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Optimisation run with statics and buckling causing constraint error

Optimisation run with statics and buckling causing constraint error

Optimisation run with statics and buckling causing constraint error

(OP)
Hi,

I am trying to optimize a wing for weight with regard to three very simple sub-cases:

SUBCASE 1
   ANALYSIS = STATICS
   LOAD     = 103050                
   DESSUB   = 6
SUBCASE 2
   ANALYSIS = STATICS            
   LOAD     = 103060                
   DESSUB   = 6
SUBCASE 3
   ANALYSIS = BUCK             
   METHOD   = 10 $Lanczos eigenvalue extraction
   DESSUB   = 5
   DISP        = ALL

I am only interested in the wing and the rest of the A/C is represented by RBE2s and CONM2s. The constraints are placed at the nose

SPC1          111    1246   33333                      
SUPORT     33333      35

Constrained in x,y,Rx and Rz with reactions in z and ry.

The constraints on each of the two statics sub cases are just material strain constraints and tip-deflection constraints. Nothing fancy. For the buckling sub cases, the only constraint is that the first buckling mode should be greater than one. Again nothing fancy there.

The static load cases are simply gravity cases where normal gravity is increased by a factor 2 and 3 respectively and responses are wanted for these two sub cases.

But for inexplicable reason I keep getting this error:

 ^^^ USER ACTION:  CONSTRAIN MECHANISMS WITH SPCI OR SUPORTI ENTRIES OR SPECIFY PARAM,BAILOUT,-1 TO                                
     CONTINUE THE RUN WITH MECHANISMS.

Suffice to say I have tried PARAM,BAILOUT,-1 but it does not work. I have spent most part of this day trying to get it to work, but with little success.

Could anyone share some insight into what it is that is going wrong?

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