Abstract
Shape memory polymers (SMPs) have gained much attention in biomedical fields due to their good biocompatibility and biodegradability. Researches have validated the feasibility of shape memory polymer stent in treatment of vascular blockage. Nevertheless, the actual application of SMP stents is still in infancy. To improve the mechanical performance of SMP stent, a new geometric model based on metamaterial is proposed in this study. To verify the feasibility and mechanical behavior of this type of stent, buckling analysis, and in vivo expansion performance of SMP stent are simulated. Numerical results exhibit that stent of a smaller radius behaves a higher critical buckling load and smaller buckling displacement. Besides, a smaller contact area with vessel and smaller implanted stress are observed compared with traditional stents. This suggests that this SMP stent attributes to a reduced vascular restenosis. To characterize the radial strength of SMP stent, an analytical solution is derived by the assumption that the deformation of stent is mainly composed of bending and stretch. The radial strength of SMP stent is assessed in form of radial force. Analytical results reveal that radial strength is depended on the radius of stent and periodic numbers of unit cell in circumferential direction.
Highlights
As a kind of smart material, shape memory polymers (SMPs) can recover to their original shape from the deformed state spontaneously with appropriate stimuli, such as heat [1,2], light [3], water [4], and so on
To solve the aforementioned issues, we proposed a new geometric model for SMP stent based on the metamaterial concept
We can say this geometric model of the SMP stent is effective to reduce the restenosis
Summary
As a kind of smart material, shape memory polymers (SMPs) can recover to their original shape from the deformed state spontaneously with appropriate stimuli, such as heat [1,2], light [3], water [4], and so on. Results showed the mechanical behaviors of the produced stent with auxetic structure depended on the size and angle of individual units. The new geometric model composed of series of modified auxetic unit cells (re-entrant structure) is developed for the SMP stent. REVIEW geometric constitutive models of expansion model, buckling analysis, and expansion materials used in expansion stent model: shape memory polymer, vessel, and plaque. To establish the geometric models and constitutive models of expansion model, buckling analysis, and expansion effective assessment rule on the radial strength and stiffness of this type of SMP stent, an analytical process simulations are conducted finite element method. 5. The analytical results compared effective assessment on the radial strength and stiffness of this type of SMP stent, an analytical rule with numerical results of FEM.
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