Not sure about C165, but compression test is a topic which is not developed enough, even for metals. Composites call for a more advanced analysis.
I am aware of the following document (for metals) which might give you a hint on what could be critical in working with C165:
Measurement Good Practice Guide No 27
Measuring Flow Stress in Hot Plane Strain Compression Tests
Revised – Summer 2002
A J Lacey+, M S Loveday*, G J Mahon**, B Roebuck*, C M Sellars+ and M R van der Winden++
*NPL Materials Centre, National Physical Laboratory
**Alcan International Ltd, Banbury, UK
+Dept of Engineering Materials, University of Sheffield
++Corus Group, Ijmuiden, The Netherlands
Abstract
This document has been produced to complement the Measurement Good Practice Guide No 3 which describes current best UK practice for measuring hot flow stress in metallic materials using Hot Axisymmetric Compression (HAC). This Guide is applicable to hot (isothermal) plane strain compression (PSC) tests at medium to high rates of strain (10-3 to 102 s-1) at deformation temperatures below the solidus. Technical input to the document has been provided by a steering group comprising academic researchers, representatives of industrial users and producers of a wide range of engineering materials. An experimental programme was conducted during the preparation of this document to underpin the procedures in this guide.