Study On Parameters Of Screw-driven Myoma Disintegrator Based On EDEM

With the progress of science and technology and the innovation of medical devices,Laparoscopic surgery is more and more field of application in clinical practice.In the wake of the improve of science,the innovation of instruments,laparoscopic surgery has been widely used in clinical practice.In laparoscopic surgery,it is necessary to use electric myoma disintegrator to remove large tissue specimens from small abdominal incisions.However,the myoma disintegrator is easy to cause tissue dissemination,planting or organ damage in the use process.Based on above,it is necessary to innovate and improve surgical instruments to better serve clinical surgery.In order to solve the problem of tissue dissemination in electric myoma disintegrator,a screw-driven rod was fixed behind the knife head of the myoma disintegrator based on the discrete element analysis software EDEM,and the flow state of tissue particles after rotary-cut was simulated and analyzed.In view of this problem,this paper mainly carries out three aspects of research:(1)Study on the histological structure and biomechanical properties of liver by analogy.The pig's fresh liver is similar to the human body in terms of its structure and biomechanical properties,and it is convenient to get materials.Choosen the pig's fresh liver as the experimental object to test static friction coefficient,collision recovery coefficient and stacking angle of liver tissue,and the physical and mechanical properties of liver tissue were explored,which provided a basis for the follow-up simulation research.The experimental data are as follows:the density of fresh liver tissue of pigs is 1.052 g/cm~3 by using the drainage method;The static friction coefficient between the liver tissue particles and the medical stainless steel plate is 0.37and the impact recovery coefficient of the two is 0,the coefficient of static friction between the particle is 0.41;on account of the image processing technology,the accumulation angle of the liver tissue particles is measured,the accumulation angle of the particles is 11.2°±0.86°;(2)A calibration method of stacking angle based on discrete element software EDEM is proposed.Measuring stacking angle of tissue particles by EDEM simulation.The orthogonal test was projected with rolling friction coefficient and JKR surface energy as factors;The contact model parameters were calibrated by batch processing method,and the optimal combination of parameters in the calibration results was checked by secondary simulation.The results are as follows:in the orthogonal test,the sixth group is the optimal parameter combination.that is,the rolling friction coefficient between the tissue particles and the stainless steel plate is 0.10,the rolling friction coefficient between the tissue particles is 0.15,the JKR surface energy between the tissue particles and the stainless steel plate is 0.0001,and the JKR surface energy between the tissue particles is 0.0005.The accumulated angle is 11.8°and the relative error of physical test is 5.1%.It has high similarity.From the results of range analysis,we can see that:the rolling friction coefficient and JKR surface energy parameters have significant effects on the fluidity of particles,which makes the particles have different accumulation patterns.The order of factors affecting the accumulation angle is as follows:JKR surface energy between the tissue particles and the stainless steel plate>the rolling friction coefficient between the tissue particles and the stainless steel plate>JKR surface energy between the tissue particles=the rolling friction coefficient between tissue particles;(3)A method of performance simulation of spiral drive myoma comminuter using EDEM is presented.First of all,the model of tissue particles was established and introduced into the three-dimensional model of the myoma disintegrator.By changing the filling coefficient of tissue particles and spiral shaft speed of the spiral axis of the myoma disintegrator,the flow state of tissue particles in the myoma disintegrator was simulated,and the results were analyzed.The results are as follows:the improve of filling coefficient has little influence on the change of velocity and axial distance of tissue particles;the raise of rotational speed will improve the change of velocity and axial distance of tissue particles;the raise of rotational speed will improve the change of velocity and axial distance of tissue particles;the raise of filling coefficient and rotational.speed of spiral axis will increase power,which will make the electric myoma disintegrator have high transportation efficiency and low energy.