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### Author Topic: BJSFM Effective Width  (Read 1293 times)

#### samoashworth

• Posts: 4
•
##### BJSFM Effective Width
« on: April 02, 2015, 08:43:16 AM »
Hi there, I'm trying to get my head around the need for effective widths in a BJSFM non FEA model I have put together.
I have a bypass load which I am applying in the Free body tab.  When I then go into the BJSFM analysis, my bypass load has been knocked down.
When I've looked into this I have found that the finite width can be altered.  Should I be increasing the finite width so that the bypass load in the BJSFM tab matches the Nx load applied in the free body tab?
Or should I be setting this to 3D.  If I do set my finite width as 3D, my MS is significantly reduced.
Any help or thoughts would be helpful.
Cheers,
S

#### James

• Administrator
• Posts: 230
•
##### Re: BJSFM Effective Width
« Reply #1 on: April 03, 2015, 11:39:48 AM »
The bypass load is not the same as the far-field loading. It is the load that bypasses around the fastener, into the next row of fasteners. HyperSizer calculates the "bypass" load from the far-field loading (average load) in the elements around the fastener hole. A force balance approach is used for this and the effective width is required to convert the bearing force into a running load. The idea with the effective width is it represents the diameter of the area affected by the presence of the hole. Typically it is set to 3D (HyprSizer default).

You can't simply input the bypass load since that is an entity that is calculated by HyperSizer. You could adjust your input load so you input the Nx load required to return the desired bypass load.

Nxinput = Nxbypass + Fxbearing/2w
In your case, where you want  I would adjust the Nx by