FE Modeling of the Orthotropic and Three-Layered Human Thoracic Aorta

The human aorta consists of three layers: intima, media and adventitia from the inner to outer layer. Since aortic rupture of victims in vehicle crashes frequently occurs in the intima and the media, latent aortic injuries are difficult to detect at the crash scene or in the emergency room. It is necessary to develop a multi-layer aorta finite element (FE) model to identify and describe the potential mechanisms of injury in various impact modes. In this paper, a novel three-layer FE aortic model was created to study aortic ruptures under impact loading. The orthotropic material model [1] has been implemented into a user-defined material subroutine in the commercial dynamic finite element software LS-DYNA version 970 [2], which was adopted in the aorta FE model. The Arbitrary-Lagrangian Eulerian (ALE) approach was adopted to simulate the interaction between the fluid (blood) and the structure (aorta). Single element verifications for the user-defined subroutine were performed. The mechanical behaviors of aortic tissues under impact loading were simulated by the aorta FE model. The models successfully predicted the rupture of the layers separately. The results provide a basis for a more in-depth investigation of blunt traumatic aortic rupture (BTAR) in vehicle crashes.