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Transferability and Constraint Effect in Fracture -- to study the effect of geometry and loading configuration on the fracture of solids under both static and dynamic loading conditions. It is one step beyond the conventional single parameter fracture theory, e.g. KIC , JIC, J-R concept. We investigate the effect of "constraint" on the fracture toughness, energy release rate, crack curving, stable crack growth, non-uniqueness in slip-line fields, cleavage fracture (shallow vs. deep crack; size effect), creep, J-R curve characterization, fatigue crack growth, and dynamic fracture toughness. Outcomes from these studies could (a) provide theoretical basis for a two parameter fracture toughness engineering testing procedure, and (b) establish the procedures for transferability of fracture toughness values from laboratory to structures.

Chao, Y.J., Ward, Jr, J.D. and Sands, R.G., “Charpy Impact Energy, Fracture Toughness and Ductile-Brittle Transition Temperature of Dual-Phase 590 Steels,” Materials and Design, 28, 551-557, 2007.

Lam, P.S., Kim, Y. and Chao, Y.J., “The Non-Constant CTOD/CTOA in Stable Crack Extension under Plane-Strain Conditions,” Engineering Fracture Mechanics, 73, 1070-1085, 2006.

Chao, Y.J. and Zhu, X. K., “Specimen Size Requirement for Two-Parameter Fracture Toughness Testing,” International Journal of Fracture, 135:117-136, 2005.

Kim, Y. and Chao, Y.J., “Prediction of stable crack growth in surface cracked plate of Aluminum 7050 alloy,” International Journal of Fracture, 130: 583-600, 2004.

Liu, S., Chao, Y.J. and Zhu, X., “Tensile-Shear Transition in Mode I/III Fracture”, International Journal of Solids and Structures, Vol. 41/22-23, 6147-6172, 2004.

Chao, Y.J., Zhu, X., Kim, Y., Pechersky, M.J., and Morgan, M.J., and Lam, P.S., “Characterization of Crack-Tip Field and Constraint for Bending Specimens under Large-Scale Yielding”, International Journal of Fracture, 127, 283-302, 2004.

Kim, Y., Chao, Y.J., Pechersky, M. J. and Morgan, M. J., “C-Specimen Fracture Toughness Testing: Effect of Side Grooves and h Factor,” ASME Journal of Pressure Vessel Technology, 126, 293-299, 2004.

Liu, S. and Chao, Y.J., “Variation of Fracture Toughness with Constraint,” International Journal of Fracture, 124 (3-4): 113-117, 2003

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Hydrogen Embrittlement of Structural Steels :

Hydrogen or Helium trend to make structural steels brittle over time. Working with Savannah River National Laboratory, we study how this environment affects the fracture toughness values of materials.

Representative Publications

Kim, Y., Chao, Y.J., Pechersky, M. J. and Morgan, M. J., “On the Effect of Hydrogen on the Fracture Toughness of Steels,” International Journal of Fracture, 134, 339-347, 2005.Kim, Y.,

Chao, Y.J., Morgan, M.J. and Lam, P.S., “Comparison of Decoupled and Coupled Analyses for Hydrogen Transport in Fracture Specimens,” Proceedings of PVP2007, 2007 ASME Pressure Vessels and Piping Division Conference, July 22-26, 2007, San Antonio, Texas.

Kim, Y., Chao, Y.J., M.J. Pecherskey and M.J. Morgan, “Investigation of Hydrogen Transport Related Fracture in Stainless Steels,” IMECE2006-13823, Proceedings of IMECE2006, 2006 ASME International Mechanical Engineering Congress and Exposition, November 5-10, 2006, Chicago, Illinois, USA.

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Kim, Y. and Chao, Y.J., “Effect of Loading Rate on Dynamic Fracture Initiation Toughness of Brittle Materials, “ International Journal of Fracture, Jan 20, 2007.

Chen, Zong-An, Zhen, Zeng, and Chao, Yuh J., “Effect of Crack Depth on the Shift of the Ductile-Brittle Transition Curve of Steels,” Engineering Fracture Mechanics, 74 (2007) 2437-2448.

Chao, Y.J., Ward, Jr, J.D. and Sands, R.G., “Charpy Impact Energy, Fracture Toughness and Ductile-Brittle Transition Temperature of Dual-Phase 590 Steels,” Materials and Design, 28, 551-557, 2007.