A recently introduced method of crack representation as a distribution of three-dimensional Volterra dislocations is used in conjunction with two-dimensional dislocation dynamics simulations to study the brittle to ductile transition behavior of Ferritic Steels. The crack-tip plasticity zone is represented as an array of discrete dislocations emitted from crack-tip sources. The dislocations shi...

Crack initiation and growth behaviour of an austempered ductile iron (ADI) austenitised at 800C and austempered at 260C has been assessed under three point bend fatigue conditions. Initiation sites have been identified as carbides remaining from the as cast ductile iron due to insufficient austenisation. The number of carbides cracking on loading to stresses greater than 275 MPa is critical in ...

Some forensic in situ investigations, such as those needed in transportation (for aviation, maritime, road, or rail accidents) or for parts working under harsh conditions (e.g., pipes or turbines) would benefit from a method/technique that distinguishes ductile from brittle fractures of metals—as material defects are one of the potential causes of incidents. Nowadays, the gold standard in mater...

AEROSPACE ENGINEERING engineering.tamu.edu/aerospace Abstract Ductile fracture in metals is an area of active research. While the mechanism of failure (void nucleation, growth and coalescence) in ductile materials is well-understood, the existing models still have several limitations in an accurate prediction of this phenomenon. These models need to be enriched with a more precise understanding...

Here we report novel phase-separation behavior accompanying mechanical fracture ("fracture phase separation"), which is observed in polymer solutions. Surprisingly, mechanical fracture becomes a dominant coarsening process of the phase separation. The transition from viscoelastic to fracture phase separation corresponds to the "ductile-to-brittle transition" in fracture of materials under shear...

The failure process ahead of a mode I crack advancing in a ductile thin metal plate or sheet produces plastic dissipation through a sequence of deformation steps that include necking well ahead of the crack tip and shear localization followed by a slant fracture in the necked region somewhat closer to the tip. The objective of this paper is to analyze this sequential process to characterize the...

In this theses the high strength steel Docol 600DP and the ultra high strength steel Docol 1200M are studied. Constitutive laws and failure models are calibrated and verified by the use of experiments and numerical simulations. For the constitutive equations, an eight parameter high exponent yield surface has been adopted, representing the anisotropic behaviour, and a mixed isotropic-kinematic ...