|
|
|
Title: DYNAMIC TESTING OF MATERIALS /WITH DISCUSSION/
Accession Number: 00213965
Record Type: Component
Availability: Transportation Research Board Business Office 500 Fifth Street, NW Abstract: DYNAMIC TESTS OF BOTH SONIC VELOCITY AND RESONANT FREQUENCY TYPES ARE DESCRIBED. SONIC VELOCITY TESTS WERE MADE TO EVALUATE THE EFFECT OF BOTH AIR-FILLED AND WATERFILLED CRACKS ON TRANSMITTAL OF SIGNALS THROUGH CONCRETE. LOW-FREQUENCY SIGNALS, ESPECIALLY THOSE GROUPS CAUSED BY HAMMER BLOWS, SHOWED LITTLE EFFECT FROM EITHER NARROW OR WATER-FILLED CRACKS. AS WOULD BE EXPECTED, ANY ATTENUATION OR DELAY WAS INCREASED AS THE CRACK SIZE INCREASED. AN INCREASE IN THE FREQUENCIES COMPOSING THE SIGNAL ALSO INCREASED THE EFFECT OF BOTH AIR- AND WATER FILLED CRACKS. ANOTHER SERIES OF INVESTIGATIONS CONSISTED OF SONIC-VELOCITY MEASUREMENTS ON MASSES OF SAND, GRAVEL, COMBINATIONS OF SAND OR GRAVEL WITH WATER, AND FRESHLY MIXED CONCRETE. DECREASING PARTICLE SIZE REDUCED THE MEASURED SONIC VELOCITIES. THE PRESENCE OF WATER IN THE ABOVE MIXTURES INCREASED THE SONIC VELOCITY IN ALL CASES. MEASURED VELOCITIES IN THIS SERIES WERE MUCH BELOW VELOCITY OF SOUND IN AIR AND, WHEN COMPARED TO DATA PRESENTED BY OTHER INVESTIGATORS, LED TO THE CONCLUSION THAT THE APPARENT VELOCITY THROUGH A LOOSE MASS IS DEPENDENT UPON THE CHARACTER AND FREQUENCY OF THE SIGNAL. THESE RESULTS LED TO THE INVESTIGATION OF VARIOUS PICKUPS AND CIRCUIT COMPONENTS WHICH DEMONSTRATED THAT ORDINARY EQUIPMENT COMPONENTS ALWAYS PRODUCED TIME DELAY FACTORS IN THE MEASUREMENT. SOME OF THESE VARIABLES ARE CAUSED BY SURFACE CONDITIONS, POWER AND TYPE OF THE ORIGINAL SIGNALS AND THE MOUNTING OF PICKUP COMPONENTS. RESONANT-FREQUENCY DYNAMIC TESTS WERE COMPARED TO SONIC VELOCITIES. FLEXURAL AND TORSIONAL RESONANT FREQUENCY TESTING ON ROCK CORES REVEALED UNUSUAL REACTIONS. SOME INDICATIONS OF HETEROGENEITY AND LOOSE STRUCTURE WERE EVIDENT EVEN IN APPARENTLY SOUND SPECIMENS. IRRATIONAL VALUES OF POISSON'S RATIO, WHICH WERE FREQUENTLY INDICATED BY THESE CORES, ARE DISCUSSED. /AUTHOR/
Supplemental Notes: Vol 33, pp 242-258, 10 FIG, 5 TAB, 10 REF, 1 APP. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved.
Monograph Title: Monograph Accession #: 01490389
Authors: Mitchell, L JMccoy, E EMather, BEditors: Burggraf, FredMiller, Walter JPublication Date: 1954
Serial:
Highway Research Board Proceedings
Volume: 33 Media Type: Digital/other
TRT Terms: Old TRIS Terms: Subject Areas: Highways; Materials
Files: TRIS, TRB
Created Date: May 22 1972 12:00AM
More Articles from this Serial Issue:
|
