Flow Field Analysis And Experimental Study Of Abrasive Flow Machining On Artificial Knee Joint Based On Level Set Method

Artificial joint is a kind of artificial organ implanted in the human body.It is used to maintain the original joint function instead of human bones and generally made of titanium alloy.In order to overcome the difficulty of polishing titanium alloy surface,the machining method of soft abrasive flow was selected and the specific research contents were as follows:(1)In the numerical simulation of abrasive flow field,the level set method,the Reynolds time-averaged equations and the standard k-? equations were combined to construct the mathematical model of flow field.Then using the Hamiltonian-Jacobi ENO scheme and the Runge-Kutta scheme to discrete the level set equations and solve it.Movement equation of a single particle was constructed.According to the viewpoint of Euler-Lagrange method,solid and liquid two phases were coupled,and proposed a turbulent dispersion model to simulate the trajectory of particles in the abrasive flow.(2)Based on the established mathematical model,the machining process of abrasive flow was simulated with the COMSOL software.After the simulation,the velocity and pressure distributions of abrasive flow field were analyzed,and a dimensionless relative removal rate model was constructed to simulate the material removal effect of the artificial knee joint surface.On the other hand,the validity of turbulent dispersion method was verified from the perspective of particles movement.By combining turbulent dispersion method and turbulent kinetic energy distribution,the trajectories of abrasive particles were analyzed.The simulation results confirmed the feasibility of the real machining.(3)A experiment platform was built for machining.On the microscopic point of view,the results of abrasive flow machining showed the surface roughness Ra after machining was reduced to 171 nm from 394 nm.The results show that: It is feasible to establish the mathematical model of the flow field by combining the level set method,the turbulent dispersion method,the Reynolds time-averaged equations and the standard k-? equations.The simulation results of flow field based on the mathematical model confirm the feasibility of the real machining.The experimental results showed that the soft abrasive flow has a significant machining effect on the surface of the artificial knee joint.