what is the meaning of plane strain condition or axisymmetric condition in PLAXIS 2D?

RE: what is the meaning of plane strain condition or axisymmetric condition in PLAXIS 2D?

Shailja Joshi — Mon, 19 Sep 2022 09:53:32 GMT

thank you sir

RE: what is the meaning of plane strain condition or axisymmetric condition in PLAXIS 2D?

Shailja Joshi — Mon, 19 Sep 2022 09:53:21 GMT

thank you sir

RE: what is the meaning of plane strain condition or axisymmetric condition in PLAXIS 2D?

Vasileios Basas — Mon, 19 Sep 2022 08:16:31 GMT

Hi Shailja,

Your question covers many topics in FEA, but I'll try to answer as best as possible.

In short, Plane strain assumes the problem in analysis is of infinite length normal to the plane section of the analysis. By definition, the out-of-plane displacement (strain) is zero in a Plane strain analysis. The Axisymmetric analysis allows you to analyze a 3D problem which is rotationally symmetric about an axis. The input is 2-dimensional, but because of the rotational symmetry, you are, in fact, analyzing a symmetric 3-dimensional problem. The axisymmetric analysis is commonly applied to circular tunnels.

When creating a new project, in the Model tab, you have the options of "Plain strain" and "Axisymmetric" in the model type. Alternatively, suppose you have already created a project. In that case, you can change the type of analysis by visiting the "Soil" or "Structures" mode (blue tabs) and then selecting the "Project properties" under the File menu.

RE: what is the meaning of plane strain condition or axisymmetric condition in PLAXIS 2D?

Stefanos Papavasileiou — Mon, 19 Sep 2022 08:16:07 GMT

Dear Shailja,

PLAXIS 2D supports two main conditions for modelling geotechnical projects. I would strongly advise you to study some basics of modelling before continuing as this is considered very important and basic.

Practically plane strain assumes that you are dealing with a cross-section that in the out-of-plane direction extends in the same way for infinite length:

Axisymmetric conditions assume that you are modelling a slice of 1 radian and the model is extending in a circular way:

Therefore which type of geometry conditions is better in your case, depends on the geometry you want to simulate.
Note that in some cases there is no other choice but to use PLAXIS 3D.