Fastener Joint Analysis 1

[Kakalip]

I am looking into fastener GK Joint Analysis and I am checking that fasteners connecting LSection to side skin on upper side of skin as shown in picture has Nx,Ny, SumNx,SumNy ,qxy loads.I am considering SumNx,SumNy loads for calculating MS for fastner.I am noting that GK Joint is calculating negative MS for tension/bypass bearing and also negative MS for bolt bending.Also there is warning message:
THE DIAMETER EXCEEDS THE VALID RANGE FOR THE BEARING STRENGTH DIAMETER FACTOR.VALUES HAVE BEEN EXTRAPOLATED.
Please advise what could be cause of this negative MS and possible action to fix same.

 

[SWComposites]

Kakalip,

GKJOINT is a Boeing Proprietary software code. Therefore I suspect that you are working on a Boeing aircraft. You need to contact the Boeing Stress Methods and Allowables group directly for questions about that code. If you are not working on a Boeing aircraft, then you should not be using that proprietary code.

I suspect that Boeing will not be too happy with you posting pictures of Boeing aircraft structure on an open forum; I suggest that you do not continue to do this.

Possible causes of negative margins: loads too high; part thickness too low, fastener diameter too small, fastener spacing too narrow, etc. Hard to determine a solution without a lot of detailed info. You need to talk to the responsible Boeing (or whatever OEM) stress group lead about this issue.

 

[MNLiaison]

If you don't understand the software I doubt you understand the analysis behind it and therefore you should not be using it for design work.