Here you have information on size of cylindrical specimens according to ASTM C39

http://framcos.org/FraMCoS-6/193.pdf

Depends on what exactly the composite is, But below are a few links to the ASTM Standards for Polymer Matrix Composites compression testing using different fixtures:

https://www.astm.org/Standards/D6641.htm

https://www.astm.org/Standards/D3410.htm

Thanx Joanna and Faisal.

Hello Piyush,

For powder metallurgy products there is a Polish standard PN-H-04947. This standard determines samples: diameter 25 mm, height 35-40 mm.

Faisal Qayyum

please prof

How can I know the standard dimension of specimen for compression test on aluminum composite by universal test machine (WAW E 600)

It is advised to maintain the l/d ratio (length to diameter) of the specimen close enough to 1.5. If the ratio deviates too much from the standard values