Sixth International Conference on Vibration Measurements by Laser Techniques: Advances and Applications, 2004
Recently, a mobile coordinate measurement machine consisting of three CCD cameras was expanded wi... more Recently, a mobile coordinate measurement machine consisting of three CCD cameras was expanded with dynamic measurement capabilities. The system is able to track three LEDs in three directions with a maximum sampling frequency of about 1000 Hz. This offers the possibility to use the measurements for dynamic system identification. To this aim, a vibrating structure is equipped with multiple lightweight infrared LEDs and excited by dynamic excitation sources. Transfer functions between force and displacements are estimated from which the modal parameters of the structure can be identified. The benefits of using the camera displacement measurement system is that information down to 0 Hz can be obtained, that mounting LEDs is much easier than installing traditional displacement transducers (LVDTs) and that the coordinates of the measurement points are also available from the measurements. In this paper a dynamic testing study is performed using a scale model of an airplane. Both LEDs and accelerometers are mounted on the structure allowing a comparison between displacement and acceleration transfer function modal analysis results. The main conclusion is that it is possible to successfully identify the modal parameters of the airplane scale model from the displacement measurements in the complete frequency range of the excitation.
Conference Proceedings of the Society for Experimental Mechanics Series, 2012
During actual operating conditions, mechanical systems, such as aerospace structures, may exhibit... more During actual operating conditions, mechanical systems, such as aerospace structures, may exhibit variations in their dynamic properties. Those variations need to be carefully tracked and identified to avoid interaction with excitation sources, leading to unstable behavior or even structural failures. In this paper, signals acquired during a static firing test on a Solid Rocket Motor will be analyzed and processed using Operational modal Analysis. To analyze the evolution of natural frequencies and modal damping as the propellant is burnt, time-histories are cut into shorter segments, which are then analyzed separately. Operational PolyMAX method is applied to identify structural properties of the system and correlation techniques are implemented to track the evolution of the modes. Finally, comparison and correlation with a numerical Finite Element model is also performed to evaluate the analysis.
In this study, a motor condition diagnostic was achieved through the implementation of an Artific... more In this study, a motor condition diagnostic was achieved through the implementation of an Artificial Neural Network (ANN), successfully applying into a predictive maintenance system. Electrical motors were monitored to obtain data to train the ANN. Out of these monitoring, vibration signatures were used as the input layer, and the motor condition was used as the expert training information. The main objective was to apply neural networks to a condition based predictive maintenance in order to detect the type of system's failure. As a result, the expert system can be utilized to decrease the possible failures in operating system and increase the availability and effectiveness of a system.
ABSTRACT Operational Modal Analysis (OMA), also known as output-only modal analysis, allows ident... more ABSTRACT Operational Modal Analysis (OMA), also known as output-only modal analysis, allows identifying modal parameters only by using the response measurements of the structures in operational conditions when the input forces cannot be measured. These information can then be used to improve numerical models in order to monitor the operating and structural conditions of the system. This is a critical aspect both for condition monitoring and maintenance of large wind turbines, particularly in the off-shore sector where operation and maintenance represent a high percentage of total costs. Although OMA is widely applied, the wind turbine case still remains an open issue. Numerical aeroelastic models could be used, once they have been validated, to introduce virtual damages to the structures in order to analyze the generated data. Results from such models can then be used as baseline to monitor the operating and structural condition of the machine.
Conference Proceedings of the Society for Experimental Mechanics Series, 2011
At the development stage of automobile constructions, many powertrain configurations may be consi... more At the development stage of automobile constructions, many powertrain configurations may be considered. Due to complicated coupling mechanisms, the natural frequencies of the combined system are difficult to predict. It is therefore necessary to run tests on automotive subsystems under realistic operating conditions. To completely understand the dynamic behaviour, a study of both torsional and translational motions along the driveshaft is necessary.
Conference Proceedings of the Society for Experimental Mechanics Series, 2013
During a field test campaign, Sandia National Laboratories acquired operational data both in park... more During a field test campaign, Sandia National Laboratories acquired operational data both in parked and rotating conditions on a modified MICON wind turbine with the Sensored Rotor 2 experiment. The objective of the test campaign was to acquire data to develop advanced system identification and structural health monitoring techniques. The data includes wind speed, tower deformations, low and high speed shaft rotational speed measurements as well as accelerations and strains on different locations of the blades. Applying Operational Modal Analysis on such data represents a difficult task due to the strong influence of rotor harmonics on the measured data. Accurately identifying and removing the harmonics is required to perform modal parameter identification. In this paper, data acquired with the turbine in both parked and operating conditions will be analyzed and the modal results compared. Several harmonic removal techniques will be applied on the operational data and their efficiency to solve this specific problem analyzed. In addition, a new enhanced identification technique will be applied, that improves the parameter estimation accuracy in the case of very noisy data and also provides uncertainty bounds of the parameters.
This paper presents selected results and aspects of the multidisciplinary and interdisciplinary r... more This paper presents selected results and aspects of the multidisciplinary and interdisciplinary research oriented for the experimental and numerical study of the structural dynamics of a bend-twist coupled full scale section of a wind turbine blade structure. The main goal of the conducted research is to validate finite element model of the modified wind turbine blade section mounted in the flexible support structure accordingly to the experimental results. Bend-twist coupling was implemented by adding angled unidirectional layers on the suction and pressure side of the blade. Dynamic test and simulations were performed on a section of a full scale wind turbine blade provided by Vestas Wind Systems A/S. The numerical results are compared to the experimental measurements and the discrepancies are assessed by natural frequency difference and modal assurance criterion. Based on sensitivity analysis, set of model parameters was selected for the model updating process. Design of experiment and response surface method was implemented to find values of model parameters yielding results closest to the experimental. The updated finite element model is producing results more consistent with the measurement outcomes.
ABSTRACT This paper presents the research activity performed on a Small Wind Turbine (SWT) test s... more ABSTRACT This paper presents the research activity performed on a Small Wind Turbine (SWT) test stand. Commercially available turbine was modified towards incorporation of the sensors system for condition monitoring. Installed sensors measure angular shaft position, torque applied from the wind loads, vibration accelerations and last but not least rotational speed. All gathered data are then transferred and processed in Test.Lab by means of automatic in house developed Visual Basic application which afterwards converts TDF files to text files and stores them in a desired directory. The numerical simulation is being run in parallel to installed sensors measurements and is as well controlled by the same Visual Basic application. By having actual measurements and numerical simulation results one will be able to compare those two outcomes. In particular, if the numerical model is tailored to the physical one, data comparison will allow identifying malfunctioning due to component damage or extreme working condition.
Contact Versus Non-Contact Measurement of a Helicopter Main Rotor Composite Blade. Marcin Luczak ... more Contact Versus Non-Contact Measurement of a Helicopter Main Rotor Composite Blade. Marcin Luczak 1,a , Kajetan Dziedziech 1,b , Marianna Vivolo 2,c Wim Desmet 2,d , Bart Peeters 1,e , Herman Van der Auweraer 1,f ,. ... 923-944. [11] Noh, H., and Kwak, H., Response ...
The use of composites in the aircraft industry has generated a great need for structural health m... more The use of composites in the aircraft industry has generated a great need for structural health monitoring (SHM) and damage detection systems, to allow for safer use of complex materials. Such is the case with helicopter blades -these components nowadays are mostly composed of carbon fiber or glass fiber reinforced plastics laminates, epoxy and honeycomb filled core structures. The use of composite materials on the main rotor blade (MRB) also allows for more complex and efficient shapes to be designed, but at the same time, their use requires an additional effort when it comes to structural monitoring, since damage can occur and go unnoticed. This work presents experimental results for structural health monitoring method based on strain energy. The test subject is a full-scale composite helicopter main rotor blade, which is a highly flexible, slender beam that can display unusual dynamic behavior with orthotropic behavior. This damage detection method is based on the modal strain properties, and a damage detection index is used to identify and quantify damage. A test setup was built to carry out an experimental modal analysis on the main rotor blade. For that purpose, a total of 55 uniaxial accelerometers were used on the helicopter blade to measure the displacement modes of the structure. To compute the strain modes from the displacement modes, central differences approximation is used. Damage is introduced on the blade by attaching a small mass to two different locations. Experimental results show the possibility of locating damage in this case.
The Øresund Bridge opened in July 2000. It is the most striking part of the fixed link across the... more The Øresund Bridge opened in July 2000. It is the most striking part of the fixed link across the Øresund connecting Copenhagen (Denmark) and Malmø (Sweden), which further includes a tunnel and an artificial island. The bridge is equipped with a PC-based continuous monitoring system, capable of measuring both static and dynamic quantities such as temperatures, wind characteristics, air humidity, strains and accelerations. The challenges for the design of the monitoring system were the long distances between the monitoring points and the variety of sensors. This paper describes the bridge and the monitoring system components. Some typical measurement data are presented. Finally, the modal parameters of the bridge are extracted from the deck, cable and tower vibrations. This shows that the system does not only give information about sudden events that exceed a certain threshold, but can also be used as a health monitoring system by tracking the evolution of the modal parameters.
Significant research efforts are presently spent to the problems of health monitoring and damage ... more Significant research efforts are presently spent to the problems of health monitoring and damage detection. This paper approaches the subject from the point of view of the organisation of the research. More specifically, it reviews the main international research programs and activities, which are devoted to this topic. Related to this are the questions of the user needs and the deployment of the research results: assuming valid research results are obtained, in what form should these results be deployed to address the user needs. While the focus is on EU-cooperative research, the main US and Far-East activities are briefly discussed as well.
The output-only vibration-based structural health monitoring problem is addressed as the task of ... more The output-only vibration-based structural health monitoring problem is addressed as the task of detecting damages modeled as changes in the eigenstructure of a linear dynamic system. The proposed damage detection algorithm is based on a residual generated from a ...
Sixth International Conference on Vibration Measurements by Laser Techniques: Advances and Applications, 2004
Recently, a mobile coordinate measurement machine consisting of three CCD cameras was expanded wi... more Recently, a mobile coordinate measurement machine consisting of three CCD cameras was expanded with dynamic measurement capabilities. The system is able to track three LEDs in three directions with a maximum sampling frequency of about 1000 Hz. This offers the possibility to use the measurements for dynamic system identification. To this aim, a vibrating structure is equipped with multiple lightweight infrared LEDs and excited by dynamic excitation sources. Transfer functions between force and displacements are estimated from which the modal parameters of the structure can be identified. The benefits of using the camera displacement measurement system is that information down to 0 Hz can be obtained, that mounting LEDs is much easier than installing traditional displacement transducers (LVDTs) and that the coordinates of the measurement points are also available from the measurements. In this paper a dynamic testing study is performed using a scale model of an airplane. Both LEDs and accelerometers are mounted on the structure allowing a comparison between displacement and acceleration transfer function modal analysis results. The main conclusion is that it is possible to successfully identify the modal parameters of the airplane scale model from the displacement measurements in the complete frequency range of the excitation.
Conference Proceedings of the Society for Experimental Mechanics Series, 2012
During actual operating conditions, mechanical systems, such as aerospace structures, may exhibit... more During actual operating conditions, mechanical systems, such as aerospace structures, may exhibit variations in their dynamic properties. Those variations need to be carefully tracked and identified to avoid interaction with excitation sources, leading to unstable behavior or even structural failures. In this paper, signals acquired during a static firing test on a Solid Rocket Motor will be analyzed and processed using Operational modal Analysis. To analyze the evolution of natural frequencies and modal damping as the propellant is burnt, time-histories are cut into shorter segments, which are then analyzed separately. Operational PolyMAX method is applied to identify structural properties of the system and correlation techniques are implemented to track the evolution of the modes. Finally, comparison and correlation with a numerical Finite Element model is also performed to evaluate the analysis.
In this study, a motor condition diagnostic was achieved through the implementation of an Artific... more In this study, a motor condition diagnostic was achieved through the implementation of an Artificial Neural Network (ANN), successfully applying into a predictive maintenance system. Electrical motors were monitored to obtain data to train the ANN. Out of these monitoring, vibration signatures were used as the input layer, and the motor condition was used as the expert training information. The main objective was to apply neural networks to a condition based predictive maintenance in order to detect the type of system's failure. As a result, the expert system can be utilized to decrease the possible failures in operating system and increase the availability and effectiveness of a system.
ABSTRACT Operational Modal Analysis (OMA), also known as output-only modal analysis, allows ident... more ABSTRACT Operational Modal Analysis (OMA), also known as output-only modal analysis, allows identifying modal parameters only by using the response measurements of the structures in operational conditions when the input forces cannot be measured. These information can then be used to improve numerical models in order to monitor the operating and structural conditions of the system. This is a critical aspect both for condition monitoring and maintenance of large wind turbines, particularly in the off-shore sector where operation and maintenance represent a high percentage of total costs. Although OMA is widely applied, the wind turbine case still remains an open issue. Numerical aeroelastic models could be used, once they have been validated, to introduce virtual damages to the structures in order to analyze the generated data. Results from such models can then be used as baseline to monitor the operating and structural condition of the machine.
Conference Proceedings of the Society for Experimental Mechanics Series, 2011
At the development stage of automobile constructions, many powertrain configurations may be consi... more At the development stage of automobile constructions, many powertrain configurations may be considered. Due to complicated coupling mechanisms, the natural frequencies of the combined system are difficult to predict. It is therefore necessary to run tests on automotive subsystems under realistic operating conditions. To completely understand the dynamic behaviour, a study of both torsional and translational motions along the driveshaft is necessary.
Conference Proceedings of the Society for Experimental Mechanics Series, 2013
During a field test campaign, Sandia National Laboratories acquired operational data both in park... more During a field test campaign, Sandia National Laboratories acquired operational data both in parked and rotating conditions on a modified MICON wind turbine with the Sensored Rotor 2 experiment. The objective of the test campaign was to acquire data to develop advanced system identification and structural health monitoring techniques. The data includes wind speed, tower deformations, low and high speed shaft rotational speed measurements as well as accelerations and strains on different locations of the blades. Applying Operational Modal Analysis on such data represents a difficult task due to the strong influence of rotor harmonics on the measured data. Accurately identifying and removing the harmonics is required to perform modal parameter identification. In this paper, data acquired with the turbine in both parked and operating conditions will be analyzed and the modal results compared. Several harmonic removal techniques will be applied on the operational data and their efficiency to solve this specific problem analyzed. In addition, a new enhanced identification technique will be applied, that improves the parameter estimation accuracy in the case of very noisy data and also provides uncertainty bounds of the parameters.
This paper presents selected results and aspects of the multidisciplinary and interdisciplinary r... more This paper presents selected results and aspects of the multidisciplinary and interdisciplinary research oriented for the experimental and numerical study of the structural dynamics of a bend-twist coupled full scale section of a wind turbine blade structure. The main goal of the conducted research is to validate finite element model of the modified wind turbine blade section mounted in the flexible support structure accordingly to the experimental results. Bend-twist coupling was implemented by adding angled unidirectional layers on the suction and pressure side of the blade. Dynamic test and simulations were performed on a section of a full scale wind turbine blade provided by Vestas Wind Systems A/S. The numerical results are compared to the experimental measurements and the discrepancies are assessed by natural frequency difference and modal assurance criterion. Based on sensitivity analysis, set of model parameters was selected for the model updating process. Design of experiment and response surface method was implemented to find values of model parameters yielding results closest to the experimental. The updated finite element model is producing results more consistent with the measurement outcomes.
ABSTRACT This paper presents the research activity performed on a Small Wind Turbine (SWT) test s... more ABSTRACT This paper presents the research activity performed on a Small Wind Turbine (SWT) test stand. Commercially available turbine was modified towards incorporation of the sensors system for condition monitoring. Installed sensors measure angular shaft position, torque applied from the wind loads, vibration accelerations and last but not least rotational speed. All gathered data are then transferred and processed in Test.Lab by means of automatic in house developed Visual Basic application which afterwards converts TDF files to text files and stores them in a desired directory. The numerical simulation is being run in parallel to installed sensors measurements and is as well controlled by the same Visual Basic application. By having actual measurements and numerical simulation results one will be able to compare those two outcomes. In particular, if the numerical model is tailored to the physical one, data comparison will allow identifying malfunctioning due to component damage or extreme working condition.
Contact Versus Non-Contact Measurement of a Helicopter Main Rotor Composite Blade. Marcin Luczak ... more Contact Versus Non-Contact Measurement of a Helicopter Main Rotor Composite Blade. Marcin Luczak 1,a , Kajetan Dziedziech 1,b , Marianna Vivolo 2,c Wim Desmet 2,d , Bart Peeters 1,e , Herman Van der Auweraer 1,f ,. ... 923-944. [11] Noh, H., and Kwak, H., Response ...
The use of composites in the aircraft industry has generated a great need for structural health m... more The use of composites in the aircraft industry has generated a great need for structural health monitoring (SHM) and damage detection systems, to allow for safer use of complex materials. Such is the case with helicopter blades -these components nowadays are mostly composed of carbon fiber or glass fiber reinforced plastics laminates, epoxy and honeycomb filled core structures. The use of composite materials on the main rotor blade (MRB) also allows for more complex and efficient shapes to be designed, but at the same time, their use requires an additional effort when it comes to structural monitoring, since damage can occur and go unnoticed. This work presents experimental results for structural health monitoring method based on strain energy. The test subject is a full-scale composite helicopter main rotor blade, which is a highly flexible, slender beam that can display unusual dynamic behavior with orthotropic behavior. This damage detection method is based on the modal strain properties, and a damage detection index is used to identify and quantify damage. A test setup was built to carry out an experimental modal analysis on the main rotor blade. For that purpose, a total of 55 uniaxial accelerometers were used on the helicopter blade to measure the displacement modes of the structure. To compute the strain modes from the displacement modes, central differences approximation is used. Damage is introduced on the blade by attaching a small mass to two different locations. Experimental results show the possibility of locating damage in this case.
The Øresund Bridge opened in July 2000. It is the most striking part of the fixed link across the... more The Øresund Bridge opened in July 2000. It is the most striking part of the fixed link across the Øresund connecting Copenhagen (Denmark) and Malmø (Sweden), which further includes a tunnel and an artificial island. The bridge is equipped with a PC-based continuous monitoring system, capable of measuring both static and dynamic quantities such as temperatures, wind characteristics, air humidity, strains and accelerations. The challenges for the design of the monitoring system were the long distances between the monitoring points and the variety of sensors. This paper describes the bridge and the monitoring system components. Some typical measurement data are presented. Finally, the modal parameters of the bridge are extracted from the deck, cable and tower vibrations. This shows that the system does not only give information about sudden events that exceed a certain threshold, but can also be used as a health monitoring system by tracking the evolution of the modal parameters.
Significant research efforts are presently spent to the problems of health monitoring and damage ... more Significant research efforts are presently spent to the problems of health monitoring and damage detection. This paper approaches the subject from the point of view of the organisation of the research. More specifically, it reviews the main international research programs and activities, which are devoted to this topic. Related to this are the questions of the user needs and the deployment of the research results: assuming valid research results are obtained, in what form should these results be deployed to address the user needs. While the focus is on EU-cooperative research, the main US and Far-East activities are briefly discussed as well.
The output-only vibration-based structural health monitoring problem is addressed as the task of ... more The output-only vibration-based structural health monitoring problem is addressed as the task of detecting damages modeled as changes in the eigenstructure of a linear dynamic system. The proposed damage detection algorithm is based on a residual generated from a ...
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