Wydział Mechaniczny / Faculty of Mechanical Engineering / W1
Stały URI zbioruhttp://hdl.handle.net/11652/1
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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 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 Elastooptyka i metoda elementów skończonych w mechanice pękania : wybrane problemy(Wydawnictwo Politechniki Łódzkiej, 2007) Niezgodziński, Tadeusz; Red. nauk. Wydziału: Kapitaniak, Tomasz; Kołakowski, Zbigniew; Niezgoda, TadeuszThe 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 Hybrid, finite element-artificial neural network model for composite materials.(Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej, 2004) Lefik, MarekAn application of Artificial Neural Networks for a definition of the effective constitutive law for a composite is described in the paper. First, a classical homogenisation procedure is directly interpreted with a use of this numerical tool. Next, a self-learning Finite Element code (FE with ANN inside) is used in the case when the effective constitutive law is deduced from a numerical experiment (substituting here a purely phenomenological approach). The new contribution to the classical self-learning procedure consists of its adaptation to a case of a non-monotonic loading (non-to-one load-deformation curve). This new ability of the method is principally due to the incremental form of the constitutive equation and the respective scheme of the neural network structure. Also an organisation of a constitutive data-base containing learning patterns is suitably modified. It is shown by examples that the training process is very quick. The error of this method is smaller, comparing to other schemes of data acquisition.Pozycja Large deformation analysis using a quasi-static material point method.(Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej, 2008) Beuth, L.; Benz, T.; Vermeer, Pieter A.; Więckowski, ZdzisławThe Finite Element Method (FEM) has become the standard tool for the analysis of a wide range of solid mechanics problems. However, the underlying structure of a classical updated Lagrangian FEM is not well suited for the treatment of large deformation problems, since excessive mesh distortions can lead to numerical difficulties. The Material Point Method (MPM) represents an approach in which material points moving through a fixed finite element grid are used to simulate large deformations. As the method makes use of moving material points, it can also be classifed as a point-based or meshless method. With no mesh distortions, it is an ideal tool for the analysis of large deformation problems. MPM has its origin in fluid mechanics and has only recently been applied to solid mechanics problems. It has been used successfully for impact analyses where bodies penetrate each other and for silo discharging problems. All existing MPM codes found in literature are dynamic codes with explicit time integration and only recently implicit time integration. In this study a quasi-static MPM formulation and implementation are presented. The paper starts with the description of the quasi-static governing equations and the numerical discretisation. Afterwards, the calculation process of the quasi-static MPM is explained, followed by the presentation of some geotechnical boundary value problems which have been solved with the newly developed quasi-static MPM code. The benchmark problems consist of an oedometer test and a slope. For validation, the results are compared with analytical solutions and FEM results, respectively.Pozycja The finite element model of the human rib cage.(Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej, 2007) Awrejcewicz, Jan; Łuczak, BartoszIn the paper, finite element analysis of the rib cage model is applied to recognize stress distributions and to determine the rate of bone fractures (especially for pathologically changed bones). Two thorax models are considered and the role of the implant is illustrated and discussed. The simulation result shows a good agreement wit h the cadaver test data.