Analyzing the impact of selective laser melting print speed on internal resonance structures of metallic phononic crystal artifacts for process monitoring

Compared to many conventional manufacturing methods, Additive Manufacturing/3D Printing (AM/3DP) techniques can produce highly optimized builds with unparalleled structural complexities, material combinations, and both internal and external geometrical intricacies, offering new degrees of freedom for optimization. However, unforeseen deviations in process parameters (e.g., laser beam scan speeds and power), material properties (e.g., powder morphology, alloy composition, mechanical and thermal properties), and machine health can lead to micro/macro-scale defects and quality concerns in the resulting builds and end-products. To address these concerns, it is crucial to assess quality and implement effective closed-loop control by understanding the sensitivity of quality attributes to perturbations and variations in process parameters, material properties, and machine health state. AM print speeds influence the material’s microstructure, affecting its elastic properties, defect states, and, consequently, spectral resonance behavior. Here, a quality monitoring framework is introduced based on specially designed Phononic Crystal Artifacts (PCAs) printed alongside the actual build. Compared to the actual build, a PCA is a substantially smaller construct with a repeating pattern (periodic) internal structure to effectively capture and measure the build’s defect state and mechanical and geometric complexities for quality assessment. In this study, we investigate the impact of varying print speeds in AM on the resonance frequencies of PCAs, which are related to mechanical properties and defects. Stainless steel 316L powder, widely used in powder-based AM/3DP, was chosen to print the Metal Phononic Crystal Artifacts (mPCAs). Our findings indicate that varying print speeds significantly influence ultrasonic waves’ resonance and modal frequencies in the printed artifacts. Specifically, high print speeds resulted in measurable shifts in these frequencies, demonstrating the potential for real-time quality monitoring and process optimization in AM/3DP. The PCA approach offers real-time, non-destructive quality monitoring by using smaller, sensitive constructs to capture essential mechanical and geometric complexities, allowing for dynamic adjustment of print speeds and enhancing overall build precision and reliability in AM/3DP.