MTS Series 315 Load Frame - Manual (Page 8)

Series 315 Load Frame 8 Introduction
Functional Description
The load frame is a stand alone testing structure. The following paragraphs
describe the components shown on the illustration in the
“Component
Identification” on page 7.
Load Frame The load frame has an integrated construction that provides high stiffness,
reducing deflection energy stored in the frame — ideal for testing brittle
materials. The actuator is integrated into the base plate which decreases
frame height and increases stiffness.
The integrated construction also provides a precision, parallel alignment
between crosshead and actuator surface for proper specimen loading.
The load frame provides a large test area for uniaxial and triaxial testing.
The front security door allows easy access to test space. The impact
resistant Lexan panels in front and back allow observation of tests in
progress and helps contain specimen fragments.
Actuator The actuator is a single ended, double acting design allows testing in
compression and tension. The actuator provides a 100 mm (4 in) actuator
stroke for tests requiring large displacements.
Proprietary seal and bearing designs, which have set an industry standard
for durability, ensure long life and performance. Direct-bonded polymer
bearings reduce friction and maximize heat dissipation.
Transducers The load frame usually includes a force transducer and an LVDT (or other
displacement measurement device.
Differential Pressure
( ∆ P) Transducer
The ∆ P transducer provides force readout without affecting load frame
stiffness. The ∆ P transducer is accurate to within ±1% of the calibrated
range at loads above 1000kN. It provides useful measure of external loads
applied to specimens inside a triaxial cell, when conducting multiple
failure state tests per ISRM. The output signal is conditioned at the Digital
Controller for closed-loop control and data acquisition.
Internal Linear Variable
Differential Transformer
(LVDT)
The LVDT is calibrated to full scale actuator travel to provide complete
positioning control. The LVDT is used for specimen positioning and
preloading, and measuring actuator displacement during the test. The
output signal is conditioned at the Digital Controller for closed-loop control
and data acquisition.