Comparison of Failure for Thin-Walled Composite Columns.

The novelty of this paper, in relation to other thematically similar research papers, is the comparison of the failure phenomenon on two composite profiles with different cross-sections, using known experimental techniques and advanced numerical models of composite material failure. This paper presents an analysis of the failure of thin-walled structures made of composite materials with top-hat and channel cross-sections. Both experimental investigations and numerical simulations using the finite element method (FEM) are applied in this paper. Tests were conducted on thin-walled short columns manufactured of carbon fiber reinforced polymer (CFRP) material. The experimental specimens were made using the autoclave technique and thus showed very good strength properties, low porosity and high surface smoothness. Tests were carried out in axial compression of composite profiles over the full range of loading-up to total failure. During the experimental study, the post-buckling equilibrium paths were registered, with the simultaneous use of a Zwick Z100 universal testing machine (UTM) and equipment for measuring acoustic emission signals. Numerical simulations used composite material damage models such as progressive failure analysis (PFA) and cohesive zone model (CZM). The analysis of the behavior of thin-walled structures subjected to axial compression allowed the evaluation of stability with an in-depth assessment of the failure of the composite material. A significant effect of the research was, among others, determination of the phenomenon of damage initiation, delamination and loss of load-carrying capacity. The obtained results show the high qualitative and quantitative agreement of the failure phenomenon. The dominant form of failure occurred at the end sections of the composite columns. The delamination phenomenon was observed mainly on the outer flanges of the structure.