SHRP-A-379 traducir

• vertical displacement of the specimen (/_v);
• radial displacement of the specimen (tSh);
The following engineering
quantities should be calculated.
• 0.11= P/A + confining stress (022 _--- 0"33); axial stress where A is the
cross-sectional area of the specimen
• Ell= tSv/h;uniaxial strain where h is the height of the specimen
5.3 Frequency Sweep Test
5.3.1 Specimen Setup--Attach vertical and horizontal LVDTs to the specimen as
shown in figure 4. The vertical LVDT is used to measure changes in specimen height as
represented by changes in the distance between the top and bottom platens. The horizontal
LVDTs measure the difference in horizontal displacement between two points on the
specimen separated by 37.5 mm. The horizontal LVDTs should be mounted such that they
contact the specimen at approximately 19 mm on either side of the specimen at mid-height.
Position the vertical test system head to allow the specimen-platen assembly to slide between
the bottom horizontal and top vertical heads. Position the horizontal test head such that the
top and bottom test heads are aligned vertically. Slide the specimen between the heads so that
it is centered between the heads. Secure the platens to the heads by activating the hydraulic
clamps.
Completely lower the environmental chamber to seal off the specimen from the outside
temperature influences. Testing is conducted at temperatures of 4°C, 20°C, and 40°C.
5.3.2 Testing--The test is conducted at constant height requiring the vertical actuator
servovalve to be controlled by the vertical LVDT. Furthermore, this is a strain-controlled
test with the maximum shear strain limited to 0.0001 mm/mm. Precondition the specimen by
applying a sinusoidal horizontal shear strain of amplitude = 0.0001 mm/mm at a frequency
of 10 Hz for 100 cycles. After preconditioning, a series of 10 tests are conducted in
descending order of frequency at each temperature level beginning with the lowest
temperature. (The shear strain is applied at the following frequencies at each test
temperature: 10, 5, 2, 1, 0.5, 0.2, 0.1, 0.05, 0.02 and 0.01 Hz.) Recording 50 data points
per load cycle is sufficient. Since the test is conducted at a constant height, the axial actuator
is under closed loop feedback control from the LVDT measuring the relative displacement
between the specimen caps.
The following test parameters
should be recorded.
• axial load (P);
• shear load (V);
• div = vertical displacement of the specimen
• t5h = horizontal displacement of the specimen
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