Zahra Matin Ghahfarokhi - Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, Iran
Mehdi Salmani Tehrani - Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, Iran
Mahdi Moghimi Zand - School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran
Mojtaba Mahzoon - Department of Mechanical Engineering, University of Shiraz, Shiraz, Iran

Needle insertion is a minimally invasive technique in diagnosing and treating tumors. However, to perform a surgery accurately, the tissue should have minimum amount of displacement during needle insertion so that it reaches the target tissue. Therefore, the tissue membrane has to move less to decrease rupturing under the membrane. In this study, the effect of different design parameters on displacement of the point where a puncture occurs during needle insertion is investigated. Finite element simulation is used to study the effect of mechanical properties of the tissues (hyper-viscoelastic coefficients) and geometric parameters of the needle (fillet radius, needle tip angle and needle diameter) and friction coefficient. To validate the simulations, the results were compared with previously published results in the literature, i.e. the hyper-viscoelastic properties of brain tissue in neurosurgical procedure and the hyper-viscoelastic properties of liver tissue. The results show that the hyper-viscoelastic constitutive is a suitable model to describe soft tissue behavior. Also, the mechanical properties of the tissue and needle velocity are effective on the displacement of the tissue s membrane and therefore in surgery accuracy.

finite element simulation, hyper-viscoelastic model, needle insertion, soft tissue