Lower-bound knockdown factor

[WillBerg]

Hello, can anyone shed a light on what a lower-bound knockdown factor is (in context of structural design)? (or an "upper-bound factor" for that matter)

 

[Lomarandil]

Not a standard term that I've heard.

Closest thing that comes to mind is a push-over analysis.

Can you provide some more context?

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The name is a long story -- just call me Lo.

 

[dik]

Are you thinking 'shakedown' factor for plastic design?

Dik

 

[EngineeringEric]

Knocking down a structure? or rounding up reactions? Fatigue?

 

[rb1957]

composites maybe (environmental and process knock-down factor ?)

another day in paradise, or is paradise one day closer ?

 

[JStephen]

Think I've seen that term some place before, certainly not a common usage, though. But the context fits this internet quote: "Shell-buckling knockdown factors (SBKF) have been used in large cylindrical shell structures to account for uncertainty in buckling loads. As the diameter of the cylinder increases, achieving the manufacturing tolerances becomes increasingly more difficult. Knockdown factors account for manufacturing imperfections in the shell geometry by decreasing the allowable buckling load of the cylinder..."

IE, it doesn't relate to knocking anything over or down, more like a safety factor, etc.

 

[WARose]

Think I've seen that term some place before, certainly not a common usage, though. But the context fits this internet quote: "Shell-buckling knockdown factors (SBKF) have been used in large cylindrical shell structures to account for uncertainty in buckling loads. As the diameter of the cylinder increases, achieving the manufacturing tolerances becomes increasingly more difficult. Knockdown factors account for manufacturing imperfections in the shell geometry by decreasing the allowable buckling load of the cylinder..."

Yes, I've seen it called that in texts on buckling of shells as well. And if that is what he is getting at.....that number can really vary based on geometry, loading, etc. It needs to come from code (like ASME). Initial imperfections can be a killer for shell buckling.