本文根據von Karman 幾何大變形理論，推導一54 個自由度高精確度的高階三角形板元素，用來分析與討論複合層板在承受溫度場改變的熱挫屈後之自由振動行為。當溫度高於臨界挫屈溫度時，可將層板之位移分為靜態位移與動態位移。靜態位移為熱挫屈後層板之變形量，利用Newton-Raphson 疊代法可求得後挫屈的靜態位移。在動態分析部分，則利用Hamilton 定理推導出動態平衡方程式後，並且帶入後挫屈靜態位移，便可在頻率域中求得自然頻率與振動模態，文中考慮兩種熱膨脹係數不同的材料，並探討其對自然頻率與振動模態所造成的影響。結果顯示對於正交性複合層板而言，因熱膨脹係數的影響，T300/5208 層板較早發生挫屈，並產生變形，使得層板之自由頻率逐漸高於AS4/3501-6 層板。另外在後挫屈範圍內，當展弦比越高，基礎振動模態越會被高階振動模態所取代。對於角交性複合層板而言，纖維角度影響著層板之彎曲勁度與x、y 方向的熱膨脹量，間接地造成自然頻率的改變，結果顯示當挫屈模態發生轉移時，會造成層板之勁度急速的改變，因此振動模態會劇烈變化。如果層板是受到非均勻溫度變化的影響，則層板的變形越大時，
會改變模態排列順序，而且在挫曲模態轉移時，振動模態的改變較緩慢，且沒有振動模態的頻率會降至零。

　　Base on the von karman large deflection plate theory, a 54 degree-of-freedom high precision higher order triangular plate element is developed for free vibration of thermally buckled composite laminated plate. For buckled plate, the total response of the plate is assumed to be the sum of displacement due to the buckled static deformation and that due to small dynamic deformation. The static deflection of the buckled plate is solved by using Newton Raphson iteration method. The natural frquency and free vibration mode of the plate can then be obtained in frequency domain after applying the static thermal postbuckling deflections into the equation of motion. Two different laminates are considered due to their distinct thermal expansion
property. Results show that T300/5208 cross-ply laminate will be buckled earlier than the AS4/3501-6 laminate that makes the T300/5208 laminate stiffer and in term gives higher natural frequencies. The higher vibration mode of the cross-ply laminates will become the fundamental mode when the aspect ratio of plate goes higher. For the angle-ply laminates, a buckle pattern　change may occur in the post-buckling region and the natural frequencies of the laminates will also be changes abruptly. If the laminate is subjected to temperature gradient through the thickness, the plate becomes more stiffer and none of the natural frequencies will drop to zero as the temperature
increases. Also, the vibration mode shift induced by buckle pattern change will occur slowly.

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