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Traditional and Advance Characterization Techniques for Natural Fibers
Published in Shishir Sinha, G. L. Devnani, Natural Fiber Composites, 2022
G. L. Devnani, Shishir Sinha, Dileep Kumar, Shailendra Kumar Pandey
Normally the thickness or diameter of the natural fiber is measured with the help of a digital micrometer or by using an optical/scanning electron microscope. The accuracy of measurement using a digital micrometer is 0.001 mm. It is well known that the diameter measurement of natural fibers is a difficult task because of the irregular shape of fibers and variation of thickness at different cross sections. For consistency, 5–10 samples are use to be tested at different locations across the length and average value of diameter is calculated. Image analysis software is used for this estimation of diameter (Sanjay et al., 2019).
Checking workpieces for accuracy
Published in David Salmon, Penny Powdrill, Mechanical Engineering Level 2 NVQ, 2012
All micrometer instruments can measure features within 0.01 mm (0.001″), although some are more accurate. There are a number of different types of micrometers, the most common being the external fixed anvil type, which is used for measuring outside (external) dimensions. This type of micrometer has a rigid bow-shaped frame, a micrometer head and a fixed anvil (measuring face). External micrometers are available in a range of sizes and in either metric (mm) or imperial (inch) units. External micrometers are made in the following range of sizes: 0−25mm(0−1″)25−50mm(1−2″)50−75mm(2−3″)75−100mm(3−4″)
Measuring
Published in Roger Timings, Engineering Fundamentals, 2007
This is the range of sizes that can be measured by any given instrument. It is the arithmetical difference between the largest size which can be measured and the smallest size which can be measured. For example, a 50 mm to 75 mm micrometer has a measuring range of 75 mm − 50 mm = 25 mm.
The ruling engines and diffraction gratings of Henry Augustus Rowland
Published in Annals of Science, 2022
Although made primarily for calibrating the photographic map, Rowland felt that others would find his measurements useful, and published a summary of this work in 1887.77 The apparatus he used had concave gratings of 21½ feet radius, the same as used for the photographic map, and 5- or 6-inches diameter with 7200 or 14 400 lines per inch. The micrometer had a run of 5 inches (127 mm), and errors of less than 1/20000 of an inch (1.25 µm). The paper listed the tiny residual corrections to the wavelength scale on the map, the ‘coincidences’ between lines in different orders of spectra that Rowland had used, and the wavelengths of about 300 standard lines. The single wavelength on which all the others depended was Louis Bell’s measurement of Fraunhofer’s D1 line, described in a paper printed alongside Rowland’s.78 Bell used two of the very few Rowland gratings ruled on glass. They were small, 30 mm wide with lines 19 mm long, ruled on plane sextant mirrors, one with about 7200 lines per inch and the other, ruled with a tangent screw fitted to the ruling engine, with 400 lines per millimetre. The grating spacings were measured against two standard bars made by William Rogers. Bell used a Meyerstein spectroscope, no doubt the one described in the laboratory apparatus list. Bell compared his measurements very carefully with all the other available measurements, especially those of C. S. Peirce.
Effect of Component Position and Inward–Outward Rotation on the Wear of Different Ultra-High Molecular Weight Polyethylenes in an Orbital Bearing Type Hip Joint Simulator
Published in Tribology Transactions, 2023
The mean wear rate of UHMWPE was of the order of 20 mg/106 cycles and it was not sensitive to the position or IOR (Fig. 4). The mean wear rate of UHMWPE-γ in station 1 and 2 was 50% higher than that of UHMWPE, whereas the mean wear rate of UHMWPE-γ in station 3 was 25% lower. VEXLPE showed by far the lowest mean wear rate, 2.1 mg/106 cycles. VEXLPE wear rate was not sensitive to the position or IOR. All liners macroscopically showed burnishing (Fig. 5). Burnishing did not extend to the equator in any of the liners. In addition to burnishing, UHMWPE showed another macroscopic phenomenon, that is, forming of a material layer on or near the dome of all liners of stations 1 and 2 (Fig. 5a). UHMWPE-γ showed similar layer formation in 1 liner of station 1 and 2 liners of station 2 (Fig. 5b). Station 3 never showed a material layer, nor did any of the VEXLPE liners (Fig. 5c). However, with UHMWPE-γ there was no correlation between the wear rate and the presence or absence of the layer in stations 1 and 2. After the tests it was found that the layer could be removed by scratching with a fingernail. The thickness of the detached chips was c. 0.05 mm, measured with a micrometer. However, since the layer was not loose debris, it was not removed prior to the weighing for Fig. 4. In optical microscopy (Fig. 6), the observations were typical of multidirectional relative motion, i.e., subtle crisscross scratches and mild protrusions caused by plastic deformation. The layers were excluded from microscopy because they were too uneven for focused views. On the alumina heads, there was no damage, such as scratching, grain removal, or layers.