Principal component analysis of the cross-axis apparent mass nonlinearity during whole-body vibration

During whole-body vibration (WBV), dynamic forces measured at the excitation-subject interface in directions other than excitation axis, i.e. cross-axis response, are analysed using principal component analysis (PCA) and virtual coherence techniques. The study applied these operations to inline with twelve semi-supine human subjects exposed longitudinal horizontal nominally random between 0.25 20 Hz root mean square acceleration levels of 0.125 ms−2 1.0 ms−2. source identification is realised by a reversed path, aiming identify relative contributions correlations response single axis excitation. vertical were found be correlated each from low (e.g. 1–3 Hz) medium frequency range 10–15 Hz). Above this range, where much reduced, two tended independent their contribution overall response. singular vectors coherences able establish degree correlation band identified. A signal processing framework then proposed take into account responses for vibration.