Engine components subjected to cyclic thermal and mechanical loads may experience low-cycle or high-cycle fatigue failures. In particular, both of these failures can easily occur in aluminum cylinder heads, which are exposed to high temperatures and combustion pressures. Predicting the fatigue characteristics of the cylinder head are very important in the design stage of engine development. In this study, a finite element analysis was performed to predict the low-cycle thermal fatigue around exhaust ports of the cylinder head. Temperature distributions are obtained through the heat transfer analysis considering thermal cyclic test. The analysis result involves large plastic deformations, indicating compressive stresses at high temperatures and subsequently turn into tensile stresses at cold conditions. And the results showed that the critical regions such as exhaust port with large plastic strains coincided well with crack locations from thermal cyclic test. Next, design changes were made to the critical areas of the exhaust ports, and the results showed that the durability was improved by about 60% over the initial model and there were no problems in the thermal fatigue test.

ABSTRACT
1. 서 론
2. 유한요소 모델
    2.1 실린더 헤드 파손현상
    2.2 유한요소 모델
    2.3 하중조건 및 온도분포
3. 해석 결과
    3.1 파손모델 해석결과
    3.2 개선모델 해석결과
4. 결 론
References

• 최복록(Gangneung-Wonju National University Department of Automotive Engineering) | Bok-Lok Choi Corresponding Author