Results for membrane

Hello. I’m looking to confirm what the types of results for a membrane represent. For example, is P_N1 the force per unit length (like kN/m) or the force per unit area (like kN/m^2)? What is N1? What defines direction 1 vs 2? Is there a way to set direction 1 aligned to an axis (like the unit x vector axis)? This is important for reporting the forces in the warp vs weft.

Hey, the forces are force/length, so e.g. kN/m depending on your chosen units. P_N1 is the first principle normal force, N1 is in the first direction, N2 .second. These are the results for warp and weft. The default direction is the projection of the x-vector to the surface and the second one is perpendicular. You can adapt the direction with the membrane settings component. There are 4 possibilities.

  • Global projection: projecting A onto the surface. Second direction per perpendicular
  • Cylyndrical projection: cross product of A and B as axis, then tangential and radial
  • local U aligned: direction 1 aligned to isolines (constant v) of the surface. Second direction per perpendicular
  • Curvilinear: both directions aligned to isolines.

Ok, that’s what I figured.

However, the results are a bit weird.

It appears as though my N1 direction is on a diagonal:

N2 is more or less the same:

I set direction 1 to X-vector, so it should more or less look like MPanel:

This is the setting I used:

Definition is attached.

16972-08_JD_Amazon Tension Sails_2022-03-14_35x35.gh (80.8 KB)