Active infrared thermography as a method for non-destructive testing (original) (raw)
Related papers
Active Infrared Thermography in Non-destructive Testing
2009
The contribution deals with state of the art non-destructive testing method-active infrared thermography. The method can be used for revealing of defects and inhomogenities inside the bodies, e.g. bubbles and cracks in materials, which can have crucial importance from the point of view of their physical-mechanical properties. Goal of the research is theoretical evaluation of the performance of the pulse active thermography as non-destructive testing method and its experimental validation.
Active Infrared Thermography Techniques for the Nondestructive Testing of Materials
Ultrasonic and Advanced Methods for Nondestructive Testing and Material Characterization, 2007
Active infrared thermography refers to the group of methods employed to inspect the integrity of materials or systems through the use of an external energy source and an infrared detector. The external stimulus can be of many forms such as warm or cold air, heat pulses, periodic thermal waves, or mechanical oscillations, e.g. ultrasounds. The way data is captured and processed, as well as the typical applications differ according to the excitation source. This chapter presents a review of three of the most common active techniques in the field of thermography: pulsed thermography, lock-in thermography and vibrothermography.
Active Thermography for Materials Non-Destructive Testing
2014
Active thermography is an advanced experimental procedure, which uses a thermography measurement of a tested material thermal response after its external excitation. This principle can be used also for non-contact infra-red non-destructive testing (IRNDT) of materials. The IRNDT method is based on an excitation of a tested material by an external source, which bring some energy to the material. Halogen lamps, flash-lamps, ultrasound generator or other source can be used as the excitation source for IR-NDT. The excitation causes a tested material thermal response, which is measured by an infra-red camera. It is possible to obtain information about the tested material surface and sub-surface defects or material inhomogeneities by using a suitable combination of excitation source, excitation procedure, infra-red camera and evaluation method. Active thermography and IR-NDT methods are introduced in this contribution. Different IRNDT configurations and their possibilities and limitations...
Review Infrared Thermography for Temperature Measurement and Non-Destructive Testing
2014
The intensity of the infrared radiation emitted by objects is mainly a function of their temperature. In infrared thermography, this feature is used for multiple purposes: as a health indicator in medical applications, as a sign of malfunction in mechanical and electrical maintenance or as an indicator of heat loss in buildings. This paper presents a review of infrared thermography especially focused on two applications: temperature measurement and non-destructive testing, two of the main fields where infrared thermography-based sensors are used. A general introduction to infrared thermography and the common procedures for temperature measurement and non-destructive testing are presented. Furthermore, developments in these fields and recent advances are reviewed.
Infrared Thermography for Temperature Measurement and Non-Destructive Testing
The intensity of the infrared radiation emitted by objects is mainly a function of their temperature. In infrared thermography, this feature is used for multiple purposes: as a health indicator in medical applications, as a sign of malfunction in mechanical and electrical maintenance or as an indicator of heat loss in buildings. This paper presents a review of infrared thermography especially focused on two applications: temperature measurement and non-destructive testing, two of the main fields where infrared thermography-based sensors are used. A general introduction to infrared thermography and the common procedures for temperature measurement and non-destructive testing are presented. Furthermore, developments in these fields and recent advances are reviewed.
Detection of Subsurface Defects using Active Infrared Thermography
2013
Active infrared thermography is a widely used technique in the field of nondestructive testing. The subsurface defects produce non-uniform heat dissipation and this phenomenon is captured by an infrared camera. The phase image gives a prominent description of the defects which are not visible in the captured image sequence. The effect of non-uniform heating and the variation in surface emissivity results in noisy data acquisition. An infrared camera of mid-wave infrared range was used for the study. A frequency modulated sinusoidal signal was used for the heating of the mild steel specimen by two halogen lamps. The source control is attained using a signal generator with frequency of modulation varied from 0.01 Hz – 0.1 Hz for the duration of 100 seconds. The images were acquired at a frame rate of 20 Hz. The specimen contains six numbers of circular flat bottom holes, at different depths from the sample top surface. The temporal profile of every pixel location in the infrared image...
Journal of Mechanical Science and Technology, 2012
In this study, a Probability of Detection (PoD) experimental study was carried out in the framework of a Belgian-Quebec/Canada collaborative research project called ThermoPoD. Experiments were implemented on a Carbon Fiber Reinforced Plastic (CFRP) specimen with embedded material simulating delamination. For active infrared thermography, different heating sources (optical or ultrasound), heating forms (pulsed or lock-in), and data processing methods, such as Fourier Transform, Thermal Signal Reconstruction, Wavelet Transform, Differential Absolute Contrast, and Principal Component Thermography are of interest. In the present study, the effects of various data processing methods on PoD curves are compared.
Study of Defect Determination Using Active Mode Thermography
Passive mode of Infrared Thermography (IRT) has proven to be an effective and reliable technique for condition monitoring and preventive maintenance purposes. However, active mode of IRT is considerably new for industry in term of measuring defect in Non-Destructive Testing (NDT) activities. For the project discussed herein, active mode of IRT, specifically Pulsed Thermal (PT) method was used to detect several simulated sub-surface defects in eight pieces of bakelite-a non-metal and low conductive material. The results demonstrate that the method has capability to detect all simulated defects where the sensitivity of the approached method is proportionately related to the size of defect diameter if the defects are at the same depth and at the same time it is inverserly related with the depth of defect if the defects have similar diameter size. As a conclusion the study has confirmed the ability and potential of active thermpgraphy as a technique for defect determination in material.
The Role of Infrared Thermography in Nondestructive testing of Civil Engineering Structures
2011
In Civil Engineering, the application of infrared thermography is not limited to passive investigations of the quality of thermal insulation of building envelopes. Basic principles of the two main techniques of active infrared thermography, which are pulse thermography (PT) and Lock-in thermography (LT), are briefly recalled. In this paper, the use of passive infrared thermography technique for detecting defects in reinforced concrete structures and possible use of active thermography with post processing techniques that can be applied for defect characterization is presented.
Infrared thermography in materials inspection and thermo-fluid dynamics
International Journal of Computational Methods and Experimental Measurements, 2013
Infrared thermography is becoming ever more popular and is being used in an ever-increasing number of applications mainly due to its accuracy as well as non-contact and two-dimensional characters. In particular, the thermal signatures, which are visualized over a body surface through the use of a remote infrared imaging device, may be exploited to gain information in both the body and the fl uid surrounding it. In fact, thermal images may contain either information about the body's material conditions at a given instant (e.g. material integrity or presence of defects), or its behaviour under mechanical load (e.g. during bending or impact) or about the ability of the fl uid fl ow passing over the body surface to convey heat (i.e. cooling or heating it). Of course, what is important is the choice of the technique and of the procedure used in taking thermographic images, as well of the computational method applied in reducing data for a correct representation and interpretation of the thermal phenomena under study. The specifi c intention of this work is to highlight the usefulness of infrared thermography within two main tasks of materials inspection and thermo-fl uid dynamics. With regard to the fi rst one, the different thermographic techniques, which can be used for non-destructive testing, are described with the data processing procedures; then some key examples, mainly involving composite materials, are reported and discussed. The second topic is illustrated through different fl ow confi gurations, such as impinging jets, which are encountered in the industrial context for heating or cooling purposes, a free stream fl owing over a body to assess separation and/or reattachment location and a disk rotating in still air. However, a part is spent in the description of theoretical approaches and standard procedures for acquisition of thermographic images, as well of methods for data reduction and computation of the required quantities.