Characterization of Materials Fabricated by Additive Manufacturing Method Using Line Focused Ultrasonic Transducer

Abstract

In this paper, we present our recent study on the characterization of the elastic properties of several metal alloys fabricated by additive manufacturing method using the line-focus ultrasonic transducer technique. Line-focused ultrasonic transducer has been used to measure leaky surface wave velocity based on the time-resolved defocusing method in recent years. Elastic properties of the materials can be calculated based on the velocities of leaky Rayleigh wave and longitudinal bulk wave, which are generated and detected by the ultrasonic transducer. In this work, a line focus ultrasonic testing system was constructed, using a PVDF thin film piezoelectric transducer, a computer controlled z-stage and a rotary stage, and data acquisition software for precision measurement of the propagation velocity of surface wave in the test materials. The transducer system was calibrated by testing the commercial stainless steel, aluminum, and copper. The surface roughness of the testing samples was measured to eliminate the possible effect on the surface wave velocity. Finally, the transducer system was used to characterize the elastic properties of specimens of nickel alloy and stainless steel which were built by additive manufacturing instruments. The results indicate good agreement with the data measured by traditional method.

Nondestructive measurement of anisotropic elastic constants of selective laser melted 316L based on a tri-mode ultrasonic method

“…Both destructive and nondestructive testing methods have been developed to characterize the elastic constants. The well-known and reference method is tensile testing [9]. Although it is a direct and reliable way to obtain mechanical properties, it will also damage the parts permanently.…”

“…Moreover, it is not efficient to evaluate the distribution or monitor the variation of the elastic constant when heterogeneity and dynamics should be considered. Li et al applied a polyvinylidene fluoride line-focused ultrasound transducer to simultaneously measure the velocities of longitudinal and surface waves to obtain the elastic constants of the nickel alloy and stainless steel in an immersed ultrasonic testing system [9]. Nevertheless, this method is limited to a small scanning range.…”