Charpy impact testing angle measurement suggestions

[ColeslawNicks]

I am designing my own Charpy impact testing machine and I am unsure what would be the best as well as relatively simple and affordable method I can use to accurately measure the angle the pendulum travels after it has broke the sample. I would also appreciate any complex and more expensive ideas too that I can consider, accuracy and reliability are the most important things.

 

I have thought of some methods but a lot of them will cause friction against the pendulum which could over complicate the final calculations.

 

For anyone that is not familiar with the Charpy method here is a link to a brief description:

 

http://www.twi.co.uk/services/technical-information/faqs/material-faqs/faq-what-is-charpy-testing/

 

Thanks.

 

 

[baxtrom]

Perhaps an indicator on the hinge, being pushed by the pendulum to its extreme position but not pulled back when the pendulum returns? The friction needed to keep the indicator needle in place would theoretically influence the test, but could probably be neglected in the real world..