本研究以脈衝激振法(IET)試驗及數值模擬檢測板狀試體材料動態模數，當以鋼珠作為敲擊器敲擊試體後，造成試體振動產生時域聲波，藉由快速傅立葉轉換所得共振頻率，求得試體之材料動態模數試驗值，配合數值模擬分析結果，探討板狀試體之適用試體尺寸範圍及應用於非均質材料之可行性。
試驗過程先以數值模擬金屬材料板狀試體隨著尺寸變化，探討共振頻率及模態改變，再以脈衝激振法檢測金屬材料，以非接觸型接收器麥克風與接觸型接收器加速規檢測九種不同尺寸板狀金屬材料動態模數，並澆置水泥砂漿試體及水泥飛灰砂漿試體，觀察其不同單位重及緻密度之水泥材料動態模數及強度成長趨勢，並以共振頻率法量測動態模數，探討脈衝激振法應用於多孔隙板狀材料可行性。
研究結果顯示:(1)數值模擬可求得共振頻率及振型佐證試驗頻率為撓曲頻率或扭曲頻率; (2)長寬比為1:1時，數值模擬之兩種撓曲振型之動態彈性模數誤差分別為-70%及150%;(3)長寬比於2:1~4:3時，數值模擬之動態彈性模數誤差小於1%;(4)長寬比為1:1時，脈衝激振法試驗動態彈性模數誤差高達60%，結果顯示脈衝激振法並不適用於方板試體;(5)長寬比為2:1時，厚度為0.3、0.4、0.5增加，脈衝激振法試驗動態彈性模數誤差值分別為0.8%、1.2%、1.5%，結果顯示脈衝激振或法試用於厚度小之板狀試體;(6)由麥克風加速規試驗求得動態彈性模數及動態剪力模數值相差小於1%，結果顯示兩種接收器均能求得材料動態模數;(7)試驗齡期28天時，水泥砂漿及水泥飛灰砂漿以脈衝激振法及共振頻率法求得動態彈性模數及動態剪力模數相差小於1%，試驗結果顯示脈衝激振法可應用於非均質水泥質材料。

This study used the Impulse Excitation Technique (IET) and numerical analysis to explore the dynamic moduli of platy specimens. When the specimens was hit by the impactor of steel ball, the resulting vibration produced the time-domain sound wave and the resonant frequencies were obtained by the Fast Fourier Transform (FFT) to calculate the experimental values of dynamic modulus Together with the results from numerical simulation, the appropriate dimension of platy specimen for testing and the feasibility of application to the heterogeneous material were addressed.
The experimental procedures started with numerical analysis of metal material with different aspect ratios to study the changes of resonance frequency and mode shape, then the IET method was used to test the dynamic modulus with non-contact receiver of microphone and contact receivers of accelerometer to detect nine kinds of different dimensions of metal material. Then both the cement mortar and fly ash cement mortar specimens were made to investigate the evolution of dynamic modulus using resonance frequency method, strength development and variations of unit weight. Afterward, the feasibility of application of the IET technique to the porous platy material.
The research results show that:(1) Numerical analysis can obtain the resonance frequency and mode shape to justify the frequency from the experimental results to be the flexural frequency or the torsional frequency;(2) When the aspect ratio of 1:1, the errors of dynamic elastic modulus from the numerical analysis with two mode shape of flexural frequency were -70% and 150%;(3) When the aspect ratios between 2:1 and 4:3, errors of dynamic elastic modulus from the numerical analysis were less than 1%; (4) When the aspect ratio of 1:1, the error of dynamic elastic modulus from the IET tested was higher than 60%, which shows that the IET is not suitable for square plate specimen; (5) When the aspect ratio of 2:1, the thickness ratio of 0.3、0.4、0.5， error of dynamic elastic modulus from the IET tested were 0.8%、1.2%、1.5%, respectively, which shows that the IET is suitable with thinner specimen; (6) The difference of dynamic elastic modulus and dynamic shear modulus was less than 1% when the wave results were received by either the microphone or the accelerometer; (7) Both the cement mortar specimen and cement fly ash mortar at age of 28days were tested by the IET and the resonance frequency method, the results show that the differences of both methods of dynamic elastic modulus and dynamic shear modulus were less than 1%, which shows that the IET method can be applied to nonhomogeneous materials like cement-based material.

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