Process and die design of cold forging for the asymmetric part, engine mount adapter has been studied. Forging of the asymmetric part frequently causes die failure because of the high forging load and local stress concentration of the die. Thus, performing process design of cold forging to minimize forging load is required. Preform for the engine mount adapter was chosen based on the forging load and filling rate of forgings by the finite element analysis. In the die design, number of stress rings, interface radius, and relative interference were investigated in several cases with maximum principle stress by the finite element method. The shape of the die was determined by comparing the load changing the radius of the flange area. Also, the life of the designed die was calculated using the Goodman theory by cyclic fatigue loading. As a result, it was confirmed that the calculation life and results of the test were identical. In this study, it is verified that stress concentration and fatigue life should be considered simultaneously in the design of cold forging die for the asymmetric part.
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Recently, as the interest in 3D printing technology has increased, many efforts have been initiated to apply 3D printing technology to various industrial fields. The 3D printing technology is also widely applied in medical, electronics, and apparel industries. Many studies on 3D printing have focused on equipment and material development. However, to use 3D printed components, it is necessary to understand friction and wear phenomenon that will occur during relative motion between two bodies. In this study, friction and wear characteristics of ABS (Acrylonitrile butadiene styrene)-like resin printed with the SLA (Stereo Lithography Apparatus) method were studies by using pin-on-disk and ball-on-disk methods. We also compared friction and wear characteristics between ABS-like resin-SUS304 and ABS-like resin-ABS-like resin. As a result, the relative motion between the ABS-like resin and SUS304 showed lower friction coefficient and wear amount than between the ABSlike resins. Markedly high frictional heat was observed because of the friction by the relative motion between the ABS-like resins. Experimental results show that further research on suitable lubricants is required to use 3D printed ABS-like resin parts as mechanical components.
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In this paper, we designed and manufactured a new manipulator (less than 15 kg) to make the total weight of SCOBOT-200 (EOD robot: its platform weight is 35 kg) commercialized by FIRSTEC Co., Ltd. Link1 and Link2 of the manipulator were designed and fabricated using CFRP (Carbon Fiber Reinforced Plastics) material, and the other components were made of AL6061 material. The fabricated manipulator has 5-DOF, and the opening width of the gripper is more than 1520 mm. As a result of the characteristic test, the weight of manipulator is 14.5 kg, the length of the manipulator is 1500 mm, the payload when the manipulator extended is 8 kg, when folded is 20 kg. Thus, the manipulator manufactured can be used as a manipulator for a small EOD (Explosive Ordnance Disposal) robot.
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This paper describes a control system for the servo prep column of High-Performance Liquid Chromatography (HPLC) based on fuzzy inference control. The key technology in pharmaceutical and biotechnology industries is refining performance and efforts to reduce costs by purifying target compounds with high purity at high yield while maintaining target compounds, is the major focus of new product development. Among the many refinement techniques, the most popular chromatographic methods require a column that can charge the resin with excellent performance and reproducibility. However, the present HPLC prep column has a hydraulic for control moving stopper and compressed chemical compound. It always causes irregular performances of the column. This paper presents automation control with a servo motor that prevents slurry issues and improves efficiency of the prep column reproducibility and provides easy automation. As an automation method, cortex-m4 as an embedded processor and operating system with LabVIEW, are used to control the HPLC system. To generate the heuristic data for the fuzzy inference control, experiments are conducted to identify correlation between data such as pressure sensor and motor speed. The result will improve performance of the servo prep column of HPLC for automation control based on fuzzy inference control.
Since the fuel consumption of automobiles increases in proportion to the weight of automobiles, and the emission of exhaust increases in proportion to the amount of fuel consumed, to improve fuel efficiency and reduce exhaust emissions, it is necessary either to develop a highly efficient engine or reduce the weight of the vehicle. In this study, we studied weight reduction using lightweight materials such as aluminum alloys to increase fuel economy. For this purpose, we propose a lightweight design process of the shock tower mounting bracket, which is the largest loaded part among the vehicle parts. The change in strength and dynamic strength was investigated by replacing the existing cast iron material with 320 MPa of aluminum A356 casting material. For strength and dynamic stiffness analysis of the shock tower mounting bracket, the load on the peripheral members was calculated. As a result of the dynamic stiffness analysis, we identified the weak part and calculated that the lifetime of the shock tower mounting bracket is safe for the calculated load conditions. Through this study, we provide a guide for lightweight design and suggest optimal design conditions for development of a vehicle shock tower mounting bracket.
In the case of paralysis caused by brain diseases and accidents, proper rehabilitation and supplementary systems for daily life are essential. In this study, we designed a system that can enable daily life by supporting the hand of a patient whose function has been lost to paralysis. The hand exoskeleton robot proposed in this study can be transported for the purpose of ADL (activities of daily living). It was designed to focus on the most important assistant for the thumb and index finger. The hand exoskeleton robot proposed in this study enables grasp and pinch motor skills during the human hand operation through the specific mechanism for the segment movement of the human finger simultaneously. Finally, the finger movement trace of the wearer through the vision system is measured, respectively.
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In this study, the fracture characteristics of structural adhesives were investigated according to the shape of a DCB and TDCB by using the FEM. First, to obtain the reliability of the finite element method, the experimental and FEM analyses were compared, and the reliability was secured. When the graph of reaction force to displacement on the TDCB test specimen was examined, it was found that the smaller the slope, the stronger the exhibited property sustaining the load to the end of the adhesive surface. Maximum reaction force occurred was just before the adhesive was removed. The shear stress of the specimen exhibited the same characteristics and an equivalent stress. Thus, the data of this study resulting in the fracture characteristics of the structural adhesives for each shape can be applied to the design with durability.
Displacement ductility and rotational ductility are used, to verify the performance of blast doors subjected to explosive loads. The values of these performance items are calculated by measuring the maximum elastic displacement in the laboratory, and the maximum displacement during the explosion test. To attain the maximum elastic displacement, the finite element analysis and the load distribution method are applied. In applying the load distribution method, the behavior of a blast door along a width direction is converted to a cantilever beam and along a height direction to a simply supported beam. The results by the load distribution method are verified by a finite element analysis and compared with those by a plate theory.
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In this study, the sensitivity of the power generation effect of the applied linear generator of the energy harvesting suspension system under various input conditions was analyzed. The energy-harvesting suspension generates electric energy through energy harvesting using the road surface vibration energy during driving. Before analyzing the power generation effect, we analyzed the structure of the eight-pole Outer PM (Permanent Magnet) linear generator model using the electromagnetic suspension system to design the efficient generator, PIANO (Process Integration and Design Optimization). The ANSYS MAXWELL program was used to perform electromagnetic simulations of a linear generator model installed inside an energy-harvesting suspension to determine the power generation of the linear generator under various input conditions. The sensitivity of each input variable was compared by comparing the power generation effect of the energy-harvesting suspension device according to road displacement, frequency, and vehicle speed. The sensitivity to the road surface frequency was 1.9451, the sensitivity to the road surface amplitude was 1.0502, and the sensitivity to the vehicle speed was 0.6258. It is confirmed that the maximum sensitivity to the road surface displacement was demonstrated.
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Research on Key Issues of Consistency Analysis of Vehicle Steering Characteristics Yanhua Liu, Xin Guan, Pingping Lu, Rui Guo Chinese Journal of Mechanical Engineering.2021;[Epub] CrossRef
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To study the geometrical scale dependency of thin film solid oxide fuel cells (SOFCs), we fabricated three thin films SOFCs with the same cross-sectional structure but with different electrode areas of 1, 4 and 9 ㎟. Since the activation and ohmic losses of SOFCs depend on their active region, we examined the variations of the power density of the cells with a Pt (anode)/sputtered YSZ/Pt (cathode) structure. We found that a cathode electrode with a low aspect ratio may suffer from high ohmic and activation losses because of the geometrical scale dependency.
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