SHRP-A-379 traducir

7.4.4 Adjust the controls for the environmental chamber to the requisite test
temperature and allow the chamber and the test assembly to stabilize at that temperature.
7.4.5 Precondition the specimen for 100 cycles with a shear stress of 7 kPa. Each
cycle is 0.7 second in duration, and consists of the application, of a 0.1 second haversine load
followed by a 0.6 second rest period.
7.4.6 At the conclusion of the preconditioning, perform the simple shear test by
increasing the shear stress at a rate of 70 kPa/s to: 345 kPa at 40°C or T_ff(PD), 105 kPa at
20°C or Teff(FC), or 35 kPa at 4°C. Maintain the stress at that level for 10 seconds and then
reduce it to 0 kPa at a rate of 25 kPa/s. Continue the test for an additional 10 seconds at a
stress level of 0 kPa.
7.4.7 Record axial deformation, shear deformation, axial load, and shear load at a
rate of about 10 data points per second.
NOTE 13.--The test takes about 20 to 30 minutes to complete from the time the specimen is placed in the
apparatus until it is removed.
7.5 Frequency Sweep Test at Constant Height
7.5.1 Prepare the test specimen in accordance with section 6.
7.5.2 Mount two LVDTs on the test assembly in such a manner that axial (vertical)
and shear (horizontal) deformations can be measured during the test with an accuracy and
precision commensurate with the requirements in M-003 (note 5).
NOTE 14.--This is a strain-controlled test. The maximum strain is limited to 1 x 10 -4 mm]mm. During the
test, the height of the specimen is kept constant. To accomplish this, the vertical load actuator is controlled by
feedback from the vertical (axial) LVDT. The feedback to the horizontal (shear) load actuator is from the LVDT
measuring the horizontal (shear) deformation.
7.5.3 Place the specimen inside the shear test device and clamp it securely in place.
7.5.4 Adjust the controls for the environmental chamber to the requisite test
temperature and allow the chamber and the test assembly to stabilize at that temperature.
7.5.5 Precondition the specimen by applying a sinusoidal shear (horizontal) strain of
approximately 1 x 10 -4 ram/ram at a frequency of 10 Hz for 100 cycles.
7.5.6 At the conclusion of the preconditioning, perform the frequency sweep test in
which 100 cycles of 1 x 10 -4 mm]mm sinusoidal shear (horizontal) strain is applied at the
each of the following frequencies in descending order: 10, 5, 2, 1, 0.5, 0.2, 0.1, 0.05, and
0.02 Hz. Repeat the test on each specimen at three different temperatures, typically 4, 20
ar:d 40°C, starting at the lowest temperature.
7.5.7 Record axial deformation, shear deformation, axial load, and shear load at a
rate of about 50 data points per load cycle.
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