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Author Topic: BJSFM Single Shear Correction Factor & Bearing Allowable  (Read 2055 times)

samoashworth

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BJSFM Single Shear Correction Factor & Bearing Allowable
« on: May 05, 2015, 11:23:11 AM »
Hi,  Can you recommend any single shear correction factors?  Previous threads have noted that the BJSFM method assumes double shear.

James

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Re: BJSFM Single Shear Correction Factor & Bearing Allowable
« Reply #1 on: May 05, 2015, 12:36:25 PM »
There are some suggested correction factors in the HyperSizer help documentation:
http://hypersizer.com/help/#Failure/BJSFM/bjsfm-joint_factors.php%3FTocPath%3DFailure%2520Analysis%7CJoints%7CBolted%7C_____4

The joint eccentricity factor (single lap shear factor) is applied to correct the bending moments present in single shear joints which are not captured in a FEM joining two co-planner meshes. The baseline is a double lap shear joint with equal splice plates, Kj = 1.0. In this case, bending is virtually eliminated. Typical single shear factors for solid laminates are 0.7 < Kj < 0.8. For single lap shear joints joining two honeycomb panels, 0.9 < Kj < 1.0.

samoashworth

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Re: BJSFM Single Shear Correction Factor & Bearing Allowable
« Reply #2 on: May 06, 2015, 05:32:03 AM »
One more question - during the BJSFM analysis I get a warning "warning: a/Diameter Ratio <4 (=3.00)".  I have based my a and b to be equal to 3d where my diameter is 4.5mm based on HyperSizer recommendations that finite width is typically 3d.

Is it acceptable for my a/Diameter ratio to be <4, i.e. is it acceptable for this warning to contradict the 3d finite width recommendations?

Thanks for your help in advance,
 :)

samoashworth

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Re: BJSFM Single Shear Correction Factor & Bearing Allowable
« Reply #3 on: May 06, 2015, 11:09:08 AM »
Hi again. 
My single and double shear material data is in carpet plot form.  How could I enter a range of data so that I don't have to set a Stress: Bearing value in the "laminate allowables" tab for each of my laminates or single/double shear requirements?

I am currently running double and single shear analyses for multiple lay-ups and have to keep entering individual data. 
For example, one lay-up I have is at 53% ±45°, 10% 90°, 37% 0° so I enter a value, xxx into the Stress:Bearing laminate property area using the property method "Percent '45' Degree Fibers" by entering 53 and xxx into "Percent '45' Degree Fibers Value" and "Y Value?" respectively. 
I then need to analyse another lay up, this time at 60% ±45°, 20% 90°, 20% 0° so re-enter my data.
Is there a method you can suggest that allows quick analysis instead of changing individual values for each lay-up/type of bolted joint?
Thanks

James

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Re: BJSFM Single Shear Correction Factor & Bearing Allowable
« Reply #4 on: May 06, 2015, 12:56:07 PM »
Carpet plots can be stored in HyperSizer for the laminate bearing allowables using the 'Polynomial' method. To derive the polynomial coefficients you can list the points in Excel and do a data regression analysis.

Here is an Excel help topic that has a simple example.
https://support.microsoft.com/en-us/kb/103839
See "CALCULATING A POLYNOMIAL CURVE"

-James

James

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Re: BJSFM Single Shear Correction Factor & Bearing Allowable
« Reply #5 on: May 06, 2015, 01:08:59 PM »
One more question - during the BJSFM analysis I get a warning "warning: a/Diameter Ratio <4 (=3.00)".  I have based my a and b to be equal to 3d where my diameter is 4.5mm based on HyperSizer recommendations that finite width is typically 3d.

Is it acceptable for my a/Diameter ratio to be <4, i.e. is it acceptable for this warning to contradict the 3d finite width recommendations?

Thanks for your help in advance,
 :)

The a/Diameter should be = 3 for the best BJSFM results. This is considered the "effective width" of the laminate that is affected by the presence of the hole.

The 4D ratio warning is just letting you know that you may need to include an e/D correction. This warning has no direct impact on the HyperSizer BJSFM results.