Buckling of thermally fluctuating spherical shells: Parameter renormalization and thermally activated barrier crossing.
Buckling of thermally fluctuating spherical shells: Parameter renormalization and thermally activated barrier crossing.
复制标题
热波动球壳的屈曲：参数重正化和热激活势垒穿越。
DOI：
10.1103/physreve.97.052801
复制
发表时间：
2018
期刊：
影响因子：
--
通讯作者：
J. Kierfeld
中科院分区：
文献类型：
--
作者：
Lorenz Baumgarten;J. Kierfeld
研究了热波动对球形弹性薄胶囊屈曲行为的影响。超过临界的均匀压力，弹性胶囊在机械上变得不稳定，并自发地弯曲成具有轴对称凹陷的形状。热波动通过两种机制影响屈曲失稳。一方面，由于不同波长的法向位移模式之间的非谐波耦合，热波动可以使胶囊的弹性性能和压力重新规范化。这有效地降低了临界屈曲压力[Košmrlj和Nelson， Phys。Rev. X. 7,011002 (2017)2160-330810.1103/PhysRevX.7.011002。另一方面，在低于经典屈曲压力的压力下，屈曲形状在能量上是有利的。然而，在这些压力下，屈曲需要克服能量障碍，而能量障碍只有在临界屈曲压力下才会消失。在存在热波动的情况下，在低于临界屈曲压力的压力下，通过热激活，胶囊可以自发地克服热能量级的能垒。我们重新研究了热波动的参数重整化，并基于尺度相关的重整化参数制定了屈曲准则，以获得温度相关的临界屈曲压力。在此基础上，利用数值能量最小化方法和解析方法，对低于临界屈曲压力的屈曲能量势垒进行了定量分析。这使我们能够通过热激活在该能垒上获得与温度相关的屈曲临界压力。值得注意的是，参数重整化和热活化都导致临界屈曲压力对温度、包膜半径、厚度和杨氏模量的参数依赖性相同。最后，我们研究了参数重正化和热激活的联合效应，利用热激活中能量势垒的重正化参数，得到了与温度相关的临界压力的最终结果，该结果明显低于只考虑参数重正化或只考虑热激活的结果。
We study the influence of thermal fluctuations on the buckling behavior of thin elastic capsules with spherical rest shape. Above a critical uniform pressure, an elastic capsule becomes mechanically unstable and spontaneously buckles into a shape with an axisymmetric dimple. Thermal fluctuations affect the buckling instability by two mechanisms. On the one hand, thermal fluctuations can renormalize the capsule's elastic properties and its pressure because of anharmonic couplings between normal displacement modes of different wavelengths. This effectively lowers its critical buckling pressure [Košmrlj and Nelson, Phys. Rev. X 7, 011002 (2017)2160-330810.1103/PhysRevX.7.011002]. On the other hand, buckled shapes are energetically favorable already at pressures below the classical buckling pressure. At these pressures, however, buckling requires to overcome an energy barrier, which only vanishes at the critical buckling pressure. In the presence of thermal fluctuations, the capsule can spontaneously overcome an energy barrier of the order of the thermal energy by thermal activation already at pressures below the critical buckling pressure. We revisit parameter renormalization by thermal fluctuations and formulate a buckling criterion based on scale-dependent renormalized parameters to obtain a temperature-dependent critical buckling pressure. Then we quantify the pressure-dependent energy barrier for buckling below the critical buckling pressure using numerical energy minimization and analytical arguments. This allows us to obtain the temperature-dependent critical pressure for buckling by thermal activation over this energy barrier. Remarkably, both parameter renormalization and thermal activation lead to the same parameter dependence of the critical buckling pressure on temperature, capsule radius and thickness, and Young's modulus. Finally, we study the combined effect of parameter renormalization and thermal activation by using renormalized parameters for the energy barrier in thermal activation to obtain our final result for the temperature-dependent critical pressure, which is significantly below the results if only parameter renormalization or only thermal activation is considered.
药物输送的高级材料和处理：过去和未来。
影响因子：
16.1
作者：
Zhang, Ying;Chan, Hon Fai;Leong, Kam W.
通讯作者：
Leong, Kam W.