Problem definition
A 10 long simply supported beam is subjected to an axial tip load of P.

Assumptions
Shear deformations are excluded. The number of internal nodes varies from 0-5.
Key results
The theoretical value for the first buckling mode is calculated using the Euler strut buckling formula:

With P = -1.0 the following buckling factors are obtained
No. internal nodes |
Solver value |
% error |
---|
0 |
12.000 |
21.59 % |
1 |
9.944 |
0.75 % |
2 |
9.885 |
0.16 % |
3 |
9.875 |
0.05 % |
4 |
9.872 |
0.02 % |
5 |
9.871 |
0.01 % |
Conclusion
As the element is subdivided the result converges to the correct theoretical value.