| Autor(en) | Adam, Till Julian | Nolte, Felix | Begemann, Benjamin | Horst, Peter |
|---|---|
| Titel | Selective laser illumination method for enhanced damage monitoring of micro cracking and delamination in GFRP laminates |
| Herausgeber | Polymer Testing, 65, S. 125-133 |
| Erscheinungsjahr | 2018 |
| Abstract | Transmitted light photography, microscopy and transmitted light scanning are well-established methods of optical damage characterization in glass fiber-reinforced composites. Subsequent damage evaluation such as determination of crack density and delaminated areas can either be done by hand or by means of image analysis software. Digital image analysis, however, is rather sensitive to damage illumination and contrast. Results tend to be inaccurate when damage states are complex, showing overlapping cracks and delamination. Therefore, a new laser-based illumination method capable of separately illuminating transverse cracks and interfacial delamination is presented. An exemplary [90/0]s cross-ply laminate tested in the very high cycle fatigue range was evaluated using transmitted light photography as well as the new method. |
| Autor(en) | Hannig, André |
|---|---|
| Titel | Static and fatigue transverse crack initiation in thin-ply fibre-reinforced composites |
| Herausgeber | Dissertation, Technische Universität Braunschweig, ISBN 978-3-928628-97-6, NFL, 2018-02 |
| Erscheinungsjahr | 2018 |
| Abstract | This work is part of the Collaborative Research Center (SFB) 880 preparing the scientific basis for future commercial aircraft characterised by low noise emission and extremely short take-off and landing capability. The presented investigations are motivated by a contour-variable leading-edge composite skin which constitutes a key component in such aircraft’s high-lift system. Hereby, a more precise prediction of transverse crack onset is required as proven classic stress criteria turn out to behave very conservative due to the usage of comparatively thin plies and the existence of large bending stress gradients. A nominally 130 µm glass/epoxy prepreg is processed which actually constitutes the thinnest standard-thickness, yet. However, distinctly retarded transverse crack onset is observed. In fact, the local crack initiation stress within laminates stacked from thin laminae may considerably exceed the unidirectional strength as crack formation is energetically unfavourable. Such scenario is denoted as ’thin-ply’ (behaviour) to distinguish it from classical stress triggered cracking. A coupled stress and energy criterion is developed to account for the ’thin-ply’ phenomenon at lamina-level. The key difference between this criterion and existing approaches of such type is the ability to capture the effects of stress gradients and especially local shear loading. The energy release associated with sudden crack formation is determined within the framework of the finite fracture mechanics. For this purpose, a 3D finite element unit-cell is developed which is able to deal with arbitrary shell-type load conditions. The new criterion is validated by means of uniaxial tension and special large bending experiments. So far, most research on ’thin-ply’ laminates is restricted to the scale of the whole laminate. This is especially true in case of fatigue investigations. In fact, impressively superior failure and fatigue characteristics are apparent in contrast to laminates stacked from thicker plies. In order to gain understanding, the new energy criterion as well as a static and a fatigue stress criterion from literature are applied to created large bending crack onset fatigue results. As a key finding, the elevated static ’thin-ply’ cracking resistance can not straightforwardly be extrapolated to fatigue conditions. It is concluded that the source of the reported superior fatigue characteristics at laminate-level is probably found in the effective suppression of secondary failure modes, like induced delamination. |
| Autor(en) | Nolte, Felix | Hannig, André | Horst, Peter |
|---|---|
| Titel | Investigation of integral composite T-joints under mixed mode loading |
| Herausgeber | Key Engineering Materials, Vol. 774, pp. 197-202 |
| Erscheinungsjahr | 2018 |
| Abstract | This paper presents experimental and numerical results on the deformations and failure of integral composite T-joints subjected to a realistic combined tensile and bending (mixed mode) load case. For this reason, standard pull-off and mixed mode load cases are experimentally studied by means of a novel test fixture which keeps the force angle constant to the T-joint’s base and allows for repositioning of the specimen in order to minimize constraining forces. Two types of specimens with varying deltoid radius are investigated. Additionally, kinematically nonlinear numerical simulations are performed to locate damage onset and deformations of the specimens. It is found that the simulations are in good agreement with the experimental results. |
| Autor(en) | Vasista, Srinivas | Nolte, Felix | Monner, Hans Peter | Horst, Peter | Burnazzi, Marco |
|---|---|
| Titel | Three-dimensional design of a large-displacement morphing wing droop nose device |
| Herausgeber | Journal of Intelligent Material Systems and Structures, DOI: 10.1177/1045389X18770863 |
| Erscheinungsjahr | 2018 |
| Abstract | The numerical three-dimensional structural design of a large-displacement flexible morphing wing leading edge, otherwise known as a droop nose, is presented in this article. The droop nose is an essential component of a novel internally blown high-lift system for a transport aircraft to delay stall and reduce internal compressor requirements. A design chain consisting of optimization procedures was used to arrive at the structural design of the droop nose composed of a composite fiberglass skin with integral stringers and supporting kinematic mechanisms. The optimization tools aim to produce a design with minimal error to the critical target shapes. A maximum final error of 10.09 mm between calculated and target trajectories of the stringers was found after the kinematic optimization stage. After inputting the kinematic optimization results into the skin optimization stage and solving, a maximum error in the order of 13 mm and curvature difference 0.0028 1/mm were calculated, occurring in the outboard region. Prior two-dimensional analyses with similar shape deviations showed 0.4% lift reduction though further three-dimensional investigations are required. Concepts for integrating industrial requirements abrasion and lightning strike protection and in-flight de-icing into a multifunctional skin show promise and the resulting aerodynamic surface quality was found to be adequate. |
| Autor(en) | Vasista, Srinivas | Riemenschneider, Johannes | Mendrock, Torsten | Monner, Hans Peter |
|---|---|
| Titel | Pressure-driven morphing devices for 3D shape changes with multiple degrees-of-freedom |
| Herausgeber | Proceedings of the ASME 2018 Conference on Smart Materials, Adaptive Structures and Intelligent Systems, SMASIS2018, San Antonio, United States, 10-12 September 2018, Paper SMASIS2018-7949 |
| Erscheinungsjahr | 2018 |
| Abstract | Early research on a new concept for a morphing system based on unit structures or cells containing pressurized fluid is presented in this article. The motivation stems from the desire to achieve 3D smooth variations with multiple degrees of freedom and variations in surface area. Such a cell is composed of a hybrid between elastomeric material and stiffening material, creating an orthotropic system. When connected in a network of cells, the morphing system is highly integrated in terms of the components of the skin, substructure and actuation means. Numerical predictions of small simple prismatic cells show a force and axial strain capability of above 200 N and 14% respectively for typical elastomeric and stiffening materials at 8 bar pressure. PolyJet™ additively-manufactured models of wings show how such actuators can be integrated into aircraft structures, including when 3D geometry is highly challenging. These additively-manufactured models were operated at low pressures in the order of 0.5 bar, and a number of open questions on the design, manufacture and operation of such structures are discussed along with intended future work towards higher grade materials and working pressures. |
| Autor(en) | Hannig, André | Nolte, Felix | Horst, Peter |
|---|---|
| Titel | EXPERIMENTAL INVESTIGATION OF INTEGRAL COMPOSITE T-JOINTS UNDER MIXED MODE LOADING |
| Herausgeber | 21st International Conference on Composite Materials, China |
| Erscheinungsjahr | 2017 |
| Abstract | This paper presents a novel test fixture for application oriented mixed-mode loading of composite T-joints where the force acts under a constant angle with respect to the T-joint’s base. Furthermore experimental data of glass fibre composite T-joints under angled mixed-mode and pull-off loading is presented for two different deltoid radii. After a short introduction the specimen manufacturing process as well as the experimental set up is described. Finally the failure phenomenology of mixed-mode loaded specimen is presented. |
| Autor(en) | Kauth, Felix | Narjes, Gerrit | Müller, Jan | Seume, Jörg | Vasista, Srinivas | Müller, Thomas | Francois, Daniela | El Sayed, Yosef | Semaan, Richard | Behr, Christian | Schwerter, Martin | Leester-Schädel, Monika | Nolte, Felix | Giesecke, Daniel | Atalayer, Caglar | Radespiel, Rolf |
|---|---|
| Titel | Progress in Efficient High-Lift |
| Herausgeber | AIAA AVIATION Forum, 35th AIAA Applied Aerodynamics Conference, Denver, 2017 |
| Erscheinungsjahr | 2017 |
| Abstract | This paper presents some of the progress in research on efficient high-lift systems for future civil aircraft achieved by the Coordinated Research Centre CRC 880 sponsored by the German Research Foundation. Several new approaches to increasing the lift are applied as part of the design of a reference aircraft with short take-off and landing ca- pability: The numerically predicted positive effect of Coanda jet blowing at the trailing edge flap is validated in water tunnel experiments. Robust miniature pressure and hot- film sensors are developed for the closed-loop control of a piezo-actuated blowing lip. A flexible leading-edge device utilizes composite materials, for which new structural designs are developed. Additionally, a potential de-icing system, as well as a lightning-strike pro- tection are presented. A high power-density electrically driven compressor with a broad operating range is designed to provide the blowing airflow. Different propulsion systems for the reference aircraft are evaluated. An ultra-high bypass ratio engine is considered to be most promising, and thus a preliminary fan stage design process is established. The rotor dynamic influences of the engine on the aircraft structure are investigated through a hybrid approach using a multibody model and modal reduction. |
| Autor(en) | Rudenko, Anton | Hannig, Andre | Monner, Hans Peter | Horst, Peter |
|---|---|
| Titel | Extremely deformable morphing leading edge: Optimization, design and structural testing |
| Herausgeber | Journal of Intelligent Material Systems and Structures, DOI: 10.1177/1045389X17721036 (First Published Date: 4 August 2017) |
| Erscheinungsjahr | 2017 |
| Abstract | The future generation of high-lift devices needs to be improved to reduce the noise footprint and increase the performance for takeoff and landing of transport aircraft. To contribute to these goals, an active blown Coandă flap-based high-lift system is being investigated within the German national Collaborative Research Center 880 as an alternative to the state-of-the-art flaps. A key part of this system is an adaptive gapless droop nose with extremely large morphing deformation. The design and construction of this component are based on a structural optimization framework. The framework consists of two hierarchical design steps: an optimization of the hybrid composite skin layout with integral T-stringers, acting as joints to the inner actuation mechanism, and the kinematic optimization of the latter. A hybrid skin structure allows a large curvature to rupture in the morphing direction, while providing high stiffness in the transverse direction. This article describes a full-scale hybrid composite morphing droop nose and its structural tests. The results of these tests are finally compared to the finite element simulation and applied for validation of the optimization framework. A sensitivity analysis is provided to evaluate the influence of modelling and manufacturing uncertainties to the shape quality. |
| Autor(en) | Sommerwerk, Kay | Woidt, Malte | Haupt, Matthias | Horst, Peter |
|---|---|
| Titel | Reissner–Mindlin shell implementation and energy conserving isogeometric multi-patch coupling |
| Herausgeber | International Journal for Numerical Methods in Engineering, Vol. 109, Nr. 7, S. 982–1012, (2017) |
| Erscheinungsjahr | 2017 |
| Abstract | A shear-flexible isogeometric Reissner–Mindlin shell formulation using non-uniform rational B-splines basis functions is introduced, which is used for the demonstration of a coupling approach for multiple non-conforming patches. The six degrees of freedom formulation uses the exact surface normal vectors and curvature. The shell formulation is implemented in an isogeometric analysis framework for computation of structures composed of multiple geometric entities. To enable local model refinement as well as non-matching domains coupling, a conservative multi-patch approach using Lagrange multipliers for structured non-uniform rational B-splines patches is presented. Here, an additional border frame mesh is used to couple geometries during structural analyses. This frame interface approach avoids the problem of excessive con- straints when multiple patches are coupled at one point. First, the shell formulation is verified with several reference cases. Then the influence of the frame interface discretization and frame penalty stiffness on the smoothness of the results is investigated. The effects of the perturbed Lagrangian method in combination with the frame interface approach is shown. In addition, results of models with T-joint interface connections and perpendicular stiffener patches are presented. |
| Autor(en) | Vasista, Srinivas | Monner, Hans Peter |
|---|---|
| Titel | 3D Design of a Large-displacement Droop-nose Wing Device |
| Herausgeber | VIII ECCOMAS Thematic Conference on Smart Structures and Materials SMART2017, June 5-8 2017, Madrid, Spain |
| Erscheinungsjahr | 2017 |
| Abstract | The 3D structural design of a morphing droop-nose device for a new high-lift system is presented in this paper. This new type of high-lift system is anticipated to reduce airframe noise, takeoff and landing speeds and thus runway length, and be capable of actively producing a range of lift coefficients as per demand. A structural design process using optimization tools was further developed and applied to the case of large target deflections required for this high-lift system. The results of the 3D optimization of thickness distribution, stringer position, and force introduction points on a hybrid fiberglass-elastomeric composite skin showed close agreement to the target shapes under different aerodynamic load cases. The design of a kinematic system of linkages was also performed and upon input actuation the outer surface conformed to the target aerodynamic shapes. Required actuator torque in this design was shown to be high in the order of 3600 Nm thought actuators are available which meet the internal space requirements. Reported strains were within design limits in the order of 1.5%. The design is set to be refined in the near future with manufacturing and ground tests to follow. |
| Autor(en) | Vasista, Srinivas | Rose, Michael | Monner, Hans Peter |
|---|---|
| Titel | Optimization Tool Assessment for a Large-displacement Compliant Morphing Wing Leading Edge |
| Herausgeber | 27th International Conference on Adaptive Structures and Technologies ICAST2016, October 3-5 2016, Lake George, New York, United States |
| Erscheinungsjahr | 2017 |
| Abstract | The design of a mandatory droop-nose morphing device for a new type of passenger aircraft is presented in this work. This work forms one of the subprojects of the Collaborative Research Center 880 in Braunschweig, Germany. The leading edge displacement requires large curvature changes against high external loads and a novel anisotropic hybrid material comprising fiberglass and an elastomer is considered to allow large chordwise displacement and high spanwise stiffness. A number of optimization tools have been developed, such as a skin optimization tool, topology optimization compliant mechanism design tool, and a heuristic genetic algorithm based method. Amongst these approaches, the design philosophies of using conventional or compliant mechanisms are considered. The tools have their advantages and disadvantages, and numerical issues have prevented the further development of the topology optimization tool. Planned demonstrator manufacture and testing of the various design philosophies will provide an insight into which philosophy is more effective. |
| Autor(en) | Rudenko, Anton | Radestock, Martin | Monner, Hans Peter |
|---|---|
| Titel | Optimization, Design and Structural Testing of a High Deformable Morphing Leading Edge of an Active Blown High Lift System |
| Herausgeber | 24th AIAA/AHS Adaptive Structures Conference, AIAA SciTech Forum, 4-8 January 2016, San Diego, California |
| Erscheinungsjahr | 2016 |
| Abstract | The future generation of high lift devices hast to play a part in reducing the noise footprint and increasing the performance for start and landing of transport aircrafts. To contribute to these goals, an active blown Coandă-flap based high lift system is investigated within the German national Collaborative Research Centre 880 as an alternative to the state of the art slats and flaps. A key part of this system is an adaptive gapless droop nose with an exceedingly high grade of leading edge morphing. The design and construction of this component is based on a structural optimization framework, developed at German Aerospace Center (DLR). The framework consists of two hierarchical design steps, an optimization of the hybrid composite skin layout with integral T-stringers, acting as joints to the inner actuation mechanism and the kinematic optimization of the latter. This paper describes a full scale hybrid composite morphing droop nose and its structural tests. The results of these tests will finally be compared with the results of the finite element simulation and applied for the validation of the optimization framework. |
| Autor(en) | Vasista, Srinivas | Rudenko, Anton | Monner, Hans Peter | Hannig, Andre | Horst, Peter |
|---|---|
| Titel | Deformable Morphing Leading Edge of an Actively Blown High Lift System |
| Herausgeber | Greener Aviation, Brussels, Belgium, 13 October 2016 |
| Erscheinungsjahr | 2016 |
| Abstract | The structural and material design of a wing leading edge droop nose morphing device is presented. The need for such a device stems from aerodynamic requirements relating to an internally-blown Coanda flap. The structural design centers upon a novel elastomer-fiberglass skin and optimization algorithms to find the best skin-substructure-actuation topologies. |
| Autor(en) | Schmitz, André | Horst, Peter |
|---|---|
| Titel | Buckling of multiple discrete composite bundles in the elastomeric foundation of a curvature-morphing skin |
| Herausgeber | Composite Structures, Volume 134, Elsevier, 1014-1023 |
| Erscheinungsjahr | 2015 |
| Abstract | A short introduction to curvature-morphing skins is given. The studied structure consists of outer hybrid layers (undergoing large curvature alterations in operation) with unidirectional discrete composite bundles embedded in an ethylene–propylene–diene rubber foundation. This work focusses on the crucial aspect of compressive behaviour along these bundles. In order to achieve a high performance, it is essential that the bundles do not reach their stability limit prior rupture due to exceeding the strength of the structure. Specimens are manufactured and tested in an appropriate set-up under almost real boundary conditions. A finite element unit-cell is implemented and validated. The boundary conditions and the manufacturing tolerances of the hybrid layer are investigated with respect to bundle-buckling. Finally, failure maps depending on key geometry parameters indicate a clear distinction between an out-ofplane and an in-plane buckling mode whereas the latter results in lower critical strains. |
| Autor(en) | Schmitz, Andre | Horst, Peter |
|---|---|
| Titel | DEVELOPMENT AND INVESTIGATION OF A HYBRID CURVATURE-MORPHING SKIN STRUCTURE |
| Herausgeber | 20th International Conference on Composite Materials, Copenhagen, 19-24th July |
| Erscheinungsjahr | 2015 |
| Abstract | A short introduction on curvature-morphing skins is given. The studied structure consists of outer hybrid layers (highly strained in operation due to large curvature alterations) with unidirectional discrete composite bundles embedded in an ethylene-propylene-diene rubber foundation. Within the morphing context, the presented work focusses on the crucial aspect of compressive strength along these bundles. However, large compressive strength is achieved if buckling of the bundles can be avoided. To characterize the buckling behaviour, samples are manufactured and tested in an appropriate set-up under almost real boundary conditions (avoidance of continuous anti-buckling guides). Results are compared to the outcome of numerical linear eigenvalue analyses. |
| Autor(en) | Schmitz, Andre | Horst, Peter |
|---|---|
| Titel | Buckling of multiple discrete composite bundles in the elastomeric foundation of a curvature-morphing skin |
| Herausgeber | Composite Structures, 0263-8223, 134, Elsevier, 1014-1023, 2015 |
| Erscheinungsjahr | 2015 |
| Abstract | A short introduction to curvature-morphing skins is given. The studied structure consists of outer hybrid layers (undergoing large curvature alterations in operation) with unidirectional discrete composite bundles embedded in an ethylene–propylene–diene rubber foundation. This work focusses on the crucial aspect of compressive behaviour along these bundles. In order to achieve a high performance, it is essential that the bundles do not reach their stability limit prior rupture due to exceeding the strength of the structure. Specimens are manufactured and tested in an appropriate set-up under almost real boundary conditions. A finite element unit-cell is implemented and validated. The boundary conditions and the manufacturing tolerances of the hybrid layer are investigated with respect to bundle-buckling. Finally, failure maps depending on key geometry parameters indicate a clear distinction between an out-ofplane and an in-plane buckling mode whereas the latter results in lower critical strains. |
| Autor(en) | Rudenko, Anton | Monner, Hans Peter | Rose, Michael |
|---|---|
| Titel | A Process Chain for Structural Optimization of a Smart Droop Nose for an Active Blown High Lift System |
| Herausgeber | 22ND AIAA/ASME/AHS ADAPTIVE STRUCTURES CONFERENCE / US Washington DC 2014 |
| Erscheinungsjahr | 2014 |
| Abstract | A detailed analysis of today’s commercial aircraft determines an increased demand for high lift systems that cannot be provided by prevailing evolutionary technology development. This especially applies to the topics of noise reduction and performance increase for start and landing. An active blown Coandă-flap based high lift system, which is investigated within the German national Collaborative Research Centre 880, would be an alternative to today’s slats and flaps and promises to contribute to those goals. An adaptive gapless droop nose with an exceedingly high grade of leading edge morphing is proven to be a key part of such a system, and thus a structural optimization framework for this technology is developed by the DLR. The content of this paper is formed by the detailed presentation of the framework for optimization of a composite skin combined with an actuation kinematics. |
| Autor(en) | Schmitz, Andre | Horst, Peter |
|---|---|
| Titel | Numerical modelling of the change in stiffness properties of cross-ply laminates subjected to large bending curvatures |
| Herausgeber | Key Engineering Materials, 978-3-03785-830-1, 577-578, Trans Tech Publications, 173-176 |
| Erscheinungsjahr | 2014 |
| Abstract | This paper presents a 3D unit-cell approach which enables the estimation of bending, inplane and coupling stiffness properties in the sense of the classical laminated plate theory for arbitrarily heterogeneous plates. Periodic boundary conditions which simultaneously allow for in-plane as well as for bending and twist deformation modes are introduced. Additionally, bending experiments of glass-fibre/epoxy cross-ply laminates with cracked outer layer at the tension side are conducted and the stiffness degradation due to these transverse cracks is compared to numerical results. |
| Autor(en) | Schmitz, Andre | Horst, Peter |
|---|---|
| Titel | Bending deformation limits of corrugated unidirectionally reinforced composites |
| Herausgeber | Composite Structures, ISSN: 0263-8223, 107, Elsevier Ltd., 103–111 |
| Erscheinungsjahr | 2014 |
| Abstract | This paper concerns about deformation limits of circular corrugated unidirectional reinforced composites for bending dominated applications. Hence, a two-dimensional analytical stress function approach is used which takes through-thickness normal stresses into account. Hereby, the possible failure modes, namely fibre fracture and layer delamination, of unidirectional laminated circular corrugated sheets are predicted. Additionally, the accurate representative bending stiffness in corrugated-direction is extracted by using an energy approach. The influence of corrugation geometric parameters on deformation limits and stiffness is experimentally as well as theoretically investigated. For this reason, large curvature validation experiments of four different corrugation types are conducted by means of a specially constructed bending device. Finally, bending charts are provided facilitating the choice of an appropriate corrugation geometry during a preliminary design phase. |
| Autor(en) | Schmitz, Andre | Horst, Peter |
|---|---|
| Titel | A new curvature morphing skin: manufacturing, experimental and numerical investigations |
| Herausgeber | 16th European Conference on Composite Materials, Seville, Spain, 2014 |
| Erscheinungsjahr | 2014 |
| Abstract | Currently, the aerospace sector tries to bring morphing technology into application in order to improve flight performance, reduce noise and extend the operational envelope. This work presents a new curvature morphing skin which is intended to be applicable at a highly contourvariable airliner’s droop nose. The key characteristic of such skin is a large curvature at rupture in droop-direction while simultaneously providing a high perpendicular sti ness. Hence, two manufacturing processes for a hybrid composite-elastomer skin have been developed. After introducing the structural concept with the appropriate manufacturing processes, large bending experiments are presented. Finally, in order to gain further understanding, some numerical investigations are performed by using a finite element unit-cell. |
| Autor(en) | Schmitz, Andre | Horst, Peter |
|---|---|
| Titel | A finite element unit-cell method for homogenised mechanical properties of heterogeneous plates |
| Herausgeber | Composites Part A, ISSN: 1359-835X, 61, Elsevier Ltd., 23-32 |
| Erscheinungsjahr | 2014 |
| Abstract | This paper presents a 3D unit-cell approach which enables estimations of all bending, in-plane and coupling properties in the sense of the classical laminated plate theory for heterogeneous plates. For this reason, periodic boundary conditions which simultaneously allow in-plane as well as bending/twisting deformation modes are introduced. In contrast to existing approaches, the 3D unit-cell is connected with the macroscopic plate theory by means of prescribed loads and the extraction of strains/curvatures. Novel bending experiments at large curvatures of E-glass-fibre/epoxy cross-ply laminate with cracking outer ply at the bending tension side are conducted. Subsequently, numerical results are validated by comparing them to the measured bending stiffness degradation. Further, the effects of the single-sided transverse cracks on relevant stiffness properties are computed. |
| Autor(en) | Rudenko, Anton | Rose, Michael | Monner, Hans Peter |
|---|---|
| Titel | Optimization Framework for Stiffness and Layout Tailoring of a Morphing High Lift System |
| Herausgeber | 6th ECCOMAS Conference on Smart Structures and Materials / Turin 2013 |
| Erscheinungsjahr | 2013 |
| Abstract | At the Institute of Composite Structures and Adaptive Systems (FA, Prof. Wiedemann) of the DLR a process chain for development of flexible and gapless wing leading edge is being evolved within the framework of the collaborative research centre SFB880. The main topic of the research is to achieve the exceedingly high grade of leading edge morphing which is a key technology for realizing an active blown Coand˘a-flap based high lift system. The overall smart droop nose concept was formed in cooperation with Airbus and EADS, whereby the DLR Institute FA dealt with the design and manufacturing technologies of the morphable composite skin. Due to the fact that the novel high lift system in SFB880 requires considerably more droop (>300%) than achieved before, a new approach based on optimization of the skin and the actuation kinematics in a loop was chosen. An additional feature of the new approach is the application of compliant mechanisms for a beneficial distribution of the skin loads. The content of this paper is formed by the detailed presentation of the framework for topology optimization of a composite skin combined with an actuation kinematics established at the institute FA of the DLR. |
| Autor(en) | Schmitz, Andre | Horst, Peter |
|---|---|
| Titel | Bending deformation limits for corrugated morphing skins |
| Herausgeber | 19th International Conference on Composite Materials, Montréal, Canada, 2013 |
| Erscheinungsjahr | 2013 |
| Abstract | Corrugated composites are widely considered as candidates for morphing applications. This presentation extends the understanding of corrugated composites with respect to deformation limits for static bending deformations. For this reason, the curvature at rupture due to layer delamination and fiber fracture of corrugated samples is predicted and compared to appropriate experimental results. Four different sample types are manufactured from unidirectional carbon-fiber/epoxy laminate. Bending experiments are conducted using a specially designed device which subjects the samples to an almost pure state of bending. |
| Autor(en) | Seume, Jörg | Burnazzi, Marco | Schwerter, Martin | Behr, Christian | Rudenko, Anton | Schmitz, Andre | Dörbaum, Michael | Atalayer, Caglar |
|---|---|
| Titel | SFB 880 – Efficient High Lift |
| Herausgeber | 62nd DLRK, Stuttgart, Germany, 2013 |
| Erscheinungsjahr | 2013 |
| Abstract | The collaborative research center (Sonderforschungsbereich, abbreviated SFB) 880 investigates the fundamentals of high-lift generation for future civil aircraft, focusing on the fields of aeroacoustics, lift generation and flight dynamics. The present paper addresses the research on efficient lift generation which is denoted as Research Area B. The underlying research hypothesis of the present work is that further significant increases in lift generation of civil aircraft compared to the current state technology are possible using active lift systems. The investigated high-lift concept utilizes a combination of internally blown flaps and circulation control to achieve high flow turning over the wing. A flexible leading edge device for the wing without gap or step is designed to reduce noise generation and to increase the efficiency of the active blowing system. Further, closed-loop control of blowing is envisaged. The overall objective of the project is to design an active lift system that requires a minimum of additional engine power to generate the required lift. A multidisciplinary, collaborative approach is taken, combining the fields of aerodynamics, material science, microtechnology, turbomachinery and electrical engineering to obtain optimum performance of the overall lift generation system. The research progress during the first two years of this ongoing work is presented in this paper. |