In Conventional ultrasonic non-destructive condition monitoring the testing personnel utilize his testing experience to interpret defects while analyzing the ultrasonic echo. Due to the coarse material structure, the ultrasonic wave attenuate more so sometimes it gives false impression of defect and provides unreliable results. The conventional inspection method is too subjective and highly relies on the effectiveness of testing personnel so the inspection reliability is low. To overcome these limitations a multi-interrogation ultrasonic technique and correlation of several parameters such as attenuation, acoustic velocity and grain size with material features is suggested in this paper.
1 Introduction
Non Destructive Testing (NDT) is the testing of materials, for surface or internal flaws or metallurgical condition, without rendering it unfit for service.
There are various NDT methods of inspecting the internal defects of complex surface parts, e.g. radiograph, eddy flow, ultrasonics, etc. Amongst these testing techniques, ultrasonic testing has an important role due to its strong penetration, good direction, high sensitivity, overall comparative low cost, and being harmless to the human body and the material of the parts.
Ultrasonic [1, 2, 3, 4] is a highly effective non destructive condition monitoring method which can detect even incipient faults. So Mean Time between Failure (MTBF) increases due to proactiveness and reduce Mean Time to Repair (MTTR) by improving trouble shooting capabilities. Ultrasonic nondestructive testing methods [5] play an important role in the physical characterization of engineering materials and in the assessment of their quality and serviceability in structures. In a wide range of different NDT me...
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The materials that fit in these criteria are ceramics compounds made of borides, nitrides and carbides. As a result of having those properties, this class of material can be applied in extreme environments such as extreme temperatures, chemical reactivity and erosive attack. Because of that, in the 1950’s, studies started to analyze the possibility of using them to coat nuclear reactor but they also have the ability to work as electrode for electric arc furnaces, handling of molten metals and for aerospace usage (e.g. rocket propulsion, atmospheric re-entry, hypersonic flight), this last application leaded to further investigations on UHTCs.3,4,5
waves were reflected back to the transducer as they crossed interfaces of different acoustic impedance. More simply, the ultrasound bounced off the
Iqbal, M. K. (2013, March 27). NED University of Engineering and Technology. Retrieved from Department of Metallurgy Engineering: http://www.neduet.edu.pk/myd/TE/MY%20302.pdf
This experiment will find, experimentally, the acoustic impedance of paraffin and water. This will be done by measuring the density of these materials and the speed of sound through them. The values obtained for the acoustic impedance will be used to find the reflection coefficient of the boundary. This value will be checked by measuring the amplitude of reflected waves off a boundary and then finding the reflection coefficient from these measurements. If the two values obtained for the reflection coefficient are close, then the acoustic impedance measurement...
A transducer is a mechanism that changes one form of energy to another form. A toaster is a transducer that turns electricity into heat; a loudspeaker is a transducer that changes electricity into sound. Likewise, an ultrasound transducer changes electricity voltage into ultrasound waves, and vice versa. This is possible because of the principle of piezoelectricity, which states that some materials (ceramics, quartz, and others) produce a voltage when deformed by an applied pressure. Conversely, piezoelectricity also results in production of a pressure whe...
Ultrasounds have been a part of the medical world since the 1940s. The affects of acoustic vibrations on the body were studied as early as the 6th century. Then, ultrasound gained widespread acceptance as a therapeutic trea...
works and can increase the quality of the products. Since the 1980s several international groups have worked to introduce such systems. One of the early collaborations was between nine steel making companies and three aluminum making companies; called “American Iron and Steel Institute for Surface Inspection Project” the collaboration produced an inspection system manufactured by Kodak. Other systems that include CCD cameras were introduced with a variety of image processing techniques [7]. Such systems are limited to certain defects i.e. those that include a color difference or geometry change, the main problems they can detect are pitting, roller marks and lubrication presence. [8] Usually such systems are implemented in the cold rolling stage as a precaution. Other systems propose constructing 3-D information about the steel sheet surface, ( Profilometer [9,10]). . Due to the small inspection area used ( 340 μm x 260 μm ), such a system is s...
"Lecture 6 - Sound Waves Ultrasound." Courses Washington. Washington.edu, n.d. Web. 10 Feb. 2014. .
Today’s ultrasound machines operate using the pulse-echo system. In order to produce an accurate representation of the anatomy being surveyed, the machine must determine echo’s strength and location. Ultrasound systems measure the time it takes for echoes to return and relates that to distance traveled to decipher location of reflectors using the range equation. Ultrasound equipment basically consists of four components, a beam former, receiver, processor, and display (Kaur, 2013). Figure 1 shows the pathway of the echo voltages through the ultrasound machine from first spark, through memory and display.
Ultrasonic testing (UT) is considered as one of the modern technology that would allow engineering constructions and solid materials to be checked and detect internal faults while keeping structures intact and undamaged. Ultrasonics use acoustic waves to disseminate through the material to test and detect any irregularity. Such irregularities are discontinuities (type and location), the material’s grain structure, thickness, internal corrosion etc. Ultrasonic testing can be used on a wide variety of plastics, composites, ceramics and metals but cannot be used on wood and paper products. Other limitations include the material’s shape, its surface, its orientation when testing and the device must be able to test the material with ease.
It is acknowledged that all materials permit sound energy to pass through, it depends on the material and frequency of sound.”Transmission Loss” is the attenuation of sound passing through a material. For acoustical purposes , the materials used for barrier between noise source and noise receiver as long as it has a TL of at least 10dB greater than the desire noise reduction. It ensures that the only nise path to be considered in acousti...
There are numerous type of defects that we can found in body side such as dent, bulging, sharp edge, spot weld spatter and wavy. These defects contribute from 4M factor such as man, method, machine and material. This type of defects can be controlled through analysis base on cases and area at body side which can be said different area different causes.
When you take ultrasound waves and apply them to your patient’s skin, the sound waves that are transmitted from your transducer and into your patient’s tissue go through a series of changes. The sound waves can be reflected, refracted, scattered about and also attenuated.
Scanning probe microscopy in nano mechanical testing has started with the invention of the scanning tunneling microscope in the year 1981. Till then based on the type of principles there are number of models developed and are in use. Scanning probe microscopy found popularity owing to its ease in versatility in dealing with a number of issues, typically it is used to identify the material properties on nano to even pico scales. Scanning probe microscopy techniques such as atomic/friction force microscopy(AFM/FFM) are increasingly finding applications in tribological studies of engineering surfaces as well for finding surface texture etc. Atomic and molecular level details can be assessed using Scanning probe microscopy with great ease and the instruments are highly versatile. AFMs with suitable tips are being used to study issues like scratching, wear etc. Scratch and wear properties of variety of materials have been measured. Mechanisms of material removal are also studied. Localized surface elasticity maps of composite materials with penetration depths less than 10nm can be found using SPM with nano mechanical testing procedures. Nano indentation hardness and the young’s modulus of elasticity can be measured with a depth of indentation as low as 1nm. Scratching and indentation on the nano scale are powerful ways to screen for adhesion and resistance to deformation of ultrathin coatings. These studies provide insight into failure mechanisms of the materials and thin coatings. SPM in nano mechanical testing provides insight into the surface characterization and provided glimpse of failure mechanisms study. (Bhushan, 2001). The manner of using interactions between the probe and the surface to obtain an image is gene...
The ultrasonic technology can be found from piezoelectric effect conducted research by Pierre Curie 1880. Pierre Curie he discover asymmetrical crystals like Rochelle salt and quartz can generate electricity charge once mechanical pressure is applied. So it is obtained mechanical vibrations from applying electrical oscillations to the crystals. The frequency of Ultrasonic wave should be higher than 20,000 Hz. (Sound waves).