scholarly journals A Comparison among Different Ways to Investigate Composite Materials with Lock-In Thermography: The Multi-Frequency Approach

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2525
Author(s):  
Ester D’Accardi ◽  
Davide Palumbo ◽  
Umberto Galietti
Keyword(s):  
Low Cost ◽  
Fiber Reinforced Polymers ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Carbon Fiber Reinforced Polymers ◽  
Reinforced Polymers ◽  
Advantages And Disadvantages ◽  
Set Up ◽  
Lock In ◽  
Non Destructive

The main goal of non-destructive testing is the detection of defects early enough to avoid catastrophic failure with particular interest for the inspection of aerospace structures; under this aspect, all methods for fast and reliable inspection deserve special attention. In this sense, active thermography for non-destructive testing enables contactless, fast, remote, and not expensive control of materials and structures. Furthermore, different works have confirmed the potentials of lock-in thermography as a flexible technique for its peculiarity to be performed by means of a low-cost set-up. In this work, a new approach called the multi-frequency via software approach (MFS), based on the superimposition via software of two square waves with two different main excitation frequencies, has been used to inspect a sample in carbon fiber reinforced polymers (CFRP) material with imposed defects of different materials, sizes and depths, by means of lock-in thermography. The advantages and disadvantages of the multi-frequency approach have been highlighted by comparing quantitatively the MFS with the traditional excitation methods (sine and square waves).

scholarly journals Inductive Thermography as Non-Destructive Testing for Railway Rails

2021 ◽  
Vol 11 (3) ◽  
pp. 1003
Author(s):  
Christoph Tuschl ◽  
Beate Oswald-Tranta ◽  
Sven Eck
Keyword(s):  
Eddy Current ◽  
Electrical Discharge Machining ◽  
Rolling Contact ◽  
Heat Diffusion ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Ir Camera ◽  
Advantages And Disadvantages ◽  
Average Crack ◽  
Non Destructive

Inductive thermography is a non-destructive testing method, whereby the specimen is slightly heated with a short heating pulse (0.1–1 s) and the temperature change on the surface is recorded with an infrared (IR) camera. Eddy current is induced by means of high frequency (HF) magnetic field in the surface ‘skin’ of the specimen. Since surface cracks disturb the eddy current distribution and the heat diffusion, they become visible in the IR images. Head checks and squats are specific types of damage in railway rails related to rolling contact fatigue (RCF). Inductive thermography can be excellently used to detect head checks and squats on rails, and the method is also applicable for characterizing individual cracks as well as crack networks. Several rail pieces with head checks, with artificial electrical discharge-machining (EDM)-cuts and with a squat defect were inspected using inductive thermography. Aiming towards rail inspection of the track, 1 m long rail pieces were inspected in two different ways: first via a ‘stop-and-go’ technique, through which their subsequent images are merged together into a panorama image, and secondly via scanning during a continuous movement of the rail. The advantages and disadvantages of both methods are compared and analyzed. Special image processing tools were developed to automatically fully characterize the rail defects (average crack angle, distance between cracks and average crack length) in the recorded IR images. Additionally, finite element simulations were used to investigate the effect of the measurement setup and of the crack parameters, in order to optimize the experiments.

Non-Destructive Testing of Mass Produced Components by Natural Frequency Measurements

1985 ◽  
Vol 199 (3) ◽  
pp. 161-168 ◽  
Author(s):  
P Cawley
Keyword(s):  
Natural Frequencies ◽  
Production Quality ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Production Quality Control ◽  
Cross Sectional ◽  
Dimensional Changes ◽  
Single Section ◽  
Set Up ◽  
Non Destructive

Vibrations in engineering components may be excited by a light tap and the vibration response may be measured with a microphone and displayed as a frequency spectrum from which the natural frequencies of the component can be extracted. Changes in the natural frequencies of the various modes are observed when small defects such as cracks are present. The use of this technique for the production quality control of mass produced components has been investigated. Tests have been carried out on a cantilever beam, a piston-shaped component and a pulley wheel. It has been shown that, in the absence of dimensional variations, defects removing between 0.5 and 2 per cent of the cross-sectional area of the component at a single section may be detected, the precise size depending on the geometry of the component and the location of the defect. Dimensional variations reduce this sensitivity, but a method has been developed for correcting the results for dimensional changes, without the need for more measurements to be taken. The results show that, unless the likely location of a defect is known in advance, it is essential to measure the natural frequencies of more than one mode of vibration. The test takes less than ten seconds to set up, about one second to carry out and is amenable to automation.

scholarly journals Porosity and Inclusion Detection in CFRP by Infrared Thermography

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
C. Toscano ◽  
C. Meola ◽  
M. C. Iorio ◽  
G. M. Carlomagno
Keyword(s):  
Infrared Thermography ◽  
Production Costs ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Evaluation Methodologies ◽  
Slag Inclusions ◽  
Aeronautical Industry ◽  
Testing Techniques ◽  
Lock In ◽  
Non Destructive

The ever wide use of composite materials in the aeronautical industry has evidenced the need for development of ever more effective nondestructive evaluation methodologies in order to reduce rejected parts and to optimize production costs. Infrared thermography has been recently enclosed amongst the standardized non destructive testing techniques, but its usefulness needs still complete assessment since it can be employed in several different arrangements and for many purposes. In this work, the possibility to detect slag inclusions and porosity is analyzed with both lock-in themography and pulse thermography in the transmission mode. To this end, carbon-fiber-peinforced polymers different specimens are specifically fabricated of several different stacking sequences and with embedded slag inclusions and porosity percentages. As main results, both of the techniques are found definitely able to reveal the presence of the defects above mentioned. Moreover, these techniques could be considered complementary in order to better characterize the nature of the detected defects.

scholarly journals Non-destructive investigation of polymer-metal bonds using a VibroMap1000 holographic vibrometer

2019 ◽  
Vol 299 ◽  
pp. 04010
Author(s):  
Zawadzki Pawel ◽  
Meijer Frans ◽  
Stachowska Ewa ◽  
Legutko Stanisław
Keyword(s):  
Processing System ◽  
Accurate Assessment ◽  
Non Destructive Testing ◽  
Data Processing System ◽  
Destructive Testing ◽  
Frequency Scanning ◽  
Polymer Metal ◽  
Set Up ◽  
Non Destructive ◽  
Metal Bonds

We developed a method to test polymer-metal bonds using a VibroMap1000 holographic vibrometer. The set-up and the data processing system allow non-destructive testing of polymer-metal bonds for samples of a specific size and structure. Frequency scanning from 200 Hz - 20 kHz provides characteristics of the sample. Because the method is non-destructive the sample can be studied afterwards with other methods too. These combined with the measurements of the holographic vibrometer, can create a complete and accurate assessment of the state of polymer-metal bonds. We present some preliminary results.

Diagnostics of aviation equipment. Methods and means of non-destructive testing of the technical condition of the aircraft

2017 ◽  
Author(s):  
Мартыненко ◽  
Elena Martynenko
Keyword(s):  
Physical Nature ◽  
Optical Devices ◽  
Civil Aviation ◽  
Measuring Instruments ◽  
Non Destructive Testing ◽  
Testing Methods ◽  
Destructive Testing ◽  
Ray Method ◽  
Advantages And Disadvantages ◽  
Non Destructive

This manual contains information about the appointment and the physical nature of the application existing non-destructive testing methods, their advantages and disadvantages. The manual contains a brief historical information about the development of non-destructive testing methods in manufacturing aircraft devices, the classification and possible causes of occurrence of various defects on which the studied method of non-destructive testing are directed. The first part of the manual, of the main methods that are used to detect the defects in any instrument control. The detailed classification of measuring instruments and optical devices are given. Moreover, the construction and the ways (the principles) of work of complex measuring instruments and optical devices, including endoscopes are given. The current devices and systems for visual inspection of fiber-hidden objects and internal cavities are considered. More detailed consideration in the manual is given to the capillary, magnetic, acoustic, eddy current non-destructive testing methods and techniques of radiographic(X-ray and gamma-ray method). Particular attention is paid to the field of practical application of different methods. A lot of attention is given to modern means of non-destructive testing of domestic and foreign production. The manual contains a significant amount of drawings and diagrams, which allows to increase the visibility and the accessibility of presentation. It is drawn up with the interdisciplinary course program MDK 01.01.03 "Technical maintenance of aircraft and engines" and is intended for students of the above mentioned specialization 25.02.01 branches of secondary vocational education. The manual can also be used by the students of the training courses for engineering and technical personnel of the enterprises of civil aviation.

Technical Note: Detection of delamination in tyres using eddy currents

1997 ◽  
Vol 211 (1) ◽  
pp. 79-82 ◽  
Author(s):  
X. E. Gros
Keyword(s):  
Eddy Currents ◽  
Structural Integrity ◽  
Low Cost ◽  
Technical Note ◽  
Quality And Safety ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Safety Standards ◽  
Current Testing ◽  
Non Destructive

Non-destructive testing (NDT) is a useful tool to assess the structural integrity of components in order to maintain quality and safety standards. A low-cost electromagnetic technique based on eddy currents induced into a material appeared promising for the inspection of composite materials. Experiments were carried out in order to assess the potential of eddy currents in detecting delamination in rubber tyres. Infrared thermography was used to verify inspection results achieved with eddy currents. Non-destructive examination results are presented in this paper; these confirm that eddy current testing is an economically viable alternative for the inspection of steel reinforced truck tyres.

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