Q. Sandwich Insert Strength per ESA PSS-03-1202

[deanzimmer]

Hello Folks,

I'm looking at estimating potted insert strength in sandwich panels, using ESA PSS-03-1202, Insert Design Handbook, Issue 1, June 1987 and I have a question regarding a discrepancy in the text. I'm hoping somebody else has looked into this before.

Page 27 shows Gc = Gw/3 for an effective core shear modulus.
Page 373 lists Gc = shear modulus of the facings.

Gc is used in the "alpha" equation on page 373; alpha = sqrt[ Gc (h-c) I / (E f^2 If) ] for equal face sheets.

I believe Gc in the "alpha" equation should be the effective core shear modulus. Does anybody have any thoughts on this?


I looked at the US Forest Labs Report 1828 for Bending of a Circular Sandwich Plate Under Normal Load. There, G is defined as the core shear modulus and equation 32 uses G. Equation 32 is similar to the "alpha" equation for the Insert Design Handbook.

Equation 32: alpha^2 = G f^2 I/( E c f^2 If )


Thanks for your help in advance.
Regards,
Dean

 

[MNLiaison]

I do not have a copy of PSS-03-1202 but reviewing the ECSS Insert Design Handbook, alpha is defined as the ratio of stiffness between core and face sheets. The alpha equation [Equation # 12.2-4] further states that Gc = shear modulus of the core.

It appears that Gc as defined on page 373 of PSS-03-1202 is in error.

Regards

 

[stressebookllc]

Insert allowable loads are usually tested for as far as I know. The insert allowable loads are heavily dependent on the process, panel type, insert type, potting compound etc.

http://www.stressebook.com

Stressing Stresslessly!