You should improve the mesh of the thin element. At least three partitions on the thickness are required. On the other hand, I wonder why you are using an axisymetric element if this this problem is not.

I agree with Richard, try using finer mesh. It will solve the problem.

Thank you sir, but my problem is solved. My problem is axisymmetric for sure. Its about Psuedobistability in hemispherical domes. Now I am using viscoelastic material with prony series and explicit analysis works fine with this material.