Strange behavior of Load-Displacement curve in a simple 2D indentation problem.

minhtran.1986.vn posted on Fri, Mar 14 2014 9:53 PM

rated by 0 users

Hello everybody,

I am a new comer, nice to meet you all here. I have one question here.

I am modelling a very simple 2D contact problem between a rigid wedge indenter and a deformable squared-shape specimen (general steel material) in frictionless contact case. I used an implicit function f to describe the rigid indenter.

I implemented Lagrange multiplier method for this contact problem and the contact condition is: Inside the contact zone of the deformable specimen, the node set is active if  f(node)<=0 and the Lagrange multiplier lambda<=0.

I also generated an exactly the same model on ABAQUS in order to make a code2code comparison of the ouputs. And these are the things I see:

a. Displacement: I must say it is 99% similar considering displacement distribution and value between my implementation and ABAQUS results. (There is only a little bit tolerance at the displacement value).

b. Load-Displacement curve: the ABAQUS curve is very reasonable with a linearly increasing. However, it is so strange in my implementation due to the fact that the load is equal to zero in 3 first steps of an increasing displacement u.

I posted my model, and the 2 load-displacement curve outputs: one is my implementation and the other is ABAQUS result in the following link since I do not know how to attach them, so that you can see how strange it is.

https://www.dropbox.com/sh/934ea2orku7heje/3FbokU5hNh

Have anybody had experience with this before? Could you please help me to explain about it?

Thank you very much,

Best regards,

Minh