GDS True Triaxial Apparatus (GDSTTA)
The True Triaxial Apparatus (TTA) has the defining characteristic that, unlike conventional triaxial apparatus, all three principal stresses can be controlled independently, rather than just 2 in a conventional triaxial system.
This allows a wider range of complex stress paths to be performed. This dynamic cyclic system is powered by electro-mechanical* actuators and is an extremely sophisticated research tool.
To read a white paper about how the GDSTTA was built click on the link, True Triaxial.