Ruga mechanics of soft-orifice closure under external pressure
Ruga mechanics of soft-orifice closure under external pressure
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DOI：
10.1098/rspa.2021.0238
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发表时间：
2021-05
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影响因子：
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通讯作者：
Hanxun Jin;A. Landauer;Kyung-Suk Kim
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文献类型：
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作者：
Hanxun Jin;A. Landauer;Kyung-Suk Kim
在这里，我们报告的关闭阻力的软材料双层孔口增加对外部压力，沿着与ruga相的演变，在传统的预测的矩阵自由圆柱壳屈曲压力。实验表明，通用软材料孔口在极限载荷压力p/μ = 1.20时以三重对称方式起皱，其中μ为剪切模量。一旦折痕开始，三重折痕翼随着压力增加而逐渐增长，直到孔口在p/μ π ι 3.0处完全关闭。相比之下，刚性表面双层孔口最初以多重对称模式起皱，随后发展褶皱相演变，随着压力增加逐渐减小孔口横截面积。屈曲起始模式由层的厚度和刚度决定，而压力由两种类型的层的不稳定模式决定-对于柔顺层的表面层屈曲模式和对于刚性层的环屈曲模式。环屈曲模式倾向于为整个后屈曲闭合过程设置双重对称性，而高频表层屈曲模式随着连续的对称性破缺而演化为最终的双重或三重对称性闭合构型。最后，我们发现，三重对称模式的整个关闭过程提供了最强的关闭阻力，和人类隐静脉显着遵循这三重对称皱演变路径。
Here, we report the closure resistance of a soft-material bilayer orifice increases against external pressure, along with ruga-phase evolution, in contrast to the conventional predictions of the matrix-free cylindrical-shell buckling pressure. Experiments demonstrate that the generic soft-material orifice creases in a threefold symmetry at a limit-load pressure of p/μ ≈ 1.20, where μ is the shear modulus. Once the creasing initiates, the triple crease wings gradually grow as the pressure increases until the orifice completely closes at p/μ ≈ 3.0. By contrast, a stiff-surface bilayer orifice initially wrinkles with a multifold symmetry mode and subsequently develops ruga-phase evolution, progressively reducing the orifice cross-sectional area as pressure increases. The buckling-initiation mode is determined by the layer's thickness and stiffness, and the pressure by two types of the layer's instability modes—the surface-layer-wrinkling mode for a compliant and the ring-buckling mode for a stiff layer. The ring-buckling mode tends to set the twofold symmetry for the entire post-buckling closure process, while the high-frequency surface-layer-wrinkling mode evolves with successive symmetry breaking to a final closure configuration of two- or threefold symmetry. Finally, we found that the threefold symmetry mode for the entire closure process provides the orifice's strongest closure resistance, and human saphenous veins remarkably follow this threefold symmetry ruga evolution pathway.