煞車系統動態穩定性分析之研究

本文是探討煞車系統在運作時，煞車系統之動態穩定性，並探討煞車高頻異音的成因。在本研究中使用LS-Dyna進行煞車系統複數特徵值分析，藉此得到煞車系統之動態特性。為了確認有限元素模型之可靠度，利用理論模態分析與實驗模態分析進行模態驗證，以確保有限元素模型與實際結構一致性，並進而探討煞車系統中，各參數對煞車系統之動態特性之影響。經由參數變化複數特徵值分析結果可知，煞車系統的負阻尼受到摩擦係數的影響最大，其次是作動壓力，來令片摩擦材料厚度，最後是碟盤的轉速。為了探討煞車異音的聲學特徵，依據SAE J2521規範內容進行煞車異音試驗，並藉由麥克風與加速規紀錄煞車異音與結構振動時域訊號，利用短時傅立葉轉換進行時頻分析。吾人將實驗與分析結果進行比對，發現分析中的次大負阻尼與最大煞車異音頻率一致，進而提出方法的有效性。

關鍵字

煞車異音；複數特徵值分析；實驗模態分析；理論模態分析；短時傅立葉轉換

並列摘要

This thesis investigates dynamic stability of a brake system and the cause of a brake squeal. This study used LS-Dyna to implement the Complex Eigenvalue Analysis (CEA) of a brake system to compute a brake system dynamic characteristic. The finite element model validity of the brake part was checked by modal verification. The dynamic stability of brake system was investigated through various the operating conditions in this thesis. The results obtained from various parameter complex eigenvalue analysis show that the brake system dynamic stability is most related with the change of friction coefficient. The other influence on the stability of brake system in order is the operating pressure, the thickness of linings, and rotation speed of the disc. To investigate the acoustic characteristic of squeal, we implement the SAE J2521 brake squeal testing. The testing sound and vibration time domain signal were recorded by microphone and accelerometer. The testing signal implements the time-frequency analysis through the Short-Time Fourier Transform (STFT). The comparison result obtained from the CEA and braking squeal frequency in the operating condition shows the submaximal frequency of negative damping same as maximum squeal frequency, and the validity of the proposed method can be confirmed.

並列關鍵字

Brake squeal ； Complex Eigenvalue Analysis (CEA) ； Theoretical Modal Analysis (TMA) ； Experimental Modal Analysis (EMA) ； Short Time Fourier Transform (STFT)

參考文獻

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