Máquina de carregamento excêntrico para ensaio de fadiga em molas helicoidais de compressão com diâmetro do arame até 10 mm

Abstract

The present work is a machine design for fatigue testing in helical compression springs. The mechanical compressive stress, to produce the fluctuant load on the spring, is provided by an eccentric. The machine element having the characteristic eccentricity, difference between the axis of rotation and the geometric center of the part, is the cam. In this case a circular cam with a flat face follower was used. The test consists of varying the eccentricity of the cam to find the infinite life point for spring. Establish the maximum force that can be applied and the corresponding deflection for a fixed rigidity. Or for the case of finite life the forces and deflections to be obtained. For the spring fatigue analysis, the Zimmerli result was used. He found that the fatigue strength limit is independent of size, material or tensile strength for wire springs up to 10 mm. In addition, the effects of the mean stress on the spring were considered, for the establishment of life, and the correction method was used by the modified Goodman diagram.