Neeraj Kumar Bhoi

Air blast attacks are rapidly increasing in the current scenario, resulting in lots of people severely injured and losing their lives, and infrastructures are critically damaged. Honeycomb sandwich panels have outstanding specific strengths with efficient energy-absorbing ability and are widely employed as protective panels against extreme air blast loadings. Improvement in the air blast mitigation performance of the honeycomb sandwich panels without increasing their mass and volume occupancy is the challenging task for weight-critical applications. Therefore, in the present explicit numerical study, the effect of honeycomb core topologies (square, reentrant, octagonal, and circular) on the blast performance of the high-strength AL-6XN sandwich panels is investigated at constant mass and volume for 1–3 TNT air blast loadings. The unit cell volume occupancy of the different honeycomb cores is also maintained constantly. The rate-dependent Johnson-Cook material model was used for achieving realistic plastic deformations in the designed sandwich panels. To identify an optimal honeycomb core design, the blast performance of the designed honeycomb sandwich panels of the equal mass is compared in terms of their face sheets center point deflections, face sheets radial deflections, changes in kinetic energy, changes in internal energy, plastic dissipation energy (PDE), deformation modes, and equivalent plastic strain (PEEQ) of the core structures. The obtained results indicated that the circular honeycomb core used sandwich panels have better blast resistance than the other designed sandwich panels of the identical mass in terms of smaller back face sheet’s center point deflection and radial deflection and higher energy absorption by the core structure. Hence, the circular honeycomb core is the most suitable candidate for designing protective structures against blast attacks, such as skid plates of armor vehicle.

Recent advancements in manufacturing industries have expanded the applications of composite tools for achieving superior machining performance. In this work, copper-silicon carbide composite tools of different compositions are fabricated using microwave sintering process and employed as tools during electro-discharge machining (EDM) of 304 stainless steel workpiece material. The performance of the composite tools is evaluated based on machining parameters such as material removal rate, tool wear rate, surface roughness of the machined surfaces and surface crack density of the machined surfaces. Surface irregularities are analysed using field emission scanning electron microscopy (FESEM) images of the machined surfaces, while energy dispersive X-ray spectroscopy (EDX) is used to examine changes in the surface composition of the workpiece after machining.

This study explores the potential of Magnetorheological Abrasive Finishing (MRAF) for ultra-precision finishing of SS-316L using a high-performance Nd-Fe-B (N-35 grade) magnetic tool. Key parameters, including the relationship between normal force (Fn) and working gap, magnetic flux distribution, and finishing spot area, were analyzed using ANSYS 2020 R1^® Magnetostatic module simulations. Material removal rate (MRR) and surface roughness (Ra) were optimized through response surface methodology (RSM) using a central composite design (CCD) with two primary input factors: SiC abrasive volume fraction (5%, 10%, 15%) and abrasive mesh size (800, 1000, 1200). Statistical analysis via ANOVA revealed a significant influence of process variables, achieving a remarkable surface finish with a minimum Ra of 52 nm in just 60 min, utilizing an MR fluid with 10% SiC abrasives. Microscopic and spectroscopic evaluations confirmed enhanced surface morphology and microstructural refinement. Moreover, bioactivity studies in simulated body fluid highlighted improved hydroxyapatite layer formation on the finished SS-316L samples, underscoring the process’s potential for biomedical applications.

This work investigated the phenomenon of interfacial debonding due to hygrothermal aging (HA), which was quantified using Field Emission Scanning Electron Microscopy (FESEM) and Atomic Force Microscopy (AFM). Several micrographs of carbon fiber/epoxy cross-ply laminate coupons were analyzed, including unaged (HA/0) samples, as well as those aged for 1000 h (HA/1000) and 2000 h (HA/2000). To quantify the extent of debonding, an image thresholding tool was employed. For HA/0, HA/1000, and HA/2000 coupons, the average interfacial debonding arc length of inner plies was longer than that of the respective outer plies by 14%, 17%, and 21%, respectively. Residual stress variation across inner plies is more pronounced compared to outer plies due to the latter's freedom of expansion. The debonding that occurred without external loading was due to the combined effects of matrix and interface plasticization, chemical reaction, viscoelastic changes, and swelling. The AFM 3-D surface topography revealed that HA/0, HA/1000, and HA/2000 specimens had progressively lower peak-valley distances of 135 nm, 113 nm, and 82 nm, respectively, due to matrix swelling.

The manufacturing of a composite material out of aluminium (Al) and yttrium oxide (Y₂O₃) was achieved via the use of the microwave hybrid sintering method, which is an energy-efficient and eco-friendly production process. Compression and dry reciprocating wear tests are conducted on the manufactured material to learn more about the function of reinforcing particles in composites. The exothermic temperature marginally shifts (1 °C) when Y₂O₃ reinforcement is added to the Al matrix. The average micro hardness of composites with 2 wt.% Y₂O₃ is 43 Hv, which is an improvement over the previous value of 36 Hv. In addition, the composite material’s compressive strength improved by 38.78% in comparison to that of Al. In a dry reciprocating wear test, the composite material with 2 wt% Y₂O₃ nanoparticle showed a reduction in mass loss of 20%. The even distribution of reinforcing components throughout the material and the advent of intermetallic Al₃Y in composites are likely responsible for this.