Reply To: The stress at a node does not reach the yield strength, but plastic deformation

[Armin]

Hi Ji,

Could you plot the eq.stress of the elements where plastic strain is non-zero (the elements displayed in red in the your first picture)? 
It appears to me that they have passed the initial yield stress of the material, 275 MPa, leading to plastic deformation. Remember that plastic deformation occurs locally at the element-level; therefore, some other regions of the model can still be in the elastic region.