Static and dynamic response of SS316L thin-wall Origami and Auxetic structures fabricated through laser powder bed fusion

In many engineering applications, vibrations are a constant concern, and mitigating their effects is crucial to preserve structural integrity, functionality, and overall safety. With their distinct geometry and material distribution, lattice structures are an intriguing solution to vibrational issues and additive manufacturing represents a production process that can meet the challenge of fabricating such geometries. This work represents a preliminary investigation of novel metal lattice specimens fabricated through additive manufacturing aiming at providing further insights into the field of damping of lattice structures. To this end, a laser powder bed fusion technique is used to fabricate SS316L thin-wall Origami and Auxetic structures. Defects analysis along with quasi-static and dynamic mechanical tests have been carried out. A numerical model to predict the stress distribution in the two structures have been developed as well. It was found that the mechanical response is influenced by defects resulting from the production process, such as porosity and dimensional errors. Furthermore, the results of the static tests show a notable decrease in the elastic modulus when compared to the bulk specimen, indicating that the thin-walled construction exhibits the scale effect. Dynamic tests have been carried out through the study of the Tan Delta parameter at different deformation and frequency amplitudes. The mechanical response presented by the two geometries is similar. For both structures, results indicate that Tan Delta decreases with the mean force, increases with frequency and stabilizes at high solicitation amplitude to approximately 0.02. The highest Tan Delta was registered for the Auxetic structure measuring 0.073 at a mean force of - 20 N, 0.006% deformation and 5 Hz.