Resonant Column Apparatus

Resonant Column

Description of Resonant Column

Resonant Column combines the features of both resonant column and torsional shear into a single unit, including a current-driven motor to apply torsional load to the sample, a series of transducers with signal conditioning, a cell and back pressure electro pneumatic control system and a data logger. In the Resonant Column test a cylindrical soil specimen is restrained at the bottom and dynamically excited at the top. The torsional force at the top is generated using an electrical motor constituting eight drive coils encircling four magnets attached to a drive plate. The generated frequency is up to 300 Hz. The fundamental mode of vibration is determined from the maximum amplitude of motion; from the Standards ASTM D4015 resonant frequency, shear wave velocity and shear wave modulus

Features of Resonant Column

• Combined Resonant Column / Torsional Simple Shear device
• Automatic detection of fundamental frequency
• RC: damping ratio from half power bandwidth and from free vibration data
• TSS: damping ratio from hysteresis loops
• Internal floating frame for large angular and axial deformation
• Confining pressure up to 1 MPa
• Suitable for 50 mm dia. specimen (or 38 mm on request)
• Integrated signal generator and oscilloscope