Bioresorbable Vascular Scaffolds (BVS) manufactured from poly (l-lactic acid) (PLLA) offer an alternative to metal scaffolds for the treatment of coronary heart disease. One of the key steps in the manufacture of these scaffolds is the stretch blow moulding process where the PLLA is biaxially stretched above glass transition temperature (T_g), inducing biaxial orientation and thus increasing ductility, strength and stiffness. To optimise the manufacture and performance of these scaffolds it is important to understand the influence of temperature and strain rate on the constitutive behaviour of PLLA in the blow moulding process. Experiments have been performed on samples of PLLA on a custom built biaxial stretch testing machine to replicate conditions typically experienced during blow moulding i.e. in a temperature range from 70 °C to 100 °C and at strain rates of 1 s⁻¹, 4 s⁻¹ and 16 s⁻¹ respectively. The data is subsequently used to calibrate a nonlinear viscoelastic material model to represent the deformation behaviour of PLLA in the blow moulding process. The results highlight the significance of temperature and strain rate on the yielding and strain hardening behaviour of PLLA and the ability of the selected model to capture it.

中文翻译：

---

表征和建模聚（l-乳酸）的机械性能的拉伸吹塑制造生物可吸收的血管支架

由聚（l-乳酸）（PLLA）制造的生物可吸收血管支架（BVS）提供了金属支架的替代品，用于治疗冠心病。这些脚手架制造中的关键步骤之一是拉伸吹塑工艺，在该工艺中，将PLLA双轴拉伸至高于玻璃化转变温度（T _g），诱导双轴取向，从而增加延展性，强度和刚度。为了优化这些支架的制造和性能，重要的是要了解温度和应变速率对吹塑成型过程中PLLA本构行为的影响。实验已经在PLLA的样品上内置双轴拉伸的自定义验机吹塑期间通常经历的复制条件从70℃至100℃的温度范围内成形，即，在1秒的应变速率下进行^-1，4秒^{- 1}和16 s ^-1分别。数据随后用于校准非线性粘弹性材料模型，以表示吹塑成型过程中PLLA的变形行为。结果突出了温度和应变速率对PLLA屈服和应变硬化行为的重要性以及所选模型捕获它的能力。