Dissertation
A CONTINUUM MODEL OF DEFORMATION AND DAMAGE IN METALS COATED WITH NANOLAMINATE METALLIC SYSTEMS FOR APPLICATIONS IN HIGH ENERGY ENVIRONMENTS
Doctor of Philosophy (PhD), Washington State University
01/2018
Handle:
https://hdl.handle.net/2376/117495
Abstract
This research develops a continuum model of deformation and damage in metals coated with nanolaminate metallic systems (NMS) for potential applications in high-energy environments. The model is developed based on continuum mechanics within the elastic/viscoplastic framework that comprises constitutive equations which include dislocation density, size effect, strain hardening, strain rate effect, and damage. In addition, evolution laws for damage and dislocation density are considered. The model investigates the deformation behavior and strength in such materials and provides a predictive capability for designing engineering structures. The model is then implemented into a user subroutine in a commercial finite element analysis subroutine. Several numerical investigations are performed for steel and NMS at various individual layer thicknesses and compared with experimental data found in the literature.
The deformation model developed for X70 steel and Copper/Niobium Cu/Nb NMS which is deformed variously based on its individual layer thickness. For X70, a modified Taylor equation is considered for hardening behavior, while for NMS, the confined layer slip (CLS) mechanism obeys a combined formula composed of Orwan’s mechanism, interface stress, and dislocation density when the individual layer thickness is between 5 nm and 100 nm. Meanwhile, the nucleation (Nu) mechanism is controlled by the nucleation of a dislocation mechanism when the individual layer thickness is less than 5 nm. Next, the model is extended to consider softening or ductile failure based on an isotropic damage model that considers voids nucleation and growth.
Finally, this research conducted an extensive numerical study on X70 and NMS. Then, X70 was coated with NMS to create a new composite called a X70 NMS composite. Likewise, the X70 NMS composite was studied based on a free damage state and damage state. A tension test according to ASTM standards was simulated to study the materials numerically. The models of the materials show good agreement with experimental results found in the literature, suggesting that the NMS coating is a good strength and ductility addition to X70 based on the X70 NMS composite study.
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Details
- Title
- A CONTINUUM MODEL OF DEFORMATION AND DAMAGE IN METALS COATED WITH NANOLAMINATE METALLIC SYSTEMS FOR APPLICATIONS IN HIGH ENERGY ENVIRONMENTS
- Creators
- Mohammed Anazi
- Contributors
- Hussein M Zbib (Advisor)David P Field (Committee Member)William F Cofer (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Mechanical and Materials Engineering, School of
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 134
- Identifiers
- 99900581509901842
- Language
- English
- Resource Type
- Dissertation