Hi @bschab

This is an interesting question but I think in the end it will be that those factors cannot be measured for a few reasons. Let me try to articulate it as best I can.

When you print a part with infill under 100% true infill, you end up with cavities in the part that can skew the results of a stress test. Another factor can be the inter layer adhesion of the part. Being that we are dealing with FDM and layers being stacked on each, a lot of the strength depends on the layers sticking together. If the correct temperature is not achieved for good layer adhesion the part will not reflect the CAD results.

These are the main two factors that come to mind, please let me know if this needs further explanation.

All the best!