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The Penn State rock mechanics lab has a state-of-the-art, servo-hydraulic biaxial testing apparatus. The vertical load frame has a maximum force of 1MN and the horizontal frame can produce forces up to 800kN. Each load frame may be operated in displacement- or load-feedback servo control. Displacement control resolution is 0.1 micron for each axis and load resolution is <0.1kN. The apparatus is powered by a 20 GPM, 50 hp hydraulic power supply. Servo-controlled load point displacement rates of 0.01 micron/s to 2 cm/s are possible.
The apparatus is set-up primarily for double direct shear
friction studies and is capable of normal stresses up to 40 MPa on samples
of nominal contact dimension 15 cm x 15 cm. Machine stiffness is
roughly 4 MN/cm and therefore ideal for friction and fracture studies.
Animation of Apparatus used in Double-Direct Shear Configuration
Animation of Apparatus with Pressure Vessel