SUBJECT: Ph.D. Proposal Presentation
   
BY: Hamad Al-Harbi
   
TIME: Monday, February 25, 2013, 3:00 p.m.
   
PLACE: Love Building, 109
   
TITLE: Crystal Plasticity Computations Using Spectral Databases
   
COMMITTEE: Dr. Surya R. Kalidindi, Chair (ME)
Dr. David McDowell (ME)
Dr. Richard W. Neu (ME)
Dr. Hamid Garmestani (MSE)
Dr. Christopher Muhlstein (MSE)
 

SUMMARY

The accelerated insertion of advanced new materials in many industrial applications demands the use of improved physics-based constitutive theories in the predictive finite element (FE) simulation tools used to optimize the performance of the final manufactured part. These improved models should reliably capture the constitutive descriptions of the materialís elastic-plastic anisotropy, while accounting for the evolution of microstructure during large plastic strains. In this context, physics-based models such as crystal plasticity theories have shown remarkable success in predicting the anisotropic mechanical response in polycrystalline metals and the evolution of underlying texture in finite plastic deformation. However, the incorporation of crystal plasticity models into FE simulation tools is extremely computationally expensive, and has not been adopted broadly by metal working industry. Furthermore, the lack of knowledge of crystal-scale plasticity parameters (e.g. slip hardening parameters) for many important multiphase polycrystalline materials is another major challenge in applying crystal plasticity theories for simulating the deformation behavior of these materials. The proposed thesis focuses on extending the recently developed spectral database approach to crystal plasticity calculations, which is found to be able to speed up the crystal plasticity computations by two orders of magnitude, to address the above challenges hindering the further adoption of crystal plasticity theories. More specifically, a new spectral crystal plasticity database based on discrete Fourier transforms is first established and validated for body centered cubic metals. Second, the new spectral database is incorporated into FE models for simulating large strain metal forming operations to help overcome the difficulty of high computational cost associated with implementing the classical crystal plasticity into FE simulation tools. In addition, spherical nanoindentation technique is used to characterize the local mechanical behavior in each individual phase in dual phase steel samples. The developed spectral crystal plasticity based finite element tool will be used to simulate the spherical nanoindentation and extract the required grain-scale hardening parameters in a dual-phase steel.