Pretension stress phenomenon is uneven

I have two case of my pretension.

 

First is my simple test model, second is my realistic model.

 

I have the same contact in my two case but at my realistic model, it can't convergence.

 

In my realistic model the stress phenomenon should be average in my result. But it doesn't. 

 

I want to ask why my phenomenon is different?

 

Is my contact error? or what instructions can I plus?

 

 

Simple test model : 

 

Realistic model : 

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