Prince Jeya Lal Lazar

As coastal regions become increasingly susceptible to extreme wind loads and debris impact, the demand for robust, self-monitoring building envelopes has become critical. It creates an urgent imperative for advanced, resilient construction solutions. The current study presents smart composite structural insulated panels (CSIPs) embedded with piezoelectric sensors for damage localization in high-risk areas. The CSIPs comprise Aluminum face sheets positioned on both the top and bottom surfaces, sandwiching an Expanded Polystyrene (EPS) core to provide superior insulation and structural integrity. Rigorous experimental tests, including four-point flexural tests per ASTM C393 and shock load simulations, assessed mechanical properties and failure modes. A shock and impact testing simulator generated planar shock waves, with pressure profiles measured using dynamic transducers. Piezoelectric sensors embedded in the EPS core, via granular rod sensors (steel hemispheres and nylon shaft), captured Lamb waves transforming into solitary waves. Time differences of arrival (TDOA) from three non-collinear sensors enabled triangulation-based localization, validated experimentally. Real-time shock identification and impact localization are demonstrated experimentally, with predicted damage locations achieving a maximum error below 5%, indicating the suitability of these panels as a foundational technology for self-resilient coastal infrastructure. The proposed approach delivers real-time information on structural integrity, supporting improved safety and predictive maintenance for buildings and infrastructure employing CSIP systems.

In this research, we examine the dynamic deformation and blast-tolerance of all-metal plates and sandwich panels under underwater explosive (UNDEX) loading. The blast performance of four alloys, Mild Steel (MS), SS304, AL6XN, and AISI 4340, was based on the Johnson–Cook (JC) plasticity model as the shock factors increased from 0.42 to 0.73. The Fluid-Structure Interaction (FSI) model and nonlinear finite-element simulations were employed in the present computational analysis to yield measurable results for the deformation and equivalent plastic strain (PEEQ) of the target plates and the plastic dissipation energy of the sandwich panels. AISI 4340 consistently showed the most stability after each blast series, indicating that the material undergoes the least deformation and exhibits the lowest PEEQ due to its extremely high yield strength and resistance to plastic deformation. AL6XN exhibited appreciable performance under moderate shock and stress levels due to its pronounced strain-hardening behaviour; however, higher load levels reduced performance due to thermal softening. The SS304 exhibited reasonable deformation in addition to exhibiting a generous energy absorption capacity. Mild Steel deformed the most and had the highest PEEQ, while also having the most plastic energy dissipation. The sandwich panels subjected to underwater shock conditions demonstrate that at lower blast intensities, most of the blast energy is absorbed by the front face sheet. However, at higher blast intensities, the core’s contribution to energy absorption increases, thereby aiding energy distribution and enhancing overall stability. The blast-mitigation properties of AISI 4340 were outstanding, whereas SS304 and AL6XN improved the suitability of moderate designs for blast-tolerant applications. These analyses will help select the steels that optimize performance in marine, defense, and subsea applications for blast-resistant protective structures.

EN31 steel is a high-carbon alloy steel used for several industrial applications like drilling & power tools. The novelty of this study lies in the optimization of liquid nitriding duration for the EN31 steel, which enhances the surface properties and a prolonged service life in tribological applications. In order to overcome the limitations, this study has aimed to investigate the impact of liquid nitriding at 570°C for 30, 60, and 90 minutes to study the hardness, corrosion and wear properties of EN31 steel. As a thermochemical surface treatment for EN31 steel, the study explores the application of liquid nitriding. Compared to traditional methods like gas nitriding, carburizing, hard chrome plating and hardening, the liquid nitriding provides uniform compound layer formation, enhanced surface hardness, and faster processing with less distortion. Performance of the modified EN31 steel post nitriding process was evaluated through various tests, like the pin-on-disk method to assess wear resistance and neutral salt spray testing as per ASTM B117 to measure corrosion resistance. Noticeable improvements in the steels tribological and anti-corrosive properties after nitriding were demonstrated through the test results. Upon analysing the microstructure, a uniform, defect-free nitride layer was revealed. The study evaluated that the 90-minute nitriding cycle resulted in the best performance related to corrosion resistance, wear resistance and surface hardness. A maximum hardness of 31.7 HRC would be achieved during the 90 minute cycle. Interestingly, this cycle also produced the deepest effective case depth thereby enhancing durability of steel under intense load bearing conditions. In addition, the outstanding corrosion resistance of steel was confirmed during 24-hour salt spray testing as no red rust was detected on the nitride samples. The test findings are validated the liquid nitriding as an economical surface treatment process for improving performance as well as durability and also reducing maintenance needs of EN31 steel for applications like drilling tools and for enhancing its reliability in abrasive and corrosive environments.