Research And Development With Test Of Fatigue Testing Machine For Ultrasonic Scalpel

Ultrasonic scalpel is a kind of surgical instrument which can realize biological cutting and separation by high speed vibration of the knife rod.It has the advantages of high precision,fast hemostasis and less smoke.Ultrasonic scalpel can produce high frequency vibration during work.The amplitude of ultrasonic scalpel with working frequency of 55kHz is about 50m.After one hour of work,the number of stress cycles in ultrasonic scalpel can reach 1.98×10~8 times,which is prone to fatigue damage.At present,the common ultrasonic scalpel is mostly made of TC4 titanium alloy.The research on ultra-high cycle fatigue of TC4 titanium alloy is based on ultrasonic fatigue test method.Ultrasonic fatigue test technology is a rapid test method for ultra-high cycle fatigue test of metal materials.At present,the frequency of ultrasonic fatigue test system is 20kHz.In this paper,a 55kHz ultrasonic fatigue test system is established.In order to better study the fatigue characteristics of ultrasonic scalpel,the fatigue test of TC4 titanium alloy is carried out,and the effects of frequency,temperature,stress and other parameters on the fatigue life of TC4 titanium alloy are explored in order to further improve the anti-fatigue performance of ultrasonic scalpel.In this paper,firstly,the magnetostrictive ultrasonic transducer was designed as the driving device of the test system,and the conical ultrasonic horn was used as the amplitude amplification device.The transducer and the amplitude-changing rod which satisfy the 55kHz resonance frequency were calculated theoretically and the finite element analysis method was used to simulate the design results.The transducer and the amplitude-change rod were tested,and the ultrasonic fatigue test system was constructed by integrating the stress loading device,cooling system and detecting device into the ultrasonic drive system.The main parts of the system were simulated to verify the natural frequency of the system.Finally,the samples satisfying the 55kHz resonance frequency were designed and made by TC4 titanium alloy,and the samples were tested by the self-designed ultrasonic fatigue test system.In order to explore the cause of fatigue fracture of ultrasonic scalpel and improve the fatigue life of ultrasonic scalpel,the fracture surface of fracture specimen was observed.