(56) here Aa, Ac and m are material parameters, a0 and c0 describe the crack depth a and crack length c, respectively, after N1 cycles and where the stress intensity ranges are and ΔKa(Δσ) ΔKa(Δσ). Failure is considered when a crack grows through the thickness of the monopile/transition piece steel and can be summarized in the following limit state function: (57) Figure68: Weld geometry parameters for crack growth model, [64]. Where t is time in the interval between 0 and service life TL. Crack dimensions at any given time within turbines service life can be calculated using following equations: (58) (59) (60) (61) (62) (63) (64) Here Ni is number of stress ranges within considered lifetime window; A1, A2 m1 and m2 Δσi are material parameters based on crack growth environment for bi-linear crack growth curves; CSIF is model uncertainty related to stress intensity magnification factors (Mkma(c) and Mma(c)); CLOAD models uncertainty related to load (stress) modelling and CSCF models uncertainty related to stress concentration factor calculation. Stress intensity magnification factors based on weld and crack geometry (see Figure 68) are calculated based on [61], [62] and [63] using f1, f2, f3, M1, M2, g, fΘ geometrical coefficients. θ is weld angle in is the crack growth direction angle in Figure 70 on the left and Figure 68 on Θ the right (90 for growth in depth direction and 0 for growth in width direction It should “a” “c”). be noted here that only loading” was considered, and thus only M(k)ma(c) stress “membrane magnification factors are used (M(k)ba(c) magnification factors are considered for “bending” loading and most applicable for tubular members in jacket structures).
(56) here Aa, Ac and m are material parameters, a0 and c0 describe the crack depth a and crack length c, respectively, after N1 cycles and where the stress intensity ranges are ΔKa(Δσ) and ΔKa(Δσ). Failure is considered when a crack grows through the thickness of the monopile/transition piece steel and can be summarized in the following limit state function: (57) Figure68: Weld geometry parameters for crack growth model, [64]. Where t is time in the interval between 0 and service life TL. Crack dimensions at any given time within turbines service life can be calculated using following equations: (58) (59) (60) (61) (62) (63) (64) Here Ni is number of stress ranges Δσi within considered lifetime window; A1, A2 m1 and m2 are material parameters based on crack growth environment for bi-linear crack growth curves; CSIF is model uncertainty related to stress intensity magnification factors (Mkma(c) and Mma(c)); CLOAD models uncertainty related to load (stress) modelling and CSCF models uncertainty related to stress concentration factor calculation. Stress intensity magnification factors based on weld and crack geometry (see Figure 68) are calculated based on [61], [62] and [63] using f1, f2, f3, M1, M2, g, fΘ geometrical coefficients. θ is weld angle in Figure 70 on the left and Θ is the crack growth direction angle in Figure 68 on the right (90 for growth in depth direction “a” and 0 for growth in width direction “c”). It should be noted here that only “membrane loading” was considered, and thus only M(k)ma(c) stress magnification factors are used (M(k)ba(c) magnification factors are considered for “bending” loading and most applicable for tubular members in jacket structures).
IRPWIND_D7.21_Validation_of_Grouted_Joint_Design.docx