Manmohan Dass Goel

With the rise in intentional and accidental explosions worldwide, several research efforts are focused on the behavior of reinforced concrete (RC) members subjected to contact explosion. The event of a contact explosion is different from a far-field explosion because it causes local damage (cratering, spalling, breaching) to the member, thus affecting its residual capacity. The present study comprehensively reviews the existing experimental, numerical, and analytical methods to quantify the blast load and behavior of RC members subjected to a contact explosion. The widely used ConWep model is unsuitable for contact explosions because it neglects the occurrence of wave superposition, reflection, member properties, etc. On studying the experiments, it has been observed that the presence of reinforcement, fibers, and meshes, along with the use of high-strength concrete and ultrahigh-performance concrete, exhibits a positive influence on the blast resistance of slabs under a contact explosion. Further, the behavior of beams (length of damage zone) is influenced by the presence of stirrups, strain development, and loading condition. The location of explosives, presence of transverse reinforcement, axial load, and aspect ratio are factors that influence the behavior of RC columns. On studying the guidelines stated in codes and standards, it was observed that the event of a contact explosion, to our best knowledge, has not yet been investigated thoroughly. This study also highlights the pressing need to develop numerical and analytical studies to predict the behavior of RC beams and columns subjected to a contact detonation.

This study presents an experimental and numerical investigation of the crashworthiness behavior of the closed-cell aluminum foam-filled hexagonal honeycomb structures under quasi-static compression. Honeycomb cores made from AA3003-H18 aluminum alloy with cell sizes of 12 mm and 19 mm were filled with closed-cell aluminum foam of 200 kg/m ³ density, to evaluate the effect of cell geometry and cell wall thickness (0.05–0.2 mm) on key crashworthiness parameters i.e. peak crushing force ( F _peak ), mean crushing force ( F _mean ), total energy absorption ( EA ), specific energy absorption ( SEA ), and energy distribution in linear, plateau and densification region. Quasi-static compression tests were conducted using a Universal Testing Machine (UTM), while numerical simulations were carried out using the explicit finite element code LS-DYNA ^® . Numerical results show good agreement with the experimental results, with crashworthiness parameter precision of above 90%, thus validating the numerical simulation approach. Compared to empty honeycomb structures, the foam-filled configurations indicate enhanced performance. In all configurations, the plateau region consistently represented the primary phase of energy absorption, comprising more than 50% of the total energy. At thinner walls, 19 mm cells benefited from greater foam volume and foam-wall interaction, while at higher thicknesses, 12 mm cells achieved superior performance through stable plastic folding. These results provide insights into the foam-filled honeycomb composites as efficient crashworthy structures for automotive, aerospace, and protective applications.

This study evaluates the performance of a ballistic helmet made from carbon nanotube reinforced Ultra-High Molecular Weight Polyethylene composites, based on experiments conducted at the Blast Impact Simulation and Testing Laboratory, Visvesvaraya National Institute of Technology (VNIT), Nagpur, India. Authors have carried out simulations using LS-Dyna ^® to understand and predict the behavior of carbon nanotube reinforced ultra-high molecular weight polyethylene composite under ballistic impact conditions. The authors have validated the Finite Element model against experimental tests using a high-pressure gas gun at VNIT, Nagpur, India, with a single impact from an ogive-shaped hardened steel projectile at an impact velocity of 573 m/s. Results showed that carbon nanotube reinforcement enhanced the composite's mechanical properties, improving its ability to absorb energy and ballistic penetration resistance. The study highlights the potential of the said composites for ballistic protection, offering a balance of lightweight material and high-impact resistance. Further, it emphasizes the importance of combining simulations with experimental tests to predict material performance and suggests further optimization for enhanced protection. This research contributes to developing advanced military, law enforcement, and civilian protective gear materials.

Glass façades have become a prominent feature in modern architecture, offering aesthetic appeal and abundant natural light. However, in regions exposed to severe weather conditions, particularly during storms, glass façades are vulnerable to damage from wind-borne debris. The impact of such debris can compromise the structural integrity of the façade, leading to potential safety hazards. Despite the significant threat posed by wind-borne debris to the safety and performance of glass façades, the behavior of these materials under impact is not extensively studied. This study presents a comprehensive numerical analysis of the impact behavior of laminated glass panels subjected to debris typically propelled by strong wind forces, using LS-DYNA ^® . The simulation models the interaction between wind-borne debris and glass panels of varying debris masses. Mechanical behavior of the glass is incorporated using fracture mechanics to simulate cracking and failure under impact. A range of impact scenarios is considered, including variations in debris mass, impact velocity, and impact locations, to replicate real-world conditions as accurately as possible. The numerical model integrates material properties, layer configurations, and impact conditions to closely reflect actual scenarios. In this study, wooden blocks of different masses are impacted on the laminated glass panels at varying locations and impact velocities. The results reveal the critical factors influencing the glass façade's response, such as the velocity of the incoming debris and the material strength of the glass. This study offers valuable insights for improving the safety and durability of glass façades. Thus, by understanding the complex dynamics of glass response to wind-borne debris, the study contributes to the development of more resilient architectural and structural systems, leading to better risk management strategies for buildings in areas prone to extreme weather events.

With rising explosive events and advanced warheads, protective structures are gaining global attention. The main component of these protective structures is the energy-absorbing core material, for which cylindrical tube-like structures provide interesting, effective, and useful properties, but understanding their plastic deformation under blast loads remains a challenge due to nonlinear behavior and high strain rates. This study analyzes innovatively designed composite steel tubes under blast loading using LS-DYNA®. The designs feature thin-walled metallic tubes and couplers in five configurations with varying diameters and orientations, crushed axially between metal plates. Energy absorption and load transfer efficiency are examined based on radius reduction and partitioning. While all designs show similar energy absorption efficiency, load transfer decreases with more partitions, making them suitable as sacrificial energy-absorbing cores. The findings enhance understanding of the physical process, enabling efficient, task-specific designs for sacrificial systems and sandwich panels.

This study explores the ballistic performance of an alumina/carbon fibre/Kevlar^Ⓡ aramid composite panel against impacts from various projectile shapes, including ogive, conical, cylindrical, hemispherical, and 5.56 mm × 45 mm NATO rounds. The aim is to analyse the influence of projectile nose shape on penetration resistance and energy absorption, critical for defence and aerospace applications. Numerical simulations carried out in LS-DYNA^Ⓡ, validated by experimental data, reveal that the ceramic layer effectively initiates projectile deceleration, while the fabric layers absorb the majority of the kinetic energy. Hemispherical projectiles exhibit minimal plastic deformation, highlighting the composite's optimal performance against this shape. In contrast, ogive projectiles demonstrate greater penetrative potential, challenging the composite's multi-layered defence. The study finds that approximately 90% of the kinetic energy is absorbed by the fabric backing, with a small portion absorbed through projectile deformation and ceramic cracking. These results underscore the importance of considering projectile deformation in simulations and suggest that the composite design is well-suited for enhancing protection against high-velocity impacts in defence and aerospace sectors.