抄録
A large aluminum alloy helicopter component under a modulated multi-axial load was investigated using thermoelastic stress analysis. Due to the considerable size of the component, the frequency of the test could not exceed 0.7 Hz. This low frequency and the high thermal diffusivity of the aluminum alloy did not allow the achievement of adiabatic conditions, thus producing an attenuation of the thermoelastic amplitude signal. While TSA allowed to precisely locate the region of appearance of a crack close to the rear vertical attachment, the fatigue crack in the region of the front vertical attachment appeared in a region not corresponding to that of the maximum thermoelastic signal. This inconsistency was explained by the presence of a considerable static component in the loads applied by two of the hydraulic jacks. A correction procedure was performed on the raw TSA amplitude values, in order to recover the adiabatic temperature distribution.
