You followed the experimental procedure described in the pap

You followed the experimental procedure described in the paper and engraved two glass samples with the following line patterns. Which sample (a or b) do you think will have a higher fracture toughness? Why?

Solution

Model a have a higher fracture toughness, this is due to the fact that stress pileup is less in model a compared to model b which have sharp corners which creates stress pileup(very high-stress concentration in model b) and thus less fracture toughness.