DLR Research Overview on Crash and High Velocity Impact

The presentation overviews the DLR research activities on crash and high velocity impact (HVI) over the last decade. The improvements to crash and HVI simulation methodologies, enhancement of high rate material testing, development of crash and HVI shielding structural concepts for helicopters, transport aircraft (A/C) and other vehicles (cars, trains), parts of the crashworthiness (CW) substantiation of the NH90, and the participation in numerous EU and national crash safety and HVI related projects will be discussed. Major parts of crash and HVI simulation methods comprise the development of improved or new composite damage models for the crash/HVI code PAM-CRASH in co-operation with ESI (fabric model and a damage mechanics based model) including models for the impactor (bird, ice, stone). Additionally, local/global approaches for full-scale helicopter and A/C crash simulation, as well as simulation approaches for A/C ditching and helicopter crashes on water including the Lagrange representation of the water bloc and applying the Smooth Particle Hydrodynamics (SPH) are of increasing importance. The capabilities of high rate material testing was enhanced by the installation of a high speed testing machine (Instron VHS 100/20) and the development of appropriate test specimens and test procedures. These databases enable systematic parameter identification for new or improved composite/metal material models which are used in the crash and HVI codes. Structural concepts were focused on CW helicopter sub-floors and on landing gear crash absorbers, and on CW concepts for transport A/C fuselage sections. For the ICT train front ends, heavy duty crash absorbers were developed and certified; they are in series production since 1997. Furthermore, a car steering column crash absorber was developed suited for mass production which is in series production since 2001. For the CLK-DTM racing car, the front and rear crash boxes were designed and successfully certified at TRL in 2000; a modification of the front crash box passed the qualification in 2003 successfully. Over several years, parts of the crashworthiness substantiation tests of NH90 sub-structures were performed in cooperation with ECD comprising sub-floor panels, intersection components, sub-floor box section with tank bladder and the complete bulkhead No. 6. In addition, a PAMCRASH study of the main landing gear attachment area (hard point) and a modification of the NH90 KRASH model were performed. The project involvements span frameworks 3 to 5 of the EU Crashworthiness of Commercial Transport A/C, CRASURV and HICAS (HVI), CRAHVI (crash/HVI), CAST (helicopter water impact) and HeliSafe (occupant protection) as well as the national programmes Schwarzer Rumpf and the CFRP-Fuselage phase 1/LuFoII. DLR and ONERA/Lille (DMSE) perform helicopter related crash/HVI research in a joint team within the framework of the research Concept 4 The Safe Rotorcraft which started in 2000. Since the beginning of 2003, also transport A/C crash/HVI research is conducted as a joint team within the Target Field Aircraft Structural Integrity under Extreme Loads