Testing and Calibration Procedures for Mistuning Identification and Traveling Wave Excitation of Blisks

2009 ◽  
Author(s):  
Darren E. Holland ◽  
Sergio Filippi ◽  
Matthew P. Castanier ◽  
Steven L. Ceccio ◽  
Bogdan I. Epureanu
Keyword(s):  
Traveling Wave ◽  
Degrees Of Freedom ◽  
Element Model ◽  
Calibration Procedure ◽  
Testing Procedure ◽  
Wave Excitation ◽  
Minimal Set ◽  
Testing Strategies ◽  
Calibration Algorithm ◽  
Alternative Testing

In this work, an integrated testing and calibration procedure is presented for performing mistuning identification (ID) and traveling wave excitation (TWE) of one-piece bladed disks (blisks). The procedure yields accurate results while also being highly efficient and is comprised of three basic phases. First, selected modes from a tuned blisk finite element model are used to determine a minimal set of measurement degrees of freedom (and locations) that will work well for mistuning ID. Second, a testing procedure is presented that allows the mistuning to be identified from relatively few vibration response measurements. A numerical validation is used to investigate the convergence of the mistuning ID results to a prescribed mistuning pattern using the proposed approach and alternative testing strategies. Third, a method is derived to iteratively calibrate the excitation applied to each blade so that differences among the blade excitation magnitudes can be minimized for single blade excitation, and also the excitation phases can be accurately set to achieve the desired traveling wave excitation. The calibration algorithm uses the principle of reciprocity and involves solving a least squares problem to reduce the effects of measurement noise and uncertainty. Because the TWE calibration procedure re-uses data collected during the mistuning ID, the overall procedure is integrated and efficient.

Testing and Calibration Procedures for Mistuning Identification and Traveling Wave Excitation of Blisks

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Darren E. Holland ◽  
Matthew P. Castanier ◽  
Steven L. Ceccio ◽  
Bogdan I. Epureanu ◽  
Sergio Filippi
Keyword(s):  
Traveling Wave ◽  
Degrees Of Freedom ◽  
Element Model ◽  
Calibration Procedure ◽  
Testing Procedure ◽  
Wave Excitation ◽  
Minimal Set ◽  
Testing Strategies ◽  
Calibration Algorithm ◽  
Alternative Testing

In this work, an integrated testing and calibration procedure is presented for performing mistuning identification (ID) and traveling wave excitation (TWE) of one-piece bladed disks (blisks). The procedure yields accurate results while also being highly efficient and is comprised of three basic phases. First, selected modes from a tuned blisk finite element model are used to determine a minimal set of measurement degrees of freedom (and locations) that will work well for mistuning ID. Second, a testing procedure is presented that allows the mistuning to be identified from relatively few vibration response measurements. A numerical validation is used to investigate the convergence of the mistuning ID results to a prescribed mistuning pattern using the proposed approach and alternative testing strategies. Third, a method is derived to iteratively calibrate the excitation applied to each blade so that differences among the blade excitation magnitudes can be minimized for a single blade excitation, and also the excitation phases can be accurately set to achieve the desired traveling wave excitation. The calibration algorithm uses the principle of reciprocity and involves solving a least-squares problem to reduce the effects of measurement noise and uncertainty. Because the TWE calibration procedure re-uses the data collected during the mistuning ID, the overall procedure is integrated and efficient.

scholarly journals Optimization of Semiautomated Calibration Algorithm of Multichannel Electrotactile Feedback for Myoelectric Hand Prosthesis

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Milica Isaković ◽  
Jovana Malešević ◽  
Thierry Keller ◽  
Miloš Kostić ◽  
Matija Štrbac
Keyword(s):  
Degrees Of Freedom ◽  
A Priori ◽  
Sensory Information ◽  
Electrode Array ◽  
Calibration Procedure ◽  
Myoelectric Prosthesis ◽  
Electrical Pulses ◽  
Calibration Algorithm ◽  
Grasping Force ◽  
Electrical Stimuli

The main drawback of the commercially available myoelectric hand prostheses is the absence of somatosensory feedback. We recently developed a feedback interface for multiple degrees of freedom myoelectric prosthesis that allows proprioceptive and sensory information (i.e., grasping force) to be transmitted to the wearer instantaneously. High information bandwidth is achieved through intelligent control of spatiotemporal distribution of electrical pulses over a custom-designed electrode array. As electrotactile sensations are location-dependent and the developed interface requires that electrical stimuli are perceived to be of the same intensity on all locations, a calibration procedure is of high importance. The aim of this study was to gain more insight into the calibration procedure and optimize this process by leveraging a priori knowledge. For this purpose, we conducted a study with 9 able-bodied subjects performing 10 sessions of the array electrode calibration. Based on the collected data, we optimized and simplified the calibration procedure by adapting the initial (baseline) amplitude values in the calibration algorithm. The results suggest there is an individual pattern of stimulation amplitudes across 16 electrode pads for each subject, which is not affected by the initial amplitudes. Moreover, the number of user actions performed and the time needed for the calibration procedure are significantly reduced by the proposed methodology.

Reduced Plate Model Used for 2D Traveling Wave Propagation

2015 ◽  
Author(s):  
V. V. N. Sriram Malladi ◽  
Mohammad Albakri ◽  
Pablo A. Tarazaga ◽  
Serkan Gugercin
Keyword(s):  
Wave Propagation ◽  
Steady State ◽  
Traveling Wave ◽  
Degrees Of Freedom ◽  
Element Model ◽  
Reduction Techniques ◽  
Point Forces ◽  
State Frequency ◽  
Computationally Intensive ◽  
Time Domain Response

The focus of this study is to understand traveling wave generation and propagation in reduced order 2D plate models. A plate with all clamped (C-C-C-C) boundary conditions was selected to be the medium through which the wave propagation occurs. The plate is excited at multiple locations by point forces which generates controlled oscillations resulting in net traveling waves. A finite element model is developed and the traveling wave response is simulated. The numerical model is complex with a large number of degrees-of-freedom making a parametric study computationally intensive. In order to overcome this computational burden, balanced truncation based and interpolation-based model reduction techniques are employed to reduce the total number of degrees-of-freedom. The capabilities of these reduction techniques to capture the steady-state frequency-domain characteristics and the steady-state time-domain response have been compared in this paper.

A Test Rig for Noncontact Traveling Wave Excitation of a Bladed Disk With Underplatform Dampers

2010 ◽  
Vol 133 (3) ◽  
Author(s):  
Teresa Berruti ◽  
Christian M. Firrone ◽  
Muzio M. Gola
Keyword(s):  
Traveling Wave ◽  
Numerical Models ◽  
Experimental Tests ◽  
Calibration Procedure ◽  
Forced Response ◽  
Wave Excitation ◽  
Test Rig ◽  
Response Measurement ◽  
Static Test ◽  
Bladed Disk

This paper presents a static test rig called “Octopus” designed for the validation of numerical models aimed at calculating the nonlinear dynamic response of a bladed disk with underplatform dampers (UPDs). The test rig supports a bladed disk on a fixture and each UPD is pressed against the blade platforms by wires pulled by dead weights. Both excitation system and response measurement system are noncontacting. This paper features the design and the setup of the noncontacting excitation generated by electromagnets placed under each blade. A traveling wave excitation is generated according to a desired engine order by shifting the phase of the harmonic force of one electromagnet with respect to the contiguous exciters. Since the friction phenomenon generated by UPDs introduces nonlinearities on the forced response, the amplitude of the exciting force must be kept constant at a known value on every blade during step-sine test to calculate frequency response functions. The issue of the force control is therefore addressed since the performance of the electromagnet changes with frequency. The system calibration procedure and the estimated errors on the generated force are also presented. Examples of experimental tests that can be performed on a dummy integral bladed disk (blisk) mounted on the rig are described in the end.

Generalized Linford formula and its application to Traveling Wave Excitation

2001 ◽  
Vol 11 (PR2) ◽  
pp. Pr2-285-Pr2-288
Author(s):  
R. Tommasini ◽  
E. E. Fill
Keyword(s):  
Traveling Wave ◽  
Wave Excitation

Effects of Population Structure and Admixture on Exact Tests for Association Between Loci

Genetics ◽  
2003 ◽  
Vol 164 (1) ◽  
pp. 381-387
Author(s):  
B Law ◽  
J S Buckleton ◽  
C M Triggs ◽  
B S Weir
Keyword(s):  
Population Subdivision ◽  
Data Sets ◽  
Multilocus Genotype ◽  
Test Statistic ◽  
Exact Test ◽  
Testing Strategies ◽  
Different Populations ◽  
Alternative Testing ◽  
Sparse Data Sets ◽  
Alternative Testing Strategies

Abstract The probability of multilocus genotype counts conditional on allelic counts and on allelic independence provides a test statistic for independence within and between loci. As the number of loci increases and each sampled genotype becomes unique, the conditional probability becomes a function of total heterozygosity. In that case, it does not address between-locus dependence directly but only indirectly through detection of the Wahlund effect. Moreover, the test will reject the hypothesis of allelic independence only for small values of heterozygosity. Low heterozygosity is expected for population subdivision but not for population admixture. The test may therefore be inappropriate for admixed populations. If individuals with parents in two different populations are always considered to belong to one of the populations, then heterozygosity is increased in that population and the exact test should not be used for sparse data sets from that population. If such a case is suspected, then alternative testing strategies are suggested.

scholarly journals Experimental Investigation on a Bladed Disk with Traveling Wave Excitation

Sensors ◽  
2021 ◽  
Vol 21 (12) ◽  
pp. 3966
Author(s):  
Luigi Carassale ◽  
Elena Rizzetto
Keyword(s):  
Data Processing ◽  
Traveling Wave ◽  
Frequency Response Function ◽  
Wave Excitation ◽  
Test Rig ◽  
Real Situation ◽  
Bladed Disk ◽  
Experimental Identification ◽  
Alternative Techniques ◽  
Processing Techniques

Bladed disks are key components of turbomachines and their dynamic behavior is strongly conditioned by their small accidental lack of symmetry referred to as blade mistuning. The experimental identification of mistuned disks is complicated due to several reasons related both to measurement and data processing issues. This paper describes the realization of a test rig designed to investigate the behavior of mistuned disks and develop or validate data processing techniques for system identification. To simplify experiments, using the opposite than in the real situation, the disk is fixed, while the excitation is rotating. The response measured during an experiment carried out in the resonance-crossing condition is used to compare three alternative techniques to estimate the frequency-response function of the disk.

scholarly journals Model Calibration for a Rigid Hexapod-Based End-Effector with Integrated Force Sensors

Sensors ◽  
2021 ◽  
Vol 21 (10) ◽  
pp. 3537
Author(s):  
Christian Friedrich ◽  
Steffen Ihlenfeldt
Keyword(s):  
Parameter Identification ◽  
Degrees Of Freedom ◽  
Force Measurement ◽  
Experimental Studies ◽  
Measurement Model ◽  
Calibration Procedure ◽  
Force Sensors ◽  
End Effector ◽  
Measurement Models ◽  
Fast Procedure

Integrated single-axis force sensors allow an accurate and cost-efficient force measurement in 6 degrees of freedom for hexapod structures and kinematics. Depending on the sensor placement, the measurement is affected by internal forces that need to be compensated for by a measurement model. Since the parameters of the model can change during machine usage, a fast and easy calibration procedure is requested. This work studies parameter identification procedures for force measurement models on the example of a rigid hexapod-based end-effector. First, measurement and identification models are presented and parameter sensitivities are analysed. Next, two excitation strategies are applied and discussed: identification from quasi-static poses and identification from accelerated continuous trajectories. Both poses and trajectories are optimized by different criteria and evaluated in comparison. Finally, the procedures are validated by experimental studies with reference payloads. In conclusion, both strategies allow accurate parameter identification within a fast procedure in an operational machine state.

On the Response of Modulated Doublet Modes to Traveling Wave Excitation

2000 ◽  
Author(s):  
J. Y. Chang ◽  
J. A. Wickert
Keyword(s):  
Periodic Structure ◽  
Traveling Wave ◽  
Illustrative Case ◽  
Wave Excitation ◽  
State Response ◽  
The Individual ◽  
Limiting Case ◽  
Backward Propagation ◽  
Fourier Harmonics ◽  
Split Frequency

Abstract The forced vibration of arotationally periodic structure when subjected to traveling wave excitation is discussed, with emphasis placed on the steady-state response of doublet modes having either repeated or split frequencies. Such vibration modes have spatially modulated shapes defined by (i) the numbers of nodal diameters present in the limiting case of axisymmetry, and (ii) certain additional, superposed, contaminating Fourier harmonics which distort their appearances. The natural frequency and mode structure of a model periodic structure is discussed in the context of an otherwise axisymmetric disk having evenly-spaced, sector-shaped, line distributions of stiffness and inertia. Through a perturbation analysis, the contamination wavenumbers present in a doublet having repeated frequency are shown to comprise two subsets, the members of which have sine and cosine coefficients of the same, or of differing, signs for each wavenumber present in the mode shape’s Fourier expansion. That structure for the wavenumber content is explored further with respect to the response of repeated and split doublets to a harmonic traveling wave excitation. The individual Fourier components comprising a modulated doublet mode shape can propagate in the same direction as the excitation, or opposite to it, depending on the wavenumber of the excitation and the subset to which the contamination wavenumber belongs. The response of the split frequency doublets and the circumstances under which traveling or standing wave responses, or a blend of the two, can occur in the structure’s reference frame are examined and discussed in the context of the model periodic structure. The qualitative character of the response, the forward or backward propagation direction of each mode’s constituent wavenumber components, and the phase speeds of those components are discussed in illustrative case studies.

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