Adjustable template stiffness device and SDOF nonlinear frequency response

摘要

Devices with displacement dependent stiffness have been explored for vibration isolation. In this paper, an adjustable template stiffness device (ATSD) is presented. The ATSD is made up of pre-compressed springs attached to rollers, rolling along curved templates that allow adjustment of stiffness as a predetermined function of displacement. The ATSD configuration is presented in detail, and an analytical model is developed and validated using test results. The ATSD is tested under harmonic motion to determine its force-displacement behavior; then, it is connected to a single degree of freedom system, with an additional linear elastic stiffness spring, and tested on a shaking table to determine its vibration characteristics. The combination of the ATSD and the additional linear spring results in a composite nonlinear elastic spring with an initial softening behavior followed by hardening behavior or vice versa, i.e., depending on the chosen curved template. Frequency response curves obtained from test results are presented to demonstrate the capability of the ATSD. The new ATSD can be used for vibration isolation studies in future studies.