應用實驗模態分析於碳纖維試片之機械性質測定

By Experimental Modal Analysis

10.6208/JPME-2010-02-03

王栢村(Bor-Tsuen Wang)；張年華(Nian-Hua Zhang)；黃裕仁(Yu-Ren Huang)；張佐銘(Zuo-Ming Zhang)

機械性質 ； 自然頻率 ； 模態振型 ； 模型驗證 ； Mechanical properties ； natural frequencies ； model shape ； model verification

機械技師學刊

3卷2期（2010 / 06 / 01）

14 - 19

繁體中文

經由一試片之振動特性試驗可獲得其機械性質。本文主要針對高爾夫球頭之碳纖維複合材料，結合實驗模態分析(Experimental Modal Analysis, EMA)與有限元素分析(Finite Element Analysis, FEA)方法，測定其機械性質包括楊氏系數、浦松比及剪力模數。本文使用加速度計及麥克風兩種感測器進行實驗模態分析，以移動衝擊鎚及固定感測器位置之方式，分別以兩種感測器進行實驗獲得試片之模態參數。結果顯示加速度計之質量效應在重量較輕之試片上，使得結構之自然頻率減少及模態振型改變。而在有限元素模型中，分別說明了有無加速度計質量效應，對其模態頻率和對應之模態振型之影響。且經由最佳化分析，使FEA和EMA所得之自然頻率誤差減到最小，並假設其正向性(orthotropic)材料模型，以求解其最佳化材料參數。由這兩種感測器應用在有限元素模型與實驗模態分析之模型驗證比對，碳纖維試片之機械性質將可以更明確認證，可應用於未來的高爾夫球頭之響應預測模擬。本文所發展確認試片材料性質之實驗方法，將有利於工業上之應用。

Mechanical properties of a test specimen can be obtained from vibration characteristics. This work aims to combine the Experimental Modal Analysis (EMA) and Finite Element Analysis (FEA) techniques to determine the mechanical properties, including Young's modulus, Poisson ratios and shear modulus, for the carbon fiber composites used in golf club heads. The EMA is conducted by two types of sensors, i,e the accelerometer and microphone, by roving the impact hammer with the fixed sensor location. Both experiments by the two sensors, are respectively, performed to obtain modal parameters of the specimen. The accelerometer causes the mass effect on the light weight specimen and decreases the structural natural frequencies and alters the model shape patterns, the finite element models for both with and without the accelerometer mass effects are, respectively, solved for the modal frequencies and corresponding mode shapes. The optimization problem is formulated to minimize the natural frequency errors between FEA and EMA by solving the optimum material parameters. The orthotropic material model is assumed in optimum solutions. Through the model verification for both the FE models, the results from FEA is compared with those from EMA for the two sensors applications. The mechanical properties of the carbon fiber composite can then be well interpreted and used for future response simulation. This work lays out the experimental approach for determining the specimen material properties and will be beneficial to industrial applications.

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