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  1. mskds545

    stress concentrations in machined piping reducer

    BSukolsky, If you only have internal pressure, it is relatively straightforward to calculate the free displacements of the ends of the two cylinders (that is, the displacement the joined ends would experience if they didn't restrain one another). Then determine the radial force and moment...
  2. mskds545

    Local failure assessment of nozzle junctions - weld sharp edges

    fem.fan, I'm late to this discussion, but I've run into this as well. I once ran a model of a lightly loaded sharp inside corner down to an absurdly fine mesh size and found that the stress and plastic strain increased slowly and steadily at an increasing rate with diminishing element edge...
  3. mskds545

    Crack Modelling , mesh

    You've attached plots of crack tip stress intensity and J along the crack front. I'm not sure what your question is. You should try modeling some cases that you know the answer to, such as a center or edge cracked plate in plane strain under uniform tension. That will help you develop...
  4. mskds545

    Hello Friends, I have some doubt ab

    ASME VIII-2 does not generally have requirements for specific environmental cracking and corrosion issues. You formal responsibilities depend on whether you are the specifier, manufacturer or owner, as well as the specifics of your contract. Regardless, it's important that the vessel is fit...
  5. mskds545

    Implementation of varying thickness of a pressure vessel

    I don't understand what the question is. If you know how the thickness varies, and it is axisymmetric, I would expect it to be easy to draw. If it is not axisymmetric, the artwork might get difficult, but I agree with DriveMeNuts that that is a CAD question. Bigger picture, though, do you...
  6. mskds545

    Ansys Norton creep power law constants?

    The t^m term is a time hardening term for primary creep. The Arrhenius rate function defines temperature dependence. You can use either of these or both in concert in Ansys, as they account for different things. You can also use strain hardening, which is more often than not more...
  7. mskds545

    ASME Sec VIII Div 2 5.2.2 Elastic Stress Analysis Method - ANSYS

    I didn't say 5.2.3.2 doesn't make sense. I said that, if taken literally, it prohibits elastic analysis of cylinders, since their stiffness decreases with deformation. For the cone-to-skirt junction, that's between you and the AI, but I probably would have included plasticity. I almost...
  8. mskds545

    Nozzle Thrust Load

    Some Curious Guy, Area replacement is more tried-and-true than rigorous, but it does take care of the pressure thrust load. If you draw a circle on the side of the vessel, there is a radial thrust load inside the circle and Pr/t takes care of that. Cutting in a nozzle adds a stress...
  9. mskds545

    Mesh failed

    I don't know if it's contributing to your problem, but your physics preference is set to CFD and it looks as if you are meshing a solid structure. -mskds545
  10. mskds545

    ASME Sec VIII Div 2 5.2.2 Elastic Stress Analysis Method - ANSYS

    When it comes to large displacements and elastic analysis, I've always enjoyed paragraph 5.2.3.2. It's under limit analysis, but applies "equally to... primary stress limits of 5.2.2." This paragraph seems to prohibit elastic analysis if the stiffness is reduced with deformation, a large...
  11. mskds545

    Nusselt number

    So, was it that I said "you measure it" rather than "someone measures it" that bothered you? The next sentence stated that data is already available for most fluids and you can look it up. The poster asked a question and I tried to help. Other people offered alternate answers. I hope one of...
  12. mskds545

    Nusselt number

    I'm not sure why you found it necessary to take a rude tone with me, but perhaps you missed where I said that there is published data available for most fluids and recommended the OP check the tables in the back of a heat transfer text. I am also an engineer, by the way, and I am quite adept at...
  13. mskds545

    Need advice on FEA settings. Result is not satisfied of required safety factor.

    In addition to high stress in the weld, it looks like the pad on the shell is highly stressed in bending. If this isn't acceptable, make the pad thicker to keep the bending stress at an acceptable level. To decide if it's acceptable, you need to elaborate on what you are trying to prevent...
  14. mskds545

    Question Regarding ASME Section VIII Division 1 and 2.

    Yes, the text is clear that welds machined to smooth profiles may be evaluated using 5.5.4. There isn't a prohibition against using 5.5.4 for non-machined welds either, as far as I am aware, although I'm not sure how you would analyze the weld toe accurately with no dressing at all. Even with...
  15. mskds545

    Question Regarding ASME Section VIII Division 1 and 2.

    DriveMeNuts -- See this article for a rundown on how to import the shape from an eigenvalue buckling analysis into a static analysis and scale the deformation in ansys: http://www.padtinc.com/blog/eigenvalue-buckling-and-post-buckling-analysis-in-ansys-mechanical/. IdanPV -- I'll second TGS4's...
  16. mskds545

    How to get S(maximum allowable stress value) in the ASME section 2, part D?

    22900 psi / 145 = 158 MPa. -mskds545
  17. mskds545

    Heat conduction with variable conductivity

    In your pdf, the next step is to substitute k1 = k0 + a/2*(T1+T2), k2 = k0 + a/2*(T2+T3), k3 = k0 + a/2*(T3+T4). Because thermal conductivity is linear with temperature, you can use the average temperature. Whether you can use this to show analytically that Q is independent of L1, or if it's...
  18. mskds545

    Nusselt number

    Viscosity is a physical property. You don't calculate it, you measure it. For most fluids you will be able to find published data, and viscosity is included in the tables in the back of most introductory heat transfer textbooks. They often list the kinematic viscosity. You want the dynamic...
  19. mskds545

    Fracture mechanics analysis with residual stresses using FEA

    I don't do these sorts of calculations so please do your own reading and research to confirm, but I will offer a few ideas on how you might approach this. I did not look at your model, and I am answering more generally. 1) If you want to calculate the residual stress distribution, you need to...
  20. mskds545

    Isochronous stress strain curves instead of direct creep analysis

    Not sure if you're saying I should decline to answer his questions about elastic follow-up on principle, or that I should pack up my welding gear and go fix his plant instead of answering... but we're under quarantine, so the latter isn't really an option, and nobody should want me welding on...

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