Principal component analysis and virtual coherence of the cross-axis apparent mass in whole-body vibration

Dynamic forces have been measured at the excitation-subject interface in directions other than the axis of excitation. Quantification of the relative importance of these forces can be achieved by principal component analysis and virtual coherence which has not been previously performed. The present study applied these operations to the inline and cross-axis forces measured with a semi-supine body exposed to longitudinal random (0.25-20 Hz) whole-body vibration at a magnitude of 1.0 ms-2 r.m.s. The source identification problem in such a context would be realised by a reversed path where the aim is to identify relative contributions and correlations between the forces in response to a single axis excitation.