Abaqus error : Solver problem, Numerical singularity when processing node

[Uguzo]

I am conducting a linear buckling analysis of a Thermoplastic Composite Pipe comprising an inner PEEK liner, reinforced mid layer and an outer PEEK cover. The analysis is in 2 steps: static analysis and Liner buckling analysis. In the first step the pipe is subjected to internal and external pressure as well as bending moments at both ends. There is a rigid constraint at both ends at a reference point tied to each end face. The BC for step 1 is U1 =U2=Ur2=Ur3=0 and Ur1, U3 are free. Applied on RP1 and RP2.

For step 2,LBA

An axial force of 1N is applied at one end, RP2. BC is fully fixed at RP1 and only U3 is free at RP 2 where the axial load is applied.

I keep getting warnings such as

Solver problem, Numerical singularity when processing node Part-1-1.222 DOF.3 ratio = 51.6669e+09. This warning is repeated a number of times

Also simulation aborts with error , no eigen value was found, this may be due to instability in the base state,

Please how do I resolve this.

 

[FEA way]

Try using the same boundary conditions for the first step as the ones defined in the second step.