Stress and strain measurements by image correlation and Thermoelasticity
In this paper image correlation and thermoelaticity are proposed as joint measurement techniques to perform a “full field” characterization of materials and mechanical components. The very interesting possibilities offered by using both these non contact measurements techniques is the ability to obtain, by measuring both stress and strain, distributions of mechanical parameters on the surface of a dynamically loaded mechanical component, made, in general, of any material. This kind of results can be very useful for non homogeneous, composite or complex materials, or for complex shapes or loading conditions of the mechanical component under analysis, nowadays largely used for machine and structure realizations. In the work a proper coating, useful to perform measurements by both the techniques, is developed and tested. The coating act as a stressstrain distributed gauges.
Simultaneous application of scanning laser vibrometry and thermoelasticity for measurement of stress-strain fields on mechanical components
The application of both scanning laser vibrometry and thermoelasticity for measurement of stress and strain fields on mechanical components is proposed. A theoretical approach on both the measurement principles is illustrated and an application to a practical case, as an automotive fan blade, is described. The problem of the fan blade failure is tightly due to the force amplitude and frequency, that are applied in working condition; it is, therefore, important, to know the blade resonance frequencies and the mode shapes. For this reason, the measurement techniques, based on scanning laser Doppler vibrometer, give the chance to quickly perform an experimental modal analysis with high accuracy and spatial resolution and to obtain the structure's mode shapes. In the same time, it is important to assess the stress distribution level on the blade associated to every mode shape. Measurement techniques, that apply thermoelastic principle, allow to quickly determine the blade stress pattern at each load frequency. It is, therefore, possible to establish the stress pattern corresponding to the mode shape and predict the fatigue life of the component.
Stress Separation From SPATE Data For A Rotationally Symmetrical Pressure Vessel
The determination of separate values of surface stresses from the SPATE stress sum data for the case of a small rotationally symmetrical pressure vessel end is described and discussed.