臺灣博碩士論文加值系統

船舶結構的低頻振動通常是利用有限元素法加以預測，對於較高頻的振
動 所產生的結構噪音，在人耳可聽到的範圍，傳統上是利用能量法加以
預測其在 結構上傳遞的行為。此頻率範圍內模態密度較高，在船舶結構
上此範圍 通常在數 kHz以上，而有限元素法可預估的船舶結構振動頂多
到幾百 Hz左右， 因此在數百∼數 kHz中間屬於人耳可聽到的頻率範圍內
結構噪音之傳遞便需要有理論 模式加以預估。 本研究採有限元素法及統
計能量法之結合，試著來預估結構噪音之傳遞量：先利用 有限元素法求
得統計能量法之參數，如輸入能量或是耦合損失因子，然後再放入統計
能量法預測模式中，將此預測結果與模型實驗所得的值加以比較，以便瞭
解此種模式之準 確度及其誤差範圍以作為日後改進此模式之用。

The predictions of low frequency ship structure vibration
are usually done by finite element method . For higher
frequency range of vibration ,in the audible range of human
ears , is termed as structural borne sound . And its
predictions are usually done by energy method. In this frequency
range , modal density is higher . For ship structure, the
frequency range can be predicted by is abover 2 KHz. Whereas
the upper frequency limit can be predicted by finite element
method is around 100 to 200 Hz for ship structures. Therefore ,
in the frequency range from 200 to 2KHz , a prediction model is
needed . In this study , the combination of energy
method and finite element method will be used to predict
vibration in these frequency range. The finite element method
will be used first to determine the input power and coupling
loss factor for the energy mode . Then , the prediction will be
made by energy method. The prediction will be compared with the
actual measurement from a model ship structure to improve the
accuracy of the prediction.