Ulterius Corrosion Health Monitoring (UCHM) using wireless sensor technologies.

Abstract

Complex metal structures operating in harsh environmental conditions are prone to various forms of coating failures and corrosion damage. The costly Scheduled-based- Maintenance (SBM) strategies are practiced for metal structures that result in huge financial overhead for industries. The current research work is aim to provide the solutions to anticipate the condition of a metal structure in terms of corrosion damage and coating failure for proactive and optimal Condition-base-Maintenance (CBM) decisions. The experimental investigation has shown that the adhesion loss between coating and substrate system in the form of blisters is driven by complex electrochemical and mechanical parameters. The propagation criteria can be defined through threshold levels of bending moment incorporating residual and diffusion-induced stresses. The current work also investigated the environmental impact on structures which are operating at remote locations. It has been observed that the accumulation of salt particles from atmosphere resulting in corrosion under the coating is primarily controlled by the speed of the wind. An algorithm has been proposed that incorporates the effect of wind speed to estimate the accumulation of salt particles and the amount of salt diffusivity. Experimental and simulation analysis has further shown that the low wind speed and low temperature are considered the most appropriate environmental conditions for structures operating at remote locations. Meanwhile, the high temperature and high wind speed can result in high corrosion damage beneath the coating. The prognostic algorithms resulted in the development of a comprehensive Condition-based- Maintenance framework to determine the cost-effective maintenance strategy among Patch recoat, Part recoat and Complete recoat. The CBM framework suggests that the Part recoating strategy is cost-effective as compared to Patch recoating strategy if the area of the part to be recoated is ‘2x’ times larger than the area of patch and number of path failure per year is more than ‘2’. Meanwhile, the Patch recoating strategy results in low cost if the annual patch failures are less than ‘7’ and area of the part to be recoated is ‘10x’ times larger than the area of the patch. Real time monitoring of the impact of significantly varying operating condition for mobile structures is very challenging for condition assessment. The combination of µ-Linear Polarisation Resistance (LPR) and µ-strain gauge sensors have been investigated to monitor the development of residual stresses and corrosion reaction beneath the coating. The measurements from µ-strain gauge sensor in response to small temperature gradients can provide instant information regarding the development of tensile or compressive stresses within the coating of structures as observed in experiments. The combination of µ-LPR and µ-strain gauge sensors has been found an effective solution for proactive corrosion detection in real time for the structures operating mobile and at remote locations.