Does anybody know the appropriate value for SEPC and SERR? I only know that they are use for error estimation of the solution but I have no idea about the acceptable value.
SEPC should be 10% or less. SERR has units of energy (consequently, SEPC is derived from SERR) but requires you to look at the contours rather than the numerical values i.e. make sure that SERR contours are uniform. Notice that at stress singularities there is a sharp change in SERR. These and other parts of the mesh which show discontinuous contours are areas for mesh refinement.