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The reliability of engine valve springs is a very important issue from the point of view of warranty. This paper presents a combined experimental and statistical analysis for predicting the fatigue limit of high tensile engine valve spring material in the presence of non-metallic inclusions. Experimentally, Fatigue tests will be performed on valve springs of high strength material at different stress amplitudes. A model developed by Murakami and Endo, which is based on the fracture mechanics approach, Extreme value statistics (GUMBEL Distribution) and Weibull Distribution will be utilized for predicting the fatigue limit and the maximum inclusion size from field failures. The two approaches, experimental and theoretical, will assist in developing the S-N curve for high tensile valve spring material in the presence of non-metallic inclusions.

The airflow through a standard automotive throttle body is not exactly proportional to the displacement of the accelerator pedal. Therefore, another method is needed to open the butterfly valve in order to ensure that airflow through the throttle body is metered equal to pedal displacement. This paper finds that the implementation of a cam-type pulley is necessary to achieve this prescribed goal.