Tribological Study of a Mechanical Component Built on a Benzine Engine Utilizing the Finisched Elements Method (F.E.M.) And Coffin-Manson's Law

摘要

In this paper, a model embeded-embeded beam with thermal gradient has been analyzed. In particular, a part of unloaded system car, denominated hot end, has been studied. This mechanical component is subject to hot gas flow (over 800°C) in some conditions and to lower hot gas flow (about 400°C) in others. So, there is a high thermal range, above all between extreme parts of component that results fixed in superior and inferior zone. Thermal gradient induces the growth of stresses and deformations in component, in particular near fixings. Repetitions of thermal cycles can determine a breaking due to thermal fatigue. According to Normative Fiat 7-A3760, hot end must resist at least to 1000 thermal cycles to can be validate in production. Knowing deformations in critical zones, it has been applied Coffin-Manson's law, obtaining breaking thermal cycles, that is thermal fatigue life. Three hypotheses have been considered: two are extreme cases, one is realistic case. All cases respect normative: hot end resists over 1000 thermal cycles.