3. Analysis of the unsteady stress-strain behavior of the launch vehicle hold-down bay at liftoff

3. Analysis of the unsteady stress-strain behavior of the launch vehicle hold-down bay at liftoff

Degtiarov М. А., Avramov K. V.

Yangel Yuzhnoye State Design Office, Dnipro, Ukraine; A. Pidgorny Institute of Mechanical Engineering Problems, Kharkiv, Ukraine

Kosm. teh. Raket. vooruž. 2020, (1); 26-33
https://doi.org/10.33136/stma2020.01.026
 
Language: Russian
Annotation:
The study of thermal strength of the hold-down bay is considered. The hold-down bay is a cylindrical shell with the load-bearing elements as the standing supports. The case of the hold-down bay consists of the following structural elements: four standing supports and the compound cylindrical shell with two frames along the top and bottom joints. The purpose of this study was the development of a general approach for the thermal strength calculation of the hold-down bay. This approach includes two parts. Firstly, the unsteady heat fields on the hold-down bay surface are calculated by means of the semi-empirical method, which is based on the simulated results of the combustion product flow of the main propulsion system. The calculation is provided by using Solid Works software. Then the unsteady stress-strain behavior of the hold-down bay is calculated, taking into consideration the plastoelastic deformations. The material strain bilinear diagram is used. The finiteelement method is applied to the stress-strain behavior calculation by using NASTRAN software. The thermal field is assumed to be constant throughout the shell thickness. As a result of the numerical simulation the following conclusions are made. The entire part of the hold-down bay, which is blown by rocket exhaust jet, is under stress-strain behavior. The stresses of the top frame and the shell are overridden the breaking strength that caused structural failure. The structure of the hold-down bay, which is considered in the paper, is unappropriated to be reusable. The hold-down bay should be reconstructed by reinforcement in order to provide its reusability.
Key words: stress-strain behavior, finite-element method, plastoelastic deformations, breaking strength, reusability.

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