Is my understanding of “load case consistent” correct?

[hootrpootr]

I’m a (mostly junior) stress engineer and have been tasked with sizing a lug. Various loadcases have been run through FEM and loads have been distributed into the lug bolt for each. In other words, each loadcase has its own set of x, y, and z loads at the bolt.

An initial analysis (spreadsheet) was run, where the lug was sized using the max x, y, and z loads across all loadcases. My understanding is that this is conservative.

Now I’m being asked to take out conservatism by applying case consistent loads. Would I go about that just by doing an analysis for each loadcase with a max value? Am I understanding the meaning of “case consistent”?

As an example:

Loadcase 1 has no maxes, so I don’t even look at it

Loadcase 2 has the max x, so I analyze the lug using all values from this loadcase

Loadcase 3 has no maxes, so I don’t even look at it

Loadcase 4 has the max y, so I analyze the lug using all values from this loadcase

Loadcase 5 has the max z, so I analyze the lug using all values from this loadcase

Sorry for the long post, but any help is appreciated.

 

[SWComposites]

Nope.
First, using all max loads may not be consevative.
Second, case consistent means analyzing with a set of x, y, z loads from the same load case.
Third, only checking the cases with max loads may not be conservative.
You need to check all load cases individually.

 

[rb1957]

Envelop analysis is usually conservative, the issue is is there a loadcase with slightly less than the critical loads which would combine to be more critical … composites have "nasty" interactions.

Consistent case means analyzing the results from each load case individually … yes a lot more work, but less conservative.

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

 

[johnie134]

enve not good. use all lc's.