Modal Response as a Validation Technique for Metal Parts Fabricated with Selective Laser Melting

This paper investigates modal analysis as a validation technique for additively manufactured parts. The Frequency Response Function (FRF) is dependent on both the geometry and the material properties of the part as well as the presence of any defects. This allows the FRF to serve as a “fingerprint” for a given part of given quality. Once established, the FRF can be used to qualify subsequently printed parts. This approach is particularly attractive for metal parts, due to the lower damping as well as use in high-value applications where failure is unacceptable. To evaluate the efficacy of the technique, tensile specimens are printed with a Renishaw AM250, the modal response of these parts is characterized prior to tensile testing, and the FRFs are compared to their engineering metrics for parts printed with both nominal and off-nominal parameters. Numerical modeling is used to understand the modal structure, and the possibility of defect prognosis is also explored by comparing the measured response to simulation results.