Shock wave induced damage in kidney tissue

In a common medical procedure known as shock-wave lithotripsy hypersonic waves are generated and focused at the kidney stone. These shock waves are thought to fragment the stone but also lead to injuries of the kidney tissue. To predict and estimate this damage we develop here a mechanical model for the response of soft tissue to the exposure of shock waves. The material model combines shear induced finite plasticity with irreversible volumetric expansion as induced, e.g., by cavitating bubbles. Dynamic effects like micro-inertia and rate sensitivity are included. The time-discretized porousviscoplastic constitutive updates are described in a fully variational manner. A finite element analysis localizes the damage in the human kidney in good agreement to clinical and experimental studies. 2004 Elsevier B.V. All rights reserved. PACS: 46.35.+z; 87.10.+e; 46.15. x