Monika Zaczynska

The paper presents an investigation to find a method for assessing the intensity of extension-bending mechanical coupling in the behavior of thin plates. The analysis considers thin, simply supported square laminate plates subjected to in-plane compression. Plates with various plies stacking sequences with extension-bending coupling phenomenon were analyzed employing the finite element method software and using a developed closed-formed equation – the analytical method. The coupling intensity was quantified using two dimensionless stiffness reduction coefficients and a nondimensional anisotropic coefficient, known from literature. A reduction in the buckling load for plates with different layer arrangements, observed during nonlinear analysis, was used as a measure of coupling intensity. The results revealed that laminates with high extension-bending coupling intensity could exhibit up to 19% reduction in the buckling load. Additionally, the individual contributions of coupling intensity parameters to this reduction were identified. The validity of the proposed method was further evaluated for plates with different boundary conditions. These findings provide a foundation for predicting the behavior of mechanically coupled laminates without the need for extensive stability analysis.

The study aims to analyse the dynamic buckling phenomenon and assess the role of the stress tensor components in the failure process of a short fibre metal laminate column under axial compressive dynamic loading. The investigation is focused on a channel-section profile composed of three aluminium layers and two doubled composite plies [Al/0/90/Al/90/0/Al]. The numerical analysis was performed on the finite element model, which was validated by experimental static buckling tests. Employing a progressive failure algorithm, this analysis incorporated the material property degradation method and Hashin’s criterion as the damage initiation criterion. Failure initiation in metal layers was based on the Huber-Mises-Hencky failure criterion. Based on the conducted analyses, it was concluded that the dominant forms of destruction in the FML structure are yielding in the metal layers due to excessive compressive stresses and the failure of the matrix in composite plies as a result of compressive and shear stresses. Through a thorough examination of the stress tensor components, critical stresses contributing to aluminium plastic deformation and laminate failure mechanisms were identified.

The interactive buckling phenomenon in thin-walled channel section beams is investigated in this paper. This study deals with medium length beams made of the step-variable functionally graded materials (FGM) which consists of aluminum and titanium layers. The interaction of local, primary and secondary global buckling mode and their effect on the load-carrying capacity is discussed. The parametric studies are performed to assess the effect of the thickness of the beam’s component, its length and position of the individual layer on the equilibrium paths. Additionally, the influence of the adhesive layer between materials was analyzed. The problem was solved using the Finite Element Method.

The distribution of the internal forces corresponding to the individual buckling modes of lip-channel (LC) beams is investigated using the Semi Analytical Method (SAM) and the Finite Element Method (FEM). Channel section beams made of 8-layered GFRP (Glass Fiber Reinforced Polymer) laminate with three different layer arrangements were considered. The effect of the internal forces on the non-linear first-order coefficients corresponding to the interactive buckling was also studied. Moreover, distributions of the internal forces corresponded to the loading, leading to structure failure for which the load-carrying capacity was determined. The results indicated a high influence of the N_x internal force component on the buckling loads and load-carrying capacity of the LC-beams.