以微泵浦傳輸流體控制質量之吸振器設計及結構減振研究

Design of a Vibration Absorber and Its Application in Structural Vibration Reduction Using Tunable Fluid Mass Driven by Micropump

陳俊元(Chun-Yuan Chen)

指導教授 ： 李春穎

國立臺北科技大學/機電學院/製造科技研究所/碩士(2014年)

https://doi.org/10.6841/NTUT.2014.00044

摘要

一般機器在操作時都會在不同轉速下運轉，造成機器結構必須承受一定頻寬範圍內之動態負載。本文旨在應用調諧質量系統(Tuned Mass Damper, TMD)於機台結構減振，配合振源(如迴轉馬達)之頻率改變，調整TMD之質量，達到機台最佳減振狀態。本研究中以微型泵浦驅動液體輸送至吸振器之儲水槽，達到控制質量，通過控制質量改變吸振器之自然頻率來減低試驗平台因機台運轉產生的外界干擾效果，以達到擾動頻率調變減振之功效。首先量測主結構之自然頻率，選擇欲控制之模態，再以理論模型設計並製作吸振器，再藉由頻譜分析儀量測不同輸入液體質量對應之吸振器自然頻率及阻尼比，實驗結果顯示此吸振器第一模態及第二模態可調變範圍皆將近40%。再將吸振器架設於主結構平台上，並將平台上之振動源調整至平台之自然頻率進行激振，再調整微型泵浦輸入吸振器達到該頻率所需之液體質量大小，測試其減振之效果。實驗結果顯示，未裝滿流體之容器內因流體自由表面跳動以致阻尼增加關係，造成減振效果難以彰顯，且系統做動時間較不穩定。為改善此情形在儲水槽中間加一層水平隔層，實驗結果顯示此方法能降低振動時產生之液體跳動，而有效降低吸振器阻尼值，且能使系統作動時間穩定，有效改善控制效率。

關鍵字

諧調質量阻尼器 ； 減振器設計 ； 微型泵浦

並列摘要

Most machines usually operate under different rotational speeds, which cause the structure of a machine subjected to varying frequency excitation over certain frequency span. A new design of tuned mass damper was proposed in this study to reduce the structural vibration of a machine platform with varying excitation frequency, e.g. disturbance from the unbalance mass of rotational motor in different speeds. The absorber mass was changed by controlling the pumping of fluid into the reservoirs of the vibration absorber. With the stiffness remained unchanged, the natural frequency of the absorber could be tuned accordingly. Thus, the reduction in vibration of the machine could be obtained by tuning the natural frequency of the absorber according to the activating frequency of the external harmonic disturbance. Firstly, the variations of the natural frequency and damping ratio of the absorber with different tuned masses were measured experimentally. The results showed that the adjustable ranges for first two modes could all reach more than 30%. Then, the absorber was installed on a machine platform and its performance was investigated under the external disturbance at the natural frequency of the platform. It was found that, due to the dominant effect of the damping originated from the fluid jumping on the free surface of the partially filled liquid reservoir, the vibration reduction effect from the absorber was limited. To improve this situation, we added a horizontal separation plate inside the fluid reservoirs, and the experiment results showed that the bouncing of the fluid on the free surface of the partially filled liquid reservoir was alleviated, and effectively reduced the damping ratio of the absorber. Thus, the system became more stable and the control efficiency was effectively improved.

並列關鍵字

Tuned mass damper, ； absorber design ； micropump

參考文獻

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