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Nondestructive Ultrasonic Inspection of Composite Materials

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Nguyễn Gia Hào

Academic year: 2023

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Table 5 shows the arrival time of the plate edge reflection signal and the defect (hole) (see Figure 2 for reference). When the size of the defect (hole) is larger, there is a higher probability of detection and the accuracy in determining the location of the defect (hole) is higher.

Figure 1. Samples used to evaluate capability and sensitivity of defect detection in single element ultrasonic (SEUT) versus phased array ultrasonic (PAUT) methods: (a) glass fiber reinforced polymer (GFRP) samples from a wind turbine blade and (b) schemati
Figure 1. Samples used to evaluate capability and sensitivity of defect detection in single element ultrasonic (SEUT) versus phased array ultrasonic (PAUT) methods: (a) glass fiber reinforced polymer (GFRP) samples from a wind turbine blade and (b) schemati

Conclusions

Guided waves can also be generated using phased array ultrasonic probes and wedges with lower frequencies. Internal damage evaluation of composite structures using phased array ultrasonic technique: Impact damage assessment in CFRP and 3D printed reinforced composites.Compos.

Introduction

Experimental investigation of defect localization in a cross-layer fiber-reinforced composite with diffuse ultrasonic waves. To date, only a few attempts have been made to investigate defect localization in fiber-reinforced composites with diffuse wave inspection.

Theoretical background

The present work aims to understand this procedure experimentally for a single defect location in a cross-layer fiber-reinforced structure.

Experiments

The wave diffusivity is a characteristic of the microstructure which relates to the arrival time of the maximum energy density and decreases with frequency. A large variation of D has been found for concrete, from 10 m2/s [32] to 70 m2/s [26], due to its internal structural variation and frequency sensitivity to the diffuse wave.

Figure 2. Representative waveforms from the S-R1 pair.
Figure 2. Representative waveforms from the S-R1 pair.

Results and Discussion

It initially decreases due to the increasing interaction between the diffusion wave and the defect. The diffuse wavefield decays rapidly, while the decorrelation coefficient decreases first with increasing sensitivity to the defect and increases later due to signal-to-noise ratio degradation.

Figure 5. Decorrelation coefficients varied according to time.
Figure 5. Decorrelation coefficients varied according to time.

Assessment of Residual Elastic Properties of a

Damaged Composite Plate with Combined Damage Index and Finite Element Methods

Materials and Methods

To determine the residual Young's modulus of the damaged plate, the detection of damage index (DId) technique is used. A structural-mechanical model of the four-point bending test was simulated using the commercial software LS-DYNA. The accuracy of the numerical model was firstly verified with respect to the four point bending tests of the two composite plates.

Then, the same numerical model was used in comparison with the experimental results of the progressively damaged plate. In particular, each part could be located longitudinally in accordance with the center of the element size. According to the location of the part in the x-direction, the corresponding third-order polynomial curve could be identified.

Table 1. Material properties.
Table 1. Material properties.

Results

Figure 6 shows the resulting correlation between the residual elastic properties of the analyzed composite and the DId parameter. As a result, a continuous variation of the Young's modulus with respect to the x-coordinate is obtained. The continuous curve is adopted in the numerical model to account for the variation of the Young's modulus.

The continuous curve allows Young's modulus to be evaluated according to the x-coordinate of each part. The model of the composite plate with variable elastic modulus is used to simulate the four-point bending test. The limited discrepancy between experimental and numerical results highlights the accuracy of the DId technique to map the residual elastic properties of the damaged plate.

Figure 3. Experimental and numerical results of the four-point bending tests.
Figure 3. Experimental and numerical results of the four-point bending tests.

Conclusions

In situ aircraft flaw detection on composite structures using nondestructive testing.Compos. A new damage index to monitor the extent of the penetration process in thick laminates.Compos. On the growth rate and extent of the steady phase of damage accumulation in repeated impact tests. Compos.

A new methodology for evaluating residual elastic properties in damaged composite components. In Proceedings of the 5th International LS-DYNA Users Conference, Southfield, Dearborn, MI, USA, 9–11 April 1998. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/4000).

A Review of Non-Destructive Damage Detection Methods for Steel Wire Ropes

  • Damage Types of Wire Ropes
  • Non-Destructive Detection Method for Steel Wire Ropes
  • Existing Shortcomings
  • Summaries and Prospects

Although the optical detection method can intuitively understand the morphological characteristics of the surface of WRs, it is rarely used due to the impact of the algorithm performance and the inability to detect internal defects. Different damage conditions and distribution have different effects on reducing the strength of WRs, and the entire WR is often canceled due to a certain section of the WR. Figure 2b is the main magnetic flux detection method based on permanent magnet excitation, in which the interpole magnetization method is adopted, taking the wire rope as a component of the magnetic circuit, and the induction coil is used to detect the change of magnetic flux inside the wire rope caused by damage.

Considering the effect of tensile stress on the strength of the MLF of a steel WR defect, Gao et al. improve the signal-to-noise ratio and ease of installation of the induction coil for non-destructive testing of steel cables. NDT E Int. Frequency analysis of the signals generated by the failure of constituent wires of a wire rope.NDT E Int.

Figure 1. Sample pictures of wire rope damage. (a) Health; (b) wire breakage; (c) wear; (d) deformation (broken strand); (e) rust; and (f) fatigue (fatigue breaking).
Figure 1. Sample pictures of wire rope damage. (a) Health; (b) wire breakage; (c) wear; (d) deformation (broken strand); (e) rust; and (f) fatigue (fatigue breaking).

Lock-In Thermography and Ultrasonic Testing of Impacted Basalt Fibers Reinforced Thermoplastic

Materials and Methods 1. Description of Specimens

The impact energy varied between 5 and 15 J and was set by suitably adjusting the drop height of the Charpy arm. The choice of impact energy was to cause mostly subtle damage at various levels without piercing. In particular, the ultrasonic device records two parameters of the reflected echo: Amplitude and time of flight of the echo relative to a zero point (pulse transit time).

In particular, the dark zone centered at the impact point E=15 J (Figure 5a) for f=0.36 Hz (Figure 5b) adopts a well H-shaped configuration representative of the delamination evolution along the direction of the vertical fiber. Figures 7 and 8 show phase images, taken from the impacted side, of the two samples PPB (Figure 7) and PC2B (Figure 8), which were subjected to three shocks at 5 J, 9 J and 15 J as indicated in the first image (a) of both Figures 8 and 9. The branches of the cross indicate the main deformation directions, while the ring can be assumed to coincide with the imprint of the impactor.

Table 1. Some specimens details.
Table 1. Some specimens details.

Data Discussion and Concluding Remarks

Instead, as already shown and described, specimen PA6B exhibits minor damage, which cannot be simplified to its displacement in only two directions; therefore, no measurements are reported for this specimen. Returning to Tables 2 and 3, it is possible to see the trend towards longer cuts in specimen PC2B. Of course, the choice of materials includes many other factors such as: performance, adaptability, green capability, easy inspection, costs, etc., leading to a compromise.

Sorrentino, Effect of Basalt Fiber Hybridization on the Low Impact Velocity Impact Behavior of Glass/Basalt Woven Fabric/Epoxy Resin Composites.Compos. Numerical system for infrared scanners and application to the underground control of materials by photothermal radiometry. Proc. Advances in Phased Array Ultrasonic Technology Applications; Manually; Olympus Scientific Solutions Americas (OSSA): Waltham, MA, USA, 2007.

Toward Creating a Portable Impedance-Based Nondestructive Testing Method for Debonding

Evaluation of the PZT–Metal Transducer Using Double-Sided Tape

The PZT-metal transducer idea proposed in [16] used a commercialized epoxy adhesive to bond to the host structure. Figure 1 shows the experimental setup to evaluate the performance of the PZT-metal transducer with double-sided tape adhesion. More details on the PZT-metal transducer with its damage detection performance can be found in [16].

This proves experimentally that signature change is significant when detachment occurs under the PZT metal transducer. Figure 2b shows the limitation of using the double-sided tape, as the five impedance signatures seen in this figure were obtained by removing and reattaching the PZT metal transducer on the same area of ​​the composite plate. Here, the RMSD value with complete removal of the bottom plate resulted in 10.98%, showing that the reliability of finding defects under a PZT metal transducer is very effective.

Figure 1. Experimental setup for the piezoelectric (PZT)–metal transducer experiment.
Figure 1. Experimental setup for the piezoelectric (PZT)–metal transducer experiment.

FEM (Finite Element Method) Simulation for Smaller PZT Patches

Figure 5a shows the actual impedance signature of the PZT-metal transducer in air using the AD5933 evaluation board, and Figure 5b shows the impedance signature of the ANSYS simulation. Furthermore, the amplitude of the large peak is approximately twice the size of the smaller resonance peak. Observing the 1 mm square PZT patch (Figure 6b), it has the highest value compared to the rest of the signatures.

Additionally, regardless of the temporary attachment method, debonding damage to a fiberglass epoxy composite can be. Therefore, to seek the possibility of detecting smaller debonding size, the size of the PZT patch should be smaller than the conventional size of 10 mm × 10 mm with 0.5 mm thickness. Four different models were created with small PZT patches to find that the size of the PZT was not the most important factor, as the 1 mm square PZT patch showed resonance with the highest peak amplitude.

Table 2. PZT properties for ANSYS simulation study.
Table 2. PZT properties for ANSYS simulation study.

A Weighted Estimation Algorithm for Enhancing Pulsed Eddy Current Infrared Image in Ecpt

Experiment Setup

In the infrared thermal imaging experiment, the specimen was heated to create different thermal distributions in the cracked and undamaged areas. In this way, the cracked area in the sample produced significantly more heat than the other areas. The heat information at different depths depends on the rich frequency components during the excitation of the pulsating eddy current.

To detect deep cracks, the period of the square wave signal can be varied by the excitation controller. The sample used in the experiment was a ferromagnetic material, and the cracks in it were artificial defects with depths of 0.1, 0.8, and 3 mm and widths of 0.5 mm. The excitation coil is 60 mm wide and placed above the sample, and the distance between the thermal camera and the sample is approx. 600 mm.

Proposed Algorithm

By verifying the step size value, we found that the method was most efficient when the step size was 8. It should be noted that this algorithm is designed to reduce the background noise imported by the temperature of the environment and the excitation. Design of the MOI method based on the artificial neural network for crack detection. Neuro computing.

In Proceedings of the 2016 International Conference on Identification, Information and Knowledge in the Internet of Things (IIKI), Beijing, Kina, 20.-21. oktober 2016. I Proceedings of the 2009 International Conference on Information Engineering and Computer Science, Wuhan, Kina, 9.-20. december 2009. Image the Proceedings of the 2009 International Conference on Information Engineering and Computer Science. Tolkning (SSIAI), Las Vegas, NV, USA, 4.-10. april 2018.

Figure 8. Meshed infrared image after processing.
Figure 8. Meshed infrared image after processing.

Hình ảnh

Figure 6. Back wall reflection signals for GFRP: (a) SEUT method and (b) PAUT method.
Figure 10. Typical PAUT guided wave signal of flaw detection for (a) Al-1 sample and (b) Al-2 sample.
Figure 9. Change of signal amplitude over distance for Al-1 and Al-2 samples.
Figure 11. Typical PAUT guided wave signal of flaw detection for CFRP sample.
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