DLR THERMEX-B Test Facility for Cryogenic Tank Wall Structures

Abstract

Within FESTIP Structures Technology De-vel-opment work concentrated on cryogenic tank structures as a dominant objective of reusable launch vehicles. The DLR THERMEX-B test facil-ity has been espe-cially improved to carry out tests on panels with high-temperature and cryogenic insulation as represen-tative parts. By the test ap-proach the specimens have been submitted to com-bined thermal and me-chanical stresses to simulate ascent and reentry cycles. The outer side was heated, the inner one was kept cool at cryo-genic temperatures. Mechanical load was simulated by compression. Temperatures, strains and deflections have been measured to be compared with numerical results from finite element analyses. A room tem-pera-ture test, five thermal and 50 mechanical cycles up to a save compres-sion load, a so-called reentry test with time-dependent compression and a tran-sient heating were applied. Finally, a failure test at room temperature to the two specimens was carried out. Cryogenic tank wall structures turned out to be complicated. Thus, sophisticated test procedures are required. The experi-ence obtained by performing combined tests on such complex specimens gave rise to recom-mend improve-ments in the development proce-dure of tank wall structures from design to qualification.