Simulation And Experimental Study Of Internal Urethral Valve Based On Magnetic-controlled

The stress urinary incontinence in male patients is usually caused by urethral sphincter failure or prostatectomy.At the same time,it is accompanied by a series of complications,which seriously affects the daily routine and mental health of the patients.At present,several common surgical treatments for urinary incontinence are artificial urinary sphincter and sling,among which artificial urinary sphincter can be used to treat different severity of urinary incontinence.AMS800,a widely used product,has become the treatment standard for urinary incontinence.However,the artificial urethral sphincter can control urine by circumferential compression of the urethra,which is easy to cause urethra damage or even necrosis.In order to solve this problem and better treat male stress urinary incontinence,a kind of urethral valve is proposed in this paper.The mathematical model and the finite element model of the magnetic driving force for opening the urethral valve are established,the analytic value and the simulation value law of the influencing factors of the magnetic driving force are compared,and the experimental platform is built for verification;the three-dimensional model of the solid domain and the fluid domain of the urethral valve is established,and the fluid domain flow field and the force in the solid domain are simulated;the structure of the male lower urethra is simplified and the fluid domain model is established,and the simulation results are obtained At the same time,the lower urinary tract simulation experiment platform was built to study the urinary flow rate characteristics after the urethral valve implantation.The specific work is as follows:First of all,according to the structural characteristics of urethra valve and human body,the structural dimensions of inner and outer magnets are designed preliminarily.By selecting the model of inner and outer magnet materials,changing the size and space position of outer magnet,the driving characteristics and whether the magnetic driving force can meet the opening requirements of urethral valve are studied.Then,the equivalent magnetic charge theory is used to deduce the mathematical model of the magnetic driving force.The analytical value is obtained by solving the model with MATLAB.The finite element model of the inner and outer magnets is established with Maxwell simulation software,and the simulation value is obtained.The driving characteristics are analyzed by comparing the change laws of analytical value and simulation value,and the accuracy of the mathematical model and the finite element model is verified by recording the experimental data on the magnetic experiment platform.Secondly,the solid domain models of conical,spherical and plane valve cores are established by Solid Works software,and the corresponding fluid domain models are also established.In this paper,the structural characteristics of urethral valve and the influence law of valve opening are studied.The opening values of multiple groups of valves under different valve core structures are taken.Based on the one-way fluid solid coupling method,the models of multiple groups of fluid domain and solid domain are analyzed,and the finite element calculation is carried out by using workbench,a multi field coupling simulation platform.Finally,the simplified model of male urethra was established by Solid Works software,and the computational fluid domain was obtained by Boolean operation with the solid domain of urethra valve.Using the professional pump valve simulation software pumplinx to study the uroflowrate characteristics of the urethral valve,using the slide valve module of the software to carry out simulation calculation,and comparing the uroflowrate laws under different urethral valve structures.At the same time,according to the structural characteristics of male lower urinary tract,a simulation experiment platform was built to study the urinary flow rate characteristics of urethral valve under the effect of approximate detrusor inlet pressure.The results show that the whole design of urethra valve is feasible,and its working principle is in line with the mechanism of human urinary storage and micturition.The magnetic driving system can provide the magnetic driving force required for the normal opening of the urethral valve.The magnetic driving force can be increased by increasing the thickness of the outer magnet,selecting the appropriate radius,reducing the air gap and eccentricity.When the opening of the valve port with different valve core structure reaches the maximum,the volume flow reaches the maximum,and the maximum equivalent stress of the variable area is the minimum.When the structural parameters of cone,sphere and plane are changed,the maximum volume flow in fluid domain and the maximum equivalent stress in solid domain are changed.After the urethral valve is implanted in the lower urinary tract,the valve core is normally opened under the magnetic driving force,and the movement of valve core is affected by the spring stiffness.The greater the spring stiffness,the stronger the vibration of valve core,and the time for different valve core structures to reach the maximum opening is different.After opening the urethral valve,the characteristic curve of urinary flow rate is close to the real curve of human urinary flow rate.The results can guide the design and optimization of the urethral valve structure,and provide new ideas and references for the clinical treatment of male stress urinary incontinence.