Papers by Keyword: Infrared Thermography (IRT)

Paper TitlePage

Authors: Jeong Guk Kim, Sung Tae Kwon, Sung Cheol Yoon, Byeong Choon Goo
Abstract: The temperature monitoring on the surface of the railway brake disc was performed using high-speed infrared (IR) camera. The railway brake disc was developed for disc braking of maximum train speed of 180 km/h. The braking tests were conducted with a full scale dynamometer, and a high-speed infrared camera was employed to monitor temperature evolution on the brake disc during braking operation. The high-speed IR camera provides the measurement of temperature change during braking as well as the images of temperature contour on the brake disc surface. In general, the hot spot generation has been considered the main degradation mechanism in railway brake disc. In this investigation, damage evolution due to generation of hot spots on railway brake disc was investigated using the infrared thermography method.
Authors: Lan Chung, In Kwan Paik, S.H. Cho, Young Sook Roh
Abstract: The corrosion reinforcing steel in concrete structures is detrimental to its service life. In order to increase lifespan and maintain serviceability, a qualitative measurement technique that can measure the extent of corrosion of reinforcing steel needs to be developed. While considerable researches have been carried out focusing only on detecting corrosion and restraining the progress of corrosion, a qualitative measurement technique that can measure the amount of corrosion in rebar need to be developed. The purpose of this research is to develop a new technique to measure the corrosion level of rebar using accumulated thermal data. Accumulated thermal data were gathered using infrared camera and digitized to distinguish the difference between various corrosion levels of rebar. The test results showed that the higher level of corrosion displays the higher level of temperature. Temperature of reinforcing steel is not severely affected by ambient temperature, however, concrete surface temperature increased as ambient temperature increased.
Authors: Bin Li, Xiao Yan Tong, Zi Yang Feng, Lei Jiang Yao
Abstract: Plain plate specimens of 2D plain woven C/SiC composites were performed on Instron8801. Infrared (IR) thermography was recorded using an infrared camera. Acoustic emission (AE) signal was detected by two AE wide band sensors attached on specimen. They were measured synchronously and real-timely. Thermal dissipation Q was deduced based on the first law of thermodynamics. When the applied stress was lower than fatigue endurance limit, Q rose in the early cyclic loading stage and then the rate of Q accumulation gradually approached a steady value as the proceeding cycles, conversely, Q rose quickly until led to failure of the composites. AE accumulated energy was discussed based on the AE data. Higher applied stress would cause more damage within the composites, and more AE signals were detected. Compared with damage calculated from modulus, Q and AE accumulated energy had fairly well agreement with the damage. It can be concluded that it is possible to employ these non-destructive evaluation methods as in-situ damage evolution indicators for 2D C/SiC composites.
Authors: Ömer Sinan Şahin, Murat Selek, Şirzat Kahramanlı
Abstract: In this study, the temperature rise of composite plates with a hole during fatigue loading was investigated. Woven glass/epoxy composite plates with eight plies were subjected to bending fatigue loading and materials were observed by using a thermal camera during the test. Previous works showed that a heat generation can form due to internal friction and damage formation. Therefore, a thermographic infrared imaging system was used to detect the temperature rise of composite specimens. During the tests, the thermal images of the specimens have been recorded by a thermal camera and then transferred to the image processing program which has been developed by using MATLAB. By using these thermal images, the spot temperatures of the specimen were obtained by using artificial neural networks. The obtained temperatures show local increase at places where the heat generation localized. These regions considered being the probable damage initiation sites. It is shown in this study that most probable damage initiation zones in the woven glass/epoxy composite material can be detected by using infrared thermography (IRT) approach prior to failure.
Authors: S. Nayak, Narendra B. Dahotre
Authors: Yun Kyu An, Ji Min Kim, Hoon Sohn
Abstract: This study proposes a new nondestructive evaluation methodology named laser lock-in thermography (LLT) for fatigue crack detection. LLT utilizes a high power continuous wave (CW) laser as a heat generation source for lock-in thermography instead of commonly used flash and halogen lamps. The advantages of the proposed LLT method are that (1) the laser heat source can be positioned at an extended distance from a target structure thank to the directionality and low energy loss of the laser source, (2) thermal image degradation due to surrounding temperature disturbances can be minimized because of high temperature gradient generated by the laser source and (3) a large target surface can be inspected using a scanning laser heat source. The developed LLT system is composed of a modulated high power CW laser, galvanometer and infrared camera. Then, a holder exponent-based data processing algorithm is proposed for intuitive damage evaluation. The developed LLT is employed to detect a micro fatigue crack in a metal plate. The test result confirms that 5 μm (or smaller) fatigue crack in a dog-bone shape aluminum plate with a dimension of 400 x 140 x 3 mm3 can be detected.
Authors: Yan Guang Zhao, Xing Lin Guo, Ming Fa Ren
Abstract: Lock-in infrared thermography method was gradually being used in fatigue studies because of its advantages such as real-time, quick-reaction, non-contact, non-destructive and so on. In this paper, non-destructive testing was applied to fatigue specimen with defects, based on lock-in infrared thermography. In parallel, the result was analyzed by using lock-in infrared thermography system developed by Cedip in French. The results show that more information of internal detects can be found from phase image than that from amplitude image. The experiment procedure indicated that a proper testing frequency was the key to the non-destructive testing. The data revealed that deeper depth and larger area of defect led to a precise testing result.
Authors: Okhyun Nam, Wonjae Yu, Man Yong Choi, Hee Moon Kyung
Abstract: The temperature at the surface of the bony recipient site during drilling for orthodontic micro-implant placement was monitored using infrared thermography. The primary objective was to identify proper drilling conditions to allow efficient drilling without raising the bone temperature above the threshold temperature of 44oC to 47oC. Bovine ribs were selected to provide cortical bone of a similar quality to the human mandible. Four drilling conditions combining 2 motor speeds (600 and 1200 rpm) and 2 pressure loads (500 g and 1000 g) were established based on clinical practice. Much care was taken to duplicate an oral environment, although no irrigation was used to allow the infrared radiation to transmit without being hindered by cooling water. Thermal images were recorded using a Thermovision 900 system (Amega, Danderryd, Sweden). The results showed that the temperature rise relys significantly on the drilling speed and pressure. When both the drilling speed and the pressure were low, the cortical bone could not be cut. However, increasing either the speed or the pressure resulted in a temperature increase. Drill speed of 600 rpm at the pressure load 1000g produced more or less the same temperature, 40- 45 o C, as when the drill speed was increased to 1200 rpm while keeping the load at 500g. Yet, a temperature as high as 62.4 o C was recorded when combining the high motor speed and high pressure. Most of the temperature rise took place during the initial 5-10 seconds of drilling, indicating that intermittent irrigation at an interval of 5 seconds or less would be of particular importance to minimize possible thermal trauma.
Authors: Zheng Wei Yang, Wei Zhang, Gan Tian, Ren Bing Li, Yuan Jia Song
Abstract: Traditional pulse infrared thermography uses a single pulse with high energy to heat the specimen. For deeper or smaller defects, more energy must be conducted into the specimen to improve the detectability, which also may cause thermal impact damage in particular for composites. Consequently, multi-pulse heating was presented in this study to solve the problem. The multi-pulse is based on heating the materials with two or more pulses separated by a proper time. In this way, more energy can be conducted into the object as well as every pulse thermal impact was separated. Simulation results show that multi-pulse method can not only enhance the defect detectability several times but also is effective to avoid thermal impact damage by restraining the maximum temperature. Ultimately, the optimum separation time for multi-pulse was chosen according to the best inspecting time of single pulse which was estimated by a very simple method.
Showing 31 to 40 of 67 Paper Titles