Analysis of Passive Vibration Measurement and Data Interrogation Issues in Health Monitoring of a HMMWV Using a Dynamic Simulation Model

Integrated health monitoring technologies are being developed for military ground vehicles to enable condition based maintenance in the short term and prognostic health management in the long term. Technical issues related to health monitoring of a military HMMWV are examined using a dynamic simulation model. Both free and forced vibration response analyses are conducted to examine the effects of damage and operational conditions on the vehicle response. The higher frequency modal properties are found to be sensitive to frame and cross member damage whereas the lower frequency sprung modal properties are not. Changes due to adding up armor are found to be much larger than those due to damage. In addition, cross member damage affects the higher frequency modes whereas damage to the left or right frames causes changes to the modal behavior across the entire frequency range making this type of damage most detectable. Composite amplitudes at all transverse degrees of freedom are calculated using the modal deflection shapes to show that certain sensor locations, for example, on the rear cross members, are most sensitive to all vehicle motions. The sensitivities of the vehicle frequency responses to damage mechanisms are determined and observations are consistent with the free response analysis; however, the anti-resonant regions of the frequency response are also shown to be highly sensitive to localized changes in the model due to damage. The frequency response studies also show that suspension response is not observable from the chassis due to the filtering action of the suspension.