Summary

Reed type valves of compressors are subject to structural failure due to bending and impact fatigues. The failure by bending is a well-known and manageable problem, although the same cannot be said about the impact fatigue. Currently, the criteria which determines if a valve will fail or not, in the presence of repetitive impacts, is either the impact velocity, defined by material suppliers, or derived from the experience of compressor manufactures. This dissertation addresses a basic study about impact stresses, with the aim of identifying the most influential parameters of the phenomenon and their relation with valve failure. Through a numerical model, a sensitivity analysis was carried out to evaluate the influences of geometry and the initial velocity condition. From a dimensional analysis of the problem, dimensionless numbers are obtained and a correlation is proposed for estimates the maximum impact stresses in different conditions.

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