DYNAMIC BEHAVIOUR OF METALLIC BELLOWS USED INCOMPENSATORS AT FEED SYSTEM FLUID LINES

摘要

Metallic extensional joints are largely used inlauncher/spacecraft engine feed-systems to compensatethermal expansions and displacements of the line sys-tem. The omega-profile of the bellow convolutions isthe usual design feature, documented by the EXPAN-SION JOINT MANUFACTURERS ASSOCIATION,INC. (EJMA). For more compact configurations the'nesting convolution bellows', e.g. the 'Gardener pro-files' have been suggested. For these joints, however,no standard analysis methods and design criteria areavailable. This paper established a mathematical modeldescribing the mechanical behaviour of such exten-sional joints, enabling static, stress, stiffness and fa-tigue estimations. Major difficulties occur because thefact, that especially during the acceptance pressure test,the local stresses in the convolutions exceed the yieldpoint of the material used. Material and geometricnonlinearities were able to explain the anomalies ex-perienced during the vibration tests.