Sam Ang KEO

CEREMA, Evaluation Non Destructive des Structures et des Matériaux, Researcher

Gangneung-Wonju National University, Civil Engineering, Post-Doc

INSA Toulouse, Civil Engineering, Post-Doc

Followers

Following

Co-authors

Public Views

2019, 2015 : Qualification of Associate Professor in Public Universities in
France (Qualification Maître de Conférence en Mécanique et
Génie Civil, CNU60)
2013 : Dr.Eng. in Civil Engineering – France
“Distinction with the congratulations of the Board of Examiners”
2009: M.Eng. in Mechanical and Civil Engineering, INSA Rennes – France
"Structural Mechanics, Modelling with FEM, Fire action, Steel
structures"
2008: B.Eng. in Civil Engineering
Institute of Technology of Cambodia (ITC), Phnom Penh, Cambodia
(1st rank student in the department for 2 years)
2005: Technician in Civil Engineering
Institute of Technology of Cambodia (ITC), Phnom Penh, Cambodia
(1st rank student in the department for 2 years)
===========Areas of Expertise and Research Interests==============
• Probability Approaches for Durability
• Thermal and Mechanical behavior of materials
• Nondestructive Testing & Evaluation (NDT&E)
• Materials for construction and Durability
• Solid and Structural mechanics
• Signal & Image Processing, Thermographic Imaging
• Electromagnetic and Hyper-frequency Protection
Supervisors: Frédéric DUPRAT (during Postdoc), Thomas DE LARRARD (during Postdoc), Sandrine GEOFFROY (during Postdoc) and Didier DEFER (PhD), Florin BREABAN (PhD)
Phone: +33766202567
Address: Angers, France

less

Austin Coffey

South East Technological University

David Seamon

Kansas State University

BORA YILDIRIM

Hacettepe University

Armando Marques-Guedes

UNL - New University of Lisbon

Januarti Jaya Ekaputri

Institut Teknologi Sepuluh Nopember

Giampaolo Salice

Università degli Studi di Cagliari

Lev Manovich

Graduate Center of the City University of New York

Alicia Camara

Universidad Nacional de Educación a Distancia

Isad Saric

University of Sarajevo

Osama El Hariri

Banha University At Egypt

InterestsView All (12)

Uploads

Papers by Sam Ang KEO

Defects detection by infrared thermography with a new microwave excitation system

Mechanics & Industry, 2014

ABSTRACT This study presents a NDT method using infrared thermography associated with a microwave... more ABSTRACT This study presents a NDT method using infrared thermography associated with a microwave excitation. The advantages of such stimulation lie in the volumic absorption of incoming waves which lead to a greater sounded depth. This method is applied to two types of samples. The first is a concrete slab reinforced with CFRP on which a bonding failure is inserted and the second is a wooden plate on which a metallic insert is placed on the back face. The device generating the microwaves is made of a commercial magnetron associated with a pyramidal horn antenna. An infrared camera is placed on the same side as the stimulated surface and thermograms are recorded at regular intervals. The whole assembly is placed in a protective room against high frequencies. The incident power density leads to heating of less than 1 ◦C of the surface of the samples. The thermograms show a higher temperature rise in front of the defect area. The non-uniformity of the beam, leads us to treat the thermograms with an algorithm of contrast. These first results show the interest of the microwave excitation to detect defects deeper than in the case of surface excitation.

$Research paper thumbnail of Analysis of effects of diffraction and interference on detection by microwave thermography$

Analysis of effects of diffraction and interference on detection by microwave thermography

by Sam Ang KEO and Razvan Dragan

Journal of Civil Structural Health Monitoring, 2019

In this paper, the effects of diffraction and interference on thermograms of steel bars in a rein... more In this paper, the effects of diffraction and interference on thermograms of steel bars in a reinforced concrete wall using microwave thermography are discussed. Three series of microwave thermography tests were conducted. Transmission approach was used for the first series of tests. The tests were carried out with a single rebar (12 mm diameter) vertically placed against a concrete wall of 1 m × 1 m × 6.5 cm. The sample was heated with an average power of 600 W for 3 min. The second and the last series of tests were carried out with a reinforced concrete wall using transmission and reflection approaches, with five angles of incident waves (0°, 15°, 30°, 45°, and 60°), and a heating power of 600 W for 5 min. The test results were analyzed based on the Snell-Descartes theory and data interpretation by multiple approaches. Detailed discussion clarifies how diffraction and interference affected the thermograms. In the reflection approach, the incident waves guided by the antenna were refracted after reaching the surface of the concrete wall, then transmitted into the concrete. The fractions of transmitted waves that reached the steel bars were reflected to the surface of the concrete wall, which made those parts of concrete hotter than the other parts without reflected waves. In the transmission approach, the interference of the diffracted waves made the concrete in the areas of wave superposition hotter than other areas and mainly affected the thermograms of the rear surface of the detected wall.

Download

Detection of Concrete Cover of Reinforcements in Reinforced Concrete Wall by Microwave Thermography with Transmission Approach

by Sam Ang KEO and Didier Defer

Applied Sciences, 2022

Concrete cover has an important role in reinforced concrete (RC) structures because it protects r... more Concrete cover has an important role in reinforced concrete (RC) structures because it protects reinforcement bars from the bad effects of weather, fire, and bad environmental conditions that cause the corrosion of the reinforcements. Although it is an essential parameter to be considered for structural health monitoring (SHM), its detection by infrared thermography, especially in the heating phase, has not been accessed yet. The detailed analysis and discussions of physical phenomena, known as diffraction and interference, affecting the thermograms during the detection of the steel bars by microwave thermography have given an essential key for resolving this issue. The present paper proposes an innovative methodology with microwave thermography for determining the concrete cover thickness of one-layer reinforcements (12 mm in diameter and regularly placed at 10 cm) in an RC wall (1 m × 1m × 6.5 cm). By using the transmission approach with five angles of microwave antenna direction (0°, 15°, 30°, 45°, and 60°) and the Snell-Descartes law and linear law, the proposed methodology leads us to deduce the approximate value of the concrete cover thickness (37.74 mm), which is close to the real value (38 mm), as well as the spacing of the steel bars and dielectric constant of the concrete. The detection of the concrete cover thickness is another new remarkable achievement of infrared thermography methods.

Download

Defects detection by infrared thermography with a new microwave excitation system

by Franck Brachelet and Sam Ang KEO

Mechanics & Industry, 2014

Download

Defects detection by infrared thermography with a new microwave excitation system

by Sam Ang KEO and Didier Defer

This study presents a NDT method using infrared thermography associated with a microwave excitati... more This study presents a NDT method using infrared thermography associated with a microwave excitation. The advantages of such stimulation lie in the volumic absorption of incoming waves which lead to a greater sounded depth. This method is applied to two types of samples. The first is a concrete slab reinforced with CFRP on which a bonding failure is inserted and the second is a wooden plate on which a metallic insert is placed on the back face. The device generating the microwaves is made of a commercial magnetron associated with a pyramidal horn antenna. An infrared camera is placed on the same side as the stimulated surface and thermograms are recorded at regular intervals. The whole assembly is placed in a protective room against high frequencies. The incident power density leads to heating of less than 1 °C of the surface of the samples. The thermograms show a higher temperature rise in front of the defect area. The non-uniformity of the beam, leads us to treat the thermograms with an algorithm of contrast. These first results show the interest of the microwave excitation to detect defects deeper than in the case of surface excitation.

Download

Development-of-an-Infrared-Thermography-Method-with-CO2-Laser-Excitation-Applied-to-Defect-Detection-in-CFRP

This paper presents a NDT by infrared thermography with excitation CO 2 Laser, wavelength of 10.6... more This paper presents a NDT by infrared thermography with excitation CO 2 Laser, wavelength of 10.6 µm. This excitation is the controllable heating beam, confirmed by a preliminary test on a wooden plate 1.2 m x 0.9 m x 1 cm. As the first practice, this method is applied to detecting the defect in CFRP heated by the Laser 300 W during 40 s. Two samples 40 cm x 40 cm x 4.5 cm are prepared, one with defect, another one without defect. The laser beam passes through the lens of a deviation device, and heats the samples placed at a determinate position and area. As a result, the absence of adhesive can be detected. This method displays prominently its application as NDT with the composite materials. This work gives a good perspective to characterize the laser beam, which is very useful for the next detection campaigns. , since 2010. He is currently working on the infrared thermography method with CO 2 LASER and microwave excitation, applying to NDT on reinforced concrete structures and CFRP. His research interests include also modeling on steel structures and fire with finite element method.

Download

Comparison between Microwave Infrared Thermography and CO 2 Laser Infrared Thermography in Defect Detection in Applications with CFRP

This paper presents two infrared thermography methods with CO 2 Laser excitation and microwave ex... more This paper presents two infrared thermography methods with CO 2 Laser excitation and microwave excitation applied to defect detection in CFRP. The tests were conducted with two specimens, one with defect, and another one without defect. On two concrete plates 40 cm × 40 cm × 4.5 cm were reinforced by CFRP; the defects were made by the absence of adhesive on an area 10 cm × 10 cm. The specimens were heated by microwave, generated by a commercial magnetron of 2.45 GHz and guided by a pyramidal horn antenna, with a power of 360 W within 150 s. Another series of the tests was conducted with CO 2 Laser, wavelength 10.6 µm, by heating the samples with a power of 300 W within 40 s. An infrared camera sensitive to medium waves in range of 3 -5 μm, with a detector of 320 × 256 matrix detector in InSb (Indium Antimonide), was used to record the thermograms. As a result, the CO 2 Laser excitation is better for the delamination detection in CFRP. This study opens interesting perspectives for inspecting other types of defects in materials sciences; the microwave excitation is suitable for the deep defects in the materials whereas the CO 2 Laser excitation is better for the defects near the surface of the materials.

Download