These discussions have arisen from the two engineering paradigms characterizing our fatigue research: i an aerospace research and technology remit for metallic airframes, and ii a materials science research programme supporting a methodology for steam turbine low pressure LP blade operations. In our opinion, this paper is of interest for other investigators of metal fatigue with respect to design requirements, life predictions and assessments.
In more detail, the paper considers the fatigue design methodologies for airframes and steam turbine LP blades. This paper discusses and compares the two engineering paradigms for fatigue design of i aircraft structures and ii steam turbine low pressure blades. We have recently and independently published a review paper Stanzl-Tschegg and a book Wanhill et al.
The research leading to these publications was done in the context of two engineering paradigms PMs : PMI: An aerospace airframe structures research and technology remit Wanhill et al. The investigations included a the aluminium alloys T, T, T6, T6, T, T and T, the high-strength steels D6ac and AF, and duplex microstructure titanium alloy Tiβ6Alβ4V; b FCG analysis methods for service failures and full-scale fatigue tests FSFTs ; and c supplemental coupon tests simulating component as-manufactured surface conditions and in-service high-cycle fatigue HCF with variable amplitude VA flight load histories.
PMII: A broad-based materials science research programme with engineering implications, in the case of martensitic stainless steels, for steam turbine low pressure LP blades Salzman et al. In this paper, we shall discuss the similarities and differences in these paradigms with respect to airframe and steam turbine LP blade engineering fatigue design requirements, life predictions and assessments.
Before proceeding to the main body of this paper, it is useful to briefly discuss the definitions of short and small cracks. Both terms appear in the literature, sometimes as synonyms. This distinction is essentially between 2D and 3D cracks. General schematics of the fatigue design methodologies for the two paradigms are given in Figure 1.
