Experiment and analysis of piezoelectric variable friction damper

[[abstract]]於結構減震消能技術中，利用摩擦原理以消散地震所引致之結構動能，已證實可改善結構物之抗震能力，各式摩擦阻尼器亦已應用於實際工程案例中。然而，傳統被動型摩擦元件只有在地震力所引致之摩擦力超過一預設之固定值下的幾個震波內始能發揮消能功效，其餘時間則與一般斜撐無異，故未能充份發揮其應有之消能能力。為能使摩擦阻尼器在各種震波強度下皆能充份發揮其消能之功能，本文利用國內現在機械加工技術，結合壓電智慧材料之力學性能，自行研發一種新型之半主動摩擦阻尼器。該阻尼器利用壓電材料具有易於控制且響應快等優點，藉以控制施加於阻尼器內部摩擦界面之正向力，以達到調控阻尼器遲滯行為之目的。同時，該阻尼器兼具被動與半主動之性能，亦即阻尼器在正常運作下具半主動之能力，而在電力中斷時則仍具有被動摩擦消能之能力，因而具有安全性、可控性、高效能等特點。在半主動設備隔震之數值模擬中，可知本文半主動隔震系統在近、遠域震波中，能有效抑制設備位移與加速度之反應，其效能可接近於主動控制力之效果。本文元件測試結果顯示，藉由改變壓電致動器之驅動電壓，本文所研製之半主動摩擦阻尼器確可即時控制其最大滑動摩擦力，因而改變阻尼器之摩擦消能特性，因此具備實用之價值。[[abstract]]It has been proved that using dry friction to dissipate seismic energy is an effective technology Various types of passive friction dampers have been applied in real structures Nevertheless recent studies have revealed that variable friction dampers whose slip force is controllable by regulating the normal contact force on the friction interface can be more efficient than passive friction dampers In order to improve the energy dissipation capability of friction dampers a variable friction damper with an embedded piezoelectric actuator is proposed in this study Because of its low energy demand and quick response a piezoelectric actuator was chosen as the control device The variable damper can function as a passive damper in case of power failure The theoretical basis for the proposed damper was developed and the design formula was derived in this study The formula for computing the control voltage of the piezoelectric actuator was also derived in this study The passive and semi-active features of the damper were tested by device cyclic tests which were conducted on a universal testing machine The test results prove the correctness of the derived formula Finally by using the experimental data of the tested piezoelectric actuator the seismic response of a semi-active isolation system composed of a sliding platform and the proposed variable damper is simulated The numerical results are discussed and highlighted in this study The result shows the feasibility of the proposed dampe