With the development of Additive Manufacturing process, lattice structures have recently been fabricated with fine quality. Lattice structures have unique performances which encompass various elastic responses. In this study, shear characteristics of the lattice structures (BCC and OTC) fabricated by SLM process, under optimized manufacturing conditions, were analyzed by 1/4 compression tests. As a result, several fracture modes and elastic configurations were found by comparing the compression test results of various lattice structures. In addition, the lattice structures possessed certain shear elasticity and normal elasticity among different types of lattices at elastic region when shearing. As the 1/4 compression test was simulating the lattice structure on concentrate load or shearing load, the test represented shock introspection characteristics of the lattice inner structure.

Microchannel-based chemical reactor is widely used to develop chemical products. High-efficiency reactors are required to produce high-quality chemical products. The reaction efficiency is highly related to the mixing ratio. In this paper, an inner structure model in the reactor was designed to improve the mixing ratio. Computational fluid dynamic (CFD) analysis was carried out for two-phase flow in a continuous flow reactor using a commercial software. A case model of the different inner structures was designed to evaluate the mixing rate. Velocity profiles, mixing ratio, and pressure fields of each model were obtained by two-fluid flow analysis using CFD. Based on the analysis results, a reactor model with a high mixing ratio was selected. Powder bed fusion based metal additive manufacturing process was performed to manufacture the 3D microchannel-based chemical reactor. It is expected that the proposed reactor could be applied to a high-efficiency reactor system to produce various chemical materials. For instance, it was possible to perform a chemical reaction based on a toxic material, such as, dimethylformamide solution, using the proposed 3D metal microchannel-based reactor.

We have designed the structural shapes of a spiral blade and the frame to be used in an Archimedes wind-power system with the objective of increasing its mechanical strength. A conical roll-bending forming process was introduced to fabricate a metallic spiral blade, based on an incremental stepwise approach. From this process, the complicated spiral blade was constructed, and it could be applied to the wind-power mill. We proposed a few structural design concepts for improvement of the mechanical strength of the blade and frame. Fixing rods between the blades increased the natural frequency of the blades three-fold, compared to the original model with no rods. Also, the strength of the frame was increased by introducing edge-flanges with a height greater than 20 mm. This study will be helpful to industrial engineers interested in the structural design of a wind-power system in understanding the structural design process.

A conical roll-shaping process was proposed for fabrication of a metallic spiral blade applied to a small-scale wind turbine system. A spiral blade has continuously different curvatures, with a range of 100 to 350 ㎜ radius. To fabricate this complex shape, we developed a conical rollshaping process having two main conical rollers for feeding a blank sheet, and two cylindrical side rollers for control of local bending. For clear understanding of the process parameters, numerical analyses were conducted using a commercial code, Pam-Stamp. This study optimized the effects of process parameters, such as gap and angle between the main rollers and side rollers, and also the movement of side rollers. In order to increase the forming efficiency, a central rotation point was also calculated by the analytical approach. This developed rolling process can thus be utilized in a sheet metal forming process for obtaining spirally curved sheet metal shapes.