Element kill above certain stress value
i am working on simple structure (steel plate) like the photo below. I want to see failure on the structure when it reach its ultimate tensile strength (460 MPa). i have used commands (APDL) to kill elements when the stress is above the ultimate strength, but it did not work.
As you can see in the photo, the max stress reach 600 MPa, however the elements are not disappear.
Can someone tell me whats is wrong with my model?