Abstract
The experimental quantification and modeling of the multiaxial mechanical response of polymer membranes of coronary balloon catheters have not yet been carried out. Due to the lack of insights, it is not shown whether isotropic material models can describe the material response of balloon catheter membranes expanded with nominal or higher, supra-nominal pressures. Therefore, for the first time, specimens of commercial polyamide-12 balloon catheters membranes were investigated during uniaxial and biaxial loading scenarios. Furthermore, the influence of kinematic effects on the material response was observed by comparing results from quasi-static and dynamic biaxial extension tests. Novel clamping techniques are described, which allow to test even tiny specimens taken from the balloon membranes. The results of this study reveal the semi-compliant, nonlinear, and viscoelastic character of polyamide-12 balloon catheter membranes. Above nominal pressure, the membranes show a pronounced anisotropic mechanical behavior with a stiffer response in the circumferential direction. The anisotropic feature intensifies with an increasing strain-rate. A modified polynomial model was applied to represent the realistic mechanical response of the balloon catheter membranes during dynamic biaxial extension tests. This study also includes a compact set of constitutive model parameters for the use of the proposed model in future finite element analyses to perform more accurate simulations of expanding balloon catheters.
Highlights
Finite element analysis (FEA) has become a powerful tool for the optimization process of coronary balloon catheters and stents
One exception is presented by Gasser and Holzapfel [7] where a versatile theory of fiberreinforced materials is used according to [8] in order to mimic the anisotropic material response of angioplasty balloon membranes
This work shows, that the decision to use an isotropic or anisotropic material model must be carefully considered. This statement is based on the key finding of this work, in which the material behavior of the PA 12 balloon catheter membrane shows a stiffer response to loading in circumferential direction (CD), as illustrated
Summary
Finite element analysis (FEA) has become a powerful tool for the optimization process of coronary balloon catheters and stents. FEA enables the prediction of the stress/strain response of stents and balloon catheters, and the constituents of the coronary artery to static and dynamic. Experimental and mathematical characterization of coronary polyamide-12 balloon catheter membranes loading. Almost all state-of-the-art FEA of expanding balloon catheter and stent included standard isotropic material models for balloon membranes, in which the mathematical formulation and the material parameters were based on data of unprocessed polymers [1,2,3,4,5,6]. In their study, the material and structural parameters of the balloon membrane model were not quantified by experimental data but fitted according to the respective inflation characteristic of the analyzed balloon catheter
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