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IEC TS 63081 pdf free download

IEC TS 63081 pdf free download.Ultrasonics – Methods for the characterization of the ultrasonic properties of materials.
5 Overview
5.1 General principles
It is important when measuring materials characteristics that the equipment set-up environment and method have as little effect on the results as possible. Clause 5 discusses some of the setup issues and items to be noted when performing these measurements.
The application of a consistent and well understood protocol is the key to deriving meaningful measurements that are reproducible and transportable. Controlling as much of the test environment as possible, from temperature to sample preparation and conditioning, has an important impact on the measurement quality and confidence.
Having water-filled tanks where the temperature can be controlled and measured to the desired accuracy is important. Similarly, other aspects of the water quality employed for the measurements (dissolved gas content and conductivity) may be important subject to the applied technique.
In addition, measurements should be repeated at different conditions (distance, orientation driving signal) depending on the property to be measured, in order to understand and minimize set-up and instrumentation effects. To this end, once the type of measurement has been selected for the particular parameter, sources of uncertainty should be investigated and quantified [1]. Type A uncertainties can be quantified by repeating measurements and building up an appropriate uncertainty budget. Type B sources of uncertainty will require modelling or parallel/confirmatory validation studies.
5.2 Sample preparation
5.2.1 Fluid samples
When working with fluids, immersing the test transducers in the fluid is ideal. However, practically fluids often need to be housed within a container which is immersed within a test tank. Such containers are typically either rigid walled vessels (such as a parallel walled cell culture flasks) or have an acoustically thin membrane at either end of the acoustic path through the material.
Rigid-walled vessels are likely to have the benefit that they have parallel walls, and therefore maintain a uniform thickness of sample. However, the material used to construct the walls of the flask is likely to be acoustically mismatched to water, leading to significant reflections at the interfaces. Additionally, they can exhibit acoustic absorption and dispersion.
Whilst membranes may be thin relative to the acoustic wavelength, their influence on the determination of ultrasonic power as part of the radiation force balance measurement is well documented [2],[3j, and such effects need to be avoided. Care should also be taken to avoid expansion of the membrane during the process of filling the measurement vessel with the fluid under test. Particularly if the vessel is surrounded by air during filling, membranes can expand to a convex shape and thus the vessel might become an acoustic lens which further perturbs the measurement. It is best practice to use flat restraining plates in contact with the membrane to minimize expansion during filling.
Given the possible artefacts introduced by a measurement vessel, measurements should be conducted in a manner that separates the properties of the fluid under test from those of the vessel containing it. A description of methods to accomplish this is given in Clause 6.
When testing fluids, the sample ideally needs to be degassed to a constant level. During sample preparation, it is easy to introduce air into the sample when pouring the liquid. Care should be taken to minimize this; however, ills likely that gas will still be introduced particularly for viscous liquids. Therefore, once the sample is prepared, it may be useful to degas the sample with agitation in a vacuum chamber jar to allow any entrapped gasses to be liberated.IEC TS 63081 pdf download.


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