IIT Madras researchers develop framework to protect critical infrastructure against Ballistic Missiles

According to an official release, this framework will help designers develop innovative solutions for improving the ballistic resistance of reinforced concrete (RC) panels.

Using computational simulations, the researchers studied the impact of missiles on Reinforced concrete (RC), which is the main material used to construct vital structures ranging from Military Bunkers, nuclear power buildings and bridges to runways.

As per the release, concrete structures face highly localised damage such as penetration, perforation, scabbing, spalling and crushing under projectile impact load. Due to the strategic importance of these structures, it is necessary to protect them against projectile and debris impact, which can result in localised damage or even the collapse of the entire structure.

Ballistics is a field of engineering that deals with the launching, flight behaviour, and impact effects of projectiles such as bullets, bombs, and rockets. This science is used not only for designing bunkers but also for designing the walls of nuclear power buildings, bridges, and other protective structures.

IIT Madras Researchers conducted the study during 'Finite Element' (FE) Simulation, a computational technique used to simulate and analyze physical phenomena in engineering and science. FE simulation relies on the Finite Element Method (FEM), a numerical approach for solving complex problems involving partial differential equations. These problems often arise in fields like structural mechanics, among others.

In this study, Dr. Alagappan Ponnalagu, Assistant Professor, Department of Civil Engineering, IIT Madras and Roouf Un Nabi Dar, Research Scholar, IIT Madras, focused on the development of the novel performance-based design framework based on 'Depth of Penetration' (DOP) and Crater Damage Area in the RC panels. In addition to that, a probabilistic formula for estimating the crater diameter in RC panels is proposed.

Elaborating on this research, Dr Alagappan Ponnalagu said, "Ballistic design is crucial for widely utilised concrete structures in today's unpredictable world. Usually, extensive experimental and numerical studies have been done to investigate concrete panels, resulting in design guidelines for local damage parameters. However, with the advent of performance-based design, the ballistic design of concrete structures lacks a comprehensive design philosophy."

"Moreover, while quantifying damage parameters, incorrect and inconsistent results are obtained by using deterministic empirical formulations. We have now provided a reliable design formula for estimating crater diameter in addition to the development a novel performance-based ballistic design framework for RC panels. This study is helpful not only in terms of providing the ballistic design framework and probabilistic crater quantifications formula but also in understanding the ballistic behaviour of RC panels," he added.

The study is helpful not only in terms of providing the ballistic design framework and probabilistic crater quantification formula but also in understanding the ballistic behaviour of RC panels.

Speaking about the next steps in this research, Dr Alagappan Ponnalagu said, "Our future work is to extend this study to develop much needed lightweight, cost-effective and sustainable blast and ballistic resistant modular panels that can be used in the construction of bunkers along the borders and highly inaccessible areas for the Indian Army."

Further, Roouf Un Nabi Dar said, "We have proposed a novel performance-based design framework for RC panels based on damage states, namely DOP and crater diameter. Each damage state has four damage levels and is effectively coupled. Hence, the framework is a novel design philosophy ensuring resiliency against projectile penetration and crater formation of RC panels."

"On the other hand, the local damage response in terms of crater formation in RC panels was studied under projectile impact. A probabilistic approach is taken to formulate a reliable formula for quantifying unexplored crater damage, based on well-established Bayesian methodology for RC panels that takes into account uncertainty. This caters the need to take care of uncertainties that deterministic models do not. The probabilistic model proposed by IIT Madras Researchers for estimating crater diameter in RC panels under projectile impact was validated with several experimental test results from the literature. The agreement of the predicted crater diameter with the experimental results ensures its reliability and accuracy," he added. (ANI)