What is a Stress Tensor and How is it Used in FEA Analysis?

[CFDFEAGURU]

Hello, I perform FEA (finite element analysis) and write massive amounts of VBA code in Access in order to streamline heat exchanger designs and I have a Boss with no experience with Tensors and the ASME (American Society of Mechanical Engineers) Section VIII, Div. 2 requires one to calculate the Stress Tensor through the use of FEA software such as ANSYS. I have tried to explain Tensors to this man before and it resulted in catastrophe. Does anyone know of a very basic paper something on the order of "Tensor for Idiots" that I could use to help him (me) out?

Thanks
Matt

 

[Andy Resnick]

Try this explanation, it's one I use frequently:

Just as a vector is typically pictured as an arrow, the stress tensor can be pictured as the surface of a cube. Each face has three directions associated with it: one normal to the surface and two which lie in the surface. The normal component corresponds to pressure which makes the cube larger or smaller, while the other two correspond to shear stress, which act to deform the cube into a parallelogram.

It helps if there's a pic to go along with the verbiage, for example:

http://www.tf.uni-kiel.de/matwis/amat/def_en/kap_5/illustr/stress_tensor.gif

 

[CFDFEAGURU]

Thanks a lot.

 

[L62]

http://www.efunda.com/formulae/solid_mechanics/mat_mechanics/stress.cfm