Hi, Everybody !

I am using Abaqus 6.12 Dynamic, Explicit to simulate 2D lamb wave propagation in a thin plate. The input load is concentrate force at a node with a Gaussian pulse wave, and the output value is extracted at a node 200mm away from the nodes. The time step is chosen to be 1e-8. The output variables are chosen as S(stress components and invariants) and U(displacement). When I open the ODB file and try to get the results at S and U (XYData), I found that for several time periods(for example 175us-185us, 193us-199us, 212us-219us) one time can have two different Y values. This phenomenon can be found when extracting the S values. Can somebody tell me the reason about it ?