טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentOsovski Shmuel
SubjectInitiation of Adiabatic Shear Bands from a Microstructural
Standpoint
DepartmentDepartment of Mechanical Engineering
Supervisors Professor Daniel Rittel
Professor Arie Venkert
Full Thesis textFull thesis text - English Version


Abstract

Adiabatic Shear Bands (ASB) are an important failure mechanism in metals subjected to high rate deformation. This research will focus on the role of the stored energy and microstructural evolution on the initiation of (ASB), as opposed to the usual thermal softening approach in which the thermo-mechanical coupling is considered to be the destabilizing effect responsible for ASB formation. Microstructural observations from a series of controlled dynamic tests on pure α-Ti will be presented, to show the emergence of dynamically recrystallized (DRX) grains prior to ASB formation. Based on the microstructural observations, a possible relation between the plastic deformation mechanisms (twins vs. slip) and a metal’s susceptibility to fail by ASB will be suggested. Although many models exist for DRX in ASB, most of them lack in relating the DRX process to its athermal nature.  To address this gap, a heuristic model correlating the thermo-mechanical response with the microstructural evolution and their combined contributions to the localization process, will be presented. The role of microstructural heterogeneities in the dynamic localization process will be discussed using the concept of Shannon’s entropy.