I want to simulate a wind turbine's tower model. The cylindrical part constructed using shell elements (S4R) and the flanges using solid elements(C3D10).Internal stiffneres also included using shell elemnts. Shell and flanges are connected via shell-to-solid constraints.Only geometric non linear analysis is considered with RIKS method.
However Abaqus give me the following warning:Excessive distortion at a total of 4732 integration points in solid (continuum) elements. This warning appears when initial RIKS step is 0.02 and maximum step is also 0.02.However, when I increase the initial step at 0.05 and maximum step at 0.05 I get no warning.
What is this error about? Can affect my results and why initial step has an influence? And how to solve it?
PS: I also upload my .inp file
Check the deformed shape for the last converged increment. Is the mesh refinement reasonable considering the deformation in the element that is distorting? If not, try refining the mesh in the areas of large deformation. • Are the elements hour-glassing? Check Hour-glassing to identify the causes and what to do about them. • Check the model definition including boundary conditions, loading, and material properties. The problem could also be due to contact over-closures. • If the error occurs in the first increment and the model contains contact pairs or tie constraints, have the slave nodes been adjusted to lie on the master surface? If nodes on the slave surface are adjusted onto the master surface by an amount that is significant compared to an element length, the elements may be highly distorted after the adjustment.
Spyros Arvanitis This warning is due to unsuccessful attempt number 1 on increment 38, when load proportionality factor increment was chosen too large (-1310.74). Correspondingly, distortional deformations took place. The attempt number 4 become successful. Of course, this was in vicinity of bifurcation point. The Riks method with larger initial increment (0.05) have passed this point more "smoothly". The choice of initial increment must not affect postbuckling results (at least if there are no neighboring postbuckling equilibrium states).
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