Dynamics of the long thin-walled structure with a local damaged thermal isolation

Аuthors

Antufiev B. A.^*, Konovalov A. V.^**

PJSC Yakovlev , 68, Leningradskiy prospect, Moscow, 125315, Russia

*e-mail: antufjev.bor@yandex.ru
**e-mail: alexey.vl.konovalov@gmail.com

Abstract

Most heated aircraft units are protected by thermal isolation. Isolation prevents structure from overheating. However, sometimes isolation could be locally destroyed. After that, discrete temperature field can appear in primary structure of the aircraft. It leads to a transient structure deformation and stresses. Also destroyed isolation has lower mass and it can affect the dynamic properties of aircraft thermal protection. All this factors are reasons for accident with space shuttle «Columbia». In fact, the thermal protection is covered on internal pipelines of aircraft. Pipelines isolation destruction leads to the unpredictable consequences. Therefore, dynamic behavior research on aircraft primary structure with local destroyed isolation has practical use.
Aircraft (or spacecraft) structure is simulated with the help of long thin-walled structure. Natural and enforced vibration analysis is provided for long thin- walled structure with local damaged isolation. Thermal protection coating has incomparably small stiffness characteristics in comparison to the supporting structure. Isolation destruction leads to the change of structure mass and inertial properties but it doesnt have influence on stiffness properties. This method of analysis also provides solution to hydroelasticity problem of fluid movement in conduit.
This problem is too comprehensive to be described in one article. Only one aspect of this problem is considered in present article. It is dynamic behavior of long thin-walled structure. This research consists of some parts.
Therefore, research on thin-walled structure dynamic behavior is illustrated by examples. The first example illustrates link between the size of isolation damaged zone and structure spectrum of eigenfrequencies. The second example illustrates forced oscillations under the influence of harmonic force. The third example demonstrates frequency response of thin- walled structure and the fourth contains research on the critical velocity of pipe fluid.

Keywords:

long thin-walled structure, local damaged heat isolation, natural frequencies of oscillations, dynamic behavior, hydroelasticity problem, fluid flow in conduit, critical speed

References

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2. Birger I.A., Panovko Ya.G. Prochnost. Ustoichivost. Kolebaniya (Strength. Sustainability. Fluctuations),Moscow, Mashinostroenie, 1968, 415 p.