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Analysis of failure modes in an impact loaded thermoviscoplastic prenotched plate. (English) Zbl 1032.74647

Summary: Kalthoff observed experimentally that the failure mode in a prenotched maraging steel plate impact loaded on the notched side changes from brittle to ductile with an increase in the impact speed. Here we numerically investigate the effect on the failure mode transition speed of the shape of the notch-tip and the presence of a hole ahead of a circular notch-tip. The shape of the notch-tip is varied by changing the ratio, \(a/b\), of the principal axes of an elliptic notch. For a circular notch-tip, we also investigate the effect, on the failure mode transition speed, of the presence of a circular void ahead of the notch-tip and situated either on or away from the axis of the notch. The Bodner–Partom thermoviscoplastic relation is used to model the strain hardening, strain-rate hardening and thermal softening response of the material of the plate. The transient plane strain thermomechanical deformations of the plate are analyzed by the finite element method. It is found that for \(a/b=2.0\) and 10.0, the brittle failure preceded the ductile failure for the six impact speeds studied herein, and for \(a/b=0.4\) and 1.0, the failure mode transitioned from the brittle to the ductile with an increase in the impact speed. The presence of a circular void ahead of the circular notch-tip shifts towards the axis of the notch the point on the the notch-tip surface where a shear band initiates.

MSC:

74R15 High-velocity fracture
74R20 Anelastic fracture and damage
74M20 Impact in solid mechanics
74S05 Finite element methods applied to problems in solid mechanics
74C10 Small-strain, rate-dependent theories of plasticity (including theories of viscoplasticity)
74F05 Thermal effects in solid mechanics
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