Date of Award
Winter 2025
Project Type
Thesis
Program or Major
Mechanical Engineering
Degree Name
Master of Science
First Advisor
Marko Knezevic
Second Advisor
David Fullwood
Third Advisor
Jinjin Ha
Abstract
This thesis investigates the deformation behavior of commercially pure titanium (CP–Ti) undercyclic bending under tension (CBT) through integrated experiments and multiscale modeling. Cyclic bending produces alternating tension and compression through the sheet thickness, delaying localization and enhancing ductility. Digital image correlation (DIC) measurements were used to quantify strain-path evolution and elongation-to-fracture (ETF). Finite-element simulations employing a continuum J2 plasticity model captured the macroscopic load–displacement response and width-dependent transition from uniaxial to plane-strain deformation. To incorporate micromechanical mechanisms, a dislocation-density-based crystal plasticity finite-element (CPFE) model with kinematic backstress was developed and calibrated using experimental data, accurately reproducing cyclic hardening and slip-system activity. A strain-gradient elastic–plastic self-consistent (EPSC–GND) formulation was further implemented to quantify curvature, lattice rotation, and geometrically necessary dislocation accumulation. The combined results establish a unified mechanistic framework linking curvature-induced GND evolution and dislocation hardening to the observed ductility improvement. Future work will couple damage and void-growth modeling within the CPFE framework to predict fracture during CBT of CP–Ti.
Recommended Citation
Oishi, Talukder Musfika Tasnim, "Mechanistic Modeling of Deformation Micromechanics in Commercially Pure Titanium under Cyclic Bending to Post-Necking Regimes" (2025). Master's Theses and Capstones. 2041.
https://scholars.unh.edu/thesis/2041