With the advancement of microstructure manufacturing technology, an array of functional surfaces based on micro/nano structures have been developed. Recently, there has been active research in the development of functional surfaces using composite materials that combine the properties of two different materials. One notable area of research is the creation of functional surfaces that utilize magnetic force to actuate microstructures. Typically, these surfaces are produced using a composite material that blends a flexible, easily deformable material with iron particles that respond to magnetic force. However, the inclusion of iron particles in the flexible material can increase its Young’s modulus, making it more challenging to effectively actuate the microstructures. To address this issue, our paper presents a fabrication method that allows for the effective actuation of microstructures by removing the residual layer of the composite material. This method enables the arrangement of iron particles at the end of the microstructure, maximizing the bending of the microstructure when magnetic force is applied. Furthermore, we conducted experiments to actuate microstructures with varying ratios of iron particles, confirming the effectiveness of this fabrication method.
Recently, with the expansion of application of polymer composite materials, high levels of deformation compensation actions have been developed. However, there is a problem of high-temperature viscoelasticity that occurs over time after completing the injection molding process. In this study, changes of mechanical properties of the Moldflow program for injection molding were analyzed to verify the viscoelasticity phenomenon through deformation analysis. In addition, deformation analysis of plastic injection molded products according to arrangement of three ribs was conducted and two products with different geometric shapes of the same function were compared. As a result, it was possible to reflect the viscoelastic effect by reducing the elastic modulus and shear modulus of the material. It was confirmed that the geometric shape with thick ribs formed in multiple longitudinal directions was mainly responsible. On the surface of the product where the rib arrangement was parallel and perpendicular to the flow direction, the orientation was orthogonal to the linear direction and the maximum residual stress was 81.17 MPa, which showed the largest value. It was judged that viscoelastic phenomena could be predicted and that an arrangement of parallel and perpendicular ribs that might intersect should be avoided.
Major aerospace developers continue to push for new structural composite applications to reduce the environmental impact of greenhouse gas emissions, improve both aircraft performance and costs. In this study, the parts that carry the load in the regions where mechanical joints are applied, require whole processing to tighten and identify stress concentration points. In addition, failure modes caused by bearing and by-pass loads were set as the main design factors. Optimum sizing was performed through the application of factors taken into account in the buckling failure mode and production using the preliminary design analysis model of the composite wing structure. In the area where the fuselage is joined with the fuselage, bearing and bypass load were considered important design factors.
A chemical ablation analysis of hypersonic missile for thermal protection design was performed using SAMCEF AMARYLLIS V.17, the specific ablation module of commercial software based on a finite element code. The pyrolysis and surface recession models based on the effects of mass loss, pore gas diffusion, and endothermic reaction energy were applied for non-linearity of material and boundary. The numerical studies were carried out to confirm the tendency of the pyrolysis and chemical ablation of theoretical ablative composite for open testing (TACOT) with a chemical composition similar to charring carbon/phenolic composites. The frequency of variation in surface recession, temperature, density and gas mass flux was reviewed to determine the characteristics of multiple decomposition reactions and oxidation via pyrolysis of gas species.
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The DSC/TGA and Ablation Analysis to Conforming Pyrolysis Characteristic and Surface Recession of Hypersonic Missile Youn Gyu Choi, Jeong Eun Kim, Kyung-Ho Noh, Young Hwan Jo, Gu Hyun Ryu Journal of the Korean Society for Precision Engineering.2021; 38(4): 279. CrossRef
In this study, application study of the life cycle assessment (LCA) is conducted on a composite small craft for sustainable design and production according to ISO 14040-14044 series. Procedure of general LCA is reconstituted to apply to composite small craft, and life cycle inventory (LCI) analysis is conducted on principal structures of composite small craft by developing a process flow diagram for boat building. Also, this study leads LCA results of structures and materials into the environmental impact category such as carbon footprint, water eutrophication, air acidification, and energy consumption. Especially, LCA results about production methodologies that are hand lay-up and vacuum infusion of glass fiber reinforced plastic are quantitatively compared and analyzed.
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Analysis of Life Cycle Assessment (LCA) for Sustainable Basic Design Alternatives for Medium-Sized LNG-DF Propulsion Ship Ki Seok Jung, Dong Kun Lee Journal of the Society of Naval Architects of Korea.2023; 60(5): 358. CrossRef
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Beyond conventional military products, technologies in the defense industry sectors around the globe are integrated and fused with newly emerging technologies such as three-dimensional printing (3DP) and smart material fabrication. Acknowledging these trends, this study proposes a miniature high-speed actuator whose fabrication process entails 3DP, smart materials, and shape memory alloy. The manufactured actuator is 25 mm long and 5 mm wide in and weighs 2.5 g, having the optimal frequency in the range of 35-40 Hz. Force and deformation measurement were also conducted, resulting in the lift force of 0.18 N per second with a bending deformation of 5 mm.
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