Crash Testing of a CFRP Commercial Aircraft Sub-Cargo Fuselage Section

Abstract

The paper addresses the testing at the ONERA (Office National d’Etudes et de Recherches Aérospatiales) crash tower of a subcargo demonstrator representative of new generation CFRP (carbon fiber reinforced polymer) commercial aircraft. The project was conducted within a technological platform coordinated by AIRBUS Germany, which aimed at designing, simulating and testing an innovative crashworthy sub-cargo structure. Technical activities were shared between AIRBUS Germany for the demonstrator design and manufacturing, DLR (German Aerospace Center) for the numerical analysis and ONERA for the crash test. The demonstrator was based on single aisle aircraft geometry and comprised 2 Integrated Cargo Units (ICU) equipped with Triggered Tube Segments (TTS) dedicated to energy absorption and CFRP stringer-stiffened skin. The crash concept was based on an integrated structural design which applied the “bend-frame-concept” where the cargo cross-beam acts as a bend frame and withstands the dynamic loads introduced by the TTS components. The testing configuration - loading system and instrumentation - was defined on the basis of numerical analysis performed by DLR at the fuselage section level. In that frame, a kinematic model with a 2-frames typical fuselage section and ICUs involving the “bend-frame” concept was numerically simulated, with the main objective to identify the loading conditions that apply at specific sections, notably those surrounding the ICU-frame coupling areas where the test fixtures were to be implemented. As the outcomes of these numerical works showed that bending/compression loading, at a specific ratio, shall be targeted in priority, the accordingly designed loading system thus consisted of articulated rigs maintaining both ends of the demonstrator. The testing was performed at the ONERA-Lille crash tower at a 6,7m/s impact velocity, with a 1050 kg trolley mass. The acquisition system cumulated a total of 48 channels, including force sensors (6), strain gauges (36), displacement laser sensors (5) and an accelerometer (1). Besides, 4 high-speed cameras were implemented to visualize the rupture phenomenon likely to develop during the crash test. Results confirmed the expected crash scenario, with the bending of the cargo cross-beams and the resulting progressive crushing of the TTS components.