I am a new Abaqus user. I tried to make a simple model of asperity flattening by imposing a downward displacement into an analytically rigid die compressing an Aluminum 3 asperity. I used Abaqus standard, pairwise contact with Hard normal behavior and friction less tangential behavior, and 2d symmetrical model.
I expect to have the maximum PEEQ and Mises stress on top layer ( based on hertz contact theory) but it is observed in under layer elements. Actually maximum PEEQ starts from contact area but gradually it goes down to the underlays. Also maximum Mises stress is a little bit lower than contact surface.
I tried surface- to-surface and node to surface discretization method, different contact constraint enforcement methods (Direct, Penalty, Augmented Lagrange), different elements (CPE4R, CPE3) also higher order elements with reduced integration points. but I still have the same problem. I have attached some pictures of initial model, Smises and PEEQ contours. Do you have any idea what's wrong?
Actually , I believe it is a contact stress problem. See Hertz contact theory etc.. So its not wrong , its as how as it should be. Try a theoretical calculation of the critical depth and compare it with FEM.
Actually , I believe it is a contact stress problem. See Hertz contact theory etc.. So its not wrong , its as how as it should be. Try a theoretical calculation of the critical depth and compare it with FEM.
Thanks. The picture i attached was Mises stress distribution. I have attached PEEQ contour. Do you think it's normal? How can i calculate the theoretical critical depth. do you have any reference?
Thanks Ming, I downloaded that article and it seems that my model is working properly. I will read the article carefully to see can i calculate the contact area analytically.
Another suggestion is, try to mesh your contact region finer. You may find a difference in your result.
Contact Mechanics - K. L. Johnson is the well written booking on Contact Mechanics. In fact, I have utilize this book for my graduate level research. and for more details feel free to refer my Thesis publication which is about Contact mechanics behavior of Cylindrical roller bearing.
Hi again Ming. I read that paper and found a reference on spherical flattening. After several attempt finally i made a simulation of flattening of a spherical fully plastic asperity. In plastic region my results are well correlated with that paper but in elastic region i have lower normal force and higher flattened area compared to that paper. I was wondering you hay have had the same problem before. Any idea?
Check the elasto-plastic properties of your material model. What type of hardening rule your are using and how those parameters are chosen.
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