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wright1150865012.pdf (4.79 MB)
ETD Abstract Container
Abstract Header
Dissipated Energy at a Bimaterial Crack Tip Under Cyclic Loading
Author Info
Daily, Jeremy S
Permalink:
http://rave.ohiolink.edu/etdc/view?acc_num=wright1150865012
Abstract Details
Year and Degree
2006, Doctor of Philosophy (PhD), Wright State University, Engineering PhD.
Abstract
A new theory of fatigue crack growth in ductile solids has recently been proposed based on the total plastic energy dissipation per cycle ahead of the crack. This, and previous energy-based approaches in the literature, suggest that the total plastic dissipation per cycle can be closely correlated with fatigue crack growth rates under mode I loading. The goal of the current research is to extend the dissipated energy approach to steady-state crack growth under mixed-mode I/II loading conditions, with application to cyclic delamination of ductile bimaterial interfaces. Such systems can occur in brazing, soldering, welding, and a variety of layered manufacturing applications, where high-temperature material deposition can result in a mismatch in mechanical properties between the deposited material and the substrate. The total plastic dissipation per cycle is obtained by 2-D elastic-plastic finite element analysis of a stationary crack in a general mixed-mode specimen geometry under constant amplitude loading. Numerical results for a dimensionless plastic dissipation per cycle are presented over the full range of relevant material combinations and mixed-mode loading conditions. Results suggest that while applied mode-mix ratio is the dominant parameter, mismatches in yield strength and hardening modulus can have a significant effect on the total plastic dissipation per cycle, which is dominated by the weaker/softer material. Results extended to general elastic-plastic mismatches provide substantial insight into the effects of crack-tip constraint, material hardening behavior and applied mode-mix ratio on the dissipated energy during fatigue crack growth. A consistent definition of the mode mix ratio is presented based on minimizing the elastic strain energy at a crack tip. Next, application of the current theory is demonstrated for thermomechanical fatigue of bonded bimaterials. Finally, the plastic dissipation computations are erformed in a probabilistic framework in an attempt to assess the variability of the fatigue crack growth rate based on variation in bulk properties.
Committee
Nathan Klingbeil (Advisor)
Pages
202 p.
Subject Headings
Engineering, Mechanical
Keywords
fatigue
;
fracture
;
bimaterials
;
plastic dissipation
;
crack growth rate
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Citations
Daily, J. S. (2006).
Dissipated Energy at a Bimaterial Crack Tip Under Cyclic Loading
[Doctoral dissertation, Wright State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=wright1150865012
APA Style (7th edition)
Daily, Jeremy.
Dissipated Energy at a Bimaterial Crack Tip Under Cyclic Loading.
2006. Wright State University, Doctoral dissertation.
OhioLINK Electronic Theses and Dissertations Center
, http://rave.ohiolink.edu/etdc/view?acc_num=wright1150865012.
MLA Style (8th edition)
Daily, Jeremy. "Dissipated Energy at a Bimaterial Crack Tip Under Cyclic Loading." Doctoral dissertation, Wright State University, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=wright1150865012
Chicago Manual of Style (17th edition)
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Document number:
wright1150865012
Download Count:
1,725
Copyright Info
© 2006, all rights reserved.
This open access ETD is published by Wright State University and OhioLINK.