scholarly journals Influence of Ice Accumulation on the Structural Dynamic Behaviour of Composite Rotors

2020 ◽  
Vol 10 (15) ◽  
pp. 5063
Author(s):  
Angelos Filippatos ◽  
Martin Dannemann ◽  
Minh Nguyen ◽  
Daniel Brenner ◽  
Maik Gude
Keyword(s):  
Renewable Energy ◽  
Dynamic Behaviour ◽  
Early Stage ◽  
Turbine Blades ◽  
Experimental Tests ◽  
Test Rig ◽  
Structural Dynamic ◽  
Composite Surface ◽  
Modal Properties ◽  
Ice Accumulation

The implementation of wind turbines as a source of sustainable, renewable energy is increasing. Although the prospects of renewable energy development are promising, ice accumulation on turbine blades still stands as a major operational issue. Excessive ice mass on turbine blades can lead to damage or total failure of the blades but also to the nacelle gearbox and to the generator. Therefore, a detailed understanding of the ice accumulation on the composite blades and the effect on their modal properties can be beneficial and give an insight before catastrophic failure occurs. On the one hand, it can be understood how ice accumulation affects the profile of the composite surface to consequently identify the relationships between ice accumulation and mass, stiffness, as well as damping distribution. On the other hand, by mapping these relationships, the first step is performed towards solving the inverse problem, which is to identify critical ice accumulation at an early stage based on modal properties. In this way, ice detection and identification can provide significant savings in time and costs. To investigate the basic relationships between ice accumulation and structural dynamic behaviour, an experimental rotor test rig is developed, combining an electromotor with a climate chamber. The test rig simulates various environmental conditions under different rotational speeds and ice distributions. The first experimental tests are performed on a glass-fibre reinforced epoxy rotor, and several measurements are conducted deploying different kinds of icing and temperature conditions. Various sensors are applied to characterise the vibration response as well as mass, type, and spatial distribution of the ice. The results are evaluated with regard to identifying unknown relations between ice accumulation and the structural dynamic behaviour of composite rotors.

scholarly journals Modal Identification of Output-Only Systems of Composite Discs Using Zernike Modes and MAC

Sensors ◽  
2019 ◽  
Vol 19 (3) ◽  
pp. 660 ◽  
Author(s):  
Minh Nguyen ◽  
Angelos Filippatos ◽  
Albert Langkamp ◽  
Maik Gude
Keyword(s):  
Composite Structures ◽  
Dynamic Behaviour ◽  
Correlation Method ◽  
Modal Identification ◽  
Diagnostic Methods ◽  
Mode Shapes ◽  
Modal Assurance Criterion ◽  
Significant Information ◽  
Structural Dynamic ◽  
Modal Properties

The analysis of the structural dynamic behaviour of composite rotor–discs by a valid description of the eigenfrequencies and mode shapes can provide significant information for action-taking before a failure occurs. Specifically, vibration-based diagnostic methods, which are able to take into consideration the interdependencies and sequential changes of the modal properties could benefit from such an analysis. Here, on the example of composite rotors, a correlation method for experimentally determined mode shapes is developed. For this purpose the Zernike polynomials are used to enhance the identification of mode shapes. Furthermore, the modal assurance criterion (MAC) in combination with the frequency response criterion and a data processing approach are applied in order to characterize changing modal properties of composite rotors. In addition, the developed algorithms can be further extended in order to simplify the experimental evaluation of the complex dynamic behaviour of composite structures.

scholarly journals Characterization of Thin Chromium Coatings Produced by PVD Sputtering for Optical Applications

Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 215
Author(s):  
Andreia A. Ferreira ◽  
Francisco J. G. Silva ◽  
Arnaldo G. Pinto ◽  
Vitor F. C. Sousa
Keyword(s):  
Automotive Industry ◽  
Vapor Deposition ◽  
Physical Vapor Deposition ◽  
Early Stage ◽  
Chemical Vapor ◽  
Experimental Tests ◽  
Scratch Test ◽  
Industrial Sectors ◽  
Deposition Processes ◽  
Optical Applications

PVD (physical vapor deposition) and CVD (chemical vapor deposition) have gained greater significance in the last two decades with the mandatory shift from electrodeposition processes to clean deposition processes due to environmental, public safety, and health concerns. Due to the frequent use of coatings in several industrial sectors, the importance of studying the chromium coating processes through PVD–sputtering can be realized, investing in a real alternative to electroplated hexavalent chromium, usually denominated by chromium 6, regularly applied in electrodeposition processes of optical products in the automotive industry. At an early stage, experimental tests were carried out to understand which parameters are most suitable for obtaining chromium coatings with optical properties. To study the coating in a broad way, thickness and roughness analysis of the coatings obtained using SEM and AFM, adhesion analyzes with the scratch-test and transmittance by spectrophotometry were carried out. It was possible to determine that the roughness and transmittance decreased with the increase in the number of layers, the thickness of the coating increased linearly, and the adhesion and resistance to climatic tests remained positive throughout the study. Thus, this study allows for the understanding that thin multilayered Cr coatings can be applied successfully to polymeric substrates regarding optical applications in the automotive industry.

scholarly journals Dynamic Stability Enhancement of a Hybrid Renewable Energy System in Stand-Alone Applications

Computation ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 14
Author(s):  
Ezzeddine Touti ◽  
Hossem Zayed ◽  
Remus Pusca ◽  
Raphael Romary
Keyword(s):  
Renewable Energy ◽  
Energy Systems ◽  
Experimental Tests ◽  
Energy System ◽  
Induction Generator ◽  
Technical Solution ◽  
Hybrid Energy ◽  
Wind Speeds ◽  
Hybrid Renewable Energy System ◽  
Stability Enhancement

Renewable energy systems have been extensively developed and they are attractive to become widespread in the future because they can deliver energy at a competitive price and generally do not cause environmental pollution. However, stand-alone energy systems may not be practical for satisfying the electric load demands, especially in places having unsteady wind speeds with high unpredictability. Hybrid energy systems seem to be a more economically feasible alternative to satisfy the energy demands of several isolated clients worldwide. The combination of these systems makes it possible to guarantee the power stability, efficiency, and reliability. The aim of this paper is to present a comprehensive analysis and to propose a technical solution to integrate a self-excited induction generator in a low power multisource system. Therefore, to avoid the voltage collapsing and the machine demagnetization, the various parameters have to be identified. This procedure allows for the limitation of a safe operating area where the best stability of the machine can be obtained. Hence, the load variation interval is determined. An improvement of the induction generator stability will be analyzed. Simulation results will be validated through experimental tests.

Regeneration-Induced Forced Response in Axial Turbines

2013 ◽  
Author(s):  
Jens Aschenbruck ◽  
Christopher E. Meinzer ◽  
Linus Pohle ◽  
Lars Panning-von Scheidt ◽  
Joerg R. Seume
Keyword(s):  
Turbine Blades ◽  
Forced Response ◽  
Response Analysis ◽  
Geometrical Parameters ◽  
Turbine Stage ◽  
Structural Dynamic ◽  
Air Turbine ◽  
Axial Turbines ◽  
Interaction Approach ◽  
Stagger Angle

The regeneration of highly loaded turbine blades causes small variations of their geometrical parameters. To determine the influence of such regeneration-induced variances of turbine blades on the nozzle excitation, an existing air turbine is extended by a newly designed stage. The aerodynamic and the structural dynamic behavior of the new turbine stage are analyzed. The calculated eigenfrequencies are verified by an experimental modal analysis and are found to be in good agreement. Typical geometric variances of overhauled turbine blades are then applied to stator vanes of the newly designed turbine stage. A forced response analysis of these vanes is conducted using a uni-directional fluid-structure interaction approach. The effects of geometric variances on the forced response of the rotor blade are evaluated. It is shown that the vibration amplitudes of the response are significantly higher for some modes due to the additional wake excitation that is introduced by the geometrical variances e.g. 56 times higher for typical MRO-induced variations in stagger-angle.

scholarly journals Influence of Gradual Damage on the Structural Dynamic Behaviour of Composite Rotors: Experimental Investigations

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2421 ◽  
Author(s):  
Angelos Filippatos ◽  
Maik Gude
Keyword(s):  
Mechanical Properties ◽  
Composite Structures ◽  
Dynamic Behaviour ◽  
Experimental Investigations ◽  
Catastrophic Failure ◽  
Structural Dynamic ◽  
Delamination Growth ◽  
Reinforced Composite ◽  
Out Of Plane ◽  
Effective Mechanical Properties

Fibre-reinforced composite structures subjected to complex loads exhibit gradual damage behaviour with the degradation of the effective mechanical properties and changes in their structural dynamic behaviour. Damage manifests itself as a spatial increase in inter-fibre failure and delamination growth, resulting in local changes in stiffness. These changes affect not only the residual strength but, more importantly, the structural dynamic behaviour. In the case of composite rotors, this can lead to catastrophic failure if an eigenfrequency coincides with the rotational speed. The description and analysis of the gradual damage behaviour of composite rotors, therefore, provide the fundamentals for a better understanding of unpredicted structural phenomena. The gradual damage behaviour of the example composite rotors and the resulting damage-dependent dynamic behaviour were experimentally investigated under propagating damage caused by a combination of out-of-plane and in-plane loads. A novel observation is the finding that a monotonic increase in damage results in a non-monotonic frequency shift of a significant number of eigenfrequencies.

scholarly journals Comparison of PVD Coatings Nacro4 and TIALN + DLC Deposited on High Contact Ratio Gearing Interacting With Conventional and Ecological Lubricants

2019 ◽  
Vol 22 (2) ◽  
pp. 48-55
Author(s):  
Adam Fürstenzeller ◽  
František Tóth ◽  
Milan Kadnár ◽  
Juraj Rusnák ◽  
Miroslav Bošanský
Keyword(s):  
Experimental Tests ◽  
Load Level ◽  
Maximum Height ◽  
Pvd Coatings ◽  
Contact Ratio ◽  
Test Rig

Abstract Proposed paper deals with experimental tests performed on the Nieman M01 FZG test rig. Experiments were carried out in accordance with STN 65 6280 standard for FZG scuffing tests, from which load values for each load level were obtained. HCR gears made of 16MnCr5 material were utilized during experimental tests. Gear surface was deposited by PVD coatings of nACRo4 and TiAlN + DLC. Conventional lubricant MADIT PP 90H and biological lubricant OMW Biogear S150 were selected for lubrication environments. Aim of the experimental tests lied in application and comparison of PVD coatings deposited on HCR gears. Values of the maximum height of the assessed profile Rz for tip and reference diameters were measured after each load level. Results of experimental tests were statistically processed and relations between the maximum height of assessed profile Rz and load levels for both utilized coatings in both environments were established on the basis of these results.

Magnetic Barkhausen Noise Technique for Early Stage Fatigue Prediction in Martensitic Stainless-Steel Samples (invited)

2021 ◽  
pp. 1-18
Author(s):  
Zi Li ◽  
Bharath Basti Shenoy ◽  
L. Udpa ◽  
Yiming Deng
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Power Plants ◽  
Early Stage ◽  
Fatigue Cracks ◽  
Turbine Blades ◽  
Barkhausen Noise ◽  
Magnetic Barkhausen Noise ◽  
Operating Cycle ◽  
Microstructure Changes

Abstract Martensitic grade stainless steel is generally used to manufacture steam turbine blades in power plants. The material degradation of those turbine blades, due to fatigue, will induce unexpected equipment damage. Fatigue cracks, too small to be detected, can grow severely in the next operating cycle and may cause failure before the next inspection opportunity. Therefore, a nondestructive electromagnetic technique, which is sensitive to microstructure changes in the material, is needed to provide a means to estimate the specimen’s fatigue life. To tackle these challenges, this paper presents a novel Magnetic Barkhausen noise (MBN) technique for garnering information relating to the material microstructure changes under test. The MBN signals are analyzed in time as well as frequency domain to infer material information that are influenced by the samples’ mate- rial state. Principal Component Analysis (PCA) is applied to reduce the dimensionality of feature data and extract higher order features. Afterwards, Probabilistic Neural Network (PNN) classifies the sample based on the percentage fatigue life to discover the most correlated MBN features to indicate the remaining fatigue life. Furthermore, one criticism of MBN is its poor repeatability and stability, therefore, Analysis of Variance (ANOVA) is carried out to analyze the uncertainty associated with MBN measurements. The feasibility of MBN technique is investigated in detecting early stage fatigue, which is associated with plastic deformation in ferromagnetic metallic structures. Experimental results demonstrate that the Magnetic Barkhausen Noise technique is a promising candidate for characterizing.

scholarly journals Potential Environmental Effects of Marine Renewable Energy Development—The State of the Science

2020 ◽  
Vol 8 (11) ◽  
pp. 879
Author(s):  
Andrea E. Copping ◽  
Lenaïg G. Hemery ◽  
Dorian M. Overhus ◽  
Lysel Garavelli ◽  
Mikaela C. Freeman ◽  
...  
Keyword(s):  
Renewable Energy ◽  
Electromagnetic Fields ◽  
Turbine Blades ◽  
Field Research ◽  
Low Carbon ◽  
Underwater Noise ◽  
Marine Animals ◽  
Mooring Lines ◽  
Ongoing Research ◽  
Marine Renewable Energy

Marine renewable energy (MRE) harnesses energy from the ocean and provides a low-carbon sustainable energy source for national grids and remote uses. The international MRE industry is in the early stages of development, focused largely on tidal and riverine turbines, and wave energy converters (WECs), to harness energy from tides, rivers, and waves, respectively. Although MRE supports climate change mitigation, there are concerns that MRE devices and systems could affect portions of the marine and river environments. The greatest concern for tidal and river turbines is the potential for animals to be injured or killed by collision with rotating blades. Other risks associated with MRE device operation include the potential for turbines and WECs to cause disruption from underwater noise emissions, generation of electromagnetic fields, changes in benthic and pelagic habitats, changes in oceanographic processes, and entanglement of large marine animals. The accumulated knowledge of interactions of MRE devices with animals and habitats to date is summarized here, along with a discussion of preferred management methods for encouraging MRE development in an environmentally responsible manner. As there are few devices in the water, understanding is gained largely from examining one to three MRE devices. This information indicates that there will be no significant effects on marine animals and habitats due to underwater noise from MRE devices or emissions of electromagnetic fields from cables, nor changes in benthic and pelagic habitats, or oceanographic systems. Ongoing research to understand potential collision risk of animals with turbine blades still shows significant uncertainty. There has been no significant field research undertaken on entanglement of large animals with mooring lines and cables associated with MRE devices.

Rotordynamics Analysis: Experimental and Numerical Investigations

2003 ◽  
Author(s):  
Jean-Jacques Sinou ◽  
David Demailly ◽  
Cristiano Villa ◽  
Fabrice Thouverez ◽  
Michel Massenzio ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Critical Speed ◽  
Experimental Tests ◽  
Element Model ◽  
Test Rig ◽  
Turbofan Engine ◽  
Rotating Structure ◽  
Vibration Problems ◽  
The Finite Element Model

This paper presents a research devoted to the study of vibration problems in turbofan application. Several numerical and experimental tools have been developed. An experimental test rig that simulates the vibrational behavior of a turbofan engine is presented. Moreover, a finite element model is used in order to predict the non-linear dynamic behavior of rotating machines and to predict the first critical speed of engineering machine. A comparison between the experimental tests and the numerical model is conducted in order to evaluate the critical speed of the rotating structure and to update the finite element model.

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