Artykuły (WM)

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

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2013 - 20153

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Autorsearch.filters.applied.operator.equals: search.filters.author.Jaroniek, MieczysławTematsearch.filters.applied.operator.equals: search.filters.subject.pęknięcia lamelarne

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  • 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
    Element Birth and Death Method Application to Lamellar Crack Analysis.
    (Lodz University of Technology. Faculty of Mechanical Engineering. Department Division of Dynamics., 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.