Comparative Dynamical Study and Repeatability of Metallic Plates Using Additive and Subtractive Manufacturing Techniques

Many times, when components are subjected to harsh operating conditions where the structural integrity of the part is of utmost importance, metal and its alloys are used. However, the high strength and durability of these materials have proved challenging to form into complex geometries. Recent discoveries in the additive manufacturing space allow engineers to harness the true potential of these materials. With this said, research has shown that the final product exhibits variability in its dynamical responses. Before these parts begin to make their way into critical applications, further investigations should be conducted into their dynamical characteristics. This research aims to address the gap in literature by investigating the vibratory properties of “identical” metal components fabricated using traditional and additive manufacturing techniques. This study has four main objectives, two of which are the preliminary findings discussed here. That being the variability in the dynamical responses of metal 3D printed components and a comparison between additive and subtractive manufacturing techniques effect on the part’s vibratory properties. To develop an understanding of the complex behavior seen in anisotropic parts, a Laser Powder Bed Fusion process is utilized to manufacture three 316 L stainless steel plates. An additional plate, which has identical dimensions and material to the 3D printed plates, is cut out of sheet metal. Using free vibration, the fundamental frequency of vibration, normalized effective damping ratio, and backbone skeleton are extracted for each plate. Next, closed-loop forced vibration in the form of a true random signal is employed at increasing excitation levels to qualitatively explore the possible presence of nonlinear backbone and nonlinear damping in the system. Random excitation analysis can capture a broadband of frequencies, and finite element analysis is used to help find higher peaks so that qualitative analysis can be conducted. This said, the remaining two objectives of this work, which will be presented at the conference, will be comparing stainless steel plates to aluminum plates and analyzing the effect an accelerometer has on the parts responses.