Equipment standardisation as a cost-effective means of rationalising maintenance spares has significantly increased the existence of several identical (similar components and configurations) 'as installed' machines in most industrial sites. However, the dynamic behaviours of such identical machines usually differ due to variations in their foundation flexibilities, which is perhaps why separate analysis is often required for each machine during faults diagnosis. In practise, the faults diagnosis process is even further complicated by the fact that analysis is often conducted at individual measurement locations for the different speeds, since a significant number of rotating machines operate at various speeds. Hence, through the experimental simulation of a similar practical scenario of two identically configured 'as installed' rotating machines with different foundation flexibilities, the present study proposes a simplified vibration-based faults diagnosis (FD) technique that may be valuable for faults detection irrespective of foundation flexibilities or operating speeds. On both experimental rigs with different foundation flexibilities, several common rotor-related faults were independently simulated. Data combination method was then used for computing composite higher order spectra (composite bispectrum and composite trispectrum), after which principal component analysis is used for faults separation and diagnosis of the grouped data. Hence, the current paper highlights the usefulness of the proposed FD approach for enhancing the reliability of identical 'as installed' rotating machines, irrespective of the rotating speeds and foundation flexibilities.

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Abstract:In an earlier study, the poly coherent composite higher order spectra (i.e. poly coherent composite bispectrum and trispectrum) frequency domain data fusion technique was proposed to detect different rotor related faults. All earlier vibration-based faults detection (VFD) involving the application of poly coherent composite bispectrum (pCCB) and trispectrum (pCCT) have been solely based on the notion that the measured vibration data from all measurement locations on a rotating machine are always available and intact. In reality, industrial scenarios sometimes deviate from this notion, owing to faults and/or damages associated with vibration sensors or their accessories (e.g. connecting cables). Sensitivity analysis of the method to various scenarios of measured vibration data availability (i.e. complete data from all measurement locations and missing/erroneous data from certain measurement locations) is also examined through experimental and industrial cases, so as to bring out the robustness of the method.http://mc.manuscriptcentral.com/shmij Structural Health Monitoring AbstractIn an earlier study, the poly coherent composite higher order spectra (i.e. poly coherent

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