Abstract: The frictional behaviors between the fenestrated jaws of laparoscopic grasper and the liver tissue are investigated by using a UMT-Ⅱseries multi-specimen biomedical micro-tribometer to simulate the surgical manipulation and traction. Based on the numerical simulation results of the clamping stress distribution between the jaws and the liver tissue, the interaction behaviors between the different fenestrated-jaws and the liver tissue are also discussed. The results show that under the same contact coefficient, increasing of the number of fenestrated holes can help to enhance the sliding friction. The jaw with three squares fenestrations has the longest contour line, and causes more deformation in the tissue at the edge of the fenestrations during the interaction with the liver tissue, which helps the tissue embed into the fenestration. Since this type of fenestrated jaw can produce the largest energy dissipation and the sliding friction, its holding stability is the best. For the same type of rectangular opening jaws, there exists a threshold value of contact coefficient. The stability of the grasper declines with decreasing contact coefficient when the contact coefficient is less than the threshold. In addition, in the contact process of the jaws and the liver tissues, the greater contact stress is concentrated at the edge of the two ends of jaw and the edge of the open window during the contact process between the jaws and the liver tissue.

Key words: clamping stability, contact coefficient, fenestrations, friction behavior, laparoscopic grasper, porcine liver