A mathematical model for failure prediction and reliability assessment of coating–substrate system is developed based on a multidisciplinary approach. Two models for diffusion and bending of bi-layer cantilever beam have been designed separately based on the concepts of material science and solid mechanics respectively. Then, these two models are integrated to design an equation for debonding driving force under mesomechanics concepts. Mesomechanics seeks to apply the concepts of solid mechanics to microstructural constituent of materials such as coatings. This research takes the concepts of mesomechanics to the next level in order to predict the performance and assess the reliability of coatings based on the measure of debonding driving force. The effects of two parameters i.e. interface roughness and coating thickness on debonding driving force have been analysed using finite difference method. Critical/threshold value of debonding driving force is calculated which defines the point of failure of coating–substrate system and can be used for failure prediction and reliability assessment by defining three conditions of performance i.e. safe, critical and fail. Results reveal that debonding driving force decreases with an increase in interface roughness and coating thickness. However, this is subject to condition that the material properties of coating such as diffusivity should not increase and Young’s modulus should not decrease with an increase in the interface roughness and coating thickness. The model is based on the observations recorded from experimentation. These experiments are performed to understand the behaviour of debonding driving force with the variation in interface roughness and coating thickness.

Electric power reliability is one of the most important factors in the social and economic evolution of a smart city, whereas the key factors to make a city smart are smart energy sources and intelligent electricity networks. The development of cost-effective microgrids with the added functionality of energy storage and backup generation plans has resulted from the combined impact of high energy demands from consumers and environmental concerns, which push for minimizing the energy imbalance, reducing energy losses and CO₂ emissions, and improving the overall security and reliability of a power system. It is now possible to tackle the problem of growing consumer load by utilizing the recent developments in modern types of renewable energy resources (RES) and current technology. These energy alternatives do not emit greenhouse gases (GHG) like fossil fuels do, and so help to mitigate climate change. They also have in socioeconomic advantages due to long-term sustainability. Variability and intermittency are the main drawbacks of renewable energy resources (RES), which affect the consistency of electric supply. Thus, utilizing multiple optimization approaches, the energy management system determines the optimum solution for renewable energy resources (RES) and transfers it to the microgrid. Microgrids maintain the continuity of power delivery, according to the energy management system settings. In a microgrid, an energy management system (EMS) is used to decrease the system’s expenses and adverse consequences. As a result, a variety of strategies and approaches are employed in the development of an efficient energy management system. This article is intended to provide a comprehensive overview of a range of technologies and techniques, and their solutions, for managing the drawbacks of renewable energy supplies, such as variability and load fluctuations, while still matching energy demands for their integration in the microgrids of smart cities.

A novel mathematical model has been developed to understand the mechanism of blister initiation and propagation. The model employs a two-part theoretical approach encompassing the debondment of a coating film from the substrate, coupled with the design components incorporating diffusion and fracture mechanics, where the latter is derived from equi-biaxial tensile loading. Integrating the two components, a comprehensive mathematical design for the propagation of blister boundaries based on specific toughness functions and mode adjustment parameters has been developed. This approach provided a reliable and efficient prediction method for blister growth rate and mechanisms. The model provided a foundation for holistic design based on diffusion and mechanic components to enable better understanding of the debondment of thin elastic films bonded to a metallic substrate.

A mathematical model for metal-coating delamination of degrading metal was developed incorporating multiple variable environmental and physical parameters. Metal-coating delamination not only depends on the electrochemical reactions at metal-coating interface but also on the factors like the type of propagating metal ions and their varying concentration with annual weather changes (summer and winter), time of exposure of the coated objects, type of coated objects, i.e. stationary or mobile vehicles and frequency with which certain vehicles are operating in various environments, e.g. controlled or uncontrolled in terms of environmental conditions. A cutting edge model has been developed to calculate the varying environmental conditions using iteration algorithm, time dependent uncertain position of objects like vehicle in various environments (controlled and uncontrolled) using stochastic approach, effect of seasonal changes (summer and winter) on ionic compounds concentration using algebraic method and instantaneous failure probability due to varying conditions. Based on the developed model, a detailed simulation study was conducted to investigate the metal-coating delamination process and the ways to regress the under coating metal corrosion.

The quality of coating and the resulting rate of corrosion of the underlying metal substrate can be measured by a variety of corrosion measurements (Tafel, Electrochemical Impedance Spectroscopy) by using standard laboratory electrochemical cells. However there is always a need of low cost, portable and non-destructive electrochemical cells which can be used on-site field for condition monitoring of large structures for example bridges and large infrastructures, complex operating systems as aircrafts, precision machines, petrochemical processes, automotive and locomotives. This research has developed state of the art cells and has commissioned for deploying this novel sensing technology for micro-defects detection, corrosion rate measurement and condition assessment of the defected coatings. Tafel measurement facilitated by these non-destructive cells is used to detect micro-defects and corrosion rate measurement while Electrochemical Impedance Spectroscopy measurement is facilitated to measure the coating condition. This technology has been successfully tested and commissioned on automotive, hazardous compartments with polymeric coatings and bridges to assess their coating condition in terms of their structural integrity. Post design testing involved the installation of these cells, running diagnostics, data acquisition and macrographs to predict structural defects and the resulting corrosion rate. This technology enables the design process to incorporate operational conditions and fully realize more durable and reliable solutions to be applied to high value large structures and complex interacting systems. Current developments in corrosion condition monitoring especially cost effective, non-destructive techniques to assess structural integrity beneath nonconductive and polymeric coating were long awaited. This reported development will revolutionise durability and reliability assessment techniques to enhance safety and mitigate catastrophic failures for cost savings and avoiding fatal accidents.

The effect of residual and diffusion-induced stresses on corrosion at the interface of coating and substrate has been analyzed within a multidisciplinary approach, i.e., material science, solid mechanics, and electrochemistry. A self-consistent equation for corrosion current density, involving the combined effect of residual stress and diffusion-induced stress is developed. The influences of temperature, moduli ratio, thickness ratio, thermal mismatch ratio, and residual stress gradient of coating and substrate on the corrosion current density are then discussed. Results indicate that when the thermal expansion of coating is greater than substrate, the decrease in temperature from fabrication temperature accounts for the same direction of both the residual and the diffusion stresses. This behavior increases the deflection of the coating-substrate system and results in the evolution of tensile residual stress in the coating. The tensile stress opens the pre-existing coating microcrack, allowing the diffusion of corrosive agents and therefore, accelerating the corrosion damage to the coating/substrate interface. The model is based on experimental observations conducted to understand the behavior of corrosion at the coating/substrate interface in the presence of tensile or compressive residual stresses. At the end, the model was validated against the experimental results showing a good quantitative agreement between the predicted theoretical and experimental trends.