Evaluation methods in real-time of the Strain Gauges fatigue life used in structural tests

Measurements taken during a test must be reliable as well as durable or be present for the duration of the test. Where this is not possible, it is advisable to adopt methods that allow to anticipate in real time the fatigue failure of the instrumentation that represents, in the context of structural tests in the aeronautical field, the first cause of loss of measurement channels, in particular as regards measurements with strain gauges electric resistance. For this puprose the first step of my thesis was to study the feasability about the implementation of Goodmann\Gerber fatigue calculation in Catman® Enterprise\AP to estimate the life expectancy (in cycles) of strain gauges attached to test articles using a Stress-Life approach. After that we proceeded with the Implementation of a preliminary model of the calculation of fatigue life into the software. In order to validate the model, a comparison has been made with experimental tests performed in HBM and Politecnico's laboratories at different strain level. In this way it is possible to monitor "zero-drift" of the deformation. When zero-drift exceed a precise level, test must be interrupted.