Hi All
I am trying to simulate scratch test with ABAQUS. I need to consider ductile damage and self contact between chip and sheet after failure along with adaptive meshing to cope with severe distortion. I selected aluminium alloy 2024-T351 as case study and simulated scratch test with a rigid conical indenter with apex angle of 120 degree. I have incorporated ductile damage model in this simulation. Defining proper contact between indenter and sheet is the first challenge. When surface elements fail, they are deleted from the calculations and therefore no contact is detected. By defining an element based surface as the contact domain that includes internal surface of elements, once an element is deleted the internal surface become active in the contact domain (See Figure 1). This feature which is called element erosion (available in general contact algorithm) allows contact between newly born surfaces with the indenter as well as contact between themselves i.e. debris can interact with sheet surface and indenter (see Figure 2). However this type of contact has one big limitation, it does not support ALE, meaning surfaces involved in general contact are non-adaptive and ALE adaptive meshing can not be used to enhance mesh quality.
Figure 1, Figure 36.4.1-2 of Abaqus analysis user’s guide showing element erosion
To overcome the excessive mesh distortion adaptive meshing is usually recommended. In Explicit the only available method is ALE adaptive meshing technique which is compatible only with contact pair algorithm (in contract to general contact algorithm). Contact pair algorithm can not consider element erosion using an element based surface. To simulate contact between new surface born after deletion of surface elements, node based surface can be used as slave surface. It means those nodes that are likely to engage in contact during simulation should be used to define a node based surface which will be used in contact definition. Good thing about this method is that it supports ALE adaptive meshing so better mesh quality can be achieved to avoid poor quality elements seen in Figure 2 and Figure 3. Bad thing, though, is that interaction between debris and sheet can not be simulated. Therefore debris after being removed from the sheet surface penetrate into the sheet without any resistance as seen in Figure 3.
So the question is that how can I avoid mesh distortion and penetration of debris into sheet surface while contact between newly generated surfaces (as a result of damage) are always active.
Figure 2, General contact using element based surface
Figure 3, Contact pair using node based surface
You can manually save the data and attach it to a manually refined mesh.
Franco
Hi Franco
Thanks for your answer to my question. I have been thinking a bout manually remeshing after some iterations. But there are many difficulties. First of all i need to remap the stress and strain to the new mesh which i don;t know how to do. Moreover, defining surface and contact with new orphan mesh is not possible. Do you have any sample or source which can help me in this regard.
Cheers
Akbar
Try here
https://books.google.it/books?id=Siu-l5SuiSwC&pg=PA44&lpg=PA44&dq=abaqus+mesh+remapping&source=bl&ots=Ax_RxbPC23&sig=So0JVAtXPpXwRACBMrDffeKCLbA&hl=it&sa=X&ei=MQiIVLSgE4msUY6khKgD&ved=0CFUQ6AEwBw#v=onepage&q=abaqus%20mesh%20remapping&f=false
Franco
Hi Akbar,
I am trying to solve a problem similar to yours.
I would like to have contact between newly formed surfaces that results from failed elements after shear failure in a localised band. I am also using ALE and the contact pair algorithm. I tried the general contact algorithm to include internal element, but it cannot be used in a 2D analysis (I was not aware that ALE works only with contact pair algorithm as you wrote).
At the moment after element deletion the tool is in contact with the new surfaces, which is good, but the new surfaces cannot contact between themselves which result in element penetration.
I wanted to ask you if you managed to solve your problem and how you did it.
Thanks,
Francesco
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