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Book ChapterDOI

Toward Improved and Reliable Estimation of Operating Life of Critical Components Through Assessment of Fatigue Properties Using Novel Fatigue Testing Concepts

01 Jan 2019-pp 193-208
TL;DR: The developments to estimate the fatigue properties of materials using small volume of sample material—similar to scooped samples are presented and the optimum electrode potential for a fatigue crack growth study has been identified.
Abstract: Accurate and reliable life prediction is one of the challenges faced by engineers working in safety-critical domains such as power plants, transportation, and offshore structures. This paper presents the developments to estimate the fatigue properties of materials using small volume of sample material—similar to scooped samples. Cyclic ball indentation and cyclic small punch testing methods have been developed over a period of nearly two decades and have been demonstrated to predict the fatigue properties of in-service materials. Some salient results are discussed in this paper. In the case of offshore structures, the synergistic effect of mechanical loading at a low frequency combined with the corrosive environment accelerates the damage. Life prediction for such structures requires data on corrosion-fatigue crack growth at low frequencies. This is a time-consuming effort and hence there is a need to estimate the properties through novel test methods. Frequency shedding method is proposed to estimate the fatigue crack growth rate behavior in corrosive environments. Further, designers and operators of offshore equipment resort to avoidance of free corrosion through the use of electrode potentials. However, the choice of electrode potential is dependent on the stress state. Through a systematic study, the optimum electrode potential for a fatigue crack growth study has been identified and the same is discussed here. It is hoped that the results of this study and the directions shown to carry out the data generation under more realistic conditions would help the life prediction and life extension community at large.
References
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Journal ArticleDOI
TL;DR: In this article, a further-miniaturized specimen punch (SP) test was developed to extract fracture strain and strength information from TEM disc specimens as small as 3 mm diameter and 0.25 mm in thickness.

325 citations

Journal ArticleDOI
TL;DR: In this paper, a Miniaturized Disk Bend Test (MDT) is proposed to extract post-irradiation mechanical behavior information from disk-shaped specimens no larger than those used for Transmission Electron Microscopy.

319 citations

01 Aug 2003
TL;DR: In this paper, a plot of plane strain fracture toughness vs. tensile yield strength for ultra-high strength steels (UHSS) and beta-Ti alloys precipitation hardened with a phase is presented.
Abstract: : Two important advances over the past 40 years enable the optimization and management of the structural integrity of components in high performance applications. First, the solid mechanics conununity established linear elastic fracture mechanics as the premier framework for modeling the damage tolerance of fracture critical components (Irwin and Wells, 1997; Paris, 1998). Second, materials scientists developed metals with outstanding balances of high tensile strength and high fracture toughness (Garrison, 1990; Wells, 1993; Boyer, 1993; Starke and Staley, 1995; Olson, 1997; Kolts, 1996). An example of achievable strength-toughness properties is provided in Fig. 1, a plot of plane strain fracture toughness vs. tensile yield strength (sigma-YS) for ultra-high strength steels (UHSS) and beta-Ti alloys precipitation hardened with a phase (Gangloff 2001). New nano-scale characterization and high performance computational methods provide for additional advances in the mechanical performance properties of structural metals. These modem alloys and analysis tools satisfy technological needs for optimization and management of component performance in demanding fatigue and fracture critical applications in the aerospace, marine, energy, transportation, and defense sectors.

166 citations

Journal ArticleDOI
TL;DR: A wide array of specimen geometries and test techniques have now been developed as discussed by the authors, and the purpose of this paper is to review these techniques and examine their status, problems, and potential for future applications.
Abstract: Small specimen test technology has evolved out of the necessity to develop and monitor materials proposed for or used in nuclear power generation systems. Development of materials for improved cladding and in-core structures for fission reactors and assessment of core materials and pressure vessel steels already under irradiation necessitated the use of specimens which fit into existing irradiation space or which could be extracted from irradiated structures, such as cladding or ducts. Interest in simulating neutron irradiation by light and heavy ion irradiation led to the development of thin foil and wire geometry specimens. Further, interest in developing materials for fusion reactors has added additional constraints on specimen sizes associated with available irradiation volumes in existing and proposed high-energy neutron irradiation facilities. Consequently, a wide array of specimen geometries and test techniques has now been developed. It is the purpose of this paper to review these techniques and examine their status, problems, and potential for future applications.

162 citations

Book ChapterDOI
01 Jan 2003

136 citations