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How to use Cohesive elements with continuum response in Direct Cyclic step (with low cycle fatigue in Abaqus)?

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I'm using direct cyclic step in Abaqus with low cycle fatigue to simulate the damage initiation and evolution in my material. In the Abaqus help it is mentioned that continuum elements like cohesive element with continuum response can be employed in direct cyclic and low cycle fatigue analysis. I have created two simple model to compare them and find out how the Cohesive element with Direct cyclic step works.

First model: My model consists of 3 elements which the middle element is Cohesive element with continuum response and elastic-plastic material properties and the other two are C3D8 (3D Solid element) with elastic response. I have defined the Damage initiation and Evolution constants for Low cycle fatigue in input file.

Second model: There is another model for comparison which the middle element is 3D solid element instead of Cohesive element.

With cyclic tension-compression test of Second model I can see damage initiation and evolution of the middle element very thorough and good but when I change the middle element type and section type to cohesive element and section respectively (Like First Model), after damage initiation, the damage evolution (SDEG) is only active at the end of cycles and after that, it will reset to zero. So the cohesive element remains active during the cycles even it has reached the final damage (SDEG=1). I have attached a curve that shows this problem. The cohesive element will be deleted at the end of cycles and it will be again active at the start of next cycle and carry loads.

I checked many parameters and I don't understand why this problem occurs. I would appreciate any help regarding this problem.

 

P.S: Input files must be run in Abaqus Command NOT Abaqus CAE because of some keywords in input file.

I have uploaded input files in this link:

https://www.researchgate.net/post/How_to_use_Cohesive_elements_with_cont...

AttachmentSize
Image icon First Model (SDEG).jpg75.49 KB
Image icon Second model(SDEG).jpg57.24 KB
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