Dear all, am performing a perfect plasticity analysis on an I-beam fixed at both ends with udl of 0.5 kN/mm. the yield stress is 0.25 kN/mm2, beam length is 3000mm. From the results the Von mises stress are greater than the yield stress. what could be the problem? any ideas please? does the value of loading affect the Von mises stress? I have attached a picture of my results to this message. thanks in advance.