| Summary: | 碩士 === 國立清華大學 === 物理系 === 101 === A spool in the opened state, the long side of the central often occur tilt phenomenon, called "Qi-Wa," because much like the roof of traditional Chinese. Since there are many causes of "Qi-Wa," such as temperature, humidity, and even mounted paper framed with composite skills will affect the result.Our study exclude these external factors can not be regulated, one on the characteristics of paper to explain the causes of "Qi-Wa" and try to use physical methods to reduce the extent of s"Qi-Wa".
Molecular dynamics simulation is a method from starting to explore micro macroscopic object often used to simulate the structure of the protein or polymer dynamics performance, but also has application in two-dimensional film .My research is inherited the code of Jun-Chao Luo ,studied crumpling paper used the same method ,to explore "Qi-Wa".The theory and experiment are done by Wei-zhao Shen and ming-Han Zhou.
At the beginning we used in the past habits, take monolayer film,put particle on each triangular lattice, and directly plus the intrinsic curvature in face to face.The film can indeed successfully rolled , but this model requires the summation of restoring force applied on the triangular lattice plane together must be zero.So that "Qi-Wa" in this model is not true.And we even have seen the opposite result.So we changed the model to two layers structure, with the upper and lower layers of the film caused by the bond length difference, that there is an equivalent bending restoring force, in this bilayer model, we found that with the experimental results broadly in line with the mechanical performance, but still have difference, which will be described in this thesis later.
In improved methods, we only discussed the most common case.We havethree remedies to mitigate Qi-Wa: align the fiber along the rolling direction, extra layer to side borders, and introducing point defects. Among these, fiber alignment is most effective.
The following URL is a movie demonstrates a process of spread finished by simulation:
http://www.youtube.com/watch?v=3dikfPc1wc0
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