GEORGIA INSTITUTE OF TECHNOLOGY

Under the provisions of the regulations for the degree

DOCTOR OF PHILOSOPHY

on Tuesday, November 12, 2019

11:00 AM
in MRDC 3515

will be held the

DISSERTATION PROPOSAL DEFENSE

for

Syed Saad Javaid

"Deformation and Damage Evolution in Thin Metal Sheets"

Committee Members:

Prof. Christopher Muhlstein, Advisor, MSE

Prof. Naresh Thadhani, MSE

Prof. Richard Neu, ME

Prof. Preet Singh, MSE

Prof. Olivier Pierron, ME

Abstract:

Modelling deformation behavior of ultrathin, ductile metal sheets is a challenge because of the unique challenges they pose. These systems combine uncontained plasticity, low thickness to width ratios, complex 3-dimensional effects (wrinkling, buckling, necking, etc.), and texture or thickness-dependent deformation properties which cannot be predicted by using conventional fracture mechanics approaches. We observe quasi-static steady-state process zones under fully-plastic crack tip conditions that are facilitated by plane stress conditions associated with the thin sheet form factor. In this work, we utilize an incremental strain framework based on high resolution, full field digital image correlation and tracking (DICT) and energy dissipation analysis to examine process zone evolution during steady-state conditions. We can quantify the shape and extent of the stationary and moving process zones and measure the energy moving into the process zone under special circumstances. We hypothesize that the steady-state zones are controlled by material hardening and material/geometric softening. We will probe this by manipulating the nature of the interaction by controlling the deformation mechanisms and switching between twinning & dislocation mediated plasticity , chemistry, temperature changes and monotonic vs cycling loading.