Samsul Rizal
Abstract: The influence of the specimen thickness on fracture has been investigated under static loading and interpreted in terms of stress conditions near a crack tip, namely crack tip plasticity under plane strain to plane stress condition. This work investigates the effect of stress conditions on void coalescences pro-duced by impulsive stress intensity of 20, 40? and 80??s duration under one-point bending test, experi-mentally and numerically. The fractographic observation shows that several voids nucleated at inclusions ahead of the crack tip coalescence with each others to form a large void, called a dominant void, and that size of the dominant void decreases as the pulse duration decreases from 40 ?s to 20 ?s, whereas the dominant void is nucleated at the constant distance from the crack tip for plane strain and plane stress condition. Finite element simulations show that the normalized hydrostatic stresses ahead of the crack tip can explain the experimental results that the dynamic fracture toughness of a 10 mm thick specimen tis much smaller than that of a 3 mm thick speciment and that the void nucleation site is independent of the speciment thickness.
No comments:
Post a Comment