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06:16 Aug-02-1999

Udo Schlengermann

Consultant, -
Standards Consulting,
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Joined Nov 1998
174
UT2 - Variables affecting test results

some comments to Ed Ginzel's paper in june 99:

1. in table 8.3 the velocity of Castor oil at 25°C must be around 1470 m/s, not 14774 m/s as shown in the paper.

2. In water the velocity does not change linearly with temperature:
starting at freezing point the velocity increases up to the maxium of 1557 m/s at 74°C, then it decreases with temperature up to the boiling point.
At 35°C water has a longitudinal velocity of 1520 m/s, not 1516 m/s as given in the paper.
The following table gives the correct results for water:

temperature velocity delta
in °C in m/s in m/s°C

5 1440 3,14
15 1472 2,65
25 1498 2,15
35 1520 1,67
45 1536 1,18
55 1548 0,68
65 1555 0,20
75 1557

3. In steels (unalloyed and alloyed) the temperature coefficient for longitudinal and transverse waves is between -0.4 m/s°C and -0,7 m/s°C in the range from 0° up to 600°C, e.g. much smaller than given in the paper (2 m/s°C).
So in practice the change of steel velocity with temperature is negligible, whereas it is not with plastics and fluids.




 


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