The current study presents the development and implementation of a bespoke experimental technique to generate and characterise mode II crack initiation and propagation in arterial tissue. The current study begins with a demonstration that lap-shear testing of arterial tissue results in mixed mode fracture, rather than mode II. We perform a detailed computational design of a bespoke experimental method (which we refer to as a shear fracture ring test (SFRT)) to robustly and repeatably generate mode II crack initiation and propagation in arteries. This method is based on generating a localised region of high shear adjacent to a cylindrical loading bar. Placement of a radial notch in this region of high shear stress is predicted to result in a kinking of the crack during a mode II initiation and propagation of the crack over a long distance in the circumferential (c)-direction along the circumferential-axial (c-a) plane. Fabrication and experimental implementation of the SFRT on excised ovine aorta specimens confirms that the bespoke test method results in pure mode II initiation and propagation. We demonstrate that the mode II fracture strength along the c-a plane is eight times higher than the corresponding mode I strength determined from a standard peel test. We also calibrate the mode II fracture energy based on our measurement of crack propagation rates. The mechanisms of fracture uncovered in the current study, along with our quantification of mode II fracture properties have significant implications for current understanding of the biomechanical conditions underlying aortic dissection.

当前的研究提出了定制实验技术的开发和实施，以生成和表征II型裂纹在动脉组织中的萌生和扩展。当前的研究始于对动脉组织的搭接剪切测试导致混合模式骨折而不是II型骨折的论证。我们执行定制实验方法（称为剪切断裂环测试（SFRT））的详细计算设计，以可靠且可重复地生成II型裂纹在动脉中的萌生和扩展。该方法基于生成与圆柱形加载条相邻的高剪切局部区域。沿圆周轴向（ca）平面的（c）方向。SFRT在切除的绵羊主动脉标本上的制造和实验实施证实了定制测试方法可导致II型纯模式的起始和传播。我们证明，沿ca平面的II型断裂强度比从标准剥离试验确定的相应的I型断裂强度高八倍。我们还根据对裂纹扩展速率的测量结果来校准II型断裂能。当前研究中发现的骨折机制，以及我们对II型骨折特性的量化，对当前对主动脉夹层的生物力学条件的了解具有重要意义。