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  1. LtBuzzkill

    Elastic buckling of plates - plasticity correction factor?

    Hi, sdm. Sorry for the late reply. The plastic reduction for compression is eta = (Et/E)^0.5. For shear stress it would be eta = (Gt/G)^0.5. Et and Gt are defined by the Ramberg-Osgood relation. Thanks, LBK
  2. LtBuzzkill

    Elastic buckling of plates - plasticity correction factor?

    Thank you sdm, for your input. Thanks for confirming there is some validity to finding the intersection of the strain line and the tangent-modulus curve. I had not found that method anywhere. Now I'm a bit more comfortable using it. I haven't followed through and compared the result with...
  3. LtBuzzkill

    Discrepancy in formula for ring doubler in shear web?

    To which Niu book are you referring? LBK
  4. LtBuzzkill

    Elastic buckling of plates - plasticity correction factor?

    It's been a while since I made the original post, so I thought I owed everyone who responded an update. When I wrote the original post my nose was out of joint because I was excited about having found a powerful, referenceable method for correcting buckling allowables for plasticity, only to...
  5. LtBuzzkill

    Elastic buckling of plates - plasticity correction factor?

    Hello. I am doing buckling analysis of a flat plate under compressive load. The plate is rather thick, so the critical buckling allowable I get from the Euler-derived formulas in my text books gives me an allowable above the proportional limit of the material. No problem, I can just go to my...
  6. LtBuzzkill

    Ultimate abuse load - is a check at limit required?

    Thanks, RB. I think that is reasonable as well. Doesn't hurt to know what abuse load will permanently deform the structure, even if I'm not asked for it or given a load level to stay under. And it makes sense that the operating load criteria could be a reasonable guide as to whether or not...
  7. LtBuzzkill

    Ultimate abuse load - is a check at limit required?

    Thank you for the responses, everyone. I have more to discuss on this and more questions to ask, and I have to do it without violating my company's social media policy and customer NDAs, so please bear with me. [smile] To rb1957, what I am looking at is a mechanism. So permanent deformation...
  8. LtBuzzkill

    Ultimate abuse load - is a check at limit required?

    Hi, SW. I understand that permanent deformation is undesirable for any structure. But then why write the load requirement as an ultimate condition, where by definition it is allowed to deform? Why not just write it as a limit load condition if that is what sizes the structure anyway? Is it...
  9. LtBuzzkill

    Ultimate abuse load - is a check at limit required?

    Thank you for the response, RB, but that doesn't completely answer my question. I am specifically asking about bending in the plastic range. I can see for myself that multiplying the stress by 2/3 to check a fictitious "limit" condition won't fail the structure if the stress at ultimate load...
  10. LtBuzzkill

    Ultimate abuse load - is a check at limit required?

    Hello. I often have to size or analyze secondary structures to abuse loads, the requirement for which I always see written as an ultimate load (150 lb, 300 lb, etc.) applied at the most critical location. Although I've never been able to find it explicitly written in the structures manuals or...

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