Elements coordinate systems.

[franc11]

Hi all,

I have a little problem. I'M using MSC Patran and I realized that when I'm meshing, the coordinates system of my different sections of meshing are not oriented the same way. Is there any way to just modify the orientation of the element?

Or, when I'm accessing the results. I can make a z stress component Quick plot that will be different from a z stress component Fringe Plot. As I understand, Fringe plot the results from Nastran as is, so in the material or element coordinate system. Quick plot is suppose to plot the result in the basic coordinate system. But the relation between the two doesn't fit. For example, let say that the element Z coordinate correspont to the basic X coordinate. So by making a fringe plot of the z component, I should get the same result is I'm making a Quick plot of the X component. But it doesn't work.

Any clue how to solve this?

Thanks.

 

[rb1957]

i don't know PATRAN, but in FEMAP there is a simple elemnt edit command to align normals (which sounds like what you want to do). Other FE packages allow you to output global stresses (orients all the elements into the global directions). otherwise plot von mises or max. principal stress (which don't rely on elemtn orientation).

 

[sdm919]

In the version of Patran I'm using, I can re-orient shell normals and/or shell x-y axes. You need the normals to be consistent for applying pressure and plotting top/bottom surface stresses, and you need consistent x-y axes if you want to look at results in element coordinates.

On the Elements menu, select Action: Modify, Object: Element, Method: Shell Orientation. Then pick the Guide Element. This is the one you want the others to follow.

Further down, it says: Match, and you can select System or Normal. System will match the x-y, but won't change the normal, so you might have to do both these operations in 2 or more steps to get all the elements consistent.

Then pick the elements you want to change and hit Apply. Plot the element axes using Display Current Orientation (at the bottom) before and after every step to make sure you're doing it right.

 

[franc11]

Thanks.