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고속 주행 상황에서 CFRP 리어 스포일러의 내부 폼 코어 종류에 따른 성능 분석
김성은 ( Sung-eun Kim ),안준걸 ( Jun-geol Ahn ),김문성 ( Moon-sung Kim ),양승지 ( Seung-ji Yang ),김기영 ( Ki-young Kim ),양현익 ( Hyun-ik Yang ) 한국복합재료학회 2024 Composites research Vol.37 No.2
내부 폼 코어는 자동차에 사용되는 탄소섬유강화플라스틱(CFRP) 리어 스포일러의 성능에 중요한 역할을 한다. 하지만, 고속 주행 상황 (200 [km/h])에 대한 내부 폼 코어에 따른 CFRP 리어 스포일러에 관한 연구는 여전히 부족한 실정이다. 이러한 동기를 바탕으로, 본 연구에서는 고속주행 조건에서 다양한 폼 코어 종류에 대한 CFRP 자동차 리어 스포일러의 성능 분석을 수행하였다. 이번 연구에서 사용한 폼 코어의 종류는 Polymethacrylimide (PMI), Polyvinyl chloride (PVC), 그리고 Styrene acrylonitrile (SAN) resin이며, 선정된 폼 코어를 활용하여 진동 특성 및 고속주행상황에서의 거동 양상을 분석하였다. 추가적으로, 고속주행 상황에서 리어 스포일러의 내부 폼 코어의 중요성을 파악하기 위해 내부 폼 코어가 존재하지 않는 중공인 경우 또한 분석하였다. 그 결과, 변형 양상에서는 PMI 폼코어가 가장 좋은 성능을 보였고, 진동 특성에서는 PVC 폼 코어가 가장 좋은 성능을 보임을 확인할 수 있었다. 또한, 중공의 경우에는 변형양상 및 진동 특성 모두에서 가장 낮은 성능을 보임을 확인할 수 있었다. 결과적으로, 본 연구를 통해 고속 주행상황에서 내부 폼 코어 구조가 CFRP 리어 스포일러의 성능을 크게 향상시킬 수 있음을 확인할 수 있었으며, 또한 내부 폼 코어의 선택에 따라 강점을 보이는 특성이 다르게 나타남을 확인할 수 있었다. The inner foam structure plays an important role in the performance of the carbon-fiber-reinforced plastic (CFRP) rear spoiler used in automobiles. However, there is still a lack of studies for the CFRP-based rear spoiler according to the type of inner foam, especially under the high-speed driving condition. With this motivation, we numerically analyze the performance of the CFRP rear spoiler using various cases of the inner foam under the highspeed driving condition. Here, polymethacrylimide (PMI), polyvinyl chloride (PVC), and styrene acrylonitrile (SAN) resins are employed as the inner foams in this work. The performances are evaluated using the deformation aspects and vibration characteristics when the driving condition is a high-speed condition (200 km/h). Furthermore, to specifically verify the importance of the inner foam in the high-speed condition, we additionally investigate the performance of the CFRP rear spoiler without the inner foam structure (i.e., hollow type). As a result, it is confirmed that among the types of inner foams utilized in this work, the PMI and PVC inner foams have the best deformation aspect and vibration characteristic, respectively. Note that the hollow-type inner foam has inferior performances compared to other inner foams invoked in this study. Consequently, through this study, it can be confirmed that the inner foam structure can significantly improve the performance of the CFRP spoiler under high-speed driving condition (200 km/h), and also that the strengths of the CFRP spoiler can manifest differently depending on the types of inner foam core.
구조동역학에서 iIRS방법을 활용한 효율적인 인공신경망 접근 방안
리숴(Shuo Li),이재철(Jae-Chul Lee),김성은(Sung-Eun Kim),안준걸(Jun-Geol Ahn),양현익(Hyun-Ik Yang) 한국생산제조학회 2021 한국생산제조학회지 Vol.30 No.6
Artificial neural network approaches are used to efficiently generate meta-prediction fields for structural dynamics problems. However, these approaches exert heavy computational burden, which makes it difficult to improve the quality of the prediction fields. Therefore, we propose an artificial neural network strategy for structural dynamics problems using the iterated improved reduced system (iIRS) method. In the proposed method, characteristics of structural data are first extracted using the transformation matrix of the iIRS method. Next, the neural network (NN) is trained using only the extracted features. The prediction fields are restored by combining the trained NN results with the transformation matrix in the iIRS method. As a result, the quality of NN for structural dynamics problems is significantly improved owing to the efficient computational procedure. The performance of the proposed method is verified using the gearbox-housing model in an electric vehicle.
강성 다중점 구속조건이 적용된 기어박스 하우징 해석모델의 효율적인 수치해석을 위한 고성능 차수 감소 모델링의 적용
김성은(Sung-Eun Kim),이재철(Jae-Chul Lee),안준걸(Jun-Geol Ahn),양현익(Hyun-Ik Yang) 한국생산제조학회 2021 한국생산제조학회지 Vol.30 No.4
The vibration analysis of a gearbox housing model is essential for the design of an electric vehicle but requires large computational costs. In this study, we applied a high-fidelity reduction technique to analyze the gearbox housing model for an efficient numerical analysis. Moreover, the rigid multi-point constraints (MPCs) were employed to establish a connection between the housing and the internal mechanical parts. A governing equation was established from the Lagrange multiplier-based formulation to unify the reduction process and the application of the rigid MPCs. Furthermore, the dynamic correction technique was applied to the unified reduction process to compensate for the reliability of the reduced model. Consequently, the reduction model had reduced computational costs and high accuracy. Thus, the proposed model that has connection points between the housing and the shaft can be used to reflect the effects of the other gear, shaft and bearing parts on the gearbox housing.