Purpose: The aim of the study was to analyse the work of a thin-walled C-shaped profile,
made of a carbon-epoxy composite, which was subjected to unified axial compression.
Design/methodology/approach: The scope of the study included the analysis of the
critical and low post-critical state by the use of numerical and experimental methods. As a
result of the experimental test, performed on the physical specimen, post-critical equilibrium
path had been determined, on the basis of which, with use of the adequate approximation
method critical load value was defined. The next stage of the research was devoted to
numerical analysis based on the finite element method. The studies were carried out on
a scope of the linear analysis of the eigenvalue problem, on the basis of witch the critical
value of load for mathematical model was found. The next step of the numerical tests was
covering the nonlinear analysis of the low post-critical state for the model with geometrical
imperfection, corresponding to the lowest form of buckling.
Findings: The result of the study was to determine the value of the critical load, on the
basis of the experimentally obtained post-critical equilibrium paths of the structure, with
use of two independent methods of Approximation: Koiter's method and the method of the
vertical tangent. The results of the analysis were compared with the value of the critical load
determined by using finite element method.
Research limitations/implications: The obtained results of study provide the important
information concerning the modelling techniques of the thin-walled structures made of
composite materials, while confirming the adequacy of the numerical models developed
both in the calculation of eigenvalue problem, as well as non-linear static analysis in the
post-critical range.
Originality/value: The research provided the necessary knowledge of the behaviour of
the critical and low post-critical of the thin-walled structure made of modern orthotropic
material (CFRP).