Simulation of Soft Tissue Failure Using the Material Point Method

Abstract

Understanding the factors that control the extent of tissue damage as a result of material failure in soft tissues may provide means to improve diagnosis and treatment of soft tissue injuries. The objective of this research was to develop and test a computational framework for the study of the failure of anisotropic soft tissues subjected to finite deformation. An anisotropic constitutive model incorporating strain-based failure criteria was implemented in an existing computational solid mechanics software based on the material point method (MPM), a quasi-meshless particle method for simulations in computational mechanics. The constitutive model and the strain-based failure formulations were tested using simulations of simple shear and tensile mechanical tests. The model was then applied to investigate a scenario of a penetrating injury: a low-speed projectile was released through a myocardial material slab. Sensitivity studies were performed to establish the necessary grid resolution and time-step size. Results of the simple shear and tensile test simulations demonstrated the correct implementation of the constitutive model and the influence of both fiber family and matrix failure on predictions of overall tissue failure. The slab penetration simulations produced physically realistic wound tracts, exhibiting diameter increase from entrance to exit. Simulations examining the effect of bullet initial velocity showed that the anisotropy influenced the shape and size of the exit wound more at lower velocities. Furthermore, the size and taper of the wound cavity was smaller for the higher bullet velocity. It was concluded that these effects were due to the amount of momentum transfer. The results demonstrate the feasibility of using MPM and the associated failure model for large-scale numerical simulations of soft tissue failure.

Numerical simulation of the failure of ventricular tissue due to deep penetration: The impact of constitutive properties

“…Another interesting finding indicates that large deformations often prevent crack tip stresses from reaching a magnitude sufficient to decohere the material, i.e., crack tip blunting and failure can only proceed by other mechanisms like void growth (Hui et al, 2003). Nevertheless the above-mentioned lack of information regarding failure mechanisms, rate-independent elasto-plasticity , damage mechanics (Balzani et al, 2006;Volokh and Vorp, 2007) and fracture mechanics (Ionescu et al, 2006;Holzapfel, 2006, 2007;Ferrara and Pandolfi, 2008) have been proposed to capture irreversible deformations towards investigating mechanisms related to balloon angioplasty or aneurysm rupture for example. However, only a very few studies have investigated tissue failure due to deep penetration, and earlier proposed failure mechanisms (Shergold and Fleck, 2004) are rare examples.…”

Mechanical Characterization of the Human Aorta: Experiments, Modeling and Simulation

“…In particular, this problem has been studied by Di Martino and Vorp [27], Li and Kleinstreuer [63] and Vorp [103] defining a maximum principal stress-based criterion for descending aortas with aneurysms. Moreover, other authors, such as Mohan and Melvin [72] and Lonescu et al [65], proposed failure criteria for soft tissues in terms of maximum stretchs. In these approaches, the maximum principal stress and stretch values are respectively compared to those measured in the tensile test.…”

Investigation of bullet penetration in ballistic gelatin via finite element simulation and experiment

“…Compared with the times of the first three ballistic sub-areas, terminal ballistics takes the longest time. Therefore, it is challenging to computationally analyze the behavior of a promptly deformed structure and many numerical and experimental approaches have been previously developed [16][17][18]. Among the various computational codes for wound ballistics, this research adopts the AUTODYN hydrocode to solve the mass conservation equation, the energy conservation equation, and the Equation of state (EOS), as shown in Fig.…”