Presented is a structural health condition diagnosis based on optimal space-time decompositions of ensembles of acceleration signals developed in the complex physical domain of marine ball bearings when interrogated by a set of diagnostic impulsive forces. Ensembles of diagnostic forces and ensembles of collocated responses acceleration signals are decomposed into proper orthogonal modes. Typical inner and ensembles of nondestructive impact diagnostic forces covering three times the inner and outer races are strongly dominated by a single POD mode with uniform spatial distribution and a sharp pulse time modulation. There exist high order modes with very small amount of energy. This indicates that the impact response of the suspended ball bearing depends slightly on the impact location. Diametrically opposite, the typical ensemble of radial acceleration signals collected at a point on the outer race has a very broad POD energy spectrum. All POD modes have energy fractions of the same order and irregular (no periodic) space modulations. Despite this spatial irregularity, all POD spatial modulations have astonishingly common statistical properties: nearly zero mean values, and nearly identical standard deviations at the value level of the uniform spatial distribution of the dominant POD mode of the ensembles of diagnostic forces. The result is that the healthy ball bearing spreads nearly evenly the energy of collocated acceleration signals to a large number of POD modes. The analysis aims at gaining a basic understanding of the behavior of collocated acceleration signals developed in the complex domains of multi-body flexible structures with applications in structural health monitoring of marine-aeronautical machinery critical elements such as propellers, bearings, brakes, clutches and gearboxes.

This content is only available via PDF.
You do not currently have access to this content.