Development And Experimental Research Of Rare-Earth Giant Magnetostrictive Ultrasonic Vibration Strengthening System

The surface quality has a very important effect on the fatigue life of parts. Rolling, stress peening and other finishing technology are usually used in manufacture to improve surface quality of parts. However, the surface quality is not improved largely because of the limitations of all these traditional finishing technology. Ultrasonic extrusion strengthening technology was used in the surface strengthening of the steel40and we got nice effect. A piezoelectric transducer was used in the experiment, but its application is limited because of its small amplitude, low power and overheating failure.As a kind of new functional material, rare-earth giant magnetostriction (Terfenol-D) is already used in manufacturing of sonar and some transducers due to its high energy density, large output amplitude and high Curie point. In this project, a rare-earth giant magnetostriction transducer structure was designed to meet the requirement of the ultrasonic strengthening technology. The composite oscillator was analyzed with the method of finite element and its natural frequency and mode graph were obtained. The magnetic field finite element analysis was also used in the whole structure of the transducer to ensure this design and the material was reasonable and valid. Soon afterwards, a rare-earth giant magnetostriction transducer sample was finished, matching ultrasonic power supply, and its output amplitude was measured and analyzed. The result showed while the simulating wave is square and the work frequency is15KHz, the output amplitude is the maximum which is12μm, five times larger than the piezoelectric transducer, which is2μm.On the basis of the above work, a tool for ultrasonic strengthening was designed and made. So far a complete ultrasonic strengthening system were finally finished. Based on this system, steel40is studied in the ultrasonic strengthening experiment. The surface roughness and hardness of steel40parts before and after the experiment are compared. The results showed:the surface of the parts became mirror finish after the ultrasonic strengthening; In the current experimental conditions, the roughness declined about65%compared to the previous process, and the surface hardness improved about20%.