PSI - Issue 42

Jochen Tenkamp et al. / Procedia Structural Integrity 42 (2022) 328–335 Jochen Tenkamp / Structural Integrity Procedia 00 (2019) 000 – 000

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In this study, a novel approach for estimation the fatigue damage tolerance of Al-Si alloys is applied and evaluated for three different materials processed by casting and additive manufacturing. The concepts of Murakami-Noguchi and Shiozawa are evaluated and the dominating fatigue indicators are identified by comparison of different fracture mechanical approaches. Nomenclature i Initial crack or defect size f Failure crack size AM Additive manufacturing Geometric factor of  area concept of Murakami CSS Cyclic stress-strain DAS Dendritic arm spacing Young’s modulus St Young’s modulus of steel (206 GPa) FDT Fatigue damage tolerance HCF High cycle fatigue HV Vickers hardness J-SIF J integral based stress intensity (equal to ∆ J,i ) (′) (Cyclic) Hardening coefficient according to Morrow ′ Coefficient of Shiozawa curve max,i Initial maximum stress intensity factor LCF Low cycle fatigue ′ Exponent of Shiozawa curve (′) (Cyclic) Hardening exponent according to Morrow N f Number of cycles to failure N p Number of cycles for crack propagation PBF-LB Laser-based powder bed fusion QSS Quasi-static stress-strain (Cyclic) Yield strength at 0.2% plastic strain

, Stress ratio Strain ratio p (′ 0 ) .2 SC Sand casting SIF Stress intensity factor YS Yield strength

Geometric factor of  area concept of Murakami

UTS Ultimate tensile strength √area Initial or failure-initiating defect size ∆ eff,i Initial effective cyclic J integral ∆ i Initial stress intensity factor range, initial cyclic stress intensity factor ∆ J,i Initial stress intensity factor based on ∆ eff,i ∆ Plastic strain range ∆ Stress range ∆ eff Effective stress range Stress amplitude Fatigue limit ,1 7 Fatigue strength at 1E7 cycles ∗ ,1 7 Estimated fatigue strength at 1E7 cycles Maximum stress min Minimum stress