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Braunschweig, Germany

Lancelle D.,German Aerospace Center | Bozic O.,German Aerospace Center | Martinez Schramm J.,German Aerospace Center | Linke S.,INVENT GmbH
IEEE Transactions on Plasma Science | Year: 2011

The technology of electromagnetic driven Lorentz rail accelerators (LRAs) has been significantly improved in the last years. Due to the extreme acceleration in LRA systems, there are high demands regarding the mechanical stresses. It is assumed that materials can withstand stresses exceeding the nominal limits related to static conditions if they are applied for a short time. To assess the short-time material strength of a hydroxyl-terminated- polybutadiene rocket fuel grain, experiments shall be carried out using the High-Enthalpy Shock Tunnel Gttingen of the German Aerospace Center in Gttingen as a high-acceleration test facility. In the first step, different samples of the rocket fuel grain and composite materials are tested under high acceleration and analyzed by a visual check. In this paper, first of all, different samples of the rocket fuel grain and composite materials are tested under high acceleration and analyzed by a visual check. In the second step, onboard electronics mounted on the piston are developed to collect the data of the strain and the deformation of the composite/fuel grain and to directly measure the acceleration. With this electronically enhanced specimen, another test is carried out, and measurement data are acquired. The evaluated experiments shall provide useful information to design a hybrid rocket engine for a small launcher, capable to be launched from an LRA. © 2010 IEEE. Source

Heimbs S.,Airbus | Schmeer S.,University of Kaiserslautern | Blaurock J.,University of Kaiserslautern | Steeger S.,INVENT GmbH
Composites Part A: Applied Science and Manufacturing | Year: 2013

An experimental test series of mechanically fastened bolted joints with countersunk head in quasi-isotropic carbon/epoxy composite laminates under quasi-static and dynamic loads with velocities up to 10 m/s has been conducted in order to investigate potential strain rate effects on the failure behaviour. The test campaign covered bolt pull-through tests, single lap shear tests with one and two bolts and coach peel tests. Identical test equipment has been used for the whole range of test velocities to avoid influences of different test machines. No rate sensitivity occurred for most test configurations. Only the single lap shear tests with two bolts showed a change of failure mode at the highest test velocity enabling higher energy absorption. © 2013 Elsevier Ltd. All rights reserved. Source

Benedix W.-S.,TU Dresden | Plettemeier D.,TU Dresden | Zanoni A.,Sudan University of Science and Technology | Preller F.,INVENT GmbH | Ciarletti V.,University of Versailles
IEEE International Conference on Wireless for Space and Extreme Environments, WiSEE 2013 - Conference Proceedings | Year: 2013

The Experiment 'Water Ice and Subsurface Deposit Observations on Mars' (WISDOM) is a Ground Penetrating Radar (GPR) selected to be part of the Pasteur payload on board the rover of European Space Agency's (ESA) ExoMars 2018 mission. The GPR antenna system described in this paper is the consequent progression of former developments [1, 2] incorporating changed requirements and further optimizations. Main constraints are the mass, the temperature range as well as the ultra-wide band demand. The antenna requirements which are to fulfill for this very specific GPR application are described here. Furthermore, it is given an overview about the lightweight design and its realization. Simulated and measured antenna performance is compared in this paper. © 2013 IEEE. Source

Geier S.,German Aerospace Center | Kintscher M.,German Aerospace Center | Heintze O.,INVENT GmbH | Wierach P.,German Aerospace Center | And 2 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012

Natural laminar flow is one of the challenging aims of the current aerospace research. Main reasons for the aerodynamic transition from laminar into turbulent flow focusing on the airfoil-structure is the aerodynamic shape and the surface roughness. The Institute of Composite Structures and Adaptive Systems at the German Aerospace Center in Braunschweig works on the optimization of the aerodynamic-loaded structure of future aircrafts in order to increase their efficiency. Providing wing structures suited for natural laminar flow is a step towards this goal. Regarding natural laminar flow, the structural design of the leading edge of a wing is of special interest. An approach for a gap-less leading edge was developed to provide a gap- and step-less high quality surface suited for natural laminar flow and to reduce slat noise. In a national project the first generation of the 3D full scale demonstrator was successfully tested in 2010. The prototype consists of several new technologies, opening up the issue of matching the long and challenging list of airworthiness requirements simultaneously. Therefore the developed composite structure was intensively tested for further modifications according to meet requirements for abrasion, impact and deicing basically. The former presented structure consists completely of glass-fiber-prepreg (GFRP-prepreg). New functions required the addition of a new material-mix, which has to fit into the manufacturing-chain of the composite structure. In addition the hybrid composites have to withstand high loadings, high bending-induced strains (1%) and environmentally influenced aging. Moreover hot-wet cycling tests are carried out for the basic GFRP-structure in order to simulate the long term behavior of the material under extrem conditions. The presented paper shows results of four-points-bending- tests of the most critical section of the morphing leading edge device. Different composite-hybrids are built up and processed. An experimental based trend towards an optimized material design will be shown. © 2012 SPIE. Source

Pfeiffer E.K.,HPS GmbH | Reichmann O.,HPS GmbH | Ihle A.,HPS GmbH | Linke S.,INVENT GmbH | And 7 more authors.
Proceedings of the 5th European Conference on Antennas and Propagation, EUCAP 2011 | Year: 2011

In November 2010 the thermo-mechanical test campaign of a Ka-Band multi beam dual reflector antenna structure has been successfully finished. The innovation of this structure lies in the full CFRP sandwich design (including honeycomb core), the use of ultra high modulus fibres for all reflectors, tower panels, base panel, curved cleats, etc.) and in the bonded intersections (e.g. between base panel and tower structure), thus, reducing the in-orbit thermo-elastic distortion to a minimum. In addition, the extremely low mass to high stiffness ratio is unique for European antenna structures. The interfaces to the spacecraft are titanium isostatic mounts compensating a possible CTE mismatch with the spacecraft top deck. The paper presents not only the design and the results of the dynamic test campaign, but also the innovative highly accurate thermo-elastic measurements performed under vacuum conditions using an ESPI measurement system and FBG optical sensors. Parent to the full CFRP antenna structure technology is the development of a new concept of Ku/Ka-Band dual gridded reflector (DGR): the front grid consists for e.g. a 1.2 m reflector of approx. 700 CFRP rods. The rear reflector can either be made of a solid full CFRP reflector shell or out of a second grid, which would lead to a revolutionary low DGR weight. The paper summarizes the results of the developments performed so far, up to the goal of first concepts for shaping the reflector grids, which would enhance significantly the application possibilities. © 2011 EurAAP. Source

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