Atherosclerotic plaque rupture is the main cause of many cardiovascular diseases, and biomechanical factors play an important role in the process of plaque rupture. In the study of plaque biomechanics, there are relatively few studies based on fatigue fracture failure theory, and most of them mainly focus on the whole fatigue propagation process from crack initiation to plaque rupture, while there are few studies on the influence of crack on plaque rupture at a certain time in the process of fatigue propagation. In this paper, a two-dimensional plaque model with crack was established. Based on the theory of fracture mechanics and combined with the finite element numerical simulation method, the stress intensity factor (SIF) and related influencing factors at the crack tip in the plaque were studied. The SIF was used to measure the influence of crack on plaque rupture. The results show that the existence of crack can lead to local stress concentration, which increases the risk of plaque rupture. The SIF at the crack tip in the plaque was positively correlated with blood pressure, but negatively correlated with fibrous cap thickness and lipid pool stiffness. The effect of the thickness and angle of lipid pool on the SIF at the crack tip in the plaque was less than 4%, which could be ignored. This study provides a theoretical basis for the risk assessment of plaque rupture with cracks.
动脉粥样硬化斑块破裂是引发众多心血管疾病的主要原因，而生物力学因素在斑块破裂过程中有着重要的作用。在斑块生物力学的研究中，基于疲劳断裂破坏理论的研究相对较少，而且大部分相关研究主要关注的是裂纹从萌生直至斑块破裂的整个疲劳扩展过程，而对疲劳扩展过程中某一时刻下裂纹对斑块破裂的影响的研究较少。本文针对这个问题建立了二维含裂纹的斑块模型，基于断裂力学理论并结合有限元数值模拟方法研究了斑块中裂纹尖端的应力强度因子（SIF）及相关影响因素，通过SIF来衡量裂纹对斑块破裂的影响程度。结果表明，裂纹的存在会引发局部应力集中进而增大斑块破裂风险。斑块裂尖SIF与血压呈线性正相关，而与纤维帽厚度和脂质池刚度呈负相关。脂质池厚度和角度对斑块裂尖SIF的影响均低于4%，可以忽略不计。本研究为含裂纹斑块的破裂风险评估提供了一定的理论依据。.
Keywords: atherosclerosis; numerical simulation; plaque rupture; stress intensity factor.