以軟調法做樑之動態設計

Dynamic Design of Beams Using Soft Tuning

本文主要提出一方法使樑結構之自然頻率調整至一指定頻率值。通常結構勁度改變，其自然頻率亦隨之而變。增加結構勁度能使結構加強；相同的，使結構減弱亦可調整其自然頻率。本文使用人為加一裂縫至樑結構，使樑結構之自然頻率調至一指定之頻率值。先使用轉移矩陣法得系統之特徵方程式，再利用此特徵方程式調整此系統之動態特性。本文並附實例說明及實驗驗證。 A technique for shifting the natural frequencies of beam structures to designated values by using a soft-tuning method is proposed. When the stiffness of beams is changed, the natural frequencies are also altered. Structural stiffness can be increased by enhancing the structures, e.g., strengthening them. Similarly, the stiffness can also be reduced by softening the structures. The natural frequencies can be shifted to the desired values by tuning the depths and locations of cracks, the procedure which is proposed in this report. This method utilizes a transfer matrix technique to obtain an analytical characteristic equation of the system, on which the dynamic frequency tuning is based. Two examples using this method are demonstrated and experimentally validated.