The GDS Resonant Column Apparatus (RCA) is used to excite one end of a confined solid or hollow cylindrical soil specimen. The specimen is excited in torsion or flexure (bending) by means of an electromagnetic drive system. Once the fundamental resonant frequency is established from measuring the motion of the free end, the velocity of the propagating wave and the degree of material damping are derived. The shear modulus (torsion) or Young’s modulus (flexure) is then obtained from the derived velocity and the density of the sample.

Unit 32 Murrell Green Business Park, London Road, Hook, Hampshire, RG27 9GR, UK. Tel.:+44 (0) 1256 382450, FAX:+44 (0) 1256 382451, e-mail:sales@gdsinstruments.com