*ERROR: increment size smaller than minimum

1

Hello, colleagues.

I try to calculate the perfect shell without imperfections with non-linear geometry.

shell
shell489×655 17.8 KB

My model

Expected

Finalize without errors for full time line.

Problem

If I draw graph force-reaction dependency of time, then error happen at the top.

graph
graph600×600 34.7 KB

average force= 0.023996
time avg. forc= 0.019977
largest residual force= 0.000198 in node 333 and dof 1
largest increment of disp= 8.813149e-05
largest correction to disp= 2.800649e-05 in node 247 and dof 2

divergence; the increment size is decreased to 2.574921e-07
the increment is reattempted


*ERROR: increment size smaller than minimum
best solution and residuals are in the frd file

exit status 201
2

As I understood now, it is happening because Calculix implement newton raphson method, but for that case need Riks method

3

After comparing by:

Nonlinear Analysis of Structures
The Arc Length Method: Formulation, Implementation and Applications

*NODE
1, 0.0, 5.0, 0.0
2, 5.0, 0.0, 0.0
*ELEMENT, TYPE=B21, ELSET=PROP
3, 1, 2
*ELSET, ELSET=PROP
3

*NSET, NSET=load
1
*NSET, NSET=fix
2

*MATERIAL, NAME=STEEL
*ELASTIC
2.05e+5, 0.3

*BEAM SECTION,MATERIAL=STEEL,ELSET=PROP,SECTION=RECT
0.01,0.01
1.,0.,0.

*BOUNDARY
1, 1, 1
1, 3, 3
1, 4, 4
1, 5, 5
*BOUNDARY
2, 1, 1
2, 2, 2
2, 3, 3
2, 4, 4
2, 5, 5

*STEP , NLGEOM, INC=1000
*STATIC
5e-6, 1.0

*BOUNDARY
load, 2, 2, -15.0

*NODE PRINT, NSET=load
U
*NODE PRINT, NSET=fix
RF

*END STEP

Result is good.

1 Like