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1

Initial geometric imperfections: a robust, closed-section cold-formed box profile application subject to local buckling

Brambatti Junior N., Walber M., de Meira Junior A. D.

International Journal of Applied Mechanics and Engineering

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2021

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Vol. 26, no. 1

18--44

EN

Initial geometric imperfections are important for simulating local buckling in numerical models. References are found in the technical literature regarding open-section cold formed profiles. This work presents new procedures applied to a robust and closed-section cold formed profile subject to local buckling, and the use of procedures described in the technical literature already successfully used for open section profiles. The difference of this work in relation to the research already carried out is in the type of profile studied, in the mode of failure of the same and in the form of determination of the initial imperfections. The object of study of this work is a closed-section cold formed box profile with a short length when compared with its cross section and with local buckling failure mode. The strategies used in the present work to consider the initial geometric imperfections were to perform the linear stability analysis using the finite element method to obtain the local buckling mode that represents the deformed box profile geometry, to apply a multiplication factor in the displacements, replace the new geometry node coordinates for all profile nodes to induce the local buckling deformation mode, with model validation through experimental testing and the Effective Width Method (MLE) (ABNT NBR 14762 [1]). Finally, using the results of the collapse load of the experimental trial as a basis, it was possible to compare the results obtained by MLE and MEF. Thus, the presentation of this work used a methodology that describes the local buckling behavior and verified the precepts of the existing norms on the subject, combining theoretical and experimental methods, as they bring a better understanding of the structural problem in question.

2

Bending Moment and Cross-Section Deformation of a Box Profile

Kut Stanisław, Stachowicz Feliks

Advances in Science and Technology. Research Journal

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2020

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Vol. 14, no 2

85--93

EN

In the process of plastic bending of thin-walled profiles, there is a significant deformation of the cross-section, which has a very significant impact on the course and effects of the shaping process construction products. In this paper, the experimental, analytical as well as numerical analyses of the box profile bending process enabled to establish the relationships determining the dependence of the cross-sectional form and bending moment on the bending curvature. The following paper discusses pure bending moment and the cross-sectional deformation of 21.5×21.5×1.8 mm and 25×25×2.5 mm square tubes made of the 6060 aluminium alloy. Satisfactory agreement of the experimental results and numerical calculations was obtained for the values of horizontal and vertical wall deflection, as well as for the experimental, calculated and numerical bending moment characteristics.

3

Spawane połączenia węzłów podatnych w kratownicach o prętach skratowania z kształtowników zamkniętych i pasach z dwuteownika

Broniewicz M.

Inżynieria i Budownictwo

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2014

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R. 70, nr 12

677--681

PL

Dokonano oszacowania nośności spoin w węzłach podatnych, określenia efektywnych długości spoin, sposobu ich rozmieszczenia w zależności od sztywności płytowej ścianek rur oraz wyznaczenia składowych naprężeń działających na poszczególne odcinki spoin. Zaproponowano sposób sprawdzenia nośności spoin pachwinowych w węźle K lub N ukształtowanym z nachodzeniem prętów o przekroju zamkniętym oraz pasach z dwuteowników.

EN

Estimation of resistance of welded semi-rigid joints is a complex issue because it requires determining of effective lengths of welds, their placement on the member walls with their different rigidity and distribution of components of the loads acting on each section of welds in various joint areas. The objective of this paper is to present the most up-to-date information to designers, teachers and researchers according design of welds for certain K and N joints with partially overlapped RHS brace members and I or H-section chord.

4

Zastosowanie sztucznych sieci neuronowych do wyznaczania parametrów gięcia profili skrzynkowych.

Litwin P., Stachowicz P.

Rudy i Metale Nieżelazne

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2000

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R. 45, nr 10-11

565-569

PL

Wyznaczenie momentu gnącego i współczynnika sprężynowania w przypadku gięcia profili skrzynkowych jest utrudnione, ze względu na deformację przekroju poprzecznego giętego elementu. Do rozwiązania tego problemu wykorzystano Perceptron Wielowarstwowy - model z grupy Sztucznych Sieci Neuronowych (SSN). Sieć trenowano na danych eksperymentalnych zawierających parametry materiałowe (podawane na wejście sieci) oraz parametry procesu gięcia (podawane na wyjściu sieci). Zbiór uczący obejmował dane pomiarowe zebrane podczas gięcia profili o różnych wymiarach. Przeprowadzony eksperyment dowiódł, że model oparty na sieci neuronowej może być wykorzystywany do wyznaczenia parametrów gięcia.

EN

Spring-back coefficient and bending moment prediction in the case of box profile bending process causes some problems because of cross-sectional distortion. To solve these problems Multilayer Perceptron type artificial neural network (ANN) was applied. Multilayer Perceptron (MLP) was trained using measured process data of box profile bending. Mechanical properties were given as the inputs and the bending process parameters as the outputs of the MLP. The data set consisted of different geometry steel box profile. The experiment confirmed that this model is a valid alternative for the quick responsible method for main bending parameters determination.