EVALUATION OF MATERIAL SUBSTITUTION IN KNITTED SPRING TUBES FOR ADVANCED STRUCTURAL SEALS

摘要

Material substitution was evaluated as a means for improving the performance of high temperature knitted spring tubes used in control surface seals for current and future reusable space launch vehicles. Control surface seals fill the space between movable control surfaces such as body flaps, rudders and elevons, and the static body structures to which they are attached. These seals must remain in continuous contact with opposing surfaces to prevent the ingestion of damaging hot gases encountered during atmospheric reentry. Resiliency loss in the current baseline control surface seal has been linked to its knitted Inconel X-750 spring tube element. Substitution of the nickel based superalloy Rene 41 for Inconel X-750 in the baseline spring tube design enhances its temperature capabilities and produces a resiliency improvement during compression testing of 2.5x at the start of compression cycle 10 at 1500 °F. Rene 41 spring tubes exhibit reasonable resiliency to at least 1750 °F throughout 20 compression cycles, whereas all resiliency is lost in Inconel X-750 samples at that point. Additional analysis shows that creep is likely the dominant deformation mechanism leading to decreased spring tube performance. These results are presented along with a description of the method used to evaluate and quantify the performance of advanced seal components.