Wyniki wyszukiwania - BazTech

1

Identification of crashworthiness indicators of column energy absorbers with triggers in the form of cylindrical embossing on the lateral edges using artificial neural networks

Ferdynus Mirosław, Gajewski Jakub

Eksploatacja i Niezawodność

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2022

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Vol. 24, no. 4

805--821

EN

The paper presents the possibility of neural network application in order to identify the most advantageous design variants of column energy absorbers in terms of the achieved energy absorption indicators. Design variants of the column energy absorber made of standard thin-walled square aluminium profile with triggers in the form of four identical cylindrical embossments on the lateral edges were considered. These variants differ in the diameter of the trigger, its depth and position. The geometrical parameters of the trigger are crucial for the energy absorption performance of the energy absorber. The following indicators are studied: PCF (Peak Crushing Force), MCF (Mean Crushing Force), CLE (Crash Load Efficiency), SE (Stroke Efficiency) and TE (Total Efficiency). On the basis of numerical studies validated by experimentation, a neural network has been created with the aim of predicting the above-mentioned indices with an acceptable error for an energy absorber with the trigger of specified geometrical parameters and position. The paper demonstrates that the use of an effective multilayer perceptron can successfully speed up the design process, saving time on multivariate time-consuming analyses.

2

Technology of producing the contact connections of superconductor metal - sheathed cable

Jakubowski A.

Management Systems in Production Engineering

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2017

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nr 2 (25)

110--119

EN

The technology of producing the current contact connections on the superconductor cable edges is presented. This lead cable is used as one of the major elements of the magnetic system in thermonuclear reactor construction, actuality for modern world energy. The technology is realized by the radial draft of metal thin-walled tube on the conductor’s package. The filling of various profiles by round section wire is optimized. Geometrical characteristics of the dangerous crosssection (as a broken ring) of thin-walled tube injured by the sector cut-out are accounted. The comparative strength calculation of the solid and injured tubes at a longitudinal compression and lateral bending is acted. The radial draft mechanism of cylindrical thin-walled sheath with the wire packing is designed. The necessity to use the nonlinear theory for the sheaths calculate is set. The resilient cooperation of wires as the parallel located cylinders with the contact stripes of rectangular form is considered.

PL

Zaproponowano technologię wytwarzania prądowych złączeń stykowych z brzegów nadprzewodnego kabla, jako jednego z najważniejszych części systemu magnetycznego w termojądrowym reaktorze. Jest to problem aktualny dla współczesnej światowej energetyki. Technologię tą można realizować przez promieniowe obciskanie cienkościennej rurki metalowej na pakiet przewodników. Optymalizacją jest zapełnienie różnych profili drutem o okrągłym przekroju. Obliczono geometryczne charakterystyki niebezpiecznego poprzecznego przekroju (rozłączony pierścień) cienkościennej rury osłabionej przez wykrój wycinkowy. Przeprowadzono porównawcze obliczenie wytrzymałości jednolitej i osłabionej rury w trakcie podłużnego ściskania i poprzecznego zginania. Zamodelowano proces promieniowego obciskania cienkościennej powłoki cylindrycznej z drucianym pakowaniem, skąd wynika konieczność użycia nieliniowej teorii dla obliczeń. Rozpatrzono sprężyste współdziałanie drutów (równolegle rozmieszczonych cylindrów), pomiędzy którymi występują powierzchnie stykowe o kształcie prostokątnym.

3

Role of filling material on defects of thin-walled tube bending process

Sedighi M., Kahnamouei J. T.

Journal of Theoretical and Applied Mechanics

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2014

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Vol. 52 nr 1

227--233

EN

This paper investigates approaches to avoid common defects such as the wrinkling, cross section distortion and changing in wall thickness in the bending process of a thin-walled tube. A series of experimental tests has been carried out by filling the tube with melted lead and different types of rubbers. Firstly, tubes were filled by several kinds of rubbers and bended, but the wrinkling was observed at the inner side of the tubes. Also the cross section distortions happened to be above the acceptable range. Therefore, rubbers could not be a suitable filling material for steel tubes. As the second case, lead was used as the filling material to avoid the defects. For this purpose, the tubes were filled by liquid lead and it was solidified to form a leady core to support the inner part of the tube bend. After the bending process, lead is melted and removed. This removable leady core was called the ‘Leady Lost Core’. To study the process numerically, a 3D finite element model of the horizontal bending process has been built using a commercial code. Experimental tests have been carried out to verify the simulation results and developed to provide additional insight. To consider the friction coefficient, in this work, “The Barrel Compression Test” method has been used. Comparisons between the experimental and finite element results have shown remarkable agreement. They show that wrinkle initiation and cross section distortion can be avoided with a lost core of low temperature melting metal like lead or tin.

4

Tensile or compressive plastic deformation of cylinders assisted by cyclic torsion

Mróz Z., Kowalczyk-Gajewska K., Maciejewski J., Pęcherski R. B.

Archives of Mechanics

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2006

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Vol. 58, nr 6

497-527

EN

Technological metal forming processes of extrusion, forging and rolling with imposed cyclic torsion or shear deformation have been recently studied in view of their advantages with respect to monotonic loading processes, cf. Bochniak and Korbel [2-4]. The present work is aimed to analyze such process in the case of simple tension or compression of a cylindrical tube with imposed cyclic torsional deformation. The material element response is assumed to be rigid-perfectly plastic or elastic-perfectly plastic. For these models, the analytical solutions can be provided for the steady cyclic responses and the effect of two process parameters, namely the ratio of shear and axial strain rates ... and the amplitude of shear strain ... , can be clearly demonstrated. Three different regimes of cyclic response can be visualized in the plane ... , ... . The cyclic response of a cylinder under combined axial compression and cyclic torsion is predicted by considering a simplified model of a set of concentric tubes and neglecting their radial stress interaction. The axial force and torsional moment are then specified by averaging the responses of consecutive tubes. The cyclic response diagrams for the cylinder are then generated in terms of axial force and torsional moment related to axial deformation and angle of twist.