Find the stress/strain on the surface of deformed shape

Hi,

I'm using Salome_meca package and during the modeling I use COQUE_3D to model a circular plate constrained at the perimeter. Initially, the plate is oriented in xy plane. Then I apply a force in -z direction at a small area on the plate.

I want to obtain the stress/strain components (similar to SIXX,SIYY,EPXX,etc..) on the surface of the deformed shape along a local coordinate system. (i.e. NOT relative to global reference system). That is, after the deformation, say a certain element has a 30 degree angle with global x axis and I want to find the stress/strain components on the surface of this element (along two perpendicular directions) and normal to this element.

Can someone advice me to achieve this?? Is there a way in code_aster to do this?

I attached an image to graphically explain my problem (with a ribbon-like geometry for the sake of simplicity).

Thank you in advance
Dinidu