%0 Generic
%D 2012
%T 迴轉式壓縮機之實驗模態分析
%A 王栢村
%P 10
%X 實驗模態分析或稱模態試驗是一種對結構系統分析的方法，常用以探討評估振動與噪音時，界定結構路徑效應之方式。本文針對使用於冷氣機壓縮冷媒及有噪音之虞的迴轉式壓縮機進行實驗模態分析，首先介紹實驗模態分析之理念，同時說明本文所採用固定加速規與移動衝擊錘的傳統實驗方式，以求得並探討結構之模態特性。三個加速規分別安置在壓縮缸及過濾瓶外殼，由單一輸入單一輸出假設，相當於進行三個獨立模態試驗，經由頻譜分析儀可量測求得結構之加速度與外力之間的頻率響應函數，透過曲線嵌合軟體則可以求得實際結構之模態參數，包含自然頻率、模態阻尼比及模態振型。由三個實驗結果所得到的模態參數進行相互比較，結果呈現有相當的一致性，僅有些微之差異。本文探討對一個典型迴轉式壓縮機進行實驗模態分析步驟，由結構模態的路徑特性，有助於未來對壓縮機之振動噪音評估。Experimental modal analysis (EMA) or modal testing that is known for system analysis on the structure is frequently performed to characterize the structural path effect for noise and vibration evaluation. This work aims to perform EMA on the rotary compressor that is used to compress the refrigerant for air conditioners and of concern for noise emission. The general approach for EMA is introduced. The conventional EMA procedure by using the roving impact hammer and the fixed accelerometer is adopted to study the structural modal properties. Three different accelerometers are applied and fixed at the compressor and evaporation chamber housings for EMA, respectively. Base on the assumption of single-input and single-out (SISO), there is equivalently three independent tests of EMA. The frequency response functions (FRFs) between the measured acceleration and applied force can be measured by using the frequency spectrum analyzer. The FRFs can then be processed to obtain structural modal parameters, including natural frequencies, modal damping ratios and mode shapes, by the curve-fitting software. The modal characteristics obtained from the three tests are comparatively studied. Results show those modal properties are quite consistent, though there exists some discrepancy among the three tests. This work layouts the EMA procedure for a typical rotary compressor. The characterized structural path information can be helpful for further diagnosis of noise and vibration spectra from receiver tests for the compressor.
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