Fong,
Great questions. I had to do a little digging.
Let’s starting with the linear solution –
When using “gaps as contact” the gap elements will react compressive axial loads regardless of constraints. I always recommend building a little test model before using analysis techniques for a project:
For the nonlinear solution –
Check out our seminar on SOL 106 on the Applied CAx webpage. I’m not sure where the stiffness values for your gaps came from (Kt=1e21!), but I reverted to my default starting place (Kc=1e6, Kt=1e-6). After doing this, the gaps connected to nodes 6550 and 6551 were no longer providing a tensile reaction force and the unit was allowed to lift up in the Z-dir.
Adrian Jensen, P.E.
Director of Engineering
Land Line: 503.206.5571 ext 120
FAX: 866.215.1220
From:Yeow, Fong [mailto:[email protected]]
Sent:Thursday, August 09, 2018 5:34 AM
To:[email protected]
Cc:FemapSupport ([email protected])
Subject:RE: Femap – Delta Airline
Hi Adrian,
Form your figure below (SOL106).
Something we don’t understand is for nodes #6548, #6549, #6550, and #6551. These nodes are connected through gap element that only has compression stiffness. As such, they all should only see reaction forces in the same direction. Can you please help us to understand why they are showing forces in two different directions, plus and minus?
For a static solution.
There are no constraints on nodes #23 and #24, except a gap element hanging in space. Why there are reaction forces shown on these nodes?
I have reattached the mode and results for your review.
Thanks,
Fong Yeow
Office: +1 404-677-0897
From:[email protected][mailto:[email protected]]
Sent:Wednesday, August 08, 2018 16:24
To:Yeow, Fong
Cc:FemapSupport ([email protected])
Subject:[EXTERNAL] RE: Femap – Delta Airline
Fong,
Upon further inspection – the model uses gap elements and a linear analysis. You either need to use a static nonlinear analysis (gaps are nonlinear elements) or you need to turn on the “Gaps as Contact” option within the analysis manager.
Here’s the solution with the static nonlinear solver (SOL 106).
Adrian Jensen, P.E.
Director of Engineering
Land Line: 503.206.5571 ext 120
FAX: 866.215.1220
From:[email protected]
Sent:Wednesday, August 08, 2018 1:12 PM
To:‘Yeow, Fong’
Cc:FemapSupport ([email protected])
Subject:RE: Femap – Delta Airline
Wait! Never mind. I see the subcases now.
Adrian Jensen, P.E.
Director of Engineering
Land Line: 503.206.5571 ext 120
FAX: 866.215.1220
From:[email protected]
Sent:Wednesday, August 08, 2018 1:11 PM
To:‘Yeow, Fong’
Cc:FemapSupport ([email protected])
Subject:RE: Femap – Delta Airline
Fong,
Here we go:
Adrian Jensen, P.E.
Director of Engineering
Land Line: 503.206.5571 ext 120
FAX: 866.215.1220
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From:Yeow, Fong [mailto:[email protected]]
Sent:Wednesday, August 08, 2018 12:17 PM
To:[email protected]
Subject:Femap – Delta Airline
Thanks,
Fong Yeow
Stress Engineer, Engineering
DELTA Flight Products, LLC
Office: +1 404-677-0897
Email:[email protected]
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