stress of the material is examined as a functionof plastic strain and strain rate. High-speed photography is applied to investigate thenecking behaviour at high strain rates. The fracture behaviour of the plate material isexamined by testing a number of notched specimens with different notch radii at variousstrain rates. The influence of the notch radius, and therefore the hydrostatic stress,becomes evident from these experiments. Failure strains decrease strongly with decreasingnotch radius; however the strain rate has negligible influence on the fracture strain.Modelling these experiments using the strain-rate-dependent flow stress derived from thetensile tests results in fairly good agreement with the experimental results. The ductiledamage is accounted for using the Rice and Tracey fracture model. Predictions of failurecannot be made so accurate, as the failure mechanism is not described very well.Investigations on the micromechanical behaviour of fracture must reveal the shortcomingsof the failure analysis.

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