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A simple truss problem

A simple truss problem

A simple truss problem

(OP)
Hi,
I made a simple truss model but I got an error(a small negative equation solver pivot term............Check for an insuffuciently constrained model). Can anybody please give me a tip to solve?

Thanks

/PREP7  
!Element type  
ET,1,LINK8  
!real constant
R,1,1.343e-4, ,
 
!Material properties  
MPTEMP,,,,,,,,  
MPTEMP,1,0  
MPDATA,EX,1,,2e11   
MPDATA,PRXY,1,,0.3  

!Keyponits
K,1,0,0,0,  
K,2,1,0,0,  
K,3,1,1,0,  
K,4,0,1,0,  
K,5,0,0,1,  
K,6,1,0,1,  
K,7,0,1,1,  
K,8,1,1,1,

!Lines  
LSTR,       5,       6  
LSTR,       6,       8  
LSTR,       8,       7  
LSTR,       7,       5  
LSTR,       1,       5  
LSTR,       2,       6  
LSTR,       3,       8  
LSTR,       4,       7  
LSTR,       5,       8  
LSTR,       7,       6

!Meshing
LESIZE,ALL, , ,1, ,1, , ,1,
FLST,2,10,4,ORDE,2  
FITEM,2,1   
FITEM,2,-10
LMESH,P51X
  
FINISH  
/SOL

!Fixed supports
FLST,2,4,3,ORDE,2   
FITEM,2,1   
FITEM,2,-4  
!*  
/GO
DK,P51X, ,0, ,0,ALL, , , , , ,  

!Forces  
FLST,2,2,3,ORDE,2   
FITEM,2,5   
FITEM,2,7   
FK,P51X,FX,10

!Solution
/STATUS,SOLU
SOLVE   
 

RE: A simple truss problem

Make sure it is actually a truss (all triangles).  Glancing at it there does not appear to be enough lines for the number of keypoints you have.

RE: A simple truss problem

(OP)

Thanks TERIO smile

i found itsmile  you are right, it is not completely truss.   

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