Analysis error

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brag006
Posts: 173
Joined: Wed Feb 15, 2012 1:26 pm
Location: University of Auckland

Re: Analysis error

Post by brag006 » Fri Nov 01, 2013 11:09 am

You need to give us more info for us to help. What are you modelling? what are your analysis options? etc.
From that error it is most likely because you have a singular stiffness matrix. You need to check the boundary conditions to make sure your model is properly restrained

shariat
Posts: 2
Joined: Mon Apr 29, 2013 7:44 am
Location: qiau

Re: Analysis error

Post by shariat » Fri Nov 01, 2013 11:08 pm

brag006 wrote:
> You need to give us more info for us to help. What are you modelling? what
> are your analysis options? etc.
> From that error it is most likely because you have a singular stiffness
> matrix. You need to check the boundary conditions to make sure your model
> is properly restrained
-------------
Thanks for your answer
My model is Jacket platform and my analysis option is ....

system SparseGeneral -piv

# Create the constraint handler, the transformation method
constraints Transformation

# Create the DOF numberer, the reverse Cuthill-McKee algorithm
numberer RCM

# Create the convergence test, the norm of the residual with a tolerance of
# 1 and a max number of iterations of 10
test NormUnbalance 1.0e-6 10

# Create the solution algorithm, a Newton-Raphson algorithm
algorithm Newton

# Create the integration scheme, the LoadControl scheme using steps of 1
integrator LoadControl 1

# Create the analysis object
analysis Static

# initialize in case we need to do an initial stiffness iteration
initialize

# ------------------------------
# End of analysis generation
# ------------------------------

# ------------------------------
# Start of recorder generation
# ------------------------------
# Create a recorder to monitor nodal displacements
recorder Node -file STATICGravity.out -time -node 907 -dof 1 2 disp
# --------------------------------
# End of recorder generation
# ---------------------------------
# ------------------------------
# Finally perform the analysis
# ------------------------------
# perform the gravity load analysis, requires 10 steps to reach the load level
analyze 1

# Print out the state of nodes 5010
print node 907

brag006
Posts: 173
Joined: Wed Feb 15, 2012 1:26 pm
Location: University of Auckland

Re: Analysis error

Post by brag006 » Sat Nov 02, 2013 11:59 pm

check you constraints. make sure your model is restrained properly against the applied loads

fmk
Site Admin
Posts: 5866
Joined: Fri Jun 11, 2004 2:33 pm
Location: UC Berkeley
Contact:

Re: Analysis error

Post by fmk » Mon Nov 04, 2013 9:21 am

your matrix is singular. check your materials, element connectivities, or add more constraints.

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