Abstract
This work explores the effects of grain orientation and T-stress on crack-front shielding and delamination cracking in modern aluminum-lithium alloys. In the crack-arrestor configuration of interest here, a primary crack extends through the grain thickness while triggering delaminations over susceptible grain boundaries that lie normal to the plane of the primary crack. A three-dimensional, small-scale-yielding framework that employs a gradient-enhanced, crystal plasticity material model reveals key features of the strain/stress fields in a simulation of pancake-shaped grains with alternating orientation near a primary crack front. The alternating grain configurations exhibit a soft/stiff behavior and alternating out-of-plane, L-T shear stress - effects observed in recently-published experiments completed by the authors and others on various Al-Li alloys. Both texture effects contribute to highly localized driving forces for delamination cracking while concurrently shielding the primary crack. Moreover, texture does not act to shield the arrestor delamination planes, thereby favoring arrestor delamination development over primary crack growth. A compressive T-stress further enhances shielding of the primary crack - a result which aids in understanding marked differences in observed fracture behavior of tested M(T) and C(T) specimens of Al-Li alloys.
Original language | English (US) |
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Pages (from-to) | 229-249 |
Number of pages | 21 |
Journal | International Journal of Fracture |
Volume | 188 |
Issue number | 2 |
DOIs | |
State | Published - Aug 2014 |
Keywords
- Aluminum-lithium
- Crystal plasticity
- Delamination
- Fracture mechanisms
ASJC Scopus subject areas
- Computational Mechanics
- Modeling and Simulation
- Mechanics of Materials