SHRP-A-379 traducir

The following engineering
quantities should be calculated.
• 011 = P/A; axial stress where A is the cross-sectional area of the specimen
• "/'12= V/A; shear stress
• _12 = 6J2h; shear strain where h is the height of the specimen
• G = T12/e12; complex shear modulus;
• _k = phase angle in degrees
5.4 Simple Shear Test (Constant Height)
5.4.1 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 a temperatures of 4°C, 20°C, and 40°C.
5.4.2 Testing--This is a stress-controlled test with the feedback to the horizontal
actuator servovalve from the magnitude of the shear load. The test is conducted at constant
height, requiring the vertical actuator servovalve to be controlled by the vertical LVDT.
(i.e., the axial actuator is under closed loop feedback control from the LVDT to measure the
relative displacement between the specimen caps.) Precondition the specimen by applying a
7 kPa shear stress for 100 cycles. After preconditioning the specimen, increase the shear
stress at a rate of 70 kPa/s and hold for 10 seconds in accordance with figure 7 (35, 105, and
350 kPa at 40, 20 and 4°C, respectively). After 10 seconds, reduce the shear stress to zero
at a rate of about 21 kPa/s. Continue to record data for an additional 30 seconds during this
recovery period. Axial and shear deformations, as well as axial and shear loads, should be
recorded at appropriate intervals during the test, i.e., approximately 10 data points per
second.
The following test parameters
should be recorded.
• axial load (P);
• shear load (V);
• _5v = vertical displacement of the specimen
• t_h = horizontal displacement of the specimen
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