Friends can you help me with this code..?
Currently I am studying about fatigue analysis on pressure retaining
equipment. I have read the ASME Section VIII Division 2, Part 5 Design by Analysis Requirement, 5.5 Protection Againts Failure from Cyclic Loading and ANNEX 3.F Design Fatigue Curve.
In ANNEX 3.F, there is table 3.F.1 Coefficient for fatigue curve 110.1 - Carbon, Low Alloy, Series 4XX, High
Alloy Steels, and High Tensile Strength Steel for temperature not exceeding 700 degree Fahrenheit, with ultimate tensile strength lower than 80 ksi. I want to ask about this curve, which something I don't understand yet. Table 3.F.1 is divided into 2 parts, the first one is 7 ksi < Sa < 31 ksi and the second one is 31 ksi < Sa < 580 ksi, while the material itself only have ultimate tensile strength lower than 80 ksi.
Is it right to assume these materials can sustain very high stress up to several times its ultimate tensile strength?
The second thing I want to ask is about the interpolation of fatigue curve 110.1, the ASME Section VIII Division 2 2010 ed. ANNEX 3.F using equation
N =10^X
where
X = (C1 + C3.Y + C5.Y^2 + C7.Y^3 + C9.Y^4 + C11.Y^5) / (1 + C2.Y + C4.Y^2 + C6.Y^3 + C8.Y^4 + C10.Y^5)
Y = (Sa / Cus)(Efc / Et)
while the ASME Section VIII Division 2 2004 ed. Mandatory Appendices, Appendix 5, Design Based on Fatigue Analysis Table 5.110.1 using this equation for interpolation of N
N / Ni = (Nj /Ni)^[log(Si/S)]/[log(Si/Sj)]
My question is, which one of those equation gives more accurate interpolation of N in fatigue curve 110.1?
Because when I did interpolation for 12,500 psi, the ASME Section VIII Division 2 2004 gives 1,000,000 cycles and the ASME Section VIII Division 2 2010 gives around 2,000,000 cycles.
Really appreciate your help, thanks in advance,
Regards.
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Originally Posted by VLks
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