Measure Young Modulus in Thickness direction

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#1

Hi,

I know the procedure to measure IN-PLANE young’s moduli along two orthogonal axes. But I want to know how to measure the modulus in third direction. Especially for plain-woven lamina.

For Unidirectional lamina: E1 > E2 and E2=E3 so no need as such to measure E3 separately.

But for woven lamina: E1=E2 and E3 is no equal to either of E1 or E2 so we do need to measure it.

Any help will be appreciated.

Best regards,
RJ Khan

#2

Hello RJ,

I am not aware of standard method for measuring the E3 modulus (ASTM or otherwise). I have not seen any design allowables for E3, as the designs usually neglect out of plane stresses or have empirical tests for fastener pullout or the like.

However, if you need to directly measure E3, I would make a thick laminate on a flat plate with a flat caul plate as well. Cut the laminate to a standard size and measure the change in thickness of the laminate under compression (or tension, but you,lol need to bond the laminate, with the adhesive limiting the amount of tension that can be applied.)