Strain-Controlled, Variable Frequency Cyclic Loading System for Soft Soils

A mechanical, strain-controlled, variable frequency loading system has been developed for cyclic testing for soft soils. The system consists of a variable speed driving system (variable speed electric motor) and a rotation/translation converter (crank and crank-shaft system). It is capable of producing a simple harmonic time history of axial strain at an infinite number of desired strain levels. The loading system is simple and can be easily fabricated at low cost. Performance of the system is verified by performing frequency sweep tests on a San Francisco Bay mud specimen