Design and Test of a Rocket Motor Expansion Joint

Authors: Reiserer, Russell Lawrence; Barden, Kenneth Perrin

Year: 1947

Degree: Engineer's thesis

Advisors: Sechler, Ernest Edwin; Dunn, Louis G.

Committee Member: Unknown, Unknown

Option: Aeronautics

DOI: 10.7907/CM3Y-6453

Abstract

The purpose of this investigation was to carry on the work of investigating stresses encountered in the design of rocket motor expansion joints. The previous work was done on a semicircular expansion joint by Commander N. J. Kleiss, U.S.N., and Lt. Comdr. S. W. Kerkering, U.S.N. in a thesis submitted to the Aeronautics Department of the California Institute of Technology.

Information was desired to make possible a more favorable design. The problem consists of continuing the investigation on a different design, thereby determining a trend for future designs.

The design chosen was a semicircular ring shell with reversed curvatures of the edges. It was felt that this configuration would eliminate most of the bending stresses found present at the weld of the semicircular design, and would make possible a more even distribution of stresses throughout the expansion joint.

Because the stresses encountered were so far beyond the elastic limit of the material, even for small total elongations of the expansion joint, no theoretical solutions of the problem were possible.

An analysis of the curves and data shows the joint to be unsatisfactory, particularly from the viewpoint of withstanding the internal pressure. Since the previous work indicated that the internal pressure was not critical for the semicircular design, it seems that a compromise of the two designs would more satisfactorily meet the requirements of withstanding both the elongation and the internal pressure.

An alternate design has been indicated which will make possible a trend of designs that should lead to a solution.

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