• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.3
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• pp.38-46
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• 2023

In this study, a bearing test was performed and analytically evaluated to evaluate the bearing performance according to the application of the aluminum stiffener in round-end concrete. In the bearing strength test, the change in bearing performance due to the aluminum stiffener using the aluminum form for manufacturing concrete with round-end, and the steel anchor bolts for member movement and assembly was confirmed. The FE analysis model was identically configured to the experimental conditions, and the result was compared with the experiment. Also, the crack patterns and stress behavior were confirmed. In addition, the effect of strength change of the aluminum stiffener on the round-end concrete was also evaluated analytically. The bearing strength of the round-end concrete increased by about 20% due to the aluminum stiffener, and it was confirmed that the steel anchor bolt did not affect the bearing strength. The maximum load and crack patterns shown as a result of FE analysis were similar to those of the experiment. As a result of FE analysis according to the strength change of the aluminum stiffener, the maximum load change according to the increase and decrease of the strength of the aluminum stiffener by 10% and 20% was evaluated to have no significant effect at a maximum of about 4% compared to before the strength change.

• Journal of Ocean Engineering and Technology
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• v.8 no.1
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• pp.96-104
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• 1994

The use of advanced composite materials has grown in recent years in aerospace and other structures. Out of various kinds of repairing methods the one selecteh for this study is an idealized case which simulates a situation where a damaged laminate has been repaired by drilling a hole and therefter plugging the hole with reinforcement. Two typesof reinforcement are investigated ;adhesively bonged plug reinforcement or snug-fit unbonded plug in the hole. For each case of reinforcement, four different sizes of hole diameter and three types of reinforcing material(steel, aluminum, plexiglass) are employed for investigation. The experiment are mainloy forced on the evaluation of ultimate strength of laminate with reinforced hole in comparison to its counterpart with the open hole.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.4
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• pp.630-648
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• 1992

The minimum weight design for simply-supported isotropic or symmetrically laminated stiffened cylindrical shells subjected to various loads (axial compression or combined loads) is studied by a nonlinear mathematical search algorithm. The minimum weight design in accomplished with the CONMIN optimizer by Vanderplaats. Several types of buckling modes with maximum allowable stresses and strains are included as constraints in the minimum weight design process, such as general buckling, panel buckling with either stingers or rings smeared out, local skin buckling, local crippling of stiffener segments, and general, panel and local skin buckling including stiffener rolling. The approach allows the consideration of various shapes of stiffening members. Rectangular, I, or T type stringers and rectangular rings are used for stiffened cylindrical shells. Several design examples are analyzed and compared with those in the previous literatures. The unstiffened glass/epoxy, graphite/epoxy(T300/5208), and graphite/epoxy aluminum honeycomb cylindrical shells and stiffened graphite/epoxy cyindrical shells under axial compression are analyzed through the present approach.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.243-244
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• 2010

Reinforced concrete beam are very diverse materials that are used to bending reinforcement. Recently the case of FRP flexural reinforcement is actively being used is an excellent weight - rigidity. However, use of FRP bending reinforcement in brittleness material properties of concrete in an actual field application causes destruction of detachment and attachment is being considered as a major cause of destruction. For hybrid laminating plates, tensile and three-point bending tests were performed considering various designs and fabricating methods for hybrid FRP plates. Tensile property of each test specimen was investigated and the research parameter of hybrid laminating plates considered here is the combining ratio of fiber to aluminum contents.

• Design & Manufacturing
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• v.11 no.2
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• pp.15-19
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• 2017

Carbon fiber reinforced plastic (CFRP) is applied as structural material. CFRP is excellent in plane strength / stiffness and don't haves rust. Lightweight, rigid and robust at the same time as transportation material. Aluminum alloy and reinforcement material The application is increasing rapidly. In this study, the prototype of a semi - Monocoque structure frame, Longeron, Stringer, Skin of the aircraft, restraining the rigidity Clips of the aircraft was designated as the target product and the experiment was conducted. ln the experiment, (1) For CFRTP 3 points, data on heating, transfer, and cooling were measured using Thermo Couple, and optimum temperature required for flexible state was obtained. Heating was performed at a temperature 15% higher than the provided temperature. (2) By using a pneumatic press during molding, by dividing LH, center and RH according to the cooling time, thickness parameter of the target product due to the load is measured, and thickness control and time-deviations were analyzed and cross sections were observed with a low magnification microscope.

• Journal of Aerospace System Engineering
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• v.14 no.3
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• pp.51-59
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• 2020

In the case of cubesat, a PCB-based deployable solar panel advantageous in terms of weight reduction and electrical circuit design is widely used considering the limited weight and volume of satellites. However, because of the low thermal conductivity of PCB, there is a limit relative to heat dissipation. In this paper, the thermal gap pad is applied to the contact between the PCB-based solar panel and the aluminum stiffener mounted on the outside of the panel. Thus, the heat transfer from the solar cell to the rear side of the panel is facilitated. It maximizes the heat dissipation performance while maintaining the merits of PCB panel, and thus, it is possible to improve the power generation efficiency from reducing the temperature of the solar cell. The effectiveness of the thermal design of the 6U cubesat's deployable solar panel using the thermal gap pad has been verified through on-orbit thermal analysis based on the results, compared with the conventional PCB-based solar panel.

• Journal of Aerospace System Engineering
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• v.15 no.1
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• pp.86-94
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• 2021

PCB-based deployable solar panel is mainly used for CubeSat due to its lightweight and easy of electrical connection. However, as the size of solar panel increases, there is a limit to ensuring the structural safety of solar cells due to excessive dynamic displacement under launch vibration environment. In previous mechanical designs, for the minimization of dynamic deflection, panel stiffness is increased by applying additional stiffeners made of various materials such as aluminum or composite. However, it could have disadvantages for CubeSat design requirements due to limited mass and volumes. In this study, a high-damping 6U solar panel was proposed. It had superior damping characteristic with a multi-layered stiffener laminated with viscoelastic acrylic tapes. Basic characteristics of this solar panel were measured through free-vibration tests. Design effectiveness of the solar panel was validated through qualification-level launch vibration test. Based on test results, vibration characteristics of a typical PCB solar panel and the high-damping laminated solar panel were predicted and a comparative analysis was performed.