Modeling the Forces of Cutting With Scissors

Abstract

Modeling forces applied to scissors during cutting of biological materials is useful for surgical simulation. Previous approaches to haptic display of scissor cutting are based on recording and replaying measured data. This paper presents an analytical model based on the concepts of contact mechanics and fracture mechanics to calculate forces applied to scissors during cutting of a slab of material. The model considers the process of cutting as a sequence of deformation and fracture phases. During deformation phases, forces applied to the scissors are calculated from a torque-angle response model synthesized from measurement data multiplied by a ratio that depends on the position of the cutting crack edge and the curve of the blades. Using the principle of conservation of energy, the forces of fracture are related to the fracture toughness of the material and the geometry of the blades of the scissors. The forces applied to scissors generally include high-frequency fluctuations. We show that the analytical model accurately predicts the average applied force. The cutting model is computationally efficient, so it can be used for real-time computations such as haptic rendering. Experimental results from cutting samples of paper, plastic, cloth, and chicken skin confirm the model, and the model is rendered in a haptic virtual environment.

Investigation and experimental measurement of scissor blade cutting forces using fiber Bragg grating sensors

“…This was verif ed by measuring the length of the slit in the sample after cut completion. A fracture toughness value of 4.36 kJ m −2 was obtained using (20), comparable to that found in other literature [19]. Error bars are included to convey the force resolution, which improves toward the end of the cut as the blades are closed by the scissor handles.…”

“…Using (19) the external work done due to combined fracture and friction, W ff , was obtained by integrating under the fracture forcedisplacement profi e in f gure 13. Similarly, the external work done due to friction only, W f , was obtained and subtracted from W ff resulting in work done due to material fracture only.…”

Characterization of fracture toughness exhaustion in pig aorta

“…Most of the work featured the slicing of test samples using an instrumented cutting implement like a guillotine (Atkins and Mai, 1979), a blade (Lake and Yeoh, 1978), or a pair of scissors (Sim et al, 1993). In haptics, fracture mechanics have enabled the modelling of the forces required to cut through soft tissue with scissors (Mahvash et al, 2008). Related to biomechanics, Pereira et al (1997) have ranked the fracture toughness of various mammalian soft tissues using a scissor testing rig.…”

Review of surgical robotics user interface: what is the best way to control robotic surgery?

“…This technology would give that advantage back to the operating surgeon. Haptic feedback, despite the argument made by Shah et al, has been shown to reduce of tissue injury and suture breakage, while at the same time maintain a reasonable operating time, under an experienced surgeon [33][34][35][36][37].…”