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1

The analysis of buckling and post buckling in the compressed composite columns

Wysmulski P.

Archives of Materials Science and Engineering

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2017

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Vol. 85, nr 1

35--41

EN

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).

2

A study of stability and post-critical behaviour of thin-walled composite profiles under compression

Wysmulski P., Dębski H., Różyło P., Falkowicz K.

Eksploatacja i Niezawodność

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2016

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Vol. 18, no. 4

632--637

EN

The object of this study is a thin-walled channel-section profile made of a carbon-epoxy composite subjected to axial compression. The study included analysis of the critical and weakly post-critical behaviour using experimental and numerical methods. As a result of the research conducted on a physical model of the structure, we determined a post-critical equilibrium path, which was then used to determine the critical load by approximation methods. Simultaneously, numerical calculations were performed by the finite element method. Their scope included a linear analysis of eigenvalue problems, the results of which led to determination of the critical load for the developed numerical model. The second step of the calculations consisted in performing a nonlinear analysis of the structure with geometrically initiated imperfection corresponding to the lowest buckling mode of the investigated profile. The numerical results were compared with the experimental findings, revealing that the developed numerical model of the structure was correct. The numerical simulations were performed using the ABAQUS® software.

PL

Przedmiotem badań jest cienkościenny profil o przekroju ceowym, wykonany z kompozytu węglowo-epoksydowego, poddany osiowemu ściskaniu. Zakres badań obejmował analizę stanu krytycznego i słabo pokrytycznego metodami doświadczalnymi i numerycznymi. W wyniku badań prowadzonych na fizycznym modelu konstrukcji wyznaczono pokrytyczną ścieżkę równowagi, na podstawie której z wykorzystaniem metod aproksymacyjnych określono wartość obciążenia krytycznego. Równolegle prowadzono obliczenia numeryczne z wykorzystaniem metody elementów skończonych. Zakres obliczeń obejmował liniowa analizę zagadnienia własnego, w wyniku której określono wartość obciążenia krytycznego modelu numerycznego konstrukcji. Drugi etap obliczeń obejmował nieliniową analizę stanu słabo pokrytycznego konstrukcji z zainicjowaną imperfekcją geometryczną, odpowiadającą najniższej postaci wyboczenia konstrukcji. Wyniki obliczeń numerycznych porównano z wynikami badań doświadczalnych, potwierdzając adekwatność opracowanego modelu numerycznego konstrukcji. Zastosowanym narzędziem numerycznym był program ABAQUS®.

3

The investigation of stability of double-layer octahedron-based geodesic domes

Bysiec D.

Structure and Environment

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2011

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Vol. 3, no. 3

30-41

EN

The paper presents the investigation of stability of two double-layer octahedron-based geodesic domes. The stability analysis includes the forces acting in the bars as well as the displacements of the nodes with a static point load of 10 kN applied to the top symmetrical node. The investigation was conducted with both identical constant cross-section of all the bars and variable cross-sections (with their adjustment to the internal forces) in each of the bar groups. Moreover, diagrams illustrating the rates of change of the values of the forces and displacements were presented. Also the limit values were determined, above which the analysed structures are unstable.