# What is the role of "Size" and "Sag" in Catia analysis

#### Mans

##### Member
Hello all after a while

I recently went back to Catia from Rhino because of a requirement, though I will never leave Catia. Using Rhino is simpler with less complexity than Catia and it has its own particular usage. I mostly chose Rhino because of participating in a freelancing web that offered some projects relative to Rhino.

Anyhow, I recently had to think about designing a ramp (150 mm height , 790 mm length and 750 mm width) that someone sent to the web to be designed for a lift truck with weight of 7 Tons. I had to go back to Catia to calculate the resistance of a steel sheet against the pressure of 2500 Kg (every wheel of the truck). I drew a piece of the sheet ( 10*400*250 mm) and transferred it to the Analysis section and tried to realize what its behavior will be against the pressure.

In the Analysis section I encountered two factors; "Size" and "Sag". I really couldn't understand what the role of these two factors is in the calculations and the level of the deformation of the piece of the steel sheet. Which numbers I should choose for Size and Sag to show the real resistance (tolerance) of the sheet and the real level of its deformation. In fact, I need to understand the role of these two factors for calculating the real behavior of the metal things against a specified pressure. This picture that I took from the screen may helps:

#### Feminem

##### Newbie
"Size" - is length of one side of a tetrahedron in a mesh. If there's less size of it when accuracy of your result will be better.
"Sag" - is a maximum deflection of one curved side of tetrahedron with curved geometry.

#### Mans

##### Member
Thank you very much for your explanation