A Study on the Mechanical Properties of an Automobile Part Additively Printed through Periodic Layer Rotation Strategies

In metal product manufacturing, additive manufacturing (AM) is a method that has the advantage of fabricating complex shapes and customized production, unlike existing machining methods. However, owing to the characteristics of the AM process, anisotropy of macrostructure occurs because of various causes such as the scan direction, melting, fusion, and cooling of the powdered material. The macrostructure anisotropy is realized from the scan direction, and when a single layer is stacked in one direction, it is expressed as orthogonal anisotropy. Here, the classical lamination theory is applied to simply calculate the individual orthotropic layers by superimposing them. Through this, the authors analyzed whether the mechanical properties of the product are isotropically expressed with a periodic layer rotation strategy. To determine if the mechanical properties can be reasonably considered to be isotropic, a shock absorber mount for a vehicle was manufactured by AM. The tensile and vibration test performed on the product was compared with the finite element analysis and experimental results. As a result of the comparison, it was confirmed that the macroscopically of the product was considered isotropic as the load-displacement diagram and the fracture location coincided, as well as the natural frequency and mode shape.

Periodic Layer Formation during Multiphase Diffusion in Silicide Systems

Periodic layered morphology may occur during displacement solid-state reactions in ternary (and higher-order) silicide and other material systems. This periodic layered structure consists of regularly spaced layers (bands) of particles of one reaction product embedded in a matrix phase of another reaction product. The number of systems that is known to produce the periodic layered structure is rather small but increasing and includes metal/metal and metal/ceramic semi-infinite diffusion couples. The experimental results on different systems, where the periodic pattern formation has been observed are systematized and earlier explanations for this peculiar diffusion phenomenon are discussed. Formation of the reaction zone morphologies periodic in time and space can be considered as a manifestation of the Kirkendall effect accompanying interdiffusion in the solid state. The patterning during multiphase diffusion is attributed to diverging vacancy fluxes within the interaction zone. This can generate multiple Kirkendall planes, which by attractingin situ-formed inclusions of “secondary-formed phase” can result in a highly patterned microstructure.