Estimation of mechanical properties of soft tissue subjected to dynamic impact

Human soft tissue is highly deformable leading to a difficulty in estimating its mechanical properties. This paper focuses on the extraction of human tissue dampening properties under dynamic impact, which enabled an efficient implementation of mechanical response of tissue, which is of growing interest and importance in biomedical research and forensic science. Such properties are not only useful for realistic surgical simulation, preoperative planning, and robot-assisted medical procedures, but also may be useful in deriving impact characteristics necessary to cause contusions for forensics purposes. The estimates of the damping properties of human soft tissue was done by using spring and damper system as a model; massdamper-spring (MDS). Spring stiffness is represented by the spring constant K and dashpot damping resistance is represented by the damper constant C. Data were collected by striking human subjects with a weighted pendulum at different levels of energy, velocity, and mass. The estimation process involved conditioning the data, such that the modeling process and estimation were feasible, resulting in estimates of K and C. In conclusion, using impact data collected on living human tissue to estimate the dampening properties is plausible. The results showed that both the stiffness and the dampening resistance are highly correlated with the mass of the striking object, its energy and velocity. Hence, knowledge of these properties may be used in determining the impact parameters required by a striking object, which might be helpful in forensic investigation when contusions were induced.