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이충우,우수성,김지선,백경윤 한국기계기술학회 2024 한국기계기술학회지 Vol.26 No.3
WAAM(Wire Arc Additive Manufacturing) has gained attention as an innovative technology in small-batch, multi-product production due to its advantages of low production costs, rapid build rates, and design flexibility. However, challenges such as relatively low geometric accuracy, surface finish defects, residual stresses, and distortion due to high heat input persist and require improvement. This study analyzes the influence of deposition path angles on deposition performance in the WAAM process. Experiments were conducted using stainless steel (STS309MoL) wire, known for its excellent heat resistance and corrosion resistance due to its relatively high ferrite content within the austenitic structure. To mitigate residual stresses and distortion caused by high heat input, the CMT(Cold Metal Transfer) process was employed for five layers of deposition. Five different deposition path angles were selected as process variables, and the impact of deposition path angles on deposition performance was evaluated based on experimental results.
와이어 압출 방법을 통한 HDPE 접합공정의 개선 형상별 실험적 연구
이충우,우수성,김지선 한국기계기술학회 2024 한국기계기술학회지 Vol.26 No.1
The overseas small ship market is witnessing a trend towards research aimed at substituting Fiber Reinforced Plastics (FRP), which poses environmental concerns, with High-Density Polyethylene (HDPE) in the shipbuilding process. Given the low melting point and high coefficient of thermal expansion of HDPE, research on joint areas is essential. This study focuses on preliminary investigations into ensuring the integrity of joints in shipbuilding processes using HDPE materials. Utilizing the Hot Gas Extrusion Welding method, which is conducive to joining large structures such as ships, HDPE joints were conducted. The material properties were evaluated based on the ASTM D638-14 international standards. This research aims to provide fundamental knowledge on the joining process of HDPE through Hot Gas Extrusion Welding and offers guidance on ensuring the integrity of joints in shipbuilding.
단부처리시설물의 충격흡수구조설계에 따른 방호성능 개선 연구
백경윤,우수성,심도식,박원균,송대빈 한국기계가공학회 2022 한국기계가공학회지 Vol.21 No.11
In the event of a collision with the end of a vehicle guardrail, the high rigidity continues to pose a threat to the safety of passengers; hence, an end treatment facility must be mandatorily installed. This requires a shock-absorbing mechanism design to reduce the impact on the occupant and a shock-absorbing structure that can protect the occupant from an abrupt deceleration movement. In this study, the structure of a guardrail was improved. For a head-on collision of a vehicle with an end treatment facility, the impact absorption performance owing to the structure of the guardrail was observed by a simulation using ABAQUS, a finite element analysis program. To improve the impact absorption performance of the end treatment facility, we designed a structure in which a groove is formed in the guardrail, pressed in the longitudinal direction, and then pushed backward according to the groove shape to absorb the impact. The calculation of the reaction force of the collision member according to the guardrail groove shape showed that the wave shape had the lowest reaction force. The actual crash test report also satisfied the absorption performance evaluation with excellent results for the passenger protection performance evaluation criteria (THIV((Theoretical Head Impact Velocity)) 15.7% and PHD (Post-impact Head Deceleration) 21.17%).