sound between 20 Hz and 20 kHz, this frequency range is described as acoustic. Any frequencies below 20 Hz are described as Infrasound and frequencies above 20 kHz (i.e. not picked up by a human ear) are described as Ultrasonic as Figure 1 describes. Figure 1: Sound Spectrum Ultrasonic flaw inspection systems work on the basic principle that sound waves are mechanical vibrations of particles in a medium. The speed of the wave in a given medium is predictable along with the direction it will travel
Accepted In Conventional ultrasonic non-destructive condition monitoring the testing personnel use his testing experience to interpret defects by analysing the ultrasonic echo. Owing to the coarse material structure, the ultrasonic waves attenuate more and sometimes it gives a false impression of defect and provides unreliable results. The conventional inspection method is too subjective and highly relies on the effectiveness of testing personnel owing to the fact inspection reliability is low.
Non-destructive testing technique to detect and characterize such defects and anomalies in the component, and also ensuring pre-service quality and monitoring in-service degradation to avoid pre-mature failure of the component. In this paper sub-surface fatigue crack that occur most commonly during service stage, ultrasonic inspection for finding sensitivity of crack in gears and its effects on life of gear during service stage is discussed. Keywords—sub-surface fatigue crack; ultrasonic inspection;
Answer. Reasons for importance of are nontraditional material removal processes (1) the need to shape new metal alloys and non-metals that are difficult to machine by conventional processes; (2) the requirement of unusual and complex workpart geometries; and (3) the need to avoid surface damage which is often associated with conventional machining. 26.2 There are four categories of nontraditional machining processes, based on principal energy form. Name the four categories. Answer. The four categories
cracks can be separated from each other with eddy current technique. However a crack which goes through grain boundary is clearly more difficult to estimate. Figure 1 shows eddy current signals from three cracks that were found with dye penetrant testing. a) 3 surface breaking cracks on a turbine blade b) Eddy current signals from cracks. Fig 1: Eddy current signals from the three cracks shown in the blade . Measuring the width of a layer is simple with eddy current technique, if there are no strong
Glass ionomer cement[GIC], invented by Wilson and Kent, has been used as a dental restorative material for more than four decades and its properties are constantly improved to overcome its shortcomings. The unique properties of GIC include direct adhesion to tooth and base metals , anticariogenic properties , thermal compatibility with tooth enamel and dentin, minimized microleakage at the tooth–enamel interface, biological compatibility, and minimal cytotoxicity. The disadvantages of GIC such
combines the advantages of both metals and composites. Used in the A380's upper fuselage crown, and being less prone to fatigue and more economic compared to pure composite material, GLARE can be manufactured into structures with little change to conventional techniques. Figure 3 Composite use on the Airbus A380 4 Boeings latest project, the 7E7 is set to become the first predominantly composite airliner since the days when aircraft were constructed from fabric and wood. The company has announced
Is Dolphin Assisted Therapy Beneficial for Special Needs Children? Dayanara Roman Keiser University ENC 43131G Abstract For over two decades Dolphin Assisted Therapy or DAT has been used as a type of sensory therapy used with children and adults diagnosed with either physical or neurological disorders. Through out this time dolphin assisted therapy has been used to assist children with a varying type of disability. Children with autism, Down’s syndrome, developmental delay,