Experimental Strength Analysis of Variable Stiffness Waffel-Grid Cylindrical Compartments. Part 1. Experimental Procedure

Abstract

This paper proposes a method of the experimental study of the static stress-strain state (SSS) of the variable stiffness tail section of a launch vehicle (LV). The tail section consists of a body and a support ring. The body is a welded structure made up of two waffel-grid shells and two end frames. On the upper and lower end frames, there are bolt holes and guide pins for mating the frames to the fuel tank and support ring, respectively. The shells are made of AMg6NPP, and the frames, of AMg6M aluminum alloys, respectively. The tail section body is loaded through the four support brackets of the power ring, which is part of the test assembly. The article summarizes the results of the experimental analysis of the static SSS of an optimized tail section body under the conditions of loading close to realistic ones. As a result of the experimental research, we achieved the following goals: obtained data on the tail section body strength taking into account the design features, manufacturing technology, and mechanical characteristics of the material; tested theoretical methods for calculating structural strength; determined stresses in the places where they can most reliably be found only experimentally; identified structural sections that have enough strength to be subsequently decreased. Different-size static force factors were applied to the tail section. The static loading of the structure was performed in stages without dynamic components. When the tail section body was tested, measurements of the displacements and deformations were made. The deformations were measured for three different values of the shell longitudinal coordinate and at various points along the circumferential coordinate of the structure. At each point, two rosette strain gauges were glued. One strain gauge was glued in the longitudinal, and the other, in the circumferential direction. With the help of the proposed method, we investigated SSS of the tail section that was designed by the Yuzhnoye Design Bureau.

Keywords

• tail section
• waffle-grid cylindrical shell
• strain gauges
• load