Complex stress-strain behaviour of a cylindrical shell with a dynamically breaking internal elastic base

Boris Antufiev,Thu Aung,Pavel Polyakov,Elena Kuznetsova

doi:10.5937/jaes0-28208

Abstract

During the operation of a solid-propellant rocket engine, the combustion products of a powder charge create increased pressure in the combustion chamber. Besides, the combustion of gunpowder is accompanied by a large release of heat, which, despite the thermal insulation, causes the appearance of deformations in the engine cowling. This leads to the need to investigate the durability of the shell under the influence of internal pressure and temperature fields. The aim of the paper is to determine the complex dynamic deformed state and vibrations of the engine cowling under the action of force and temperature loads. The problem of a complex axisymmetric stress-strain state and vibrations of a thin cylindrical shell with a dynamically breaking internal elastic foundation, obeying Winkler's hypothesis, is approximately solved. The shell is under the action of internal pressure and temperature fields on a part of its length free from an elastic base. The resolving equation of the problem of the shell deflection is solved by the Bubnov-Galerkin method, reducing the problem to a system of linear algebraic equations. The examples are considered, in which the basic frequencies of natural vibrations of the structure are determined depending on the conditions of shell fastening. Parametric studies are carried out.

Highlights

The problem of dynamic deformation of a cylindrical shell of a solid-propellant engine under the influence of internal pressure of gases and temperature fields that change in time as the powder charge burns out is of immense complexity
We simulate the engine cowling with a thin cylindrical shell, inside on a part of its length there is an elastic base that burns out with a constant velocity V over the cross-sectional area corresponding to the powder charge (Fig. 1)
Applying the procedure of the Bubnov-Galerkin method to equation (1), we reduce the problem to a coupled system of linear algebraic equations with respect to wi

Summary

Introduction

The problem of dynamic deformation of a cylindrical shell of a solid-propellant engine under the influence of internal pressure of gases (combustion products) and temperature fields that change in time as the powder charge burns out is of immense complexity. The most important dynamic characteristics of the engine cowling are the natural frequencies of its oscillations, and especially its lowest (fundamental) frequency [6] If it or some other natural frequencies coincide with the frequencies of forced vibrations of the engine in its operation mode, arising as a result of uneven (pulsating) combustion of the powder charge, this inevitably leads to the occurrence of resonant vibrations [7,8,9]. This is a direct and short path to the destruction of the entire structure. The proposed approximate solution to the problem under consideration is of great practical importance and is relevant for the design of solid fuel engines

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