Ply-Level Strength Calculator Leave a Comment / By GULSHAN SHAFI / March 3, 2024 Ply-Level Strength is a Maximum stress a ply endures before failure.The formula is given by: Where: σply​ is the ply-level strength (stress), Fmax​ is the maximum force applied to the ply before failure, and tply​ is the thickness of the ply. Related