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Title: | 藉由光彈顆粒流動態與光條紋特徵於穩態斜坡顆粒流中進行非侵入式應力量測 Non-intrusive stress measurement in a steady inclined surface granular flow of photoelastic disks through their dynamics and fringe characteristics analysis |
Authors: | 陳冠睿 Guan-Rui Chen |
Advisor: | 楊馥菱 Fu-Ling Yang |
Keyword: | 光彈顆粒流,梯度平方法,應力量測, photoelastic granular flow,gradient square method,stress measurement, |
Publication Year : | 2022 |
Degree: | 碩士 |
Abstract: | 穩態的斜坡顆粒流是多相的:它可以從自由表面附近多碰撞的類氣體快速運動連續過渡到底部以摩擦為主的類固體慢速運動。雖然已經開發了顆粒動力學理論來估計來自單顆粒碰撞引起的應力分量,但顆粒之間的摩擦如何在流動應力模型中發揮作用尚不清楚。因此,本研究旨在利用光彈材料的雙折射性質來開發一種非侵入式摩擦應力測量技術。我們不僅依文獻測量條紋強度來估計摩擦法向應力,我們還提出新的影像處理演算法來測量條紋角度以估計摩擦切向應力。我們使用光彈顆粒在溜槽中進行實驗,以非侵入的方式估計碰撞和摩擦應力分量。將這兩種分量與解析靜水壓進行比較,以確認應力確實從表面的純碰撞過渡到無滑移底部的純摩擦。當顆粒相互作用在碰撞和摩擦之間交替的中間層時,相較於總應力的大小,碰撞和摩擦應力分量的疊加會低估,這尚須改進。 A steady inclined surface granular flow is multiphasic: it can transit continuously from a collision-rich gas-like fast motion near the free surface to a friction-dominated solid-like creeping motion at the base. While the granular kinetic theory has been developed to estimate collision-induced stress components from individual grain dynamics, how inter-particle friction plays a role in a flow stress model is yet unclear. Hence, this work aims to develop a non-intrusive frictional stress measurement technique by exploiting the birefringence of photoelastic material. We not only follow the literature to measure the fringe intensity to estimate frictional normal stress, but we also propose the first method to evaluate the tangential frictional stress from the fringe angle with novel image processing algorithms. We conducted experiments on a photoelastic granular chute flow facility to estimate the collisional and frictional stress components non-intrusively. These two components are compared to the analytic hydrostatic profiles to confirm that the bulk stress does transit from pure collisional at the surface to pure frictional at the no-slip base. When grain interaction alternates between collision and friction in mid-layer, a superposition of the collisional and frictional stress components would underestimate the total stress, necessitating a refined algorithm. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/83931 |
DOI: | 10.6342/NTU202201080 |
Fulltext Rights: | 未授權 |
Appears in Collections: | 機械工程學系 |
Files in This Item:
File | Size | Format | |
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ntu-110-2.pdf Restricted Access | 8.74 MB | Adobe PDF |
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