Dear,

For the compressive strenghth, you haver to prepare your samples while taking into account that  the height equal to twice the diameter as is mentionned in the Afnor  Standard NF P 94 420 (see the attached file). 

Should you have further requirements, dont hesitate de contacte me.

Good luck

Thank you very much for your answer. This is not a normal metallic material .. this is a composite sandwich structure material where the sample cross section will in the range from 1 square inch to 9 square inch as listed in the ASTM standard.

I couldn't find any attached file you are referring to (Afnor Standard NF P 94 420)