Assessment of mechanical-loss property of 3D printing metal and its application to ultrasonic transducers as vibrating bodies

As miniaturized ultrasonic transducers with sophisticated structure have become increasingly demanded, the vibrating bodies made by conventional metals face the problem of fabricating difficulty and high expenses. The 3D printing metals are prospective materials for their flexibility in forming complicated configurations, but their mechanical-loss properties need clarification as they greatly affect the vibration properties. As a pilot trail, first, an approach to measure the attention coefficients according to the distributions of the vibration velocity and the phase was developed to evaluate their dependence on the strain and the frequency. Then, an aluminum alloy via 3D printing (AlSi10Mg) was employed as the vibrating bodies to form the ultrasonic transducers, whose performance, e.g., vibration properties, temperature rise, and sound pressure level (SPL) in water, was assessed and compared with conventional aluminum alloy (7075). As typical results, AlSi10Mg's damping coefficient is 1.16 times that of 7075 at 33 kHz frequency; this implies the 3D printing process does not deteriorate the aluminum alloy's mechanical-loss property. Meanwhile, AlSi10Mg's damping coefficient reaches 2.19 × 10^-4 at the laser power of 350 W, relatively small compared to the values corresponding to other laser powers; this indicates the capability to reduce the mechanical loss by adjusting the parameters during 3D printing possesses. Moreover, the maximum vibration velocity and the SPL of the AlSi10Mg transducer are 1.13 and 1.11 times those of the 7075 transducer that has the same configuration and operates in the same vibration modes. This study enriches the candidate materials as the vibrating bodies of ultrasonic transducers, which potentially meet the demands in wider ultrasonic application fields.