Fatigue Crack Growth Behavior in Dissimilar Metal Weldment of Stainless Steel and Carbon Steel
Constant amplitude fatigue crack growth (FCG) tests were performed on dissimilar metal welded plates of Type 316L Stainless Steel (SS) and IS 2062 Grade A Carbon steel (CS). The plates were welded by TIG welding using SS E309 as electrode. FCG tests were carried on the Side Edge Notch Tension (SENT) specimens of 5 mm thickness, with crack initiator (notch) at base metal region (BM), weld metal region (WM) and heat affected zones (HAZ). The tests were performed at a test frequency of 10 Hz and at load ratios (R) of 0.1 & 0.6. FCG rate was found to increase with stress ratio for weld metals and base metals, where as in case of HAZ, FCG rates were almost equal at high ΔK. FCG rate of HAZ of stainless steel was found to be lowest at low and high ΔK. At intermediate ΔK, WM showed the lowest FCG rate. CS showed higher crack growth rate at all ΔK. However, the scatter band of data was found to be narrow. Fracture toughness (Kc) was found to vary in different locations of weldments. Kc was found lowest for the weldment and highest for HAZ of stainless steel. A novel method of characterizing the FCG behavior using an Infrared thermography (IRT) camera was attempted. By monitoring the temperature rise at the fast moving crack tip region, the amount of plastic deformation was estimated. Keywords—Dissimilar metal weld, Fatigue Crack Growth,
Mixed Modes Fracture and Fatigue Evaluation for Lithium Iron Phosphate Batteries.
STAMPS, MICHAEL ANTHONY. Mixed Modes Fracture and Fatigue Evaluation for Lithium Iron Phosphate Batteries. (Under the direction of Dr. Hsiao-Ying Shadow Huang.) Lithium ion batteries have become a widely known commodity for satisfying the world’s mobile energy storage needs. But these needs are becoming increasingly important, especially in the transportation industry, as concern for rising oil prices and environmental impact from fossil fuels are pushing for deployment of more electric vehicles (EV) or plug in hybrid-electric vehicles (PHEV) and renewable energy sources. The objective of this research is to obtain a fundamental understanding of degradation mechanisms and ratecapacity loss in lithium-ion batteries through fracture mechanics and fatigue analysis approaches. In this study we follow empirical observations that mechanical stresses accumulate on electrode materials during the cycling process. Crack induced fracturing will then follow in the material which electrical contact surface area is degraded and over capacitance of the battery reduces. A fatigue analysis simulation is applied using ANSYS finite element software coupled with analytical models to alleviate these parameters that play the most pivotal roles in affecting the rate-capacity and cycle life of the lithium-ion battery. Our results have potential to provide new models and simulation tools for clarifying the interplay of structure mechanics and electrochemistry while offering an increased understanding of fatigue degradation mechanisms in rechargeable battery materials. These models can aid manufacturers in the optimization of battery materials to ensure longer electrochemical cycling life with high-rate capacity for improved consumer electronics, electric vehicles, and many other military or space applications. © Copyright 2012 by Michael A Stamps All Rights Reserved Mixed Modes Fracture and Fatigue Evaluation for Lithium Iron Phosphate Batteries by Michael Anthony Stamps A thesis submitted to the Graduate Faculty of North Carolina State University in partial fulfillment of the requirements for the degree of Master of Science Mechanical Engineering Raleigh, North Carolina
Komprimierte Materie in Stoßwellen
Mit Stoswellen konnen in Flussigkeiten und Festkorpern sehr viel hohere Drucke und Temperaturen als in statischen Systemen erreicht werden. In dieser Ubersicht wird uber die Bestimmung von Zustandsgleichungen mittels Stoswellen fur Metalle, Ionenkristalle, Flussigkeiten u. a. bis zu Drucken, die teilweise uber 106 bar lagen, berichtet. Weiter werden Messungen von Phasenumwandlungen, optischen und elektrischen Eigenschaften von einigen Stoffen bei sehr hohen Drucken in Stoswellen besprochen. 
 
 
 
Using shock waves, liquids and solids can be compressed to pressures and temperatures much higher, than those available in static systems. In this review the determination of equations of state of metals, ionic cristals, liquids a.o. is reported for high pressures, in some cases higher than 106 bar. In addition recent measurements of phase transitions, optical and electric properties of various substances at very high pressures in shock waves are discussed.