Wyniki wyszukiwania - Biblioteka Nauki

1

Influence of Polyglycidyl-type Bonding Agents on the Viscoelastic Properties of a Carboxyl-terminated Poly(butadiene-co-acrylonitrilе)-based Composite Rocket Propellant

100%

Brzić S. , Dimić M. , Jelisavac L. , Djonlagić J. , Ušćumlić G. , Bogdanov J.

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2015

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tom Vol. 12, no. 2

307--321

EN

In the present study, functionally substituted bonding agents (triglycidyl isocyanurate and diglycidyl dimethylhydantoin) were incorporated into a composite propellant formulation based on carboxyl-terminated poly(butadiene-co-acrylonitrilе) and ammonium perchlorate. Bonding agents are an important component of a composite propellant, making up to 0.5 wt.% of the formulation. They affect processing, mechanical properties, ballistics, ageing and the characteristics of insensitive munition (IM) propellants. All of the testing has been done using an unmetallized propellant formulation (80 wt.% bimodal ammonium perchlorate and 20 wt.% binder). The focus has been on the mechanical properties of the propellant, as influenced by the presence of these bonding agents. Mechanical uniaxial tensile tests were accompanied by a dynamic mechanical analysis (DMA) over a wide range of temperatures. The storage modulus, loss modulus, loss factor and glass transition temperature for each propellant sample have been evaluated. The network characteristics, such as sol-gel content and crosslink density have been calculated and successfully correlated with the mechanical properties. The dynamic mechanical studies showed that the content of the bonding agent did not influence the glass transition temperature; however, the loss factor was shown to be a function of the crosslink density.

2

Experimental Approaches to Develop a High Thrust Ratio in a Single Chamber Dual Thrust Motor Using a Composite Propellant Formulation Based on HTPB/AP/Al

88%

Kurva R. , Ukey S. , Modgi M. , Mehilal

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tom Vol. 14, no. 4

917--932

EN

A high thrust ratio in a single chamber dual thrust motor is required to reach a peak velocity very quickly. To achieve a high thrust ratio in a single chamber dual thrust motor, a composite propellant grain, which acts both as booster and sustainer, based on HTPB/AP/Al (84% solid loading) with low aluminum content and having a burning rate of 25±0.5 mm/s at 7 MPa, was successfully developed. This was studied for viscosity build-up, mechanical and ballistic properties, followed by casting and curing as a single type propellant grain. The high burning surface area was created by making grooves of 3 mm width and 60 mm depth over the surface of the nozzle side of the grain while casting and a prototype, thus obtained, was static tested. The data revealed that a grain with one groove demonstrated a thrust ratio of 8, while two grooves, realized a thrust ratio of 30. The experimental thrust ratio values achieved are also in agreement with the predicted values of the thrust ratio of the same composition.

3

Biuret: a Potential Burning Rate Suppressant in Ammonium Chlorate(VII) Based Composite Propellants

88%

Dey A. , Ghorpade V. G. , Kumar A. , Gupta M.

Central European Journal of Energetic Materials

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2014

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tom Vol. 11, no. 1

3--13

EN

Several composite propellant compositions containing various concentrations of biuret, a new burning rate suppressant, were formulated and studied to optimize the concentration of biuret in the composite propellant. Biuret was used here for the first time in a composite propellant as a burning rate suppressant. The theoretical properties of the compositions containing different concentrations of biuret were computed by using the NASA CEC-71 programme and the burning rate performances were evaluated. In addition, the sensitivity, thermal and mechanical properties of the compositions were also evaluated. The composition containing ammonium chlorate(VII) (AP) 65%, Al 15%, binder 20% and biuret 0-6% over the batch were prepared. The composition containing 6% biuret over the batch was insensitive to friction and impact. As the amount of biuret was increased, the energy, burning rate and sensitivity decreased, whilst the auto ignition temperature increased. The formulation containing 4% biuret over the batch was found to be the optimum with respect to energy, burning rate, pressure index, and sensitivity.

4

Simulation of Stress Relaxation Behaviour of Composite Propellants with Varying Solid Loading Using the Generalized Maxwell Model

75%

Bihari B. K. , Kumaraswamy A. , Jain M. , Kurva R. , Vipin L.

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tom Vol. 20, no. 2

221--235

EN

Hydroxyl-terminated polybutadiene (HTPB) based composite propellants possess viscoelastic behaviour and hence time and temperature dependent mechanical properties. The mathematical analysis of viscoelastic behaviour of composite propellants becomes complex due to the non-linearity involved under various loading conditions. In the present study, a linear viscoelasticity assumption was considered to simulate stresses related to storage conditions. In this paper, a study of stress relaxation behaviour of composite propellants was carried out using the Generalized Maxwell model to obtain the material viscoelastic characteristics. The relaxation behaviour of composite propellants having solid loading varying from 85% to 89% were studied at different temperatures, from -27 to +32 °C, using a Dynamic Mechanical Analyser (DMA). The generated relaxation curves were curve fitted using MATLAB (R2022a) with the Generalized Maxwell model. The simulation demonstrated that a maximum of four elemental parameters of the Generalized Maxwell model are sufficient and can represent a best fit of the relaxation behaviour of the studied composite propellants. The equilibrium modulus was also evaluated at different temperatures, along with other material constants that are essential parameters for performing the structure integrity analysis of a solid propellant rocket motor. It was observed that the equilibrium modulus decreases with an increase in temperature, but increases with an increase in solid loading in the propellant composition formulations.

5

Opracowanie technologii i badania balistyczne zespołu napędowego do 122 mm pocisku rakietowego o wydłużonym zasięgu

63%

Florczak B. , Cholewiak A. , Białek M.

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2015

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tom Vol. 6, Nr 1 (19)

103-118

PL

W artykule przedstawiono wyniki badań balistycznych silnika rakietowego demonstratora 122 mm pocisku rakietowego o wydłużonym zasięgu z heterogenicznym stałym paliwem rakietowym. Opracowana technologia wytwarzania materiału pędnego stałego może być wdrożona w zakładach przemysłu obronnego i wykorzystana do produkcji silników rakietowych różnego przeznaczenia.

EN

The paper presents the results of ballistic studies on the demonstrator missile 122 mm rocket motor of an extended range with the heterogeneous solid propellant. The technology for producing the solid propellant can be deployed in the defense industry plants and used for the production of rocket motors for various purposes.