I need to attend a meeting today regarding a tank design I ran some analysis on. We distributed a draft of the analysis last week and one of the questions was whether the FOS is based on the Stress or the Strain. I believe that it is based on the the yield stress but I just wanted to double check with others. Also he wanted to know if the Von Mises stress is w/i the limits. I would also assume that if my stress calculated was Von Mises then the FOS would be calculated with Von Mises values and therefore would tell whether it is w/i the limits.