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  1. TomLee777

    Primary Membrane Stress Range for Thermal Stress Ratchet

    ASME Sec. VIII, Div. 2 uses stress amplitude for fatigue life assessment, not stress range as people normally do.
  2. TomLee777

    Internal diameter of Economizer Header - HRSG

    You need to do a flow calc to determine the minimum I.D. in addition to tubing arrangement.
  3. TomLee777

    PREHEAT

    The welding code does not require preheating on gouging.
  4. TomLee777

    Unknown Proprietary Steel Joist Identification

    It looks like a bottom chord so that the web members can be welded in the slot at the middle of the profile. All commercial joists should have a tab on each joist (typically at an end diagonal web member), and that would give you some information.
  5. TomLee777

    Cold bend steel plate

    The cold bending will force the steel to yield, leaving residual stresses built in the plate. But that's fine and typical in cold working. As for the bending radius, it should be at least 1 x t, but the larger the better stress wise, so it depends on your equipment and aesthetic looking.
  6. TomLee777

    Shear Connection - Short Slotted Holes in the Connector or the Beam?

    If the slotted holes are cut on the beam web, the shear and bearing capacity of the beam is compromised. If cut on the connector, the thickness of the connector can be increased as required to meet shear and bearing demand.
  7. TomLee777

    Local Vs global stress and fatigue analysis in fea analysis

    The topic of this thread is about EN 13445-3. In this code, for welded joints, the required stresses are nominal stresses, peak stresses are already considered in Detail Classes, hence linearization is required in FEA to filter out peak stresses. Yes, use M + B only. ASME code, Section VIII...
  8. TomLee777

    Linearized Triaxial Stress Limit

    The purpose of linearization is to filter out peak stress in FEA, leaving only M + B stresses for assessment.
  9. TomLee777

    Helicopter crash Hudson River

    Winds of 9 to 21 mph, reported by a nearby weather station, could have interacted with mechanical vulnerabilities or prompted abrupt maneuvers, potentially triggering “mast bumping,” a condition where rotor blades tilt excessively and strike the aircraft, causing catastrophic loss of control.
  10. TomLee777

    Determining the Fracture Mode: Brittle Fracture vs. Fatigue in a Pump Shaft

    Other possible reasons I can think of: (1) High load rate instantly decreased the material toughness; (2) Surface damage size exceeded critical crack-like flaw size, leading to fracture.
  11. TomLee777

    Fatigue stress category for weld shear flow

    If you investigate fatigue on base metal, use detail category E; if your interest is on the weld itself, use detail category F.
  12. TomLee777

    Local Vs global stress and fatigue analysis in fea analysis

    You can do a linearization in ANSYS, and the software will give you a breakdown of the stresses: membrane, bending, peak and total. You have to select a linearization path that makes sense. Throw away the peak stress that can be a result of singularity, and use (membrane + bending) stress for...
  13. TomLee777

    Fatigue analysis according to EN 13445-3

    Clause 17 is simplified and conservative - stresses are by "code calcs". Clause 18 is detailed analysis, more accurate and less conservative. Since you have done stresses by FEA, why not use Clause 18. Code calcs does not capture notch stresses; FEA does. Which FEA software are you using? If you...
  14. TomLee777

    Question regarding fatigue in AS/NZS 1664.1

    The fatigue curves for aluminum alloys are very different from steels. Different aluminum alloys also have different fatigue curves. Fatigue properties are material specific; fatigue curves are derived from tests. You need to select a appropriate fatigue curve for the material you use...
  15. TomLee777

    Inquiry about pressure vessels

    You should first work with your client to determine which ASME code is to be used. ASME Section VIII Division I is a rule-based code, it needs less engineering time but results thicker walls; Division II use rigorous analysis with more certainties, resulting saved materials cost, but engineering...
  16. TomLee777

    nozzle to head weld NDE

    Consider using UT.
  17. TomLee777

    Residual strength

    Performing an inelasitc finite element analysis should solve the residual stress.
  18. TomLee777

    Pipe Shoe temperature profile

    If you are talking about piping design temperature (not shoe design temperature), taking temperature at boundary of insulation is anti-conservative, as at that location, temperature is lower, if I understand your point correctly.
  19. TomLee777

    Cambering Steel Decks

    Bending about the strong axis of the deck is not a good idea as the deck is think-walled section and will certainly buckle before reaching plasitc state. Bending about weak axis is very easy and can be accomplished in elastic state without local buckling. In the weak axis direction the flutes...
  20. TomLee777

    Fatigue evaluation with equivalent STRAIN method

    @mskds545 Yes, you are right, DNV-RP-C203 1 mm radius is only verified in local notch stress method and the associated specific fatigue curve. I agree that a structural stress method, or hot spot method, maybe preferable. ASME code currently does not provide this method. It is popular in...

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