Damage diagnostics with limited sensors handling environmental variability

What is it about?

In this article, we present a damage diagnostic scheme with very limited measurements. The influence of environmental and operational variabilities has been considered in the present investigations apart from measurement noise. We employ null subspace analysis in the first stage to confirm the presence of damage using ambient vibration data through online monitoring. Once the presence of damage is established, in the second stage, through offline monitoring, we use the zero strain energy node concept to localize damage through inference from the set of excitation frequencies at which the structure with localized damage behaves like a healthy structure. The proposed technique requires the numerical model of the healthy structure to establish the relationship between zero strain energy nodes and excitation frequencies. In order to evaluate the proposed technique, numerical simulation studies are carried out initially on a simple beam-like structure and later considering a more practical example of the bridge existing across the Amaravathi River in Tamil Nadu, India. These investigations are subsequently complemented with an experimental study on steel I beam girder. It can be concluded from the investigations that the proposed approach is capable of detecting and localizing multiple and also subtle damages under varying environmental conditions with very limited noise-contaminated measurements.

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Why is it important?

In this article, we present a damage diagnostic scheme with very limited measurements. The influence of environmental and operational variabilities has been considered in the present investigations apart from measurement noise. We employ null subspace analysis in the first stage to confirm the presence of damage using ambient vibration data through online monitoring. Once the presence of damage is established, in the second stage, through offline monitoring, we use the zero strain energy node concept to localize damage through inference from the set of excitation frequencies at which the structure with localized damage behaves like a healthy structure. The proposed technique requires the numerical model of the healthy structure to establish the relationship between zero strain energy nodes and excitation frequencies. In order to evaluate the proposed technique, numerical simulation studies are carried out initially on a simple beam-like structure and later considering a more practical example of the bridge existing across the Amaravathi River in Tamil Nadu, India. These investigations are subsequently complemented with an experimental study on steel I beam girder. It can be concluded from the investigations that the proposed approach is capable of detecting and localizing multiple and also subtle damages under varying environmental conditions with very limited noise-contaminated measurements.