Wydział Mechaniczny / Faculty of Mechanical Engineering / W1

Stały URI zbioruhttp://hdl.handle.net/11652/1

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2003 - 200972010 - 201816

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Ma przypisane plikisearch.filters.applied.operator.equals: TakTematsearch.filters.applied.operator.equals: search.filters.subject.metoda elementów skończonych

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Teraz wyświetlane 1 - 10 z 23
  • 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
    Advanced mechanical engineering : (with elements of numerical engineering analysis)
    (Wydawnictwo Politechniki Łódzkiej, 2006) Kotełko, Maria; Kubiak, Tomasz; Scientific Editor of the Division : Kapitaniak, Tomasz; Niezgoda, Tadeusz; Zielnica, Jerzy
    [...] The book is divided into three parts: the first one contains the foundations of mechanics of solids (particularly of the theory of elasticity) including the stress and strain analysis (concept of the stress and strain tensor in the rectangular co-ordinate system, as well as constitutive stress-strain relations for the general case of elastic anisotropic materials. The first part provides also a reader with a knowledge of yield criteria of not only ductile, isotropic material but also of modern orthotropic materials. The first part concludes with the energy methods in mechanics of materials. Although this part is devoted to advanced topics of mechanics of materials it contains as well some very basic problems (like the concept of equivalent stress for combined load) since they are not included into the syllabus of prerequisite subjects of Basic Mechanical Engineering I and II delivered to the students of Mechanical Engineering and Applied Computer Science (IFE), to whom the book is devoted mainly. The second part contains the theoretical foundations of the Finite Element Method, preceded with the description of the general concept of FEM and the short review of matrix algebra. Afterwards, the basic types of finite elements are discussed and their stiffness matrices are derived. The last part is devoted to selected advanced problems of mechanics of materials, including bending of thin plates, axi-symmetrical problems of the theory of elasticity and very basic introduction to the analyses of buckling of structural members. Each problem is discussed on the basis of analytical methods and simultaneously examples of numerical FE solutions are presented. In the section dealing with bending of rectangular plates the finite difference method is presented as an example of another, alternative numerical method that can be used in mechanics of materials. The third part concludes with the short chapter introducing a reader the problems of fatigue of structures. Some of the discussed topics are illustrated using exemplary problems with detailed solutions. However, the authors assume that a reader can find more of such problems in special text-books containing collections of problems of mechanics of materials to be solved.
  • 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
    Elastooptyka i metoda elementów skończonych w mechanice pękania : wybrane problemy
    (Wydawnictwo Politechniki Łódzkiej, 2007) Niezgodziński, Tadeusz; Red. nauk. Wydziału: Kapitaniak, Tomasz; Kołakowski, Zbigniew; Niezgoda, Tadeusz
    The book contains results of numerical calculation and their comparison with experimental tests carried out on the specimens CT. Crack propagate until damage specimen was achieved. The angle between the direction of crack propagation and the direction of the artificial crack was measured. Author during numerical investigations compare Burzynski and Huber-MisesHencky hypothesis. The Burzynski hypothesis gives very good results for brittle materials which has different properties for tensile and compression it means that relationship between limit stress for compression Re to limit stress for tension Rm is greater than 1 (for example: epoxy resign, cast iron). Influence of relation R.!Rm on angle of crack propagation was carried out. The results of investigation gives information that for relation R.!Rm greater than 1,3 the value of angle of crack propagation is constant, and its value is about 76°. The experimental investigation is solved by photoelastic method. The numerical results were obtained using finite element method package ANSYS. The problem is solved by "element birth and death" method. Results of investigations of cracking of reinforced specimens are presented.
  • 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.