• 에너지공학
• /
• 제27권4호
• /
• pp.92-97
• /
• 2018

본 연구는 자동차 엔진룸 내부에서 엔진과 연계된 부품의 냉각효과를 높이기 위해 후드 개발을 위한 수치해석을 다루고 있다. 급격한 온도편차에서 유발되는 엔진룸내 부품 온도를 저감시키면 부품에 대한 내구성 저하를 최소화 할 수 있다. 따라서, 본 연구에서는 차량 엔진룸 주요 부품 중에서도 온도제어가 비교적 용이한 발전기, 배터리, ECU 및 파워스틸 오일 등 4가지 부품을 목표로 엔진룸 냉각용 후드 개발을 위한 수치해석을 수행하였다. 그리고 수치해석을 검증하기 위하여 수치해석에서 가정하였던 동일한 조건으로 실험을 수행하여 비교하였다.

• 한국전자통신학회논문지
• /
• 제14권3호
• /
• pp.513-518
• /
• 2019

와전류를 이용한 비파괴검사장비가 자동차 변속기 부품의 결함유무를 판단하기 위해 개발되었다. 본 탐상기에서는 부품에서 발생하는 결함을 패턴별로 검사하기 위한 결함 마스터 샘플을 만들고, 결함의 형태별로 탐상 가능한 와전류 탐상기를 제작하여 시험을 하였다. 또한 실제 결함이 있는 불량품을 대상으로 결함발생 원인 및 결함발생 형태를 조사하며, 탐상시험을 통해 결과를 비교 분석하였다. 본 연구에서 개발된 와전류 탐상기는 비전문가도 모니터에 나타난 탐상기 결과로부터 부품의 결함여부를 쉽게 판단할 수 있도록 시스템 소프트웨어를 개발하였다.

• 소성∙가공
• /
• 제28권5호
• /
• pp.266-274
• /
• 2019

Metal sealing is used to connecting the parts between valves and fuel pipes for a FCEV which utilizes hydrogen gas of 700 bar. Instead of general carbon steel, stainless steel is the primary material used to manufacture fuel pipes due to hydrogen embrittlement. The shape of deformation between metals is an important factor on the air-tightness of the metal to metal contact. Since the stainless steel pipe is hardened using the plastic forming during the tip shaping stage, this work hardening could have an effect on the deformed shape and characteristics of contact surfaces in fastening of pipes. In this paper, the deformation history of the pipe model was considered in order to analyze the hydrogen-tightness on the metal sealing part. The contact distance and the forward displacement for fastening were compared using experimental results and the simulation results. The simulation of the effect of material change on the fitting body demonstrated that the hardness or the strength of the formed tip of the pipe was designed to a proper valued level since the characteristics of the contact surface was exhibited better when the strength of the pipe was lower than that of the fitting body.

• 한국기계가공학회지
• /
• 제19권11호
• /
• pp.102-108
• /
• 2020

The demand for lightweight materials and high-strength steel has rapidly increased to help reduce the weight of a vehicle body; it improves the fuel efficiency of automobiles and provides passenger safety. Additionally, as the material becomes thinner, the demand for its resistance against corrosion becomes higher. Hence, the application of the surface-treated steel sheet has surged rapidly. In this study, a weld bonding experiment using a delta spot welding machine is performed on a thin sheet of a different material (Al6061-T6/GA440). The thickness of the material was kept at 1 mm to reduce the weight of the automobile body parts. Additionally, the purpose of this study is to control the heat input by applying the welding conditions of a multi-stage pressure pattern to improve corrosion resistance shear strength. The analysis of nugget diameter measurement, shear tensile test, and salt spray test was performed to achieve the aim.

• 한국기계가공학회지
• /
• 제19권12호
• /
• pp.56-61
• /
• 2020

Fuel economy has always been a major issue in the automobile industry, especially owing to the associated environmental concerns. It is widely known that only 5-20% of the energy generated by automobiles running on internal combustion engine engines is used as power, while the rest is consumed because of friction between components. The main components of the reciprocating piston type compressor used in vehicles, such as the shaft, swash plate, piston, and cylinder, cause severe energy loss owing to frictional contact between each other. The wear contact between the main shaft and the other components is particularly severe. Most quality issues arise owing to the sticking phenomenon that occurs between these parts. In this study, a coating solution to reduce friction is prepared by mixing adhesive solid lubricant, organic binder-polyadimide, inorganic binder (Binder), and graphite in four different ratios, and the best combination is determined.

• 대한금속재료학회지
• /
• 제46권11호
• /
• pp.713-724
• /
• 2008

The need to lower the weights of automotive vehicle and to improve the safety of cars has resulted in the development of high strength steels such as TRIP(Transformation Induced Plasticity) and DP (Dual Phase) steel. It is well known that the higher strength of steel shows the poorer press formability. Among the high strength steels, DP steel shows several good characteristics such as low yield ratio, high initial n value, high elongation, high bake hardenability and anti-aging property. However, there's a certain limit in application of DP steels to the automotive panel parts because their poor deep drawbility caused by martensite. In this study, the effect of alloying elements on the deep drawability and recrystallization texture in TS 440MPa grade DP steel with 0.015~0.02% carbon has been investigated on the base of SEM, TEM, XRD and EBSD analysis.

• Tribology and Lubricants
• /
• 제37권3호
• /
• pp.112-116
• /
• 2021

Appropriate friction model usage is important for impact analysis because the relative motions between parts that are in contact for very short durations can vary greatly depending on the friction model. Vehicle seat components that have significant effects on impact analysis are also considered. This paper presents an experimental investigation of various material contact pairs to obtain the friction parameters of the Benson exponential friction model for impact simulation. The Coulomb friction model has limitations for impact analysis because of singularity at zero velocity. Metal/nonmetal materials are prepared, and friction tests are conducted for various sliding speeds, loads, and lubrication conditions. The obtained data are used in the friction model to implement finite element analysis. The parameters of the friction model are obtained by the curve-fitting method. The experimental results show that the friction coefficient with metal/nonmetal contact pairs is stable regardless of the working conditions. The friction model used in this study can also be applied for finite element analysis of the crash conditions, where the friction changes abruptly at the contact interface; the obtained friction parameters are also expected to be more accurate with more precise tests under different working conditions. These results can help improve the accuracy of the finite element analysis.

• 한국기계가공학회지
• /
• 제20권5호
• /
• pp.128-134
• /
• 2021

A press-fitted shaft is an essential part used in industrial machines, and it is generally used to transmit large quantities of power. Very high contact pressure occurs at the end parts of the contact between the shaft and boss, which are press-fitted shaft components. Such contact pressure not only damages the contact surface of a press-fitted shaft but also reduces its fatigue strength. To improve a press-fitted shaft's fatigue strength, the contact pressure on the contact surface, which directly affects the fatigue strength, should be minimized. Thus, in this study, the design configuration optimization of the end part of the boss was based on the approximate optimization method and was aimed at minimizing the contact pressure at the end of a press-fitted shaft. Comparison of the contact pressure and the contact stress of a conventional press-fitted shaft with those of the optimized press-fitted shaft showed that the boss design of the optimized press-fitted shaft effectively improved the fatigue life.

• 센서학회지
• /
• 제32권3호
• /
• pp.159-163
• /
• 2023

Salt cores have attracted considerable attention for their application to the casting process of electric vehicle parts as a solution to ecological issues. However, the salt core still has low mechanical strength for use in high-pressure die casting. In this study, we investigated the improvements in the bending strength of KCl-based salt cores resulting from the use of reinforcing materials. KCl and Na₂CO₃ powders were used as matrix materials, and glass fiber and carbon fiber were used as reinforcing materials. The effects of carbon fiber and glass fiber contents on the bending strength properties were investigated. Here, we obtained a new fiber-reinforced salt core composition with improved bending strength for high-pressure die casting by adding a relatively small amount of glass fiber (0.3 wt%). The reinforced salt core indicates the improved properties, including a bending strength of 49.3 Mpa, linear shrinkage of 1.5%, water solubility rate of 16.25 g/min·m² in distilled water, and hygroscopic rate of 0.058%.

• International journal of advanced smart convergence
• /
• 제12권2호
• /
• pp.47-55
• /
• 2023

The automotive industry is undergoing a paradigm shift due to the convergence of IT and rapid digital transformation. Various components, including embedded structures and systems with complex architectures that incorporate IC semiconductors, are being integrated and modularized. As a result, there has been a significant increase in vehicle defects, raising expectations for the quality of automotive parts. As more and more data is being accumulated, there is an active effort to go beyond traditional reliability analysis methods and apply machine learning models based on the accumulated big data. However, there are still not many cases where machine learning is used in product development to identify factors of defects in performance and durability of products and incorporate feedback into the design to improve product quality. In this paper, we applied a prediction algorithm to the defects of automotive door devices equipped with automatic responsive sensors, which are commonly installed in recent electric and hydrogen vehicles. To do so, we selected test items, built a measurement emulation system for data acquisition, and conducted comparative evaluations by applying different machine learning algorithms to the measured data. The results in terms of R² score were as follows: Ordinary multiple regression 0.96, Ridge regression 0.95, Lasso regression 0.89, Elastic regression 0.91.