Quantifying rate-dependence of a nonlinear hysteretic device

Hysteretic systems are extensively used in vibration control and in a wide range of mechanical problems. The first issue is to know whether the system is rate-dependent or not. In order to address the problem for a specific device employed for vibration isolation, laboratory measurements using a uniaxial testing machine are performed. The device is represented by a wire rope spring. Different types of tests are conducted in displacement control acquiring the device restoring force: cyclic ramps with increasing amplitudes and displacement time histories are obtained applying simple and random homeomorphisms to the ramp histories. The rate-dependence is evaluated comparing the restoring forces measured for the different tests and estimating a quantitative parameter which is chosen to measure the rate-dependence degree.