薄膜的皺摺力學與聲紋分析

張國煜(Kuo-Yu Chang)

指導教授 ： 洪在明

國立清華大學/理學院/物理學系/碩士(2010年)

摘要

在本文中我們使用了自行設計的高壓壓力腔作為主要實驗設備，完成了四個目標：(1檢驗)薄膜在受均向壓力的壓縮時，進入堵塞區域(jamming state)之後，持續加壓至1500 PSI的力學反應。(2)改採揉皺或裁剪過的薄膜，檢驗其對指數 的影響。(3) 證實在均向受壓的揉皺實驗中，所產生的爆裂聲(crackling noise) 同樣具有 的冪次方關係。(4)提出模型解釋為何指數 與材料性質相關。

關鍵字

皺摺力學

並列摘要

We designed a high-pressure chamber that can sustain up to 1500 PSI, to study the crumpling process of a thin sheet under an ambient pressure. Special attention is devoted to the following four aspects: (1) having confirmed the power-law behavior in our previous efforts, we study the mechanical response of the thin sheet in the so-called jammed region, where the power-law behavior ceases. Upon the application of our highest pressure 1500 PSI, we confirm the internal structure of HDPE is polycrystalline instead of a single crystal. (2) We use a precrumpled or shredded sheet as the sample. Part of our motivation is to study (a) how these conditions affect the power-law behavior, (b) determine the percentage of work into the ridge formation. (3) Study the properties of crackling noises generated during the crumpling process. We confirm that the probability and energy of the noises obey the power-law relation. However, when the samples are preprocessed as in (2), the noises deviate from such a simple universal behavior. (4) A simple model is proposed to explain why the exponent of the power-law relation is sample-dependent, as opposed to the predictions of existing computer simulations..

參考文獻

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