Hello everyone, i'm trying to run repeated punching impacts on concrete plate. After first impact with element deletion off (because energy balance was not maintaining with element deletion turned on, i don't know why), the results came out in good aggrement with experimental results. Now, i want to use this plate for next impact, i can use initial state using predefined field for concrete plate and embedded rebars, however the problem is with the distorted elements which can not be deleted from the results of previous analysis. I thought of an approach where i imported the native mesh of the plate from previous analysis and give initial state to the mesh and manually deleted elements which were distorted from the mesh (only which were seen). Now the problems arises with negative volume elements. Then, i tried to make a set of elements and nodes from previous .odb whose stress value is <0. Now the problem is how to import this set of nodes of elements to new analysis as part instance set, so that i can delete the zero stress elements and respective nodes from the imported mesh which requires the definition as a set of part instance. Sorry to say that I'm a rookie in python scripting. If someone has any idea please.