Welcome to the forums. Please post in English or French.

You are not logged in.

#1 2020-05-25 05:00:25

Registered: 2019-04-16
Posts: 20

stress and strain in the plane of deformed shape


I have a basic question about the stress and strain components (eg: SIXX, SIYY, EPXX, EPYY) that we get for SIGM_ELNO and EPSI_ELNO. Let's say we use shell elements (COQUE_3D modeling), and our mesh deforms (say bends downward) for a applied load. When I obtain the above mentioned stress/strain components (SIXX,SIYY,etc..), are they expressed on the plane of the deformed shape (on the surface of the mesh)? or relative to the global x,y,z directions? I do not understand when our mesh deforms with the applied load, how do we know the correct x,y and z directions on the deformed mesh and obtain the stress/strain results on the plane of the mesh.

I am very new to FEA. So, any help will be highly appreciated.

Thank you


#2 2020-06-19 09:04:18

From: Arcore (MI) Italy
Registered: 2008-02-19
Posts: 22

Re: stress and strain in the plane of deformed shape

Hi Dinidu,
my opinion is that Stresses and Strains are referred to 'element reference system'.
This means that, in case your structure is a simple quadrangular plane laying in Oxy plane, using Small Displacements the two system (element vs. Global) could be coincident, but if your analysis is a Large Displacements case, so they necessarily will be divergent.
Be aware that it is only my opinion!

Ciao, Piero

Piero Cirrottola
hw: AMD Ryzen Threadripper 1900X 8-Core Processor × 8 - 64GB Ram
OS: Ubuntu-Mate 18.04 (preferred) + Windows 10Pro (needed)


#3 2020-07-09 12:42:26

Registered: 2015-10-16
Posts: 21

Re: stress and strain in the plane of deformed shape

The stress are expressed in the internal shell coordinate system 'utilisateur', including deformations.