Wyniki wyszukiwania - Biblioteka Nauki

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Dynamic mechanical characterization of epoxy composite reinforced with areca nut husk fiber

100%

Muralidhar N. , Vadivuchezhian K. , Arumugam V. , Reddy, I. Srinivasula , Muralidhar N. , Vadivuchezhian K. , Arumugam V. , Reddy, I. Srinivasula

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2

Mathematical model analysis of sample from polyurethane vibroinsulation mat

89%

Dzikowska W.

Postępy w Inżynierii Mechanicznej

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2014

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tom nr 3(2)

13--20

EN

The paper presents further developments in mathematical modelling of vibroinsulation mats. There was proposed the introduction of new parameters for characterizing the properties of the mat. An attempt to analyze the model in terms of its dynamic properties resulting from the determination of frequency transfer function was made. In conclusion the methodology of the studies necessary to quantify the material constants model was described.

PL

W pracy zaprezentowano kolejny etap rozwoju modelu matematycznego poliuretanowej maty wibroizolacyjnej. Zaproponowano wprowadzenie nowych parametrów chrakteryzujących własności maty. Podjęto próbę analizy modelu ze względu na jego własności dynamiczne wynikające z określenia transmitancji częstotliwościowej. W podsumowaniu opisano metodykę badań koniecznych do ilościowego określenia stałych materiałowych modelu.

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Dynamic Mechanical Properties of Artifcially Aged Double Base Rocket Propellant and the Possibilities for the Prediction of Their Service Lifetime

89%

Matečić-Mušanić S. , Sućeska M.

Central European Journal of Energetic Materials

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2013

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tom Vol. 10, no. 2

225--244

EN

The ageing of double base (DB) rocket propellants, as a consequence of the chemical reactions and physical processes that take place over time, has a signifcant effect on their relevant properties, such as chemical composition and mechanical and ballistic properties. The changes to relevant properties limit the safe and reliable service life of DB rocket propellants. Accordingly, numerous research efforts have been undertaken to fnd reliable methods to measure the changes caused by ageing in order to assess the quality of DB rocket propellants at a given moment of their lifetime, and to predict their remaining service lifetime. In this work we studied the dynamic mechanical properties of DB rocket propellant artifcially aged at temperatures of 80, 85 and 90 °C, in order to detect and quantify changes in the dynamic mechanical properties caused by ageing, and to investigate the possibilities for the prediction of service lifetime. Dynamic mechanical properties were studied using a dynamic mechanical analyser (DMA). The results obtained have shown that ageing causes signifcant changes in the storage modulus (E´), the loss modulus (E˝) and the tan δ curves’ shape and position. These changes are quantifed by following some characteristic points on the E´-T, E˝-T, and tan δ-T curves (e.g. glass transition temperatures; storage modulus, loss modulus and tan δ at characteristic temperatures, etc.). It has been found that the monitored parameters are temperature and time dependent, and that they can be shown to be functions of the so called ‘reduced time of artifcial ageing’. In addition, it has been found that, on the basis of known changes in viscoelastic properties as a function of time and ageing temperature, and the known kinetic parameters of the ageing process, it is possible to calculate (determine) the change in the properties at any ageing temperature provided that the mechanism of the ageing process does not change. Unfortunately, the use of kinetic parameters obtained by artifcial ageing at high temperatures (above 60 °C) for the prediction of the propellant lifetime will not give reliable results, because the mechanisms of ageing at 85 °C and 25 °C are not the same.

4

Evaluation of physical and dynamic mechanical properties of coconut husk ash (CHA) reinforced polyester composites

89%

Ipilakyaa T. , Tuleun L. , Sule T.

Journal of Mechanical and Energy Engineering

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2020

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tom Vol. 4, No 4

315--324

EN

The evaluation of physical and dynamic mechanical analysis (DMA) properties was carried out on a developed Coconut Husk Ash Reinforced Polymer Composite. Sieve analysis of pretreated coconut husk ash was done to obtain 75 μm, 150 μm and 300 μm particles sizes. These particles were used at varying compositions of 5%, 10%, 15%, 20% and 25% as reinforcements for polyester composites. The catalyst and accelerator used were Methyl Ethyl Ketone Peroxide and Cobalt Naphthenate respectively. The densities of the evaluated composites made with 150 μm particles were found to be less dense with values ranging from 0.9792 g/cm3 to 1.2561 g/cm3 than those made with 75 μm and 300 μm. The results also show that the percentage water absorbed by samples increased, ranging from 0 to over 2000 E’/MPa for all percentage reinforcements of coconut husk ash, with an increase in the duration of immersion of the samples in distilled water. However, 25% reinforcement had better results for all particle sizes. There were obvious variations of storage modulus, loss modulus and mechanical loss factor with percentage weight of reinforcement, temperature and frequency. The composite with 15%reinforcement displayed better results. The composite shows promising results as a material for interior components in aerospace and automobile industries.

5

Storage and loss modulus investigations of magnetorheological elastomers

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Skalski P. , Dębek C.

Logistyka

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2015

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tom nr 3

4408--4412, CD 1

EN

In this paper, the magnetorheological elastomers (MREs) based on natural rubber were studied. Several MRE samples, with different weight percentages of carbon iron particles, were fabricated without applying a magnetic field. Their microstructures were observed by using an environmental scanning electron microscope (SEM), and their rheological measurements were carried out using ARES rheometer. The MR effect was investigated by changing the volume of carbon iron particles.

PL

W pracy zaprezentowano badania elastomerów magnetoreologicznych (MR) zbudowanych na kauczuku naturalnym. Kilka próbek elastomeru MR z różną zawartością cząstek pyłu karbonylkowego zostało wytworzonych bez obecnego pola magnetycznego. Struktura próbek została przedstawiona na podstawie zdjęć z mikroskopu elektronowego, a pomiary reologiczne zostały przeprowadzone na reometrze ARES. Efekt magnetoreologiczny został przebadany pod kątem wielkości zawartości pyłu karbonylkowego.

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Diagram temperatura zeszklenia-temperatura-właściwość (TgTP) układu epoksydowego EPY®

71%

Urbaniak M.

Polimery

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2008

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tom T. 53, nr 7-8

537-543

PL

Metodą termicznej analizy dynamicznych właściwości mechanicznych (DMTA) badano zmiany modułu zachowawczego (E') i modułu stratności (E'') z postępem konwersji (rys. 3, 4 i 5) napełnionego układu epoksydowego EPY® (Epidian 6 z trietylenotetraaminą). Materiał ten jest stosowany do produkcji podkładek fundamentowych maszyn. Wyniki tych badań razem z wynikami uzyskanymi wcześniej za pomocą różnicowej kalorymetrii skaningowej (DSC) (tabela 1) i wiskozymetrii rotacyjnej pozwoliły na wyznaczenie diagramu temperatura zeszklenia-temperatura-właściwość (TgTP) tego układu (rys. 1, 2 i 6), gdzie Tg jest bezpośrednią miarą postępu konwersji, a P oznacza rozpatrywaną właściwość - moduł stratności. Użycie Tg jako bezpośredniej miary postępu konwersji w tym diagramie umożliwia linearyzację zależności między wartościami temperatury odpowiadającymi maximum i minimum właściwości fizycznych a postępem sieciowania. Linie na diagramie TgTP odzwierciedlają przebieg przemian strukturalnych materiału: zeszklenie (Tg), ß-przejście (Tß) i żelowanie (gelTg). Linie te wyznaczają również podobszary, w których materiał, w miarę postępu konwersji, wykazuje różne właściwości fizyczne. Opracowany diagram TgTP tworzywa EPY® umożliwia lepsze zrozumienie zależności między przemianami zachodzącymi w układzie a właściwościami materiału.

EN

Evolution of storage and loss moduli during conversion progress of the filled epoxy system EPY® (Epidian 6 with triethylenetetramine), applied for the production of machine foundation chocks, was studied using dynamic mechanical thermal analysis (DMTA). The results obtained and the results previously reached by differential scanning calorimetry (DSC) and rotational viscometry made possible to determine the diagram glass transition temperature-temperature-property (TgTP) for the investigated system, where Tg is the direct measure of conversion and P denotes property under investigation - loss modulus. This way of using Tg in this diagram makes possible the linearization of the relationships among the temperatures corresponding to the maxima and minima of the physical properties and the extent of cure. The lines within TgTP diagram show the courses of structural transformations during cure i.e. glass transition (Tg), ß-transition (Tß) and gelation (gelTg). The diagram lines separate several regions which are dependent on the extent of cure and the material shows different physical properties within each of them. TgTP diagram calculated for the EPY® material can facilitate understanding of the relationships among transitions and material properties.

7

Dynamic mechanical characterization of epoxy composite reinforced with areca nut husk fiber

71%

Muralidhar N. , Kaliveeran V. , Arumugam V. , Srinivasula Reddy I.

Archive of Mechanical Engineering

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2020

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tom LXVII, nr 1

57--72

EN

Natural fiber polymer composites are gaining focus as low cost and light weight composite material due to the availability and ecofriendly nature of the natural fiber. Fiber composites are widely used in civil engineering, marine and aerospace industries where dynamic loads and environmental loads persist. Dynamic analysis of these composites under different loading and environmental conditions is essential before their usage. The present study focuses on the dynamic behavior of areca nut husk reinforced epoxy composites under different loading frequencies (5 Hz, 10 Hz and 15 Hz) and different temperatures (ranging from 28◦C to 120◦C). The effect of loading and temperature on storage modulus, loss modulus and glass transition temperature was analyzed. Increase in storage modulus is observed with increase in loading frequency. The storage modulus decreases with increase in temperature. The glass transition temperature of the composite is determined to be 105◦C. The elastic modulus calculated from the DMA data is compared with three point bending test