Stanovení materiálových parametrů kompozitů s matricí z akrylátové pryskyřice vyztužených přírodními materiály a určení jejich tlumících vlastností
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V této práci byly připraveny dva typy kompozitních materiálů, jeden s tkaninovou výztuží z juty a druhý s kombinací tkaniny a korkových částic. Matrici tvořila acrodurová pryskyřice. Na vzorcích byla provedena rozsáhlá měření elastických parametrů. Youngův modul byl měřen jak z tahu, tak z ohybu. Pro namáhání kompozitní desky ve směru T byla shoda obou metod velmi dobrá. Elastické vlastnosti vykazují silnou anizotropii pro výztuž z juty, v přítomnosti korku byla menší a elastické moduly zhruba poloviční. V porovnání s ocelí jsou moduly minimálně o řád nižší, totéž platí i pro pevnost. Statické tahové i další zkoušky vykazovaly lineární průběh v oblasti praktického využití, takže moduly jsou s vysokou přesností konstantní. Při dynamickém měření s vysokým předpětím byla zjištěna velmi slabá hystereze. I v dynamické oblasti lze tedy v praxi použít lineární model. Z útlumu volných kmitů vetknutého nosníku byl určen koeficient útlumu. Pomocí metody konečných prvků byly simulovány všechny zkoušky. Bylo dosaženo dobré shody mezi simulací a experimentem. V případě volných kmitů vetknutého nosníku souhlasily frekvence naměřené a vypočtené pomocí systému Comsol Multiphysics. V teoretické části je uveden dvourozměrný elastický model desky vyříznuté z kompozitu. Do matice elastických parametrů lze dosadit naměřené, příp. odhadnuté, hodnoty a tak získat odezvu na zvolenou dvourozměrnou napjatost.
In this thesis two types of composite materials were prepared. The first one was with knitted jute reinforcement and the other one with a combination of knitwear and cork particles. The matrix was made of acrodur resin. There have been made large measurements of elastic parameters on these samples. Young's modulus was measured by means of stroke and bend methods. The conformity of these two methods was proved for the strain of the composite board in direction T. Elastic properties showed strong anisotropy for the jute reinforcement, while the anisotropy was not so strong in the presence of the cork and the elastic modules were roughly half. In comparison to steel the modules are at least one order lower, which applies also for the solidity.Static tensile and also other tests showed a linear course in the area of practical use and so the modules are constant with high accuracy. During the dynamic measuring with high prestress there was detected weak hysteresis. The linear model is also possible to use in the dynamic area in the practical use. From the attenuation of free oscillation of the sticked girder was determined coefficient of attenuation.With the aid of the method of infinite elements were simulated all the testings. Good conformity was reached between the simulation and the experiment. I the case of free oscillation of the sticked girder correspended the frequencies, which were measured by the Comsol Multiphysics system.In the theoretical part two-dimensional elastic model of board, which is cut out from the composit, is mentioned. It is possible to put measured alternatively etimated figures into the matrix of elastic parameters and get a response to the selected two-dimensional strain.
In this thesis two types of composite materials were prepared. The first one was with knitted jute reinforcement and the other one with a combination of knitwear and cork particles. The matrix was made of acrodur resin. There have been made large measurements of elastic parameters on these samples. Young's modulus was measured by means of stroke and bend methods. The conformity of these two methods was proved for the strain of the composite board in direction T. Elastic properties showed strong anisotropy for the jute reinforcement, while the anisotropy was not so strong in the presence of the cork and the elastic modules were roughly half. In comparison to steel the modules are at least one order lower, which applies also for the solidity.Static tensile and also other tests showed a linear course in the area of practical use and so the modules are constant with high accuracy. During the dynamic measuring with high prestress there was detected weak hysteresis. The linear model is also possible to use in the dynamic area in the practical use. From the attenuation of free oscillation of the sticked girder was determined coefficient of attenuation.With the aid of the method of infinite elements were simulated all the testings. Good conformity was reached between the simulation and the experiment. I the case of free oscillation of the sticked girder correspended the frequencies, which were measured by the Comsol Multiphysics system.In the theoretical part two-dimensional elastic model of board, which is cut out from the composit, is mentioned. It is possible to put measured alternatively etimated figures into the matrix of elastic parameters and get a response to the selected two-dimensional strain.
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Kompozitní materiál, juta, korek, modul pružnosti, útlum, metoda konečných prvků, Composite material, jute, cork, modulus of elasticity, damping, finite element method