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Stały URI dla kolekcjihttp://hdl.handle.net/11652/206

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2003 - 200952010 - 201816

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Teraz wyświetlane 1 - 10 z 21
  • Pozycja
    Wpływ modułu sprężystości postaciowej na stateczność płyt trójwarstwowych
    (Katedra Wytrzymałości Materiałów i Konstrukcji, Politechnika Łódzka, 2003) Mania, R.
    W pracy podano wyniki analizy stateczności globalnej płyt trójwarstwowych w kształcie trapezu równoramiennego swobodnie podpartych na całym obwodzie, poddanych osiowemu ściskaniu. Omówiono szczególny wpływ materiału rdzenia - jego modułu odkształcenia postaciowego - na wybór modelu płyty dla rozwiązania zagadnienia stateczności oraz na poziom obciążenia krytycznego płyty. Zamieszczono i omówiono wyniki rozwiązania analitycznego i rozwiązania numerycznego metodą elementów skończonych.
  • Pozycja
    Numeryczna analiza zniszczenia absorbera energii zbudowanego z rur cienkościennych poddanych zgniotowi
    (Katedra Wytrzymałości Materiałów i Konstrukcji, Politechnika Łódzka, 2003) Kotełko, M.; Lipa, S.
    W pracy przedstawiono zagadnienie nośności w fazie zniszczenia absorbera energii zbudowanego z rur cienkościennych poddanych bocznemu (promieniowemu) zgniotowi. Omówiono metody analizy fazy zniszczenia absorberów energii. Przedstawiono model obliczeniowy metody elementów skończonych (MES) oraz wyniki obliczeń numerycznych MES. Przeprowadzono analizę wpływu liczby elementów rurowych i ich wymiarów oraz sformułowano wstępne wnioski dotyczące tego wpływu na nośność w fazie zniszczenia i ilość energii dysypowanej przez absorber. Wyniki obliczeń MES przedstawiono w postaci wykresów obciążenia w funkcji odkształcenia absorbera oraz map odkształceń i naprężeń.
  • Pozycja
    Element Birth and Death Method Application to Lamellar Crack Analysis
    (Wydawnictwo Politechniki Łódzkiej ; Katedra Dynamiki Maszyn - Wydział Mechaniczny Politechniki Łódzkiej, 2015) Jaroniek, Mieczysław; Niezgodziński, Tadeusz
    Load structure, the maximum permissible load is usually determined by the strength calculation (bearing data. Yield stress or strength of the material), or the parameters of fracture mechanics. The paper analyzes the calculations lamellar cracks formed in the lower crane girders steel belts. These cracks are formed in rolled sheets of non-metallic inclusions. The determination of the cracks in the existing designs are extremely difficult. It requires testing metallographic, ultrasonic or acoustic methods. Based on typical images of metallographic steel plates specified place of occurrence of cracks lamellar and sampling, and has subsequently been adopted for the calculation of numerical models of material structure and distribution of artificial joints. In order to analyze the propagation of cracks and formation of lamellar phase slots and destruction was carried out modeling studies and numerical methods cracking process.
  • Pozycja
    Buckling of TWCFS open-section members under eccentric compression
    (Wydział Mechaniczny. Katedra Wytrzymałości Materiałów i Konstrukcji Politechniki Łódzkiej, 2018) Kotełko, M.; Karmazyn, A.; Borkowski, Ł.; Ungureanu, V.; Dubina, D.
  • Pozycja
    Propagation of the Lamellar Cracks.
    (Lodz University of Technology. Faculty of Mechanical Engineering. Department Division of Dynamics., 2014) Jaroniek, Mieczysław; Niezgodziński, Tadeusz
    The aim of the study is to include studying the effects of the interaction of lamellar cracks and their effect on the degradation of the structure. Lamellar cracking phenomenon is most common in the construction of welded ship hulls, bridges, pressure vessels and piping. The structures of these, as a result of errors in production and welding cracks. The sudden breakage occurs in the construction of real time, although they have been designed properly in terms of both the volume of the stress and strain. The growth of these cracks, at a rate equal to the speed of sound in the material, it is a sudden breakage.
  • Pozycja
    Study of the Formation of Lamellar Cracks.
    (Lodz University of Technology. Faculty of Mechanical Engineering. Department Division of Dynamics., 2014) Jaroniek, Mieczysław; Niezgodziński, Tadeusz
    In rolled sheets, non-metallic inclusions are distributed along the thickness of the sheet as narrow lines running parallel to the rolling direction. Such inclusions are the nuclei of lamellar cracks. This work presents the application of the numerical method for study of lamellar cracking. Numerical models of samples with long artificial fissures set in the area of the sheet axis were studied along with other encountered inclusion distributions. Changes in the stress state in the area of the inclusion were observed as the load increased. Stress concentration leads to the formation of lamellar cracks - the joining of voids in the direction parallel to the exterior surface of the sheet (so-called "terraces" are formed) and at angles (so-called "jogs" are formed). The results of experimental tests were compared with the results of numerical calculations using the finite element method.
  • Pozycja
    Modeling Lamellar Cracks.
    (Lodz University of Technology. Faculty of Mechanical Engineering. Department Division of Dynamics., 2013) Jaroniek, Mieczysław; Niezgodziński, Tadeusz
    In this work, studies of models simulating lamellar cracks were conducted. These cracks are formed in rolled sheets with non-metallic inclusions. Studies of lamellar cracks began in the 1960s, but there is still no satisfactory theory explaining their formation. In this work, the application of modeling of samples with non-metallic inclusions for the study of lamellar cracking has been presented. Studies were conducted using two research methods: the photoelastic method and the finite element method. The possibility of crack formation was analyzed in models generated from images obtained from metallographic specimens.
  • Pozycja
    Application of Photoelasticy for Study of Lamellar Cracks.
    (Lodz University of Technology. Faculty of Mechanical Engineering. Department Division of Dynamics., 2013) Jaroniek, Mieczysław; Niezgodziński, Tadeusz
    In rolled sheets, non–metallic inclusions are distributed along the thickness of the sheet as narrow lines running parallel to the rolling direction. Such inclusions are the nuclei of lamellar cracks. This work presents the application of the photoelastic method for study of lamellar cracking. Photoelastic models of samples with long artificial fissures set in the area of the sheet axis were studied along with other encountered inclusion distributions. The studied samples were placed in a polariscope and subjected to uniform tension; isochromatic images were obtained. Changes in the stress state in the area of the inclusion were observed as the load increased. Stress concentration leads to the formation of lamellar cracks – the joining of voids in the direction parallel to the exterior surface of the sheet (so–called ”terraces” are formed) and at angles (so–called ”jogs” are formed). The results of photoelastic tests were compared with the results of numerical calculations using the finite element method.
  • Pozycja
    Dynamic Response of Viscoplastic Thin-Walled Griders in Torsion.
    (Lodz University of Technology. Faculty of Mechanical Engineering. Department Division of Dynamics., 2013) Czechowski, Leszek
    This work deals with an analysis of isotropic or orthotropic girders subjected to transient dynamic loads. The duration of dynamic loading was assumed to be equal to a period of the natural fundamental flexural vibrations of a structure under analysis. Numerical calculations were performed with the finite element method using ANSYS® 11.0 software. The results of computations were presented as maximum angle of the rotation of the girder in a function of the dynamic load factor, DLF (the ratio of pulse loading amplitude to static critical load). In study it has been taken into account apart from the elastic–plastic range of material with isotropic hardening as well as the strain rate effect described by Perzyna model.
  • Pozycja
    Mathematical and Experimental Analysis Tension of Steel in Bi-Polar Coordinates.
    (Lodz University of Technology. Faculty of Mechanical Engineering. Department Division of Dynamics., 2016) Jaroniek, Mieczysław
    A series of experiments was carried out to examine the effects of elastic–plastic deformation on the state of stress and the flow stress mechanism under static tension. The strain distribution determined from the fringe pattern using the Moire method allows one to determine the strain and the crack propagation of not–notched specimens an isotropic and elastic–plastic materials. In the analysis of stress the method of calculating using the bipolar coordinate is proposed. The theoretical model is divided into two elements and the condition of incompressibility is satisfied in each element. The proposed method is compared with the elastic-plastic FEM (ANSYS 12, 14) and it is satisfied approximately. The tensile test is aimed to verify the mathematical model that can be applied in the logarithmic stain in further computations.