Papers by Claus-Peter Fritzen
Procedia Technology, 2014
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Mechanical Systems and Signal Processing, 2003
In this paper an extension of the antiresonance-based model updating method that—by estimating an... more In this paper an extension of the antiresonance-based model updating method that—by estimating antiresonances of unmeasured point FRFs—allows the use of previously identified modal data, is applied to the finite element model updating of the GARTEUR benchmark. The various steps of the process (modelling assumptions, selection of correction parameters, sensitivity analysis, model updating and validation) are carefully described and discussed.
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Journal of Applied Mathematics and Mechanics, 1993
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Sensors, 2021
Since stringers are often applied in engineering constructions to improve thin-walled structures’... more Since stringers are often applied in engineering constructions to improve thin-walled structures’ strength, methods for damage detection at the joints between the stringer and the thin-walled structure are necessary. A 2D mathematical model was employed to simulate Lamb wave excitation and sensing via rectangular piezoelectric-wafer active transducers mounted on the surface of an elastic plate with rectangular surface-bonded obstacles (stiffeners) with interface defects. The results of a 2D simulation using the finite element method and the semi-analytical hybrid approach were validated experimentally using laser Doppler vibrometry for fully bonded and semi-debonded rectangular obstacles. A numerical analysis of fundamental Lamb wave scattering via rectangular stiffeners in different bonding states is presented. Two kinds of interfacial defects between the stiffener and the plate are considered: the partial degradation of the adhesive at the interface and an open crack. Damage indic...
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PAMM, 2019
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ABSTRACT
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Structural Control and Health Monitoring, 2015
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Journal of Civil Structural Health Monitoring, 2013
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Transactions on Engineering Technologies, 2014
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Structural Health Monitoring
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ABSTRACT The research aims at an experimental confirmation of the trapping mode effect that was t... more ABSTRACT The research aims at an experimental confirmation of the trapping mode effect that was theoretically predicted for a layered plate with a delamination. The trapping modes are eigensolutions of the related diffraction problem associated with nearly real complex points of its discrete spectrum. The effect occurs at the central frequencies coinciding with the spectral points of the integral equation to which the diffraction problem is reduced. The laser vibrometer based measurements have confirmed the trapping mode effect. The waves trapped at the delamination manifest themselves as dark spots in the snapshots of scanned surface.
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Fracture of Nano and Engineering Materials and Structures
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Materials Science Forum, 2007
In the present paper examples for propagating and non-propagating conditions of slip bands and sh... more In the present paper examples for propagating and non-propagating conditions of slip bands and short fatigue cracks in a ferritic-austenitic duplex steel are given, which were quantified by means of SEM in combination with automated EBSD. To classify the results within the scope of predicting the service life under HCF- and VHCF-loading conditions a numerical model based on the boundary-element method has been developed, where crack propagation is described by means of partially irreversible dislocation glide on crystallographic slip planes in a polycrystalline model microstructure (Voronoi cells). This concept is capable to account for the strong scattering in fatigue life for very small strain amplitudes and to contribute to the concept of tailored microstructures for improved cyclic-loading behaviour.
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Encyclopedia of Information Science and Technology, Third Edition
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Abstract. Structural components made of composite materials are being used more often in aerospac... more Abstract. Structural components made of composite materials are being used more often in aerospace and aeronautic structures due to their well-known properties such as high mass specific stiffness and strength. However, their application also increases the analysis complexity of such structures. Structural health monitoring (SHM) systems for these structures aim to determine the status of the system in real time such that a longer safe life and lower operational costs can be guaranteed. On that account, this paper is concerned with the experimental validation of a structural health monitoring methodology where a damage detection and classification scheme based on an acousto-ultrasonic (AU) approach is applied to a composite panel incorporating stiffening elements using a piezoelectric active sensor network in conjunction with time-frequency multiresolution analysis and non-linear feature extraction. Therefore, structural dynamic responses from the simplified aircraft composite skin ...
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Fatigue of Materials at Very High Numbers of Loading Cycles
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The knowledge of the material properties in testing situations, especially for wave propagation p... more The knowledge of the material properties in testing situations, especially for wave propagation plays an important role to obtain correct diagnostic results. It is well-known that environmental and operational conditions (EOC) like temperature and loads have a high impact in this context. In the field of damage detection with acousto-ultrasonic in thin plate structures, the frequencydependent phaseand group velocity are the main characteristic parameters of the propagating waves, representing the dispersion properties of the guided waves. The proposed paper aims at the determination of the wave velocities without measuring the EOC like temperature or load, but measuring the velocities under the current conditions directly with an additional set of a reference sensor trio. To reach this goal, the continuous phase technique (CPT) is introduced. With this procedure a calculation of the phase difference between two measured wave burst is possible for each frequency. The calculated phase...
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XI International Conference on Structural Dynamics
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Structural Health Monitoring-an International Journal, 2017
Load monitoring and damage identification are important tasks in the field of Structural Health M... more Load monitoring and damage identification are important tasks in the field of Structural Health Monitoring. Reconstructing unknown force inputs or system parameters usually involves the solution of an inverse problem which is mostly ill-posed. In the last decades a lot of effort has been spent in solving these problems separately. However, unknown loads and damage both have influence on the structural vibration pattern. The difficulty of simultaneous identification of external forces and structural damage is to distinguish these influences by using only the measured vibration effects. The use of prior knowledge of the unknown quantities is advisable for solving the combined inverse problem and to obtain meaningful solutions. In this contribution a sparsity-based reconstruction method in time domain is developed for identifying the unknown structural force excitation and damage parameter simultaneously by using output-only acceleration data. Sparsity means the majority of the solutio...
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Impact is a common source of in-service damage that critically compromises the safety and perform... more Impact is a common source of in-service damage that critically compromises the safety and performance of aerospace structures. For this reason, online impact detection systems are essential and require automatic and intelligent techniques providing a probabilistic interpretation of their diagnostics. On that account, a Bayesian framework within the context of Gaussian Processes is adopted in the present work for the purpose of impact magnitude estimation and localization. An aircraft fuselage from an Airbus A320 and an isotropic plate are used as examples to test the proposed approach. Firstly, structural dynamic responses captured by a piezoelectric sensor network due to impact events are recorded from simple impact experiments. In a second step, the discrete wavelet transform and multiway nonlinear principal component analysis are used and evaluated for signal filtration, feature extraction and data compression of the time histories. Afterwards, a probabilistic model is constructe...
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Papers by Claus-Peter Fritzen