Fatigue
-
Evaluation and modelling of the fatigue damage behaviour of polymer composites at reversed cyclic loadingThe object of this joint research project (ISD - Leibniz Universität Hannover, ILK - TU Dresden, IKV - RWTH Aachen, IPC - TU Hamburg-Harburg) is the investigation of damage to continuous fibre-reinforced plastics caused by cyclic loading with load reversals. The main focus is on the physically based generalisation of existing damage evolution models as an essential part of the fatigue damage prediction of composite structures. Independent of the scale level considered, the type and amount of damage under cyclic loading is determined mainly by the imposed mean stress and amplitude and thus by the orientation of the varying load vector regarding to fibre direction. In the research project the damage phenomena and the degradation behaviour are analysed in detail by means of cyclic tests on microscopic model composites, single layers and laminates using optical stress analysis and in-situ computer tomography. With the help of further numerical analyses at micro level, physically based mathematical expressions are formulated for different stress ratios. The mathematical approaches developed are implemented in the FE-based fatigue damage model of the ISD, for which first validations for pulsating cyclic loads have already been carried out. Thus, it will be possible to overcome the current limitation of the known model approaches to mostly constant amplitude pulsating loading and to make an essential development step towards a realistic lifetime analysis of composites under variable amplitude loading.Led by: Prof. Dr.-Ing. habil. Raimund RolfesTeam:Year: 2015Funding: German Research Foundation(DFG) -Project number 281870175Duration: 01.04.2016-31.10.2019
![]()
![]()
-
Global-local thermomechanical analysis of fracture in polycrystalline silicon shells using a phase-field approach.The photovoltaic (PV) modules containing multiple polycrystalline silicon solar cells (PSSCs) are one of the most common and widely used devices for the production of solar energy. However, the energy production efficiency degrades during their lifespan, which can be primarily associated with the cracking in a polycrystalline silicon wafer (PSW). The aim of this joint research project (ISD - Leibniz Universität Hannover, IAM - TU Braunschweig) is to evaluate the overall stiffness degradation of polycrystalline silicon solar cells (PSSCs) due to microcracking. PSSCs are intricate component consisting of multiple materials and modeling becomes computationally expensive. Therefore, modeling reduction techniques such as numerical homogenization were employed for evaluating the effective material properties of PSSCs including cracks. The cracks are to be modeled using a phase-field approach. An improved Voronoi-tessellation scheme was used to generate polycrystalline patterns of the PSW and a mean-field homogenization scheme was employed to determine the homogenized response of PSSCs. The accuracy of the homogenization scheme was verified and the material response of the heterogeneous and homogeneous PSSCs was compared.Led by: Prof. Dr-Ing. habil. Raimund RolfesTeam:Year: 2018Funding: DFG, German Research FoundationDuration: 01.08.2018 - 31.07.2021
![]()
![]()
-
Challenges of industrial application of nanomodified and hybrid material systems in lightweight rotor blade design (HANNAH)The HANNAH research project is the follow-up to the LENAH research project. In LENAH, material systems from the fields of nanomodified materials and hybrid laminates were developed, tested and numerically simulated. This allowed the high potential of these material systems for the application in rotor blade design to be demonstrated under laboratory conditions. The investigated material systems are far superior to currently established materials, especially with regard to fatigue resistance. In the follow-up project HANNAH the (further) development of production and simulation methods for these material systems for industrial standards is now in the foreground. On the one hand, the aim is to guarantee the excellent properties of the developed material systems in large-scale production and to be able to simulate the mechanical behaviour to answer industry-related issues. In this context, the ISD develops material-specific simulation models in order increase time and cost efficiency for processes of material development and component design for nanomodified materials and hybrid laminates.Led by: Prof. Dr-Ing. habil. Raimund RolfesTeam:Year: 2019Funding: Bundesministerium für Wirtschaft und Energie (BMWI) - FKZ 0324345ADuration: 01.03.2019 – 28.02.2022
![]()
![]()
-
New methods for failure and fatigue analysis of suction panels for laminar flow controlAlthough the suction panel concept holds a high potential to increase the sustainability of future aircrafts, it comes with some structural mechanical challenges that need to be carefully examined. With the panel’s underlying backbone structure adopting the load-carrying function of the outer airfoil in the suction area (see Fig. 1), the stress flux in the airfoil is considerably disturbed, resulting in multiple, potentially critical stress concentrations. To ensure a sufficient robustness of the suction panel concept in terms of static strength and fatigue resistance, the backbone structure is to be analyzed numerically by means of finite element simulations. With deep knowledge in the field of continuum damage mechanics and progressive fatigue analysis, ISD will perform high fidelity strength and fatigue analyses of the backbone structure to identify sufficiently robust designs of the backbone structure. To calibrate the numerical methods, experimental coupon tests of the backbone structure’s base material are scheduled to identify respective static and fatigue-related material properties. Beside the identification of mechanically robust designs of the suction panel, the numerical simulations are also to address topics like scalability of the suction concept and the benefits of thin ply laminates, which are well known to feature a superior fatigue resistance.Led by: Prof. Dr-Ing habil Raimund RolfesTeam:Year: 2019Funding: DFG, German Research FoundationDuration: 01.04.2019-31.12.2022
-
SE2A-Excellence Cluster sustainable and energy efficient aviationAlthough the suction panel concept holds a high potential to increase the sustainability of future aircraft, it comes with some structural mechanical challenges that need to be carefully examined. With the panel’s underlying backbone structure adopting the load-carrying function of the outer airfoil in the suction area, the stress flux in the airfoil is considerably disturbed, resulting in multiple, potentially critical stress concentrations. To ensure sufficient robustness of the suction panel concept in terms of static strength and fatigue resistance, the backbone structure is to be analyzed numerically employing finite element simulations. With deep knowledge in the field of continuum damage mechanics and progressive fatigue analysis, ISD will perform high-fidelity strength and fatigue analyses of the backbone structure to identify sufficiently robust designs of the backbone structure. From the mechanical standpoint, thin-ply (TP) laminates are known to have better static strength and fatigue resistance in contrast to conventional laminates. A well-established fatigue damage model (FDM) was calibrated and modified in order to consider the influence of ply thickness under static and cyclic loading.Led by: Prof. Dr-Ing. habil. Raimund RolfesTeam:Year: 2019Funding: DFG, German Research FoundationDuration: 01.04.2019-31.12.2022
![]()
![]()
-
Modeling and simulation of the fatigue damage behavior of fiber composites under variable block loading conditionsThe goal of this research project is the extension and application of a progressive fatigue damage model for unidirectional multi-layered fiber composites for damage analysis under variable cyclic block loading patterns. The focus is on the development of damage evolution laws to accurately predict the degradation of strength and stiffness properties based on the load direction and the stress level. In addition to the influence of load sequence effects, particular attention will be paid to the effects of passive damage occurring under combined cyclic tension and compression loading. Finally, the extended fatigue damage model is to be applied to a fuselage structure segment of a future passenger aircraft for fatigue analysis.Led by: Prof. Dr.-Ing. habil. Raimund RolfesTeam:Year: 2020Funding: Internes ProjektDuration: seit 2020
![]()
![]()
-
Experimental analysis and numerical modelling of microcrack induced delaminations under cyclic loading with load reversalsThe aim of this joint research project (ISD - Leibniz Universität Hannover, ILK - TU Dresden) is to develop a profound understanding of the damage process during delamination growth in fibre-reinforced polymer laminates (FRP) based on existing inter fibre failures during cyclic loading with load reversals. By analysing and quantifying the relevant damage processes during loading, the influence of the level and direction of the applied load on delamination growth in FRP laminates is clarified. Based on the experimental work, detailed numerical simulations on a macro- and mesoscopic level are developed which allow a purposeful analysis of the delamination process in DCB- and ENF- as well as in laminate experiments. Thus, the delamination length-dependent analysis of the fracture modes, which cannot be implemented experimentally, is made possible. Consequently, it is analysed whether characteristic values determined by standardised crack propagation investigations (DCB, ENF etc.) can be transferred to embedded layers. In addition, the investigations provide extensive experimental results on the delamination process in FRP laminates under in-plane loading and thus create a basis for the development of suitable analytical and numerical models. It is investigated to what extent existing numerical damage models (e.g. cohesive zone approaches) allow reliable and efficient modelling of cyclic delamination growth and how the mesoscopic simulation results can be used for macroscopic simulations in terms of continuum mechanics.Led by: Prof. Dr.-Ing. habil. Raimund RolfesTeam:Year: 2021Funding: German Research Foundation (DFG) - Project number 457043708Duration: 01.09.2021-31.08.2023
![]()
![]()
-
Fatigue behavior and fatigue damage prediction of short fiber - reinforced adhesives in Blades of wind turbine (Add2ReliaBlade)The reliability of rotor blades has a special importance for a safe and economic operation of wind turbines (WT). Turbine manufacturers have gained a lot of experience in the design of rotor blades and damage during operation over the past decades. Nevertheless, cracks in the rotor blade structure are still causes of costly repairs and operational failures. This indicates that there are still knowledge gaps in the design of fatigue damage in rotor blades, which is especially (but not exclusively) true for rotor blade bonding. To address these knowledge gaps and increase rotor blade reliability, the Add2RelaiBlade project was established in 2021 as a complementary addition to the ReliaBlade project. The focus of the Add2ReliaBlade project is on the development, characterization and validation of simulation methods and models for the description of the (fatigue) damage behavior of (short fiber reinforced) adhesive joints in rotor blades. The focus is on trailing edge bonding, as this is particularly susceptible to damage. This sub-project provides substantial contributions in the context of extended material testing and non-destructive imaging for short fiber reinforced adhesives, modeling of the spatial distribution of fiber orientation in short fiber reinforced trailing edge bonding, continuum mechanical and energy based modeling of the fatigue damage behavior of (short fiber reinforced) bonded joints as well as the establishment of data based methods of numerical mechanics for the analysis of fatigue damage of short fiber reinforced bonded joints.Led by: Prof. Dr.-Ing. habil. Raimund RolfesTeam:Year: 2021Funding: Federal ministry for Economic Affair and EnergyDuration: 01.05.2021-30.4.2024
Structures
-
Development of a safety cockpit for gliders (CraCpit)In the joint project "CraCpit", the partners are developing solutions for a safety cockpit for gliders. The LCC and the Akaflieg München at the TU Munich are concentrating on the new development of a cockpit structure, while the ISD and the Akaflieg Hannover at the Leibniz Universität Hannover (LUH) are addressing a retrofit solution for existing aircraft types. The goal of the partners at the LUH is the design and the certifiable draft of retrofittable structural elements for the production of a safety cockpit in older, existing glider types according to current requirements. In the event of a crash, cockpit structures are subjected to high stresses that lead to large deformations and material failure. The retrofitted structural components take on different (opposing) functions, such as ensuring the pilot's survival space or energy dissipation to reduce the impact. The effectiveness of the individual components can be assessed and optimised using FEM simulations. For this purpose, appropriate material formulations are required that are able to physically represent the structural response from the onset of loading far into the post-failure range with sufficient accuracy. The focus of the work at the ISD lies in the material modelling, the simulation and the evaluation of the component function of the retrofit elements. The validation of the material models is carried out through tests at sub-component level. After the optimisation of the components through simulation, a test at the structural level (simulation of the entire fuselage and crash test of an example fuselage (prototype)) concludes the project. The experimental work is carried out in close cooperation with the partner Akaflieg Hannover e.V.. For this purpose, various test specimens and prototypes will be built and tested. In addition, an industrial partner will be involved to ensure commercial exploitation.Led by: Prof. Dr-Ing habil. Raimund RolfesTeam:Year: 2017Funding: Federal Ministry for Economic Affairs and Energy – 20E1703DDuration: 2018-2021
![]()
![]()
-
Improved structural performance through the use of random field analysisThe research performed within this project uses the effect of random variations in structure’s geometry and/or material to get information on local sensitivity of structures to deviations from their baseline value. This information cannot only be useful in quality assurance, by finding areas most sensitive to deviations, but can also be used to improve the design. This approach can load to an increase in structural parameters such as buckling load, fatigue life and others.Led by: Prof. Dr-Ing habil. Raimund RolfesTeam:Year: 2019Funding: SE²A excellence, Cluster of DFGDuration: 2019-2022
-
Multistable Morphing Structures using Variable Stiffness CompositesThe research project aims at developing multistable structures with morphing capabilities. A variable stiffness composite is used which allows stiffness tailoring with much larger design space. The developed semi analytical method is validated well within a Finite element framework. In this work, the concept of static, smart and dynamic actuations are exploited on bistable laminates to reduce the snap-through requirements.Led by: Prof. Dr-Ing habil. Raimund RolfesTeam:Year: 2019Funding: Deutscher Akademischer Austauschdienst (DAAD)Duration: 2019-2021
-
FANFOLD – Fast nonlinear machine learned analysis for rotor bladesThe performance and reliability of the rotor blade is crucial for the efficiency of a wind turbine. The blades account for a large part of the turbine costs - their repair and maintenance costs are comparatively high. Rotor blades need to be less prone to failure and less often in need of repair. Concepts of predictive maintenance and the digital twin, which will probably account for a significant part of the profits in the rotor blade market in the future, also point in this direction of reducing repair and maintenance costs. A prerequisite for the implementation of the above concepts is a fast analysis method for fibre composite structures (prediction and evaluation of damage progression and service life). For the overall simulation of the rotor blade, FE analyses using linear-elastic material models are used today. Non-linear effects due to damage or even continuous damage evolution must be investigated on a smaller scale by means of experiments or detailed simulations. In order to go one step further and, for example, to record the influence of non-linear, progressive damage processes on the aeroelasticity and service life, or in order to be able to base the quasi-static simulation in the design on less conservative reduction factors, the overall simulation on the rotor blade would have to be carried out directly taking progressive damage processes into account (load redistribution effects). Obstacles so far are the too high calculation effort and the costly experimental characterisation of existing material models. Two main topics are to be addressed in order to meet these challenges: 1. development of a new, non-linear and fast structure simulation at blade level 2. reduction of the material characterisation effort through machine learning The aim of this sub-project is a valid, efficient and cost-effective non-linear rotor blade simulation as mentioned under point one.Led by: Prof. Dr-Ing. habil. Raimund RolfesTeam:Year: 2020Funding: Federal Ministry for Economic Affairs and Energy – FKZ 03EE3028ADuration: 2020 –2023
![]()
![]()
Nanocomposites
-
Acting Principles of Nano-Scaled Matrix Additives for Composite Structures (FOR 2021)The research project aims at gaining a comprehensive understanding of the acting mechanism of nano-scaled additives to polymer matrices of continuous fibre reinforced polymer composites with respect to improved matrix dominated properties. Particularly, a sequential multi-scale simulation scheme for the prediction of mechanical properties is developed, ranging from particle-matrix interactions on nano scale up to fibre reinforced materials on micro/meso scale. It combines Finite Element and atomistic simulations based on the Molecular Dynamic Finite Element Method (MDFEM).Led by: Prof. Dr-Ing. habil. Raimund RolfesTeam:Year: 2017Funding: Deutsche Forschungsgemeinschaft (DFG)Duration: 01.07.2017 – 31.10.2020
![]()
![]()
-
Challenges of industrial application of nanomodified and hybrid material systems in lightweight rotor blade design (HANNAH)The HANNAH research project is the follow-up to the LENAH research project. In LENAH, material systems from the fields of nanomodified materials and hybrid laminates were developed, tested and numerically simulated. This allowed the high potential of these material systems for the application in rotor blade design to be demonstrated under laboratory conditions. The investigated material systems are far superior to currently established materials, especially with regard to fatigue resistance. In the follow-up project HANNAH the (further) development of production and simulation methods for these material systems for industrial standards is now in the foreground. On the one hand, the aim is to guarantee the excellent properties of the developed material systems in large-scale production and to be able to simulate the mechanical behaviour to answer industry-related issues. In this context, the ISD develops material-specific simulation models in order increase time and cost efficiency for processes of material development and component design for nanomodified materials and hybrid laminates.Led by: Prof. Dr-Ing. habil. Raimund RolfesTeam:Year: 2019Funding: Bundesministerium für Wirtschaft und Energie (BMWI) - FKZ 0324345ADuration: 01.03.2019 – 28.02.2022
![]()
![]()
-
Functionalized, multi-physically optimized adhesives for inherent structural health monitoring of rotor blades (Func2Ad)The performance and reliability of the rotor blade is crucial for the efficiency of a wind turbine over its entire life cycle. The blades make up a large part of the equipment cost - their manufacturing and maintenance costs are extremely high. The adhesive technology in the rotor blade is a key technology for achieving competitive advantages in the wind industry. The processing and curing properties (processability) of the adhesives as well as their operational stability (fatigue strength) in the cured state are two key parameters with regard to the system economy and the return on investment. A third would be the remote diagnosis of the glued joints of the rotor blade (Structure Health Monitoring). The research project proposed here on particle-modified adhesive systems for the wind industry starts with the three points mentioned. A main innovation is the functionalization of the adhesive resin through particle modification to implement a structural monitoring system inherent in the adhesive connections on the rotor blade. This is said to be done by modifying the electrical properties of the adhesive resin. At the same time, the processability and fatigue strength of the adhesive should be positively influenced by the modification. If the modified resin system is only optimized for one of the three aspects mentioned, there is a risk of poor performance with regard to the other. The physical properties of the adhesive must therefore not be separated for the three requirement areas, but must be considered and optimized together in their interaction and their interrelationships. In order to optimize this and increase the efficiency of the multiphysical material models, machine learning methods are used within the simulation framework.Led by: Prof. Dr-Ing. habil. Raimund RolfesTeam:Year: 2023Funding: Bundesministerium für Wirtschaft und Klimaschutz, FKZ 03EE3069 A-FDuration: 01.01.2023-31.12.2026
![]()
![]()
Material Modeling
-
Virtual Materials and their Validation: German-French School of Computational Engineering (ViVaCE)Compressive failure mechanism of unidirectional fibre composites has been studied extensively over the past decades. Stochastic fibre misalignments were identified as an essential factor in the prediction of compressive strength. There is a need to characterize the effects of distribution of misalignment on the strength values in compressive regime. Hence, the scope of this project is to further the development in this regard and extend the definition of failure surfaces under compressively dominated loads by statistical information. A probabilistic definition of failure surface based on imperfections at micro level, and a subsequent experimental validation are the goals of the project. This would lead to subsequent better representation of material properties at the macro scale.Led by: Prof. Dr-Ing. habil. Raimund RolfesTeam:Year: 2016Funding: Deutsche Forschungsgemeinschaft – DFG (International Research and Training Group IRTG1627)Duration: 01.12.2016 – 30.09.2019
![]()
![]()
-
Development and validation of a virtual process chain for composite structural components considering imperfections with application to a rotor blade component (Prosim R)Within the scope of this research project, the essential parts of the process chain in the production of a rotor blade are to be numerically simulated and fundamentally investigated. The primary goal is the reduction of defects in the production of fiber composite materials with the help of simulating the full process chain (manufacturing simulation and structural analysis). In order to obtain a statement on material behaviour and progressive failure, the ISD will extend the sequential multi-scale analysis by including imperfections at the ISD. The results of the draping and infusion simulation are thereby the input information.Led by: Prof. Dr-Ing. habil. Raimund RolfesTeam:Year: 2017Funding: German Research Foundation (DFG) - Project number 329147126Duration: 01.08.2017 – 31.07.2020
![]()
![]()
-
Challenges of industrial application of nanomodified and hybrid material systems in lightweight rotor blade design (HANNAH)The HANNAH research project is the follow-up to the LENAH research project. In LENAH, material systems from the fields of nanomodified materials and hybrid laminates were developed, tested and numerically simulated. This allowed the high potential of these material systems for the application in rotor blade design to be demonstrated under laboratory conditions. The investigated material systems are far superior to currently established materials, especially with regard to fatigue resistance. In the follow-up project HANNAH the (further) development of production and simulation methods for these material systems for industrial standards is now in the foreground. On the one hand, the aim is to guarantee the excellent properties of the developed material systems in large-scale production and to be able to simulate the mechanical behaviour to answer industry-related issues. In this context, the ISD develops material-specific simulation models in order increase time and cost efficiency for processes of material development and component design for nanomodified materials and hybrid laminates.Led by: Prof. Dr-Ing. habil. Raimund RolfesTeam:Year: 2019Funding: Bundesministerium für Wirtschaft und Energie (BMWI) - FKZ 0324345ADuration: 01.03.2019 – 28.02.2022
![]()
![]()
-
Modeling and simulation of the fatigue damage behavior of fiber composites under variable block loading conditionsThe goal of this research project is the extension and application of a progressive fatigue damage model for unidirectional multi-layered fiber composites for damage analysis under variable cyclic block loading patterns. The focus is on the development of damage evolution laws to accurately predict the degradation of strength and stiffness properties based on the load direction and the stress level. In addition to the influence of load sequence effects, particular attention will be paid to the effects of passive damage occurring under combined cyclic tension and compression loading. Finally, the extended fatigue damage model is to be applied to a fuselage structure segment of a future passenger aircraft for fatigue analysis.Led by: Prof. Dr.-Ing. habil. Raimund RolfesTeam:Year: 2020Funding: Internes ProjektDuration: seit 2020
![]()
![]()
-
Abstract modelling of the nonlinear mechanical response of joints in fiber reinforced composite assembliesIn Aviation, Automobile and Wind turbine industries, there are large composite structures which are connected using thousands of mechanical joints or adhesives. For the efficient construction of such composite structures, it is essential to evaluate the behavior of such composite joints, which is usually very complex due to the presence of non-linearities and the joint has distinct failure modes. Accurate simulation of composite joints using detailed models gives a good estimate of the joint behavior and its failure properties but it comes at the cost of computational time. The project aims to reduce the computational cost involved in the simulation of composite joints by developing an abstract model with reduced degrees of freedom. The reduction in degrees of freedom of the model is sought by using structural elements such as Shells and Beams. The project aims to create a model which will capture the behavior of the joint in the finite strain regime, such that the anisotropy of composite material and various non-linearities such as plasticity, damage, contact, friction etc. can be simulated efficiently.Led by: Prof. Dr-Ing. habil. Raimund RolfesTeam:Year: 2022Funding: DFG, German Research FoundationDuration: 01.07.2022-30.06.2025
-
Functionalized, multi-physically optimized adhesives for inherent structural health monitoring of rotor blades (Func2Ad)The performance and reliability of the rotor blade is crucial for the efficiency of a wind turbine over its entire life cycle. The blades make up a large part of the equipment cost - their manufacturing and maintenance costs are extremely high. The adhesive technology in the rotor blade is a key technology for achieving competitive advantages in the wind industry. The processing and curing properties (processability) of the adhesives as well as their operational stability (fatigue strength) in the cured state are two key parameters with regard to the system economy and the return on investment. A third would be the remote diagnosis of the glued joints of the rotor blade (Structure Health Monitoring). The research project proposed here on particle-modified adhesive systems for the wind industry starts with the three points mentioned. A main innovation is the functionalization of the adhesive resin through particle modification to implement a structural monitoring system inherent in the adhesive connections on the rotor blade. This is said to be done by modifying the electrical properties of the adhesive resin. At the same time, the processability and fatigue strength of the adhesive should be positively influenced by the modification. If the modified resin system is only optimized for one of the three aspects mentioned, there is a risk of poor performance with regard to the other. The physical properties of the adhesive must therefore not be separated for the three requirement areas, but must be considered and optimized together in their interaction and their interrelationships. In order to optimize this and increase the efficiency of the multiphysical material models, machine learning methods are used within the simulation framework.Led by: Prof. Dr-Ing. habil. Raimund RolfesTeam:Year: 2023Funding: Bundesministerium für Wirtschaft und Klimaschutz, FKZ 03EE3069 A-FDuration: 01.01.2023-31.12.2026
![]()
![]()
Structural Health Monitoring
-
Monitoring the Suction Bucket Jacket at the Offshore Wind Farm Borkum Riffgrund 1 (Monitoring SBJ)The research project “Monitoring SBJ” is a joint project between DONG Energy, Leibniz Universität Hannover (LUH), and the Federal Institute for Materials Research and Testing (BAM). It is based on measured data gathered from the comprehensive monitoring system mounted on the recently installed Suction Bucket Jacket prototype foundation, located at the offshore wind farm Borkum Riffgrund 1. The tasks of ISD are the processing of measurement data from ambient vibration during installation and operation and the improvement of a numerical model in terms of the soil-structure-interaction.Led by: Prof. Dr.-Ing. habil. Raimund RolfesTeam:Year: 2014Funding: Federal Ministry for Economic Affairs and EnergyDuration: 01.08.2014 - 28.02.2017
![]()
![]()
-
German Research Facility for Wind Energy (DFWind)The project aims to lay the foundation of a research and development platform which concentrates on the usage of wind turbines throughout the entire functional chain in a so far unattained quality. The research is focused on the interaction of the subsystems as part of the overall structure, under consideration of mutual influences of two separate wind turbines and the effect on the integrated network as well. The ISD will be concentrating on intelligent measurement data analysis, Structural Health Monitoring as well as the calculation of coupled dynamical systems.Led by: Prof. Dr.-Ing. habil. Raimund RolfesTeam:Year: 2016Funding: Federal Ministry for Economic Affairs and Energy - FKZ 0325936EDuration: 01.01.2016 – 31.12.2020
![]()
![]()
© DLR
-
Multivariate Structural Health Monitoring for Rotor BladesEssential goals of the project “Multivariate Structural Health Monitoring for Rotor Blades” are to develop, combine and test global and local SHM methods for rotor blades of wind turbines. In sense of a multivariate procedure, different structure-mechanical and acoustic approaches, which are able to capture different indicators and damage parameters, will be considered. The SHM methods are to guarantee an automated and reliable detection and classification of relevant damages during the early stage.Led by: Prof. Dr-Ing. habil. Raimund RolfesTeam:Year: 2017Funding: Federal Ministry for Economic Affairs and Energy - FKZ 0324157ADuration: 01.03.2017 – 31.12.2020
![]()
![]()
© ISD
-
Optimierung der Bemessung hybrider Türme und Entwicklung eines geeigneten Monitoringkonzepts (HyTowering)As tower heights continue to rise, hybrid towers made of pre-stressed concrete segments and mounted steel towers are increasingly being used for onshore wind turbines. The risk of instability or damage to the structure increases with height. The subject of the approved research project are large-scale tests on concrete segment towers. It is planned to develop design models and to test monitoring concepts.Led by: Prof. Dr.-Ing. habil. Raimund RolfesTeam:Year: 2018Funding: Federal Ministry for Economic Affairs and EnergyDuration: 01.01.2018 - 31.12.2020
![]()
![]()
© ISD
-
Quality assured flow production of lightweight UHSC rod elements using artificial neural networksTogether with the Institute of Building Materials Science, ISD is doing research on novel manufacturing processes for components made of ultra-high-strength concrete with a reinforcement of steel sheet and carbon fibres. An innovative extrusion process is used to produce rod-shaped components with a core of ultra-high strength concrete. They are reinforced by a combination of carbon fiber reinforced plastic and sheet steel. A sensor concept is being developed which is capable of monitoring the components "from the birth of the component". Various heterogeneous measurement data are used to control and monitor the extrusion process by means of an artificial neural network, so that a consistently high quality of the components can be guaranteed.Led by: Prof. Dr.-Ing. habil. Raimund RolfesTeam:Year: 2019Funding: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 402702316Duration: 2019 - 2022
![]()
![]()
-
SONYA: Increasing the reliability of segmented rotor blades through Hybrid condition monitoringThe aim of the project is to ensure the reliability of future, complex rotor blades with new structural technologies through targeted and reliable monitoring of the structural condition and to increase the overall availability of the plant. The research focus is on the development and application of a hybrid, intelligent structural monitoring system using the example of a highly loaded joint from a segmented rotor blade. This system will combine independent component monitoring systems (ultrasonic and strain-based) into a hybrid system, thereby increasing the reliability and accuracy of damage detection. For this purpose, it is particularly necessary to avoid false positives of the monitoring system. In this context, the ISD will deal with the application of machine learning methods for the hybrid SHM system when evaluating the measurement data.Led by: Prof. Dr-Ing. habil. Raimund RolfesTeam:Year: 2020Funding: Bundesministerium für Wirtschaft und Energie - Projektnummer 60451751Duration: 01.07.2020-30-06-2023
![]()
![]()
© DLR
Acoustics
-
Investigation of Sonar Transponders for Offshore Wind Farms and Technical Integration to an Overall ConceptOffshore Wind Energy Converters require the installation and operation of sonar transponder units in order to achieve an acoustical warning of submarines. In order to assure a sufficient signal-to-noise ratio and a certain operation distance even under bad conditions the source level of the sonar transponder has to be high enough. On the other hand the bad influence on marine mammals has to be minimized. Beside the dimensioning of the transponders according to the requirements of the German navy an additional goal is the modeling of the sound propagation by means of a hybrid approach.Led by: Prof. Dr.-Ing. habil. Raimund RolfesTeam:Year: 2009Funding: Federal Ministry for the Environment, Nature Conservation, Building and Nuclear Safety - FKZ 0325104ADuration: 01.02.2009 - 31.03.2011
![]()
![]()
-
Realistic underwater noise scenarios on the basis of forecasting models and monitoring for the construction of offshore wind farms in the German North Sea (HyproWind)The research project aims at the development of a multi-stage numerical method for the prediction of underwater sound immissions related to pile driving in the German North Sea. The focus is not on the modeling of the source, but on an efficient calculation of the sound propagation for longer distances with a subsequent visualization in noise maps. Moreover, hydro-acoustic long-term measurements for model validation near the research platforms FINO1 and FINO3 are planned.Led by: Prof. Dr.-Ing. habil. Raimund RolfesTeam:Year: 2010Funding: Federal Ministry for the Environment, Nature Conservation, Building and Nuclear Safety - FKZ 0325212Duration: 01.09.2010 - 31.12.2013
![]()
![]()
-
Predicting Underwater Noise due to Offshore Pile Driving: Modeling of Noise Reduction Methods (BORA)The global target of the joint project BORA is to develop a calculation model to predict waterborne noise due to offshore pile driving. This includes especially models to predict the sound development at the source due to pile deformation and vibration, the sound transmission into water and soil and the consideration of the sound attenuation due to the air-water mixture produced by bubble curtains or due to other sound reduction methods.Led by: Prof. Dr.-Ing. habil. Raimund RolfesTeam:Year: 2012Funding: Federal Ministry for Economic Affairs and Energy - FKZ 0325421BDuration: 01.12.2009 - 30.11.2014
![]()
![]()
-
From the source to the perceptionIn the project WEA-Akzeptanz an interdisciplinary approach will be followed, which links the physical sound generation, radiation and propagation with the perception at the immission site. In cooperation with the industrial partner Senvion, the IKT and the IMUK of the Leibniz Universität Hannover, an acoustic overall model will be developed comprising the sound generation at the wind turbine, the sound propagation to the receiver under realistic atmospheric conditions and a perception model.Led by: Prof. Dr-Ing. habil. Raimund RolfesTeam:Year: 2017Funding: Federal Ministry for Economic Affairs and Energy - FKZ 0324134ADuration: 01.04.2017 – 30.11.2020
![]()
![]()
© ISD
Coupled Dynamic Systems
-
Life time - Research on Support Structures in the Offshore Test Site alpha ventus (GIGAWIND life)Goal of the comprehensive project is the enhancement of the economic dimensioning concept for offshore wind turbine support structures, that has been developed in GIGAWIND alpha ventus, by consideration of long-time operation. There are both degradation mechanisms on the resistance side of the environmental surrounded support structure (damages of structure and welds, fatigue, damages of corrosion protection systems, scour, degradation of pile support behavior) and the determination of acting loads from waves and marine growth.Led by: Prof. Dr.-Ing. habil. Raimund RolfesTeam:Year: 1000Funding: Federal Ministry for Economic Affairs and Energy - FKZ 0325575ADuration: 01.02.2013 - 31.01.2018
![]()
![]()
-
Innovative Wind Conversion Systems (10-20 MW) for Offshore Applications (INNWIND.EU)The research project with a total of 27 European partners is an ambitious successor for the UpWind project, where the vision of a 20MW wind turbine was put forth with specific technology advances that are required to make it happen. The overall objectives of the INNWIND.EU project are the high performance innovative design of a beyond-state-of-the-art 10-20MW offshore wind turbine and hardware demonstrators of some of the critical components.Led by: Prof. Dr. Ing.-habil. Raimund RolfesTeam:Year: 2012Funding: European UnionDuration: 01.11.2012 - 31.10.2017
![]()
![]()
-
Suction bucket foundations as an innovative and installation noise-reducing concept for offshore wind turbines (WindBucket)The overall goal of the research project „WindBucket“ is to assess the feasibility and possible applications and limitations as well as creating necessary conditions for planning, design and construction of bucket foundations of steel and reinforced concrete in German offshore fields. The tasks of ISD include the preparation of an integrated multi-physical model of the offshore wind turbine to study the dynamic behavior applying modal analysis and transient simulation under the consideration of soil-structure-interaction.Led by: Prof. Dr.-Ing. habil. Raimund RolfesTeam:Year: 2012Funding: Federal Ministry for Economic Affairs and Energy - FKZ 0325406BDuration: 01.07.2012 - 30.09.2014
![]()
![]()
-
Integrated Research Programme on Wind Energy (IRPWIND)The aim of the IRPWIND is to foster better integration of European wind energy research activities with the aim of accelerating the transition towards a low-carbon economy and maintain and increase European competitiveness. IRPWIND focusses on three main research aspects. The first one is the optimization of wind farms through the validation of integrated design models. The second one is the reduction of the uncertainty in order to increase efficiency and reliability of future wind turbines. The last one is the transformation of the energy supply system.Led by: Prof. Dr.-Ing. habil. Raimund RolfesTeam:Year: 2014Funding: European UnionDuration: 01.03.2014 - 30.04.2018
![]()
![]()
-
Dynamical behavior and strength of structural elements with regeneration induced imperfections and residual stresses (SP B4 "Stochastic Structural Analysis" of CRC 871)Real components comprise regeneration induced imperfections (geometry, material and residual stresses), that affect the structural behavior significantly. For the application example of the complex capital good of a compressor blisk, the regeneration influence is quantified in the starting dynamics and durability. The bases for the necessary probabilistic structural analysis are efficient computation approaches. Finally, an evaluation of the possible regeneration paths (competing and non-competing) is performed.Led by: Prof. Dr.-Ing. habil. Raimund RolfesTeam:Year: 2014Funding: German Research Foundation (DFG)Duration: 2010-2021
![]()
![]()
© ISD
-
Probabilistic Safety Assessment of Offshore Wind Turbines (PSA)In diesem themenübergreifenden Verbundprojekt soll die für den Bemessungsprozess zentrale Frage der Versagenswahrscheinlichkeit in den aktuellen Bemessungen von OWEA geklärt werden. Hierfür werden mit Hilfe von probabilistischen Methoden Versagenswahrscheinlichkeiten für die Grenzzustände berechnet. Die vorhandenen Versagensarten der Tragstruktur werden in einer Fehlerbaumanalyse zusammengeführt und die wahrscheinlichste Versagensart sowie die resultierende Versagenswahrscheinlichkeit können bestimmt werden.Led by: Prof. Dr-Ing. habil. Raimund RolfesTeam:Year: 2014Funding: Ministry for Science and Culture in Lower SaxonyDuration: 01.12.2009-30.11.2014
![]()
![]()
-
Joint research for raising the efficiency of wind energy converters within the energy supply system (ventus efficiens)The research project focuses the efficiency of wind energy converters within the energy supply system. Although the production, installation and operation procedures of these are on a high level, a continuous raise of their efficiency is indispensable. Only with a constant raise in efficiency, costs of electricity can be reduced distinctly. For wind energy, this is of special interest due to the essential role that it will have in Europe’s future energy supply.Led by: Prof. Dr.-Ing. habil. Raimund RolfesTeam:Year: 2015Funding: Ministry for Science and Culture of Lower SaxonyDuration: 01.12.2014 - 31.12.2019
![]()
![]()
© ForWind
-
Precise measuring system for contactless recording and analysis of the dynamic flow behaviour of wind turbine rotor blades (PreciWind)Within the framework of the PreciWind project, a mobile thermographic measuring system for the continuous recording and analysis of the dynamic flow behaviour of rotor blades on wind turbines in operation is being developed. With the system developed for use on operational turbines in wind parks, the aerodynamic performance of wind turbines in operation can be quantified and evaluated. The analysis of the boundary layer flow conditions is carried out with a geometrically high-resolution infrared camera in the long-wave radiation range. In combination with a laser distance measuring system to record the rotor blade distance and geometry, the measuring system is fixed on a co-rotating measuring system carrier in order to examine the flow behaviour during a complete revolution of the rotor for the first time. This arrangement enables the compensation of the relative movements between the measuring system and the wind turbine rotor and at the same time enables an analysis of the structural dynamics of the wind turbine due to changing force effects within a rotor revolution. Using a mobile power supply, measurements can be carried out in real wind park conditions from distances of up to 300 m to the wind turbine. The main task of the ISD is to numerically investigate the full measuring activities by applying the concept of a digital twin. A virtual image of the wind energy turbine and the entire measurement system will be designed in detail. To determine effective positions and adjustments of the measurement system, various simulations under different environment conditions will be performed. A validation of the simulations is carried out using high-quality measurement data.Led by: Prof. Dr-Ing. habil. Raimund Rolfes, PD Dr.-Ing. habil. Cristian Guillermo GebhardtTeam:Year: 2020Funding: Bundesministerium für Wirtschaft und Energie - FKZ 03EE3013BDuration: 01.01.2020 – 31.12.2022
![]()
![]()
© BIMAQ
Uncertainty
-
Efficient modelling of wind turbines in time-domain considering uncertain parameters (ENERGIZE)Wind energy is a promising technology to achieve the objectives set for the development of renewable energy. To increase competitiveness, costs have to be reduced and the structural reliability has to be improved. A promising approach are more realistic simulations of wind turbines by considering polymorphic uncertainty. In this context, uncertainty is, for example, variability, incompleteness, and inaccuracy of data. Polymorphic uncertainty can be modelled by using imprecise probability. In research, for classical applications of civil engineering, imprecise probability becomes increasingly popular in recent years. However, for wind turbine applications, there are no approaches that use imprecise probability. The main reason is the complexity of wind turbines that combine challenges regarding uncertain and scattering inputs (typical for civil engineering) and complex controller actions (typical for mechanical and electrical engineering). This complexity leads to high computing times and hinders accurate meta-modelling, that is normally used, if computing times are not manageable. That is why in this project, at first, adequate imprecise probability methods are applied to wind turbine models. Subsequently, the efficiency of the uncertain analysis is increased by reducing the required number of model evaluations. This is the core of this project. First, the increase in efficiency is achieved by using enhanced sensitivity analyses, which can be applied when imprecise probability is utilised. By means of sensitivity analyses, the number of uncertain parameters can be reduced. Second, sampling techniques are developed, which can be combined with imprecise probabilities and load extrapolations for wind turbine fatigue loads. This enables an efficient modelling of complex wind turbines using polymorphic uncertain data. At the same time, computing times are kept manageable. Hence, more realistic simulations are possible.Led by: Prof. Dr.-Ing. habil. Raimund Rolfes, Dr.-Ing. Cristian GebhardtTeam:Year: 2019Funding: Deutsche Forschungsgemeinschaft (DFG)Duration: 2019 – 2022
![]()
![]()
© ISD
-
Transdisciplinary end-of-life analysis of wind turbines for the development of technically and economically optimal end-of-funding strategies (TransWind)Wind energy is an important pillar for achieving the energy transition in Germany. Electricity generation costs are still high in relation to market compensation, so that there is a need for development. Hence, the end-of-life topic of wind turbines - i.e. the analysis and design of the period after the end of the funding by the “Erneuerbare Energien Gesetzes” (EEG) or after the design lifetime has been exceeded – is currently of particular interest. To develop technically and economically sustainable strategies for post-EEG wind turbines, a joint and at least partly coupled consideration of different aspects of structural dynamics, logistics, spatial planning, and economics is indispensable. For example, it only makes sense to analyse the economic feasibility of continued operation by retrofitting if this is also technically possible. Therefore, within TransWind project, a probabilistic, structural-dynamic model of a wind turbine will be combined with site-specific wind simulations, spatial planning tools and economic analyses in an integrated modelling approach. To enable the automated application of this transdisciplinary approach, the modelling approach will be implemented in a software solution, and thus, takes advantage of the increasing digitalisation of the energy industry. The focus of the ISD is on the structural-dynamic, probabilistic lifetime calculations.Led by: Dr.-Ing. Clemens Hübler, Prof. Dr-Ing. habil. Raimund RolfesTeam:Year: 2020Funding: Federal Ministry for Economic Affairs and Energy - FKZ 03EE3029ADuration: 01.11.2020 – 31.10.2023
![]()
![]()
© WIV GmbH
-
VIPile – Influence of vibration parameters on the installation and load-bearing behaviour of monopilesThe results of the first two rounds of auctions for German offshore wind farms with commissioning from 2021 to 2025 illustrate the necessity of exploiting further cost reduction potentials in order to realise these future projects within the targeted cost ranges. One possibility is the use of vibratory pile driving as an environmentally friendly and cost-effective construction method for the realisation of further expansion plans for offshore wind energy in Germany. The VIPile project pursues the overall goal of developing validated simulation models for predicting the load-bearing behaviour of vibrated monopile foundations by means of large-scale experiments and numerical simulations. This aims at enabling an economic evaluation and reducing the corresponding risks during project realisations. In addition, a simplified, less computationally intensive, linearized soil-structure interaction model will be developed, which can be integrated into fully coupled aero-elastic wind turbine simulations. This simplified model will be derived from the previously developed detailed models and validated with the help of dynamic measurements. The focus of the ISD is on the simplified soil-structure interaction model.Led by: Prof. Dr.-Ing. habil. Raimund Rolfes, Dr.-Ing. Clemens HüblerTeam:Year: 2020Funding: Bundesministerium für Wirtschaft und Energie - FKZ 03EE3022Duration: 01.08.2020 – 31.07.2023
![]()
![]()
© ISD
