Elastic Plastic Fracture Mechanics: J-Integral Experiments

The J-integral is a useful tool for predicting crack growth in different materials, including polymers. In this video I will discuss how you can experimentally measure the critical J-integral using simple force-displacement experiments.
0:00 Introduction
1:01 Measurements
2:38 ASTM Standard
2:54 J-Resistance
4:46 Summary

[@AlexandruIsaincu]

What about short fiber reinforced polymers?
Usually the thickness for plates is around 2-3mm.
I do not think the geometric conditions given in ASTM D5045-14 can be fulfilled (eq.(1) from 7.1.2) considering this small thickness.
Thank you for all your videos.
Really informative.👍

[@Alex753m]

Dear PolymerFEM,
I have tested SENB specimens acc. to D5045-14 standard. PLA material, but half of my specimen groups didn't meet the requirements of the standard. My idea is to use J-integral, for the interpretation of them all. I did the indentation tests on them. Unfortunately, I am not able to conduct further tests.
Is the equation J0=eta*U/(B(W-a0)), with U=U_suf_area - U_indentation , suitable for interpretation in this case?
Is this okay, is there any better solution for this problem?

[@kencasa]

What is 'B' in the equation J(a)=(-1/B)(dU/da)? The audio was a little unclear.

[@PolymerFEM]

B is the through thickness-width of the test specimen.