PSI - Issue 68

Robert Basan et al. / Procedia Structural Integrity 68 (2025) 782–787 R. Basan et al. / Structural Integrity Procedia 00 (2025) 000–000

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2

Nomenclature b

fatigue strength exponent fatigue ductility exponent

c

Young’s modulus error criterion goodness of fit

E E f E a

2N f number of load reversals to failure 2N f,exp number of load reversals to failure calculated using experimental fatigue parameters 2N f,est number of load reversals to failure calculated using estimated fatigue parameters R m ultimate tensile strength s width of the scatter band D e /2 total strain amplitude e f ' fatigue ductility coefficient s f ' fatigue strength coefficient LS abbreviation for low strength HS abbreviation for high strength

As a result, in early design studies engineers as well as researchers in their fields of work might want to use estimation methods to obtain reasonably accurate cyclic and fatigue parameters from monotonic properties and to determine components fatigue lives without incurring experiment-related expenses, Arcieri et al. (2023a, 2023b, 2024a, 2024b), Basan et al. (2023), Grbovic et al. (2024), Papageorgiou et al. (2024). 2. Estimation methods Over the course of past almost 60 years, numerous estimation methods have been developed for various materials groups. Methods relevant for estimation of fatigue parameters of aluminum and titanium alloys can be divided into those developed for all metallic materials that address aluminum and titanium indirectly, such as the Original Universal Slopes Method by Manson (1965), Four-Point Correlation Method by Manson (1965), Modified Universal Slopes Method by Muralidharan and Manson (1988), Modified Four-Point Correlation Method by Ong (1993), and those that propose dedicated expressions for estimation of fatigue parameters of aluminum and/or titanium alloys such as Uniform Material Law by Bäumel and Seeger (1990), Modified Mitchell’s Method proposed by Park and Song (2003), Medians Method by Meggiolaro and Castro (2004), Modified Park-Song’s Method by Li, Zhang and Li (2018) and FKM Method by Wächter and Esderts (2018). While the main research this investigation is part of will cover evaluation of all mentioned estimation methods for aluminum and/or titanium alloys, here, only those that require most readily available monotonic properties (Young’s modulus E and ultimate tensile strength R m ) for estimation of fatigue parameters are included: Uniform Material Law, Medians Method, Modified Park-Song’s Method and FKM Method. Basquin-Coffin-Manson expressions with individual fatigue parameters σ f ′ , b, ε f ′ and c replaced with pertinent estimation terms or values according to these methods are given in expressions (1) to (4): • Uniform Material Law for aluminum and titanium alloys: ! # " =1,67 $ ! % &2 & ) '(,(*+ + 0,35&2 & ) '(,,* , (1) • Medians Method for aluminum alloys (and possibly, titanium): ! # " =1,9 $ ! % &2 & ) '(,-- + 0,28&2 & ) '(,,, , (2)