Publications
131 results found
Ondra V, Riethmueller R, Brake M, et al., 2016, Comparison of nonlinear system identification methods for free decay measurements with application to MEMS devices, International Conference on Noise and Vibration Engineering (ISMA) / International Conference on Uncertainty in Structural Dynamics (USD), Publisher: KATHOLIEKE UNIV LEUVEN, DEPT WERKTUIGKUNDE, Pages: 2547-2547
Gross J, Armand J, Lacayo RM, et al., 2016, A Numerical Round Robin for the Prediction of the Dynamics of Jointed Structures, Editors: Allen, Mayes, Rixen, Publisher: SPRINGER, Pages: 195-211, ISBN: 978-3-319-29762-0
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- Citations: 7
Lacayo RM, Pesaresi L, Fochler D, et al., 2016, A numerical round robin to predict the dynamics of an experimentally-measured Brake-Reuss beam, International Conference on Noise and Vibration Engineering (ISMA) / International Conference on Uncertainty in Structural Dynamics (USD), Publisher: KATHOLIEKE UNIV LEUVEN, DEPT WERKTUIGKUNDE, Pages: 2545-2545
Grolet A, Hoffmann NP, Schwingshackl C, 2015, Solitons in Non-Linear Cyclic Systems, Euromech Colloquium 573: Coupling and Nonlinear Interactions in Rotating Machinery
Armand J, Salles L, Schwingshackl CW, 2015, Numerical Simulation of Partial Slip Contact Using a Semi-Analytical Method, 27th Conference on Mechanical Vibration and Noise, Publisher: American Society of Mechanical Engineers
Almost all mechanical structures consist of an assembly of components that are linked together with joints. If such a structure experiences vibration during operation, micro-sliding can occur in the joint, resulting in fretting wear. Fretting wear affects the mechanical properties of the joints over their lifetime and as a result impacts the non-linear dynamic response of the system. For accurate prediction of the non-linear dynamic response over the lifetime of the structure, fretting wear should be considered in the analysis.Fretting wear studies require an accurate assessment of the stresses and strains in the contacting surfaces of the joints. To provide this information, a contact solver based on the semi-analytical method has been implemented in this study. By solving the normal and tangential contact problems between two elastic semi-infinite bodies, the contact solver allows an accurate calculation of the pressure and shear distributions as well as the relative slips in the contact area. The computed results for a smooth spherical contact between similar elastic materials are presented and validated against analytical solutions. The results are also compared with those obtained from finite element simulations to demonstrate the accuracy and computational benefits of the semi-analytical method. Its capabilities are further illustrated in a new test case of a cylinder with rounded edges on a flat surface, which is a more realistic contact representation of an industrial joint.
Ruffini V, Schwingshackl C, Green J, 2015, Experimental and Analytical Study of Coriolis Effects in Bladed Disk, ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, Publisher: American Society of Mechanical Engineers
Modern aero-engines have reached a high level of sophistication and only significant changes will lead to the improvements necessary to achieve the economic and environmental targets of the future. Open rotors constitute a major leap in this direction, both in terms of efficiency and of technological innovation. This calls for a revision of the accepted design practices, and a new focus on phenomena that have been little investigated in the past, such as the Coriolis effect, or the gyroscopic coupling of the blades with the shaft. Experimental results from modern fans, with large blades and strong stagger angles, are showing dependence on Coriolis gyroscopic effects already, an effect that is expected to be strongly enhanced with the proposed open rotor designs.For an accurate prediction of the Coriolis and gyroscopic effects in rotating assemblies a fully experimentally validated approach is needed. Today’s FE models can capture the basic physical phenomena, but experimental confirmation is still needed for the evolution of the mode shapes with angular speed, and the influence of damping and geometric nonlinearities when gyroscopic coupling is considered. To support this validation effort a new rotating test rig will be introduced, initial measurement data will be discussed, and a comparison with a finite element analysis presented.Different forcing patterns, including forward and backward travelling-wave engine order excitation could be experimentally excited in the new rig, Coriolis-induced frequency splits were found in the dynamic response, showing a significant change in the dynamic behaviour of the investigated dummy disk, and only a minor impact of the mistuning was observed on the frequency splits due to Coriolis effects. The experimental results have been compared to a finite element analysis, and after some updating a good agreement between the predicted and measured Campbell diagrams could be obtained, demonstrating the reliability of the modelling
Ruffini V, Schwingshackl CW, Green JS, 2015, Prediction capabilities of coriolis and gyroscopic effects in current finite element software, Pages: 1853-1862, ISSN: 2211-0984
The progress towards a whole-engine design philosophy and the development of new technologies like open rotors, where coupled behaviour due to Coriolis and gyroscopic effects could be more pronounced, calls for an assessment of the prediction capabilities currently available in commercial FE software packages. Finite element models including these rotational effects are rarely used in simulations of bladed disc-shaft assemblies, and the confidence in FE codes to provide reliable frequency and mode shape data can therefore be improved. Different models were used as benchmark test cases in the evaluation, including the classic Stodola-Green rotor, and a blade-disc-shaft assembly, and the resulting Campbell diagrams were compared to analytical solutions from the literature. The ability of the codes to exploit the cyclic symmetry of bladed discs for computational efficiency was also assessed. The results show that all investigated codes are able to capture the Coriolis-induced frequency splits, but discrepancies arise at high speeds and in the vicinity of instabilities.
Panunzio AM, Salles L, Schwingshackl C, et al., 2015, ASYMPTOTIC NUMERICAL METHOD AND POLYNOMIAL CHAOS EXPANSION FOR THE STUDY OF STOCHASTIC NON-LINEAR NORMAL MODES, ASME Turbo Expo: Turbine Technical Conference and Exposition, Publisher: AMER SOC MECHANICAL ENGINEERS
Peradotto E, Panunzio AM, Salles L, et al., 2015, STOCHASTIC METHODS FOR NONLINEAR ROTORDYNAMICS WITH UNCERTAINTIES, ASME Turbo Expo: Turbine Technical Conference and Exposition, Publisher: AMER SOC MECHANICAL ENGINEERS
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- Citations: 6
Pesaresi L, Schwingshackl CW, 2014, Automated Measurement Grid Generation for Scanning Laser Doppler Vibrometers, Pages: 645-653, ISSN: 2191-5644
Full field measurement techniques can provide fast, accurate and detailed vibration response data for finite element model validation and are being wildly used in industrial applications. A Scanning Laser Doppler Vibrometer (SLDV) measures the full field operating deflection shapes of a structure by changing the location of the laser spot on the target surface. However the setup of a measurement and in particular the measurement grid definition, can take up a significant part of the overall measurement time. To optimise the setup time a novel technique for SLDV measurement grids has been developed. The suggested method includes an automated identification of the vibrating target, based on the measured vibration signal of a scan covering the entire field of view of the LDV. Alpha-shape techniques for target identification and geometric algorithms for shape recognition are used to define the measurement area. Novel approaches for symmetry and orientation capture allow the generation of point grids and continuous patterns for various target shapes. The introduced approach allows a quick SLDV setup of the full field scan with a minimum input from the user. © The Society for Experimental Mechanics 2014.
Schwingshackl CW, Joannin C, Pesaresi L, et al., 2014, Test method development for nonlinear damping extraction of dovetail joints, ISSN: 2191-5644
The traditional measurement techniques to acquire the linear dynamic response of a single component are well established and have been in use for many decades to provide reliable input data for model updating. The measurement of assembled structures normally follows a very similar approach, although the presence of joints can introduce a nonlinear dynamic behaviour, which impacts the measurement results. Applying traditional linear test methods to a highly nonlinear structure, such as a dovetail joint in an aircraft engine blade-disk connection, does not necessarily take the special features of the nonlinear response into account and may lead to unreliable data. This is particularly true, if modal information such as damping are required. The influence of the measurement setup and the test procedures must be well understood for an accurate measurement. In this paper the influence of the different measurement components on a simple clamped beam and a compressor blade dove tail test rig will be investigated. A particular focus will be on the support of the test rig, the location and control of the excitation and the influence of the accelerometer on the response. Based on the findings an approach will be recommended that allows a reliable measurement of the dynamic behaviour of this heavily nonlinear structure.
Schwingshackl CW, D'Antonio G, Tacconelli S, et al., 2014, Automated full field measurement system for nonlinear model validation, International Conference on Noise and Vibration Engineering (ISMA), Publisher: KATHOLIEKE UNIV LEUVEN, DEPT WERKTUIGKUNDE, Pages: 885-893
Botta F, Dini D, Schwingshackl C, et al., 2013, Optimal Placement of Piezoelectric Plates to Control Multimode Vibrations of a Beam, Advances in Acoustics and Vibration, Vol: 2013, ISSN: 1687-627X
Damping of vibrations is often required to improve both the performance and the integrity of engineering structures, for example, gas turbine blades. In this paper, we explore the possibility of using piezoelectric plates to control the multimode vibrations of a cantilever beam. To develop an effective control strategy and optimize the placement of the active piezoelectric elements in terms of vibrations amplitude reduction, a procedure has been developed and a new analytical solution has been proposed. The results obtained have been corroborated by comparison with the results from a multiphysics finite elements package (COMSOL), results available in the literature, and experimental investigations carried out by the authors. © 2013 Fabio Botta et al.
Schwingshackl CW, Di Maio D, Sever I, et al., 2013, Modeling and Validation of the Nonlinear Dynamic Behavior of Bolted Flange Joints, JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER-TRANSACTIONS OF THE ASME, Vol: 135, ISSN: 0742-4795
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- Citations: 55
Di Maio D, Bennett P, Schwingshackl C, et al., 2013, Experimental non-linear modal testing of an aircraft engine casing assembly, Pages: 15-36, ISSN: 2191-5644
This paper aims to present experimental work on an aircraft engine casing assembly. Nowadays single components of casings can be modeled with such high accuracy that they can be validated by carrying out the model validation process using measured data from a sector of the entire assembly. This smart validation process can be achieved by carrying out the modal analysis with a Scanning LDV (Laser Doppler Vibrometer) system which allows good spatial resolution of the measured mode shapes. The validation process can be assumed valid under linear response conditions obtainable for low vibration amplitudes. Casings are typically connected together by joints which may or may not respond non-linearly under high levels of vibration. Therefore, prior to conducting any non-linear validation, the mode(s) responding non-linearly must be identified beforehand in order to correctly specify the non-linear modal testing required. The work presented here will use a large civil engine casing assembly comprising a Combustion Chamber Outer Casing (CCOC), High Intermediate Pressure Turbine Casing (HIPTC) and Low Pressure Turbine Casing (LPTC.) The Fine Mesh Finite Element Model (FMFEM) was successfully validated using linear modal analysis test data. One of the objectives of this work is to define the key points for conducting non-linear modal testing of such large casing assemblies and sub-assemblies. One outcome of the experimental work was a set of recommendations for performing measurements, which should be carried out within the frequency bandwidth selected during the model validation process. Experimentally derived non-linear response curves arc presented in this paper. © The Society for Experimental Mechanics, Inc. 2013.
Ruffini V, Schwingshackl CW, Green JS, 2013, LDV measurement of local nonlinear contact conditions of flange joint, Pages: 159-168, ISSN: 2191-5644
The traditional approach to evaluating the linear dynamic behavior of structures for modal validation is based on the acquisition of frequency response functions and their modal analysis. With small modifications, a similar technique can be used to validate nonlinear response predictions. The use of nonlinear dynamic analysis of flange joints for sealing and wear predictions makes it necessary to also provide validation information for the localised nonlinear mechanisms at the contact surface. For this purpose, a technique based on two Laser Doppler Vibrometers has been developed. The experimental set-up can provide data of the relative out-of-plane displacement of the bolted flange joint during a vibration cycle, which indicates contact separation and permanent gap locations. The observed influence of different excitation levels and bolt torques on the global and local dynamic response led to an understanding of the nonlinear behaviour of the flange and of the local contact conditions. © The Society for Experimental Mechanics, Inc. 2013.
Giuliani P, Di Maio D, Schwingshackl CW, et al., 2013, Six degrees of freedom measurement with continuous scanning laser doppler vibrometer, MECHANICAL SYSTEMS AND SIGNAL PROCESSING, Vol: 38, Pages: 367-383, ISSN: 0888-3270
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- Citations: 25
Salles L, Schwingshackl C, Green J, 2013, Modelling friction contacts in nonlinear vibration of bladed disks
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- Citations: 1
Schwingshackl CW, Di Maio D, Green JS, 2013, MODELLING AND VALIDATION OF THE NONLINEAR DYNAMIC BEHAVIOUR OF BOLTED FLANGE JOINTS, ASME Turbo Expo: Turbine Technical Conference and Exposition, Publisher: AMER SOC MECHANICAL ENGINEERS
Botta F, Marx N, Schwingshackl C, et al., 2013, A WIRELESS VIBRATION CONTROL TECHNIQUE FOR GAS TURBINE BLADES USING PIEZOELECTRIC PLATES AND CONTACTLESS ENERGY TRANSFER, PROCEEDINGS OF THE ASME TURBO EXPO: TURBINE TECHNICAL CONFERENCE AND EXPOSITION, 2013, VOL 7A
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- Citations: 6
Schwingshackl CW, Petrov EP, 2012, Modeling of Flange Joints for the Nonlinear Dynamic Analysis of Gas Turbine Engine Casings, JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER-TRANSACTIONS OF THE ASME, Vol: 134, ISSN: 0742-4795
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- Citations: 25
Schwingshackl CW, 2012, Measurement of friction contact parameters for nonlinear dynamic analysis, Pages: 167-177, ISSN: 2191-5644
Detailed linear finite element simulations and accurate modal testing techniques ensure a reliable validation of linear dynamic response predictions of engineering structures. The good agreement between simulation and measurement for single components is often diminished when an assembly is considered, since nonlinear effects of the joints influence the response behaviour. To re-establish the agreement between analysis and measurement the nonlinear behaviour must be included in the simulation. Analysis tools are available today to take these nonlinear effects into account which require accurate input parameters, to represent the nonlinear contact interface. Research at Imperial College London has focused on the reliable measurement of the dynamic friction contact parameters for over a decade. The extraction of the dynamic friction coefficient, μ, and the tangential contact stiffness, k t, requires the measurement of the nonlinear hysteresis loop with a minimum interference from the test rig. A newly developed friction, with a high test accuracy and a large test range will be presented and its behaviour compared to previous data. © The Society for Experimental Mechanics, Inc. 2012.
Schwingshackl CW, Petrov EP, Ewins DJ, 2012, Measured and estimated friction interface parameters in a nonlinear dynamic analysis, Mechanical Systems and Signal Processing, Vol: 28, Pages: 574-584, ISSN: 0888-3270
The modelling of nonlinear friction contact interfaces in structural dynamics currently attracts large research interest since the accurate characteristics of the friction interfaces are required in the nonlinear dynamic analysis of assembled structures. For an accurate representation of friction contact interfaces it is important to ensure that a sufficient number of parameters are provided to characterise all aspects of the friction contacts that the measured values are accurate and reliable, and that the contact parameters are interpreted and used correctly in the numerical modelling of the contact interfaces. This investigation focused on three major parameters used in the nonlinear friction contact analysis: (i) the friction coefficient, (ii) the tangential contact stiffness, and (iii) the normal load distribution in the contact. The accuracy of the measured friction input parameters is evaluated and possibilities to obtain reliable normal load distributions for a successful prediction of the measured frequency response function are investigated. Average friction input parameters, based on a large set of experimental data, are introduced, and their effect on the nonlinear resonance response is discussed.
Schwingshackl CW, Petrov EP, Ewins DJ, 2012, Effects of Contact Interface Parameters on Vibration of Turbine Bladed Disks With Underplatform Dampers, JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER-TRANSACTIONS OF THE ASME, Vol: 134, ISSN: 0742-4795
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- Citations: 48
Schwingshackl CW, Massei L, Zang C, et al., 2012, A constant scanning LDV technique for cylindrical structures: Simulation and measurement, Mechanical Systems and Signal Processing, Vol: 24, Pages: 394-405, ISSN: 0888-3270
The reliance of the aerospace industry on finite element models during the design of new products requires the best possible models for the prediction of the dynamic behaviour and so it is usually necessary to validate an original model using some additional reference data as the basis - usually data measured on a test structure. Finite element model updating can lead to the required accuracy, and while attempts are under way to minimise the required experimental testing involved in the process, measurements still are an integral part of the procedure. To improve the validation process, a major aim of current experimental research is to provide a more complete set of data from a single experiment in a shorter amount of time, so as to increase the overall efficiency of the updating routine. To this end, a new continuously-scanning laser Doppler vibrometery measurement technique is presented for application to cylindrical structures. It allows the measurement of the dynamic behaviour of a cylindrical structure with a previously-unachievable spatial resolution in a much shorter time than conventional measurement methods. The introduced method is evaluated through a detailed simulation in order to investigate its robustness and to ensure data quality, and the results from a proof-of-concept test rig are presented.
Schwingshackl CW, Petrov EP, Ewins DJ, 2012, EFFECTS OF CONTACT INTERFACE PARAMETERS ON VIBRATION OF TURBINE BLADED DISKS WITH UNDERPLATFORM DAMPERS, ASME Turbo Expo 2011, Publisher: AMER SOC MECHANICAL ENGINEERS, Pages: 867-876
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- Citations: 3
Botta F, Marx N, Gentili S, et al., 2012, Optimal placement of piezoelectric plates for active vibration control of gas turbine blades: experimental results, SENSORS AND SMART STRUCTURES TECHNOLOGIES FOR CIVIL, MECHANICAL, AND AEROSPACE SYSTEMS 2012, PTS 1 AND 2, Vol: 8345, ISSN: 0277-786X
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- Citations: 8
Schwingshackl CW, Petrov EP, 2012, MODELLING OF FLANGE JOINTS FOR THE NONLINEAR DYNAMIC ANALYSIS OF GAS TURBINE ENGINE CASINGS, ASME Turbo Expo 2012, Publisher: AMER SOC MECHANICAL ENGINEERS, Pages: 1283-1293
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- Citations: 1
Schwingshackl CW, Petrov EP, Ewins DJ, 2010, VALIDATION OF TEST RIG MEASUREMENTS AND PREDICTION TOOLS FOR FRICTION INTERFACE MODELLING, ASME Turbo Expo 2010, Publisher: AMER SOC MECHANICAL ENGINEERS, Pages: 1015-1024
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- Citations: 7
Schwingshackl CW, Zolfi F, Ewins DJ, et al., 2009, Nonlinear friction damping measurements over a wide range of amplitudes, ISSN: 2191-5644
The measurement of nonlinear friction damping properties has become a major topic over recent years, as the measurement and analysis of linear systems has reached very high levels of accuracy, allocating much more relevance to the nonlinearities. For this purpose a special test rig will be presented here that allows the measurement of nonlinear damping from friction interfaces, both for small and large amplitude vibrations in the micro and macro slip regime. A transient excitation method is used first for the micro slip range, allowing an accurate measurement of the lower interface friction damping values down to material damping levels, and a forced excitation method is applied for the macro slip region, in order to extract the large-amplitude-dependent damping behaviour. The measurement of large amplitude vibration proved to be a particular challenge, as additional rig damping and large energy dissipation limited the testable range. A discussion of the measurement method and its advantages and disadvantages will be the focus of this paper. © 2009 Society for Experimental Mechanics Inc.
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