Hypermesh Optistruct Dequation Syntax

XxComposite69xX

Dear fellow FEM engineers,

I am trying to define a custom constraint using dequations for my optimization with optistruct.  Sadly i am unable to get it running due to syntax errors.

The formula i am trying to use is the following:

m(xa,xb,ya,yb,za,zb,aa,ab,ba,bb,ca,cb) = (xa+xb)**2+(ya+yb)**2+(za+zb)**2-(xa+xb)*(ya+yb)-(xa+xb)*(za+zb)-(ya+yb)*(za+zb)+3*((aa+ab)**2+(ba+bb)**2+(ca+cb)**2)

 

I found out that apparently there is some character limit, which just cuts off my equations after approximately 52 characters resulting in open brackets etc.

 

So then i tried splitting the equation into multiple lines:

x(xa,xb) = xa+xb;

y(ya,yb) = ya+yb;

z(za,zb) = za+zb;

a(aa,ab) = aa+ab;

b(ba,bb) = ba+bb;

c(ca,cb) = ca+cb;

f(x,y,z,a,b,c)=x*x+y*y+z*z-x*y-x*z-y*z+3*(a*a+b*b+c*c)

 

but i get the following error:

 *** ERROR # 1608 ***
  Syntax error in DEQATN # 2.
 Unknown function name "y".
 Syntax error in expression # 2.

 

what am i doing wrong?

Adriano A. Koga

There is no limit for the solver itself.

Maybe this is an issue for the equation export from HyperMesh.

If that's the case, you might want to keep the equation separated into a include file, as a workaround, so that you don't need it to go thourgh HM all the time.