scholarly journals Unsteady processes in stiffened by thin shell viscoelastic cylinder under pulse loading

Author(s):  
I. K. Senchenkov ◽  
O. P. Chervinko

Solid propellant rocket motor is considered as hollow viscoelastic cylinder inserted in multilayered elastic shell-like case. The material of propellant is considered to be compressible. An estimation of maximum unsteady stresses on cylinder-shell boundary and shell under growing pressure on interior or external cylindrical surface were calculated by FEM. Four corner isoparametric finite element is utilized. Numark method to integrate by time the dynamic equations is used. The problem of linear viscoelasticity have been employing of the Schapery method. `In the case of internal pressure, the possibility of tensile radial stresses on the contact surface of the propellant-shell during the transition process has been established. The dependence of the maximum contact stresses as well as circumferential stresses in the shell on the shell thickness is established. In the case of external pressure pulse, the presence of significant tensile radial stresses on the propellant-shell interface is shown. Insignificant tensile circumferential stresses in the transient wave process are possible in the shell.

Author(s):  
J. Richard ◽  
T. Morel ◽  
F. Nicoud

Large solid propellant rocket motors may be subjected to aero-acoustic instabilities arising from a coupling between the burnt gas flow and the acoustic eigenmodes of the combustion chamber. Given the size and cost of any single firing test or launch, it is of first importance to predict and avoid these instabilities at the design level. The main purpose of this paper is to build a numerical tool in order to evaluate how the coupling of the fluid flow and the whole structure of the motor influences the amplitude of the aeroacoustic oscillations living inside of the rocket. A particular attention was paid to the coupling algorithm between the fluid and the solid solvers in order to ensure the best energy conservation through the interface. A computation of a subscaled version of the Ariane 5 solid propellant engine is presented as illustration.


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