Measurement and simulation of cyclic deformation of oligocrystalline structures using the example of coronary stents

以冠状动脉支架为例进行寡晶结构循环变形的测量和模拟

• 批准号: 407576368
• 负责人: Professor Dr. Siegfried Schmauder
• 金额: --
• 依托单位: Fachgebiet Metallkunde und Werkstofftechnik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/407576368?language=en
• 关键词: Measurement; simulation; cyclic; deformation; oligocrystalline

Most metallic micro components, for example coronary stents, consist of oligocrystalline microstructures. Therefore such components have only few crystals, to the point of only one crystal in cross section. The deformation behavior of such structures is remarkably different with respect to the one of polycrystals because anisotropy of single crystallites as well as neighboring grains have to be taken into account.Commercially available materials are generally well investigated regarding their cyclic properties. But the respective data are based on experimental data of standard test specimens with much larger dimensions than the ones of micro components.In a previous project the deformation mechanisms of oligocrystals have been investigated with respect to their static uniaxial deformation behavior. Differently oriented flat specimens as well as notched wires have been used. Based on these results a continuum mechanical model as well as a crystal plasticity analysis have been developed to predict the uniaxial static deformation behavior of micro components.The goal of the proposed project is fundamental experimental research accompanied with simulation on the deformation mechanisms of oligocrystals during cyclic deformation using the example of stent materials. The results will be transferable to various miniaturized material systems, because for all types of deformation, static as well as cyclic, size effects occur during mechanical load if the grain size reaches the magnitude of the component wall thickness.Based on the experimental know how and the previously developed simulation models experiment as well as simulation will be extended to uniaxial cyclic deformation and multiaxial static as well as cyclic (bending or bending fatigue respectively) load taking statistics due to different grain orientations into account.

大多数金属微型部件，例如冠状动脉支架，由寡晶微结构组成。因此，此类组件只有很少的晶体，以至于横截面只有一个晶体。这种结构的变形行为与多晶的变形行为显着不同，因为必须考虑单晶以及相邻晶粒的各向异性。通常对市售材料的循环特性进行了很好的研究。但相应的数据是基于尺寸远大于微型部件尺寸的标准测试样本的实验数据。 在之前的项目中，已经研究了寡晶的静态单轴变形行为的变形机制。使用了不同方向的扁平样本以及缺口线。基于这些结果，开发了连续介质力学模型和晶体塑性分析来预测微部件的单轴静态变形行为。该项目的目标是基础实验研究，并以支架材料为例，模拟循环变形期间寡晶的变形机制。结果将可转移到各种小型化材料系统，因为对于所有类型的变形（静态和循环），如果晶粒尺寸达到部件壁厚的大小，则在机械负载期间会发生尺寸效应。基于实验知识和先前开发的模拟模型，实验和模拟将扩展到单轴循环变形和多轴静态以及循环（弯曲或弯曲疲劳） 分别）负载考虑了由于不同晶粒取向而产生的统计数据。