Application of the Scattering Analysis Method for Guided Waves Measured by Laser Scanning Vibrometry

Humer, Christoph; Kralovec, Christoph; Schagerl, Martin

doi:10.12783/shm2019/32321

Cited by 5 publications

(7 citation statements)

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“…In this way, the approach can be used to identify damages. However, numerically calculated damage interaction coefficients C AA deviate from coefficients evaluated from laser scanning vibrometer measurements [73,74], as presented in Figure 10 for a cylindrical steel obstacle bonded to an aluminum plate (similar to the one depicted in Figure 8b). Therefore, a reliable method for correlation of numerical and experimental results has to be found.…”

Section: Damage Identification With Ugwmentioning

confidence: 90%

“…An example for this stepwise process is the identification of size and type of a damage by UGW scattering patterns, which requires readily knowing the damage location, i.e., from which direction the scattered wave is approaching (cf. Figure 8b) [74]. However, this is not a straightforward process.…”

Section: Definition Of Data Evaluation Proceduresmentioning

confidence: 99%

“…Comparison of numerically calculated (FE) and with laser scanning vibrometry measured (EXP) damage interaction coefficients C AA for burst center frequency: (a) f c = 190 kHz; and (b) f c = 200 kHz[74].…”

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confidence: 99%

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Review of Structural Health Monitoring Methods Regarding a Multi-Sensor Approach for Damage Assessment of Metal and Composite Structures

Kralovec

Schagerl

2020

Sensors

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140

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Structural health monitoring (SHM) is the continuous on-board monitoring of a structure’s condition during operation by integrated systems of sensors. SHM is believed to have the potential to increase the safety of the structure while reducing its deadweight and downtime. Numerous SHM methods exist that allow the observation and assessment of different damages of different kinds of structures. Recently data fusion on different levels has been getting attention for joint damage evaluation by different SHM methods to achieve increased assessment accuracy and reliability. However, little attention is given to the question of which SHM methods are promising to combine. The current article addresses this issue by demonstrating the theoretical capabilities of a number of prominent SHM methods by comparing their fundamental physical models to the actual effects of damage on metal and composite structures. Furthermore, an overview of the state-of-the-art damage assessment concepts for different levels of SHM is given. As a result, dynamic SHM methods using ultrasonic waves and vibrations appear to be very powerful but suffer from their sensitivity to environmental influences. Combining such dynamic methods with static strain-based or conductivity-based methods and with additional sensors for environmental entities might yield a robust multi-sensor SHM approach. For demonstration, a potent system of sensors is defined and a possible joint data evaluation scheme for a multi-sensor SHM approach is presented.

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Section: Damage Identification With Ugwmentioning

confidence: 90%

Section: Definition Of Data Evaluation Proceduresmentioning

confidence: 99%

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Review of Structural Health Monitoring Methods Regarding a Multi-Sensor Approach for Damage Assessment of Metal and Composite Structures

Kralovec

Schagerl

2020

Sensors

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140

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“…Recently, scaled demonstrators equipped with multiple sensors have also been built to develop and test the applicability of promising SHM methodologies [19][20][21]. SHM methods that are capable of monitoring large thin-walled structures, e.g., spoilers, are guided waves [22][23][24][25][26], electrical impedance tomography (EIT) through conductive surface layers [27,28], and direct measurements of a structure's electrical impedance [29]. Furthermore, strain-based methods with distributed strain sensors, e.g., fiber optical sensors (FOSs), are expected to efficiently monitor large thin-walled structures, which are typical for lightweight design [30][31][32][33].…”

Section: Introductionmentioning

confidence: 99%

Development of Aircraft Spoiler Demonstrators for Cost-Efficient Investigations of SHM Technologies under Quasi-Realistic Loading Conditions

2021

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An idealized 1:2 scale demonstrator and a numerical parameter optimization algorithm are proposed to closely reproduce the deformation shape and, thus, spatial strain directions of a real aerodynamically loaded civil aircraft spoiler using only four concentrated loads. Cost-efficient experimental studies on demonstrators of increasing complexity are required to transfer knowledge from coupons to full-scale structures and to build up confidence in novel structural health monitoring (SHM) technologies. Especially for testing novel sensor systems that depend on or are affected by mechanical strains, e.g., strain-based SHM methods, it is essential that the considered lab-scale structures reflect the strain states of the real structure at operational loading conditions. Finite element simulations with detailed models were performed for static strength analysis and for comparison to experimental measurements. The simulated and measured deformations and spatial strain directions of the idealized demonstrator correlated well with the numerical results of the real aircraft spoiler. Thus, using the developed idealized demonstrator, strain-based SHM systems can be tested under conditions that reflect operational aerodynamic pressure loads, while the test effort and costs are significantly reduced. Furthermore, the presented loading optimization algorithm can be easily adapted to mimic other pressure loads in plate-like structures to reproduce specific structural conditions.

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“…Sensor readings are processed and analyzed according to the applied SHM method [ 3 ]. Examples of state-of-the-art monitoring methods are guided waves [ 4 , 5 , 6 , 7 ], conductive surface layers [ 8 , 9 , 10 ], direct measurements of the electrical impedance of a structure [ 11 ] and the electro-mechanical impedance (EMI) method [ 12 , 13 , 14 , 15 ].…”

Section: Introductionmentioning

confidence: 99%

Crack Identification in Necked Double Shear Lugs by Means of the Electro-Mechanical Impedance Method

Winklberger

Kralovec

Humer

et al. 2020

Sensors

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This contribution investigates fatigue crack detection, localization and quantification in idealized necked double shear lugs using piezoelectric transducers attached to the lug shaft and analyzed by the electro-mechanical impedance (EMI) method. The considered idealized necked lug sample has a simplified geometry and does not includes the typical bearing. Numerical simulations with coupled-field finite element (FE) models are used to study the frequency response behavior of necked lugs. These numerical analyses include both pristine and cracked lug models. Through-cracks are located at 90∘ and 145∘ to the lug axis, which are critical spots for damage initiation. The results of FE simulations with a crack location at 90∘ are validated with experiments using an impedance analyzer and a scanning laser Doppler vibrometer. For both experiments, the lug specimen is excited and measured using a piezoelectric active wafer sensor in a frequency range of 1 kHz to 100 kHz. The dynamic response of both numerical calculations and experimental measurements show good agreement. To identify (i.e., detect, locate, and quantify) cracks in necked lugs a two-step analysis is performed. In the first step, a crack is detected data-based by calculating damage metrics between pristine and damaged state frequency spectra and comparing the resulting values to a pre-defined threshold. In the second step the location and size of the detected crack is identified by evaluation of specific resonance frequency shifts of the necked lug. Both the search for frequencies sensitive to through-cracks that allow a distinction between the two critical locations and the evaluation of the crack size are model-based. This two-step analysis based on the EMI method is demonstrated experimentally at the considered idealized necked lug, and thus, represents a promising way to reliably detect, locate and quantify fatigue cracks at critical locations of real necked double shear lugs.

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Application of the Scattering Analysis Method for Guided Waves Measured by Laser Scanning Vibrometry

Cited by 5 publications

References 0 publications

Review of Structural Health Monitoring Methods Regarding a Multi-Sensor Approach for Damage Assessment of Metal and Composite Structures

Review of Structural Health Monitoring Methods Regarding a Multi-Sensor Approach for Damage Assessment of Metal and Composite Structures

Development of Aircraft Spoiler Demonstrators for Cost-Efficient Investigations of SHM Technologies under Quasi-Realistic Loading Conditions

Crack Identification in Necked Double Shear Lugs by Means of the Electro-Mechanical Impedance Method

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