Abstract
Dimple fracture of aluminum alloy 7075-T651 subjected to various stress intensity pulses with durations of 20, 40 and 80 μs is investigated by discrete dislocation dynamics and the Gurson-Tvergaard-Needleman constitutive model (GTN-model). A dominant void ahead of macro crack tip is modeled by a micro crack. The evolution of principal stress component along the inner ligament is computed by the sum of the crack tip stress field and the interaction stress field of dislocations emitted from both the micro crack and macro crack. The yielding flow of GTN-model is used to estimate void volume fraction, which is used for a fracture initiation criterion. The numerical results of the dimple fracture are obtained in a reasonable agreement with the experimental ones.
Highlights
Dimple fracture usually results from nucleation, growth, and coalescence of microscopic voids that initiate at inclusions and second-phase particles
The fracture surface is examined by a scanning electron microscope (SEM) and the observation result shows that the fracture surface is entirely covered by dimples, and that a large void was initiated ahead of the crack tip prior to the small voids
Similar to the main crack simulation process, dislocations are emitted on the slip lines ahead of micro crack and the stress component ahead of it is calculated by the distribution of crack tip stress field and the interaction of emitted dislocations stress field
Summary
Dimple fracture usually results from nucleation, growth, and coalescence of microscopic voids that initiate at inclusions and second-phase particles. In the review of ductile fracture [1], the initiation criterion of dimple fracture could be considered in terms of the critical crack tip opening displacement (CTOD) exceeding the mean void initiating particle spacing. A certain critical condition must be achieved at the crack tip, and it must be achieved over a characteristic distance. The fracture surface is examined by a scanning electron microscope (SEM) and the observation result shows that the fracture surface is entirely covered by dimples, and that a large void was initiated ahead of the crack tip prior to the small voids. The crack tip is blunted further with the load increment and the nucleated dominant void grows. It is considered that the fracture initiation takes place when a
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
