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A comparative study of ultimate load and stiffness of metal-to-composite joints
Tchír, Michal ; Šebek, František (oponent) ; Vrbka, Jan (vedoucí práce)
Nowadays, one of the method for joining especially thick and highly loaded composite components is mechanically fastened bolted joint which allows disassembly of compo-nents e.g. for repair unlike adhesively bonded joint. Traditional sizing method is first-ply-failure, however prediction post first-ply-failure behavior is important too. For structural analysis of the joints as well as for other components is widely used the finite element method. Since modern nonlinear solvers have capability for investigation post first-ply-failure behavior of laminate, this capability of one of them was used in this thesis for investigation of mechanical behavior of laminate made of GFRP layers which was joined to aluminium bracket using bolts. Progressive damage finite element models of two metal-to-composite joints were built in order to determine post first-ply-failure behaviour using three different failure criteria - maximum stress, Hill and Tsai-Wu using Nastran solver. Force-displacement curves, stiffness-displacement curves and values of loads at ultimate displacement were compared with experimental data. As residual stiffness factor influences the results of progressive failure analysis, sensitivity studies of the factor were done, in which accuracy and achieving conver-gence were investigated. In the case of the first joint an agreement is less satisfying, however, the agreement in the case of the second joint, which has a thin steel reinforc-ing plate on its bottom side, is considerably better. Excellent agreement is especially with interactive criteria Hill and Tsai-Wu.
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Možnosti analýz progresivního porušování kompozitních materiálů metodou konečných prvků
Častulík, Lubomír ; Cejpek, Jakub (oponent) ; Mališ, Michal (vedoucí práce)
Bakalářská práce se zabývá možnostmi analýzy progresivního porušování vrstvených kompozitních stěn a desek. Nejprve je uveden teoretický úvod do mechaniky kompozitních materiálů. Následně se práce zabývá popisem druhů mechanismů porušování, včetně kritérií porušení, které je při výpočtu možné použít k jejich matematickému popisu. Poté je uvedena nezbytná teorie k pochopení iteračního výpočtu při progresivním porušování laminátů. Na závěr pak aplikace získaných poznatků k analýze modelu vzorku pro tahovou zkoušku. Tato analýza byla provedena s využitím programů MSC Patran/Nastran.
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A comparative study of ultimate load and stiffness of metal-to-composite joints
Tchír, Michal ; Šebek, František (oponent) ; Vrbka, Jan (vedoucí práce)
Nowadays, one of the method for joining especially thick and highly loaded composite components is mechanically fastened bolted joint which allows disassembly of compo-nents e.g. for repair unlike adhesively bonded joint. Traditional sizing method is first-ply-failure, however prediction post first-ply-failure behavior is important too. For structural analysis of the joints as well as for other components is widely used the finite element method. Since modern nonlinear solvers have capability for investigation post first-ply-failure behavior of laminate, this capability of one of them was used in this thesis for investigation of mechanical behavior of laminate made of GFRP layers which was joined to aluminium bracket using bolts. Progressive damage finite element models of two metal-to-composite joints were built in order to determine post first-ply-failure behaviour using three different failure criteria - maximum stress, Hill and Tsai-Wu using Nastran solver. Force-displacement curves, stiffness-displacement curves and values of loads at ultimate displacement were compared with experimental data. As residual stiffness factor influences the results of progressive failure analysis, sensitivity studies of the factor were done, in which accuracy and achieving conver-gence were investigated. In the case of the first joint an agreement is less satisfying, however, the agreement in the case of the second joint, which has a thin steel reinforc-ing plate on its bottom side, is considerably better. Excellent agreement is especially with interactive criteria Hill and Tsai-Wu.
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Možnosti analýz progresivního porušování kompozitních materiálů metodou konečných prvků
Častulík, Lubomír ; Cejpek, Jakub (oponent) ; Mališ, Michal (vedoucí práce)
Bakalářská práce se zabývá možnostmi analýzy progresivního porušování vrstvených kompozitních stěn a desek. Nejprve je uveden teoretický úvod do mechaniky kompozitních materiálů. Následně se práce zabývá popisem druhů mechanismů porušování, včetně kritérií porušení, které je při výpočtu možné použít k jejich matematickému popisu. Poté je uvedena nezbytná teorie k pochopení iteračního výpočtu při progresivním porušování laminátů. Na závěr pak aplikace získaných poznatků k analýze modelu vzorku pro tahovou zkoušku. Tato analýza byla provedena s využitím programů MSC Patran/Nastran.
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