|Ph.D Student||Zhang Longhui|
|Subject||Controlling Adiabatic Shear Failure by Tailoring|
Microstructural Toughening Factors
|Department||Department of Mechanical Engineering||Supervisors||Professor Daniel Rittel|
|Dr. Shmuel Osovski|
|Full Thesis text|
The prediction of the onset of adiabatic shear band (ASB) formation and subsequent failure is a major issue due to the unstable character of this failure mechanism. During the last decade, our group has proposed a new approach to the phenomenon, based on the dynamically stored energy of cold work and dynamic recrystallization (DRX), which are identified as key factors for the onset of shear localization. A physical explanation to dynamic shear localization was the development of DRX as a microstructure-related instability. The deeper identification of the toughening-softening mechanisms will pave the road for a control of the propensity to adiabatic shear localization.
Ti6Al4V is chosen as a model material to study the influence of impact-induced dynamic recrystallization (DRX) on the subsequent quasi-static flow properties through a systematic combination of dynamic tests up to a pre-defined level of strain, followed by static testing to fracture.
A systematic characterization of the Taylor-Quinney Coefficient (TQC) for seven different metals loaded in dynamic tension, compression and dominant shear is presented and a unified database of Taylor-Quinney coefficient for those materials is provided, as well as its dependence on strain and loading mode (for some of the characterized materials).
A joint thermal-mechanical characterization of near α Ti3Al2.5V and near β Ti-55511 titanium alloys at high strain rates is carried out to study the thermomechanical response and dynamic failure of these two titanium alloys.