Analysis of viscoelastic behavior of a filled elastomer under action of different loads

Nikola I. Gligorijević, Saša Ž. Živković, Nenad V. Kovačević, Nenad P. Dimitrijević, Bojan M. Pavković, Miloš Pavić, Vesna Ž. Rodić

Abstract


Mechanical properties of viscoelastic filled polymers strongly depend on temperature and strain rate and vary for several orders of magnitude. During service life, a viscoelastic body, especially carboxy-terminated polybutadiene (CTPB) composite solid rocket propellant grain, is subjected to many stress-inducing loads. Its structural integrity analysis (hereafter: “structural analysis”), unlike elastic bodies, is quite complex and sometimes impossible under the action of just a single load. An even greater problem occurs when multiple dif­ferent types of loads act simultaneously. This study is based on a complete uniaxial mech­anical characterization of a viscoelastic CTPB composite rocket propellant, made in MTI-Belgrade, whose results were used for the analysis of the propellant grain reliability. Through an example, this paper shows a behavior of the viscoelastic propellant grain when it is subjected to extremely different environmental loads at the same time. Similar explicit examples are difficult to found in the literature, except in the form of recommended prin­ciples for analysis. It is shown that the tensile strength under the action of fast load due to the pressure may be almost 20 times greater than the tensile strength under the slow temperature load. A probabilistic approach is presented in evaluation the reliability and service life. An example is shown for a rocket propellant grain as a viscoelastic body. The presented principles of the analysis can be applied to any arbitrary viscoelastic body in other areas.


Keywords


composite propellant; viscoelasticity; time–temperature shift factor; ultimate strength; damage; probability of failure

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References


M.L. Williams, P.J. Blatz, R.A. Schapery, Fundamental Studies Relating to Systems Analysis of Solid Propellants, Final report Galcit 101, 1961.

M.L. Williams, Structural analysis of viscoelastic mat-erials, AIAA J. 2 (1964) 785–808.

R.F. Landel, T.L. Smith, Viscoelastic properties of rubber-like composite propellants and filled elastomers, ARS J. 31 (1960) 599–608.

N. Gligorijević, V. Rodić, S. Živković, B. Pavković, M. Nikolić, S. Kozomara, S. Subotić, Mechanical characterization of composite solid rocket propellant based on hydroxy-terminated polybutadiene, Hem. Ind. 70 (2016) 581–594.

S. Brzić, Lj. Jelisavac, J. Galović, D. Simić, J. Petković, Viscoelastic properties of hydroxil-terminated poly-(butadiene)-based composite rocket propellants, Hem. Ind. 68 (2014) 435–443.

M.A. Miner, Cumulative damage in fatigue, J. Appl. Mech.-T. Asme 12 (1945) 159–164.

В.В. Москвитин, Сопротивление вязко-упругих материалов, изд. Наука, Москва, 1972.

J.E. Fitzgerald, W.L. Hufferd, Handbook for the Engineering Structural Analysis of solid Propellants, CPIA publication 214, 1971.

NASA SP-8073, Solid propellant grain structural integrity analysis, 1973.

N. Gligorijević, S. Živković, V. Rodić, S. Subotić, I. Gligorijević, Effect of cumulative damage on rocket motor service life, J. Energ. Mater. 33 (2015) 229–259.

N. Gligorijević, Strukturna analiza pogonskih punjenja raketnih motora sa čvrstim gorivom, Scientific-Technical Information 1 (2013) (in Serbian).

N. Gligorijević, Prilog strukturnoj analizi vezanog pogonskog punjenja raketnog motora sa čvrstom pogonskom materijom, Мagistarski rad, Mašinski fakultet u Beogradu, 1989 (in Serbian)

Agard-AR-350, Structural Assessment of Solid Propellant Grains, 1997.

M.L. Williams, R.F. Landel, J.D. Ferry, The temperature dependence of relaxation mechanisms in amorphous polymers and other glass-forming liquids, Ј. Аm. Chem. Soc. 77 (1955) 3701–3707.

N. Gligorijević, Istraživanje pouzdanosti i veka upotrebe raketnih motora sa čvrstom pogonskom materijom, PhD Thesis, Military Academy, Belgrade, 2010 (in Serbian).

N. Gligorijević, V. Rodić, R. Jeremić, S. Živković, S. Subotić, Structural analysis procedure for a case bonded solid rocket propellant grain, Scientific-Technical Review 61 (2011) 3–11.

R.А. Heller, М.P. Singh, Thermal storage life of solid-propellant motors, J. Spacecraft Rockets 20 (1983) 144–149.

R.А. Heller, М.P. Singh, H. Zibdeh, Environmental effects on cumulative damage in rocket motors, J. Spacecraft Rockets 22 (1985) 149–155.

S. Cerri, A.M. Bohn, K. Menke, L. Galfetti, Ageing behavior of HTPB based rocket propellant formulations, Cent. Eur. J. Energ. Mater. 6 (2009) 149–165.

N. Gligorijević, S. Živković, S. Subotić, B. Pavković, M. Nikolić, S. Kozomara, V. Rodić, Mechanical properties of HTPB composite propellants in the initial period of service life, Scientific-Technical Review 64 (2014) 8–16.

C.T. Liu, Cumulative Damage and Crack Growth in Solid Propellant, Media Pentagon Report No A486323, 1997.

J.F. Tormey, S.C. Britton, Effect of cyclic loading on solid propellant grain structures, AIAA J. 8 (1963) 1763–1770.

H.S. Zibdeh, R.A. Heller, Rocket motor service life calculations based on the first passage method, J. Spacecraft Rockets 26 (1989) 279–284.




DOI: http://dx.doi.org/10.2298/HEMIND160627042G

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