Wires for spring construction: full scale fatigue experimental tests

The paper deals with the experimental assessment of the fatigue life of wires for spring construction. Fatigue testing of full-scale wires is not a well established procedure. The aim of the paper is to demonstrate that the fatigue properties of full-scale wires for spring construction can be assessed with a level of accuracy comparable with tests performed on standard small-scale specimens. For this purpose, a new bench able to perform high frequency tests for the characterization of the wires in the high and very high cycle fatigue regions is designed, built and employed. The failure mechanism of the tested wires is described by an in-depth analysis of the fractured surfaces. By a comparison with available literature data, the difference with respect to similar tests performed on small-scale specimens is highlighted. Performing the tests on the full-scale wires allows the assessment of the effectiveness of the manufacturing process. The effect of the actual surface finishing on the fatigue life of wires can be assessed.