FATIGUE FAILURE
　

RELATED REFERENCES
　 

Last updated 02/02/03 by Yong Gao (ygao@lbl.gov)

Failure analysis and prevention are important to all of the engineering disciplines, especially for the aerospace industry. Aircraft accidents are remembered by the public because of the unusually high loss of life and broad extent of damage.

High-cycle fatigue (HCF), proved as the severest cause of turbine engine failures in aircraft, has resulted in the loss of aircraft and human life. Due to the high vibration frequencies, microcracks can initiate from defects, which are often associated with microstructural damage caused by fretting or foreign object impact, subsequently propagate to failure in short time periods, possibly within a single flight segment. Therefore, HCF-critical materials in engine components must be used below the fatigue-crack initiation or growth threshold such that crack propagation rate is lower than 10⁹ m/cycle. There is an extensive database on the high-cycle fatigue threshold behavior of the materials used in turbine engines, however, the question as to whether microstructures of these materials can be optimized to promote HCF resistance has not been addressed.

Microstructurally designed materials are playing an increasingly important role in material processing and manufacturing because such materials are important not only as components with superior mechanical performance but also in hush-environment applications. For example, Ni- or Ti-base alloys are extensively applied in aviation and power generation because they have reliable and excellent mechanical properties and chemical inertness even at high temperatures. Material properties are invariably related to their microstructure. A thorough understanding of these structure-property relations gains particular importance in most of materials processing, wherein the desired properties are determined by the level of microstructure control.

We aim to understand and optimize the microstructural dependence of both fracture toughness and high cycle fatigue life for Ni- and Ti base superalloys used in aircraft.

Related References:

1	Environmental effects on tensile and low cycle fatigue behavior of single crystal nickel base superalloys, Scripta Materialia, Volume 48, Issue 5, 3 March 2003, Pages 519-524 M. Nazmy, J. Denk, R. Baumann and A. Künzler SummaryPlus | Full Text + Links | PDF (322 K)

13	Influence of hold period on creep–fatigue deformation behaviour of nickel base superalloy, Materials Science and Engineering A, Volumes 319-321, December 2001, Pages 637-642 J. Zrník, J. Semeák, V. Vrchovinsk? and P. Wangyao SummaryPlus | Full Text + Links | PDF (314 K)

52	Retardation of creep in <001>-oriented superalloy CMSX-4 single crystals by superimposed cyclic stress, Materials Science and Engineering A, Volumes 234-236, 30 August 1997, Pages 459-462 P. Luká, L. Kunz and J. Svoboda Abstract | PDF (281 K)

54	Influence of cycling frequency on cyclic creep characteristics of nickel base single-crystal superalloy, Materials Science and Engineering A, Volumes 234-236, 30 August 1997, Pages 884-888 J. Zrnik, J. A. Wang, Y. Yu, L. Peijing and P. Horak Abstract | PDF (341 K)