Failure damage mechanical properties of thoracic and abdominal porcine aorta layers and related constitutive modeling: phenomenological and microstructural approach

Abstract

Despite increasing experimental and analytical efforts to investigate the irreversible effects of arterial tissue failure, the underlying mechanisms are still poorly understood. The goal of this study was characterize the failure properties of the intact wall and each separated layer (intima, media and adventitia) of the descending thoracic and infrarenal abdominal aorta and to test the hypothesis that the failure properties of layer-separated tissue depend on the location of the aorta. To test this hypothesis, we performed uniaxial tests to study the mechanical behavior of both intact and layer-separated porcine aortic tissue samples taken from descending thoracic and infrarenal abdominal aorta until complete failure. The fracture stress is higher in the infrarenal abdominal aorta than in the equivalent descending thoracic aorta. It was also found that the extrapolation of the elastic mechanical properties from the physiological to the supra-physiological regime for characterizing the mechanical response of the aorta would be inappropriate. Finally, we report values of constitutive parameters using phenomenological and microstructural damage models based on Continuum Damage Mechanics Theory. The phenomenological damage model gives an excellent fit to the experimental data compared to the microstructural damage model. Although the fitting

Methodology for estimation of undeformed thickness of arterial tissues

“…The choice of 10 s is an arbitrary trade-off value between instantaneous and long-term response. Shorter times would be more suitable for simulation of in-vivo response while longer times would better correspond with quasi-static tensile tests at which mechanical properties are often measured 2,13,23 . A second limitation can be seen in the 24-h time delay between in measurements of larger and smaller samples.…”

Failure properties and microstructure of porcine aortic adventitia: fiber level damage vs tissue failure

“…Through this study, we have presented a unique set of data relating to the uniaxial failure properties of porcine adventitial specimens and the underlying collagen microstructure. Layer-specific constitutive modeling of the arterial tissue has been performed for capturing both the elastic [46, 47] and failure response [26]. However, especially in the case of modeling arterial failure, a phenomenological model for anisotropic damage is limiting.…”

“…The role of adventitia as the final barrier is often overlooked. Only a handful of studies have reported the mechanical strength of and failure properties of the adventitial layer [26, 27]. Further, there are very few experimental investigations of the damage and rupture mechanisms of arteries [28, 29].…”

A Review on Damage and Rupture Modelling for Soft Tissues

“…Saez et al [ 79 ] have extended the model for anisotropic soft tissues by neglecting fibre crosslinks and sliding between fibres and the surrounding matrix. However, the fit between the experimental stress-stretch data and that predicted by the microstructural model of Saez et al [ 79 ] was reported to be not satisfactory by Pena et al [ 82 ]. Particularly, the correlation between the experimental data and the prediction by the microstructural damage model was found to be worse, as compared to the phenomenological model by Pena [ 83 ].…”