EXPERIMENTAL VALIDATION OF PHASE SYNCHRONISATION EFFECTS IN OPTIMISING IMPACT-SYNCHRONOUS TIME AVERAGING

A novel modal analysis technique called Impact-Synchronous Modal Analysis (ISMA) was introduced in previous research. With the utilisation of Impact-Synchronous Time Averaging (ISTA), modal testing can be performed in presence of ambient forces whereas the conventional method requires machines to be shut down. However, lack of information of phase angles with respect to impact in ISTA has caused this modal testing method to be labour-intensive and time-consuming. The effect of the phase angle of the disturbance with respect to the impact is found to be very important when performing modal testing on structures with dominant periodic responses from cyclic loads. Synchronisation of phases between impacts and periodic response from cyclic loads should be avoided to enhance the effectiveness of ISTA. The assessment showed that a few averages are sufficient to eliminate the non-synchronous components when the phase angles with respect to the impact are inconsistent for every impact applied.