Wykeham Farrance’s Resonant Column is a versatile system that combines Resonant Column and torsional shear tests into one convenient device for evaluating Shear Modulus and Damping Ratio. It includes:
How it works
The system consists of the following components:
Stainless steel cell with acrylic transparent cylinder with 170 mm int. dia. x 200 mm ext. dia., including
channels for bottom and top drainages; internal floating frame for assembling the electrical
motor that applies the torsional load. Test accessories for 50 mm (or 38 mm available on request)
N°2 calibration bars kit + n°1 calibration weight.
MAIN CONTROL BOX, LAPTOP PC AND SOFTWARE
Compact unit connected to laptop PC contains all control, power supply as well as electrical and pneumatic
devices. This system also contains air actuators (I/P converters) and amplification equipment.
High resolution 7” color touchscreen display for cell, and pore pressure monitoring.
The sensor kit contains: Axial LVDT transducer, Volume Change Apparatus, three pressure transducers,
two Eddy current displacement sensors with high precision motorized proximity sensors positioning,
low noise MEMS accelerometer.
The complete system includes a high-quality PC supplied with pre-installed intuitive Windows-based software that allows you to perform both Resonant Column and Torsional Shear tests. The test stages are as follows:
Ramped increase of cell and back pressure is applied causing the air to dissolve for a complete saturation of the specimen. All the pressure readings are shown in real time using an intuitive high resolution colour display.
The confining pressure is applied through the cell pressure until the soil is consolidated, i.e. when pore pressure is dissipated, and volume change is negligible. The soil specimen is restrained at the bottom and dynamically excited at the top.
Frequencies up to 300 Hz are increased automatically in “steady-state” mode by steps (RC discrete) or continuously (RC chirp), or in “free-decay” mode by only an initial frequency. Since the frequency of the input signal varies, the dynamic response of the specimen results in a varying motion amplitude. The secant shear modulus G is determined by the resonant frequency.
The damping ratio D can be evaluated with two methods:
The technique used is the input torsional rotation through a sinusoidal current applied to the coils.
Cyclic torque application in Torsional shear.
86-D2015: Laboratory air compressor. 8 BAR max constant pressure. 230V/50Hz/1Ph 28-WF4051/G: Hand sampler complete of cutter, dolly and receiver for 50mm samples 28-WF2016/2: Water Trap for Air/Water assembly 28-WF4051/A: Membrane placing tool for 50mm samples 28-WF4051/B: O Ring placing tool for 50mm samples: 28-WF4051/E: Filter drains (pack of 50) for 50mm samples 28-WF4055: Rubber membrane 50mm diameter x 200mm long (pack of 10) 28-WF4056: O ring 50mm diameter (pack of 10) 31-WF4051/H1: Two parts split former with vacuum attachment for 50mm sample suitable for Resonant Column.
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