Article citation info: (*) Tekst artykułu w polskiej wersji językowej dostępny w elektronicznym wydaniu kwartalnika na stronie www.ein.org.pl IntroductionThin-walled load-carrying structures are characterized by high strength and rigidity as well as low weight. Given the above properties, these structures are widely applied not only in the aerospace and automotive sectors, but also in designs where low structure weight is crucial. A disadvantage of thin-walled structures is that they are prone to loss of stability under compressive or shearing loads [2, 3, 9, 13, 21-25, 28, 29]. Nonetheless, thin-walled structural elements can operate even after their stability loss provided that they do it in the elastic range [11,14,21,27]. These structures are particularly sensitive to geometric inaccuracies, which is critical regarding their use. For this reason, they must be precisely manufactured to prevent premature loss of stability. Uniform thin-walled plates are relatively cheap to produce, yet they can carry relatively low loads due to their low flexural rigidity. When subjected to compression, these plates lose stability even under small loads. With common methods for improving load capacity such as the use of stiffeners or ribs, the form of a structure is not only considerably modified, but its weight can increase, too. However, there is a way in which load capacity of thin-walled structures can be greatly improved while the structures themselves can be used as both carrying structures and elastic elements. This can be done by forcing these structures to operate in a higher buckling mode (flexural and torsional). To do so, it is necessary to make a cut-out in the plate and slightly displace the vertical zone in the opposite direction. This displacement will be realized in a special frame -so that the jump on basic mode was impossible. In this way, the plate acquires the desired characteristics, i.e. stable operation in the post-buckling range.Issues of the stability and post-buckling behaviors of plate structure with all sorts of holes was described in [19], where you can find a very comprehensive review of the literature on this issue. At that work as the author of the earliest elaboration, in numerical terms, is given Pennington Vanna [16], who as first considered the problem of the stability of elastic uniaxially compression plate with a cut-out. The article presents the results of FEM calculations and compared to the results of experimental studies. The earliest post-buckling behavior analysis of plate structures with cut-out are reported in [18]. A major contribution brings the works [15,17,20,30], where are considered the postcritical states and limited carrying capacity of this type of structures. Not encountered of research, where was investigated plate structures with cut-out and in which attempted to force of the higher flexural and torsional mode deformation of the structure.In the researched load-carrying structure, one can clearly distinguish a vertical zone where this thin-walled element undergoes com...

The subject of the presented research was a thin-walled composite column made of CFRP (carbon-epoxy laminate). The test sample had a top-hat cross-section with a symmetrical arrangement of laminate layers [90/−45/45/0]s. The composite structure was subjected to the process of axial compression. Experimental and numerical tests for the loss of stability and load-carrying capacity of the composite construction were carried out. The numerical buckling analysis was carried out based on the minimum potential energy criterion (based on the solution of an eigenvalue problem). The study of loss of load-carrying capacity was performed on the basis of a progressive failure analysis, solving the problem of non-linear stability based on Newton-Raphson’s incremental iterative method. Numerical results of critical and post-critical state were confronted with experimental research in order to estimate the vulnerable areas of the structure, showing areas prone to damage of the material.

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EnErgy absorption capability numErical analysis of thin-wallEd prismatic tubEs with cornEr dEnts undEr axial impact numEryczna analiza EnErgochłonności ciEnkościEnnych słupów pryzmatycznych z przEtłoczEniamiThe paper presents results of a parametric study into energy absorption capability of thin-walled square section columns with redrawn dents, subjected to axial impact compressive load. Thin-walled aluminum tubes with four dents in the corners were under investigation. The varying parameters were the dent's depth and distance of the dent to the base. The study was performed using Finite Element numerical code. Three crashworthiness indicators were examined: peak crushing force, crash load efficiency and stroke efficiency. The numerical results are shown in load-shortening diagrams, as well as diagrams and maps of crashworthiness indicators. It was found, that the main factor influencing a crushing mode and, subsequently, energy absorption capability, is a dent depth. The dent distance from the base is of less importance. Also a position of a dent, either at the bottom, or at the top base (the load application point) does not influence the crushing behavior significantly. For the deepest dents the relative increase of crash load efficiency (CLE) amounts 25% in comparison with the column without dents.

Crashworthiness of conical shells is known to depend on various factors. This study sets out to determine the extent to which the cross-sectional diameter contributes to their energy-absorbing properties. The object of the study was thin-walled aluminium tubes varying in upper diameter and wall thickness. The components were subjected to dynamic axial crushing kinetic energy equal to 1700 J. The numerical analysis was performed using Abaqus 6.14 software. The specific aim of the study was to determine the extent to which variable wall thickness affects the energy absorption capacity of the components under study. From the simulations, we have managed to establish a relationship between total energy absorption capacity and wall thickness. The results from the conducted analyses and the purpose-specific neural networks could provide the base for the future methodology for forecasting and optimisation of energy-absorbing systems.

The paper presents the results of numerical tests of impact and energy absorption capacity of thin-walled columns, subjected to axial impact loading, made of aluminum alloy, and having a square cross-section and spherical indentations on their lateral surfaces. The numerical models were validated using an experiment that was conducted on the Instron CEAST 9350 High Energy System drop hammer. Material properties of the applied aluminum alloy were determined on the basis of a static tension test. The crushing behavior of the columns and some crashworthiness indicators were investigated. On the basis of the results of the conducted analyses, conclusions were drawn about the most beneficial design/constructional variants in terms of achieved crashworthiness parameters.