When a hyperelastic tube is inflated, the inflation pressure has a maximum for almost all rubber material models, but has no maximum for commonly used arterial models. It is generally believed that the pressure having a maximum is a necessary condition for localized bulging to occur, and therefore aneurysms cannot be modeled as a mechanical bifurcation phenomenon. However, recent theoretical studies have shown that if the axial stretch is fixed during inflation, localized bulging may still occur even if a pressure maximum does not exist in uniform inflation. In this paper, numerical simulations are conducted to confirm this theoretical prediction. It is also demonstrated that if the axial pre-stretch is not sufficiently large, unloading near the two ends can reduce the axial stress to a value close to zero and Euler-type buckling then occurs.

中文翻译：

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固定端膨胀超弹性管局部胀形的数值模拟

当超弹性管充气时，几乎所有橡胶材料模型的充气压力都有最大值，但常用的动脉模型没有最大值。一般认为，具有最大值的压力是局部膨出发生的必要条件，因此不能将动脉瘤建模为机械分叉现象。然而，最近的理论研究表明，如果在充气过程中轴向拉伸固定，即使在均匀充气中不存在压力最大值，局部鼓胀仍然可能发生。在本文中，进行了数值模拟以证实这一理论预测。还表明，如果轴向预拉伸不够大，在两端附近卸荷可以将轴向应力降低到接近零的值，然后发生欧拉型屈曲。