Search Results (31)

Aero-engine casings with excellent impact resistance are a practical requirement for ensuring the safe operation of aero-engines. In this paper, we report on numerical simulations of broken rotating blades impacting aluminum honeycomb sandwich casings under different temperatures and optimization of structural parameters. Firstly, an impact test system with adjustable temperature was established. Restricted by the temperature range of the strain gauge, ballistic impact tests were carried out at 25 °C, 100 °C, and 200 °C. Secondly, a finite element (FE) model including a pointed bullet and an aluminum honeycomb sandwich plate was built using LS-DYNA. The corresponding simulations of the strain–time curve and damage conditions showed good agreement with the test results. Then, the containment capability of the aluminum honeycomb sandwich aero-engine casing at different temperatures was analyzed based on the kinetic energy loss of the blade, the internal energy increment of the casing, and the containment state of the blade. Finally, with the design objectives of minimizing the casing mass and maximizing the blade kinetic energy loss, the structural parameters of the casing were optimized using the multi-objective genetic algorithm (MOGA). Full article

Polycarbonate laboratory safety glasses and facial shields were tested for impact resistance. Impacts from 22-caliber bullets fired from a firearm were compared with impacts of pellets fired from an air rifle. A low-weight pellet fired from an air rifle is a suitable and safer alternative to the use of a firearm. The results show that if there is a need for protection from flying projectiles, one should use multiple layers of protection. Furthermore, already-damaged protective equipment, even if the damage appears to be minor, may not provide any protection and should not be used. The resulting impacted polycarbonate lenses and sheets were used in a classroom discussion with the undergraduate chemistry students about polymer properties and adequate safety protection. Full article

Deep learning has brought substantial progress to medical imaging, which has resulted in continuous improvements in diagnostic procedures. Through deep learning architecture implementations, radiology professionals achieve automated pathological condition detection, segmentation, and classification with improved accuracy. The research tackles a rarely studied clinical medical imaging issue that involves bullet identification and positioning within X-ray images. The purpose is to construct a sturdy deep learning system that will identify and classify ballistic trauma in images. Our research examined various deep learning models that functioned either as classifiers or as object detectors to develop effective solutions for ballistic trauma detection in X-ray images. Research data was developed by replicating controlled bullet damage in chest X-rays while expanding to a wider range of anatomical areas that include the legs, abdomen, and head. Special deep learning algorithms went through a process of optimization before researchers improved their ability to detect and place objects. Multiple computational systems were used to verify the results, which showcased the effectiveness of the proposed solution. This research provides new perspectives on understanding forensic radiology trauma assessment by developing the first deep learning system that detects and classifies gun-related radiographic injuries automatically. The first system for forensic radiology designed with automated deep learning to classify gunshot wounds in radiographs is introduced by this research. This approach offers new ways to look at trauma which is helpful for work in clinics as well as in law enforcement. Full article

The ballistic performance of fiber-reinforced polymer composites (FRPC) is influenced by the adhesive’s mechanical properties, such as stiffness, toughness, and energy dissipation. However, the specific contributions of these properties remain unclear. This study explores how varying the hard segment (HS) content in water-based polyurethane (WPU) impacts the thermal, mechanical, and ballistic performance of FRPCs. By increasing HS content, the storage modulus and tensile strength of WPU improved, while elongation at break decreased, transitioning the adhesive from soft and ductile to rigid and brittle. Quasi-static tests, ballistic experiments, and SEM analysis were conducted on UHMWPE fiber-reinforced WPU-HS% composites. Results reveal that adhesives with high hardness and modulus hinder fiber deformation, reducing energy dissipation and causing severe delamination, which diminishes ballistic performance. Conversely, soft and ductile adhesives allow deformation alongside fibers during bullet impact, suppress delamination, and absorb more kinetic energy while transferring load. Among the tested formulations, WPU with 45% HS content exhibited the best balance of mechanical properties, achieving the most significant improvement in ballistic performance by enhancing energy absorption and minimizing damage. This study establishes a clear relationship between WPU properties and composite protective behavior, providing insights for designing high-performance ballistic materials. Full article

In this study, the ballistic effectiveness of Kevlar 29 composites was analyzed by combining 400 and 460 GSM grammages with a polyurethane matrix. Plates measuring 300 mm × 250 mm were fabricated using hand lamination and compression techniques, with reinforcement designs consisting of 10, 14, and 18 layers of Kevlar 29 fabric oriented at a 90° angle. Ballistic tests were conducted following the parameters of the NIJ 0108.01 standard, applying five impacts with 9 mm FMJ and 22 (5.5 mm) caliber bullets. Both the composites and pure Kevlar were evaluated. Post-damage visual analysis was conducted on the front and back faces, as well as the interior of the composite, to identify delamination and fractures. The results show that .22 caliber bullets were captured at various stacking levels depending on the configuration, whereas 9 mm bullets penetrated all the plates. Localized fractures and delamination associated with the impacts were observed, highlighting the importance of stacking design and grammage in the material’s energy dissipation capacity. Full article

Given the significantly large deformation and high strain exhibited by explosively formed projectiles (EFP) in penetration, their penetration performance into multi-layer targets differs from that of ordinary bullets or rigid projectiles. Therefore, it is necessary to investigate the ballistic performance and the damage mechanism of target deformation when an EFP penetrates a multi-layer target. This study conducted high-velocity impact tests of EFPs on four types of multi-layer steel targets, analyzing the damage morphology and deformation characteristics of multi-layer steel targets subjected to EFP penetration from both macro and micro levels. To investigate the anti-penetration performance of more target combinations at different EFP velocities, an accurate symmetrical finite element model of EFP penetration into multi-layer targets was established using Autodyn 16.0 finite element software and the SPH-FEM algorithm based on the symmetrical characteristics of the EFP and target structure. The experimental and simulation results showed that for a three-layer composite target, when the thickness of the middle layer remained constant, using the target layers with a front–rear target thickness ratio of less than one was beneficial for enhancing the anti-penetration performance of the targets against EFPs; when the EFP velocity was low and the residual velocity for penetrating a single-layer target was no more than 200 m/s, the anti-penetration performance of the two-layer target was optimal. When the EFP velocity exceeded 1500 m/s, the single-layer target exhibited the best anti-penetration performance to the EFP, and the more layers, the smaller the ballistic resistance. When the number of layers was more than six, the ballistic resistance of the multi-layer targets gradually tended to remain constant. Full article

Background: Infectious diseases caused by bacteria are life-threating and are among the major causes of death in the world. Antibiotics have offered humans a new approach to infection control. Antibiotics are reckoned as the “magic bullets” for the fight against bacterial infections, therefore increasing life expectancy and decreasing mortality and morbidity. However, the overuse of antibiotics has resulted in the persistent growth of resistant bacterial pathogens. New antimicrobial approaches against resistant pathogens are being examined. Mushrooms seem to be a promising, and possibly more efficient, alternative method to that of conventional antimicrobials. This work aimed to investigate the phytochemical constituents and antimicrobial potential of ethanolic, aqueous, and dual solvent extracts of mushroom Ganoderma lucidum. Methods: The antimicrobial studies were carried out by broth dilution against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli. The present research work was also carried out to examine genomic changes associated with ethanolic, aqueous, and dual solvent extracts of G. lucidum in S. aureus and E. coli. Results: Our data quantitatively showed that all the extracts of G. lucidum were found to exhibit various degrees of antimicrobial effects against S. aureus and E. coli where the ethanolic extract exhibited the most potent antimicrobial activity. SEM images showed untreated cells with normal cell characteristics while, after treatment with extracts of G. lucidum, cells appeared damaged with irregular cell surfaces and cell wall defacement. The results of HPLC analysis showed that ethanolic and aqueous extract of G. lucidum consisted of beta[1-3] glucans, ganoderic acid, and triterpenoids. Genomic analysis identified selective sweeps in several genes associated with growth, biosynthesis transport, and stress. Conclusions: This study concludes that the extracts of three solvents of G. lucidum have antimicrobial activity against infectious bacteria causing morphological changes and the acquisition of mutations in genes. Therefore, the extracts of G. lucidum may be candidates for preventing infectious diseases in the future. Ganoderma lucidum mushroom is therefore a reliable source of antimicrobial agent that can be used against infectious diseases. Full article

Ataxia Telangiectasia and Rad3-related protein (ATR) is an apical kinase of the DNA Damage Response (DDR) pathway responsible for detecting and resolving damaged DNA. Because cancer cells depend heavily on the DNA damage checkpoint for their unchecked proliferation and propagation, ATR has gained enormous popularity as a cancer therapy target in recent decades. Yet, ATR inhibitors have not been the silver bullets as anticipated, with clinical trials demonstrating toxicity and mixed efficacy. To investigate whether the toxicity and mixed efficacy of ATR inhibitors arise from their off-target effects related to ATR’s multiple roles within and outside the DDR pathway, we have analyzed recently published studies on ATR’s non-canonical roles. Recent studies have elucidated that ATR plays a wide role throughout the cell cycle that is separate from its function in the DDR. This includes maintaining nuclear membrane integrity, detecting mechanical forces, and promoting faithful chromosome segregation during mitosis. In this review, we summarize the canonical, DDR-related roles of ATR and also focus on the non-canonical, multifaceted roles of ATR throughout the cell cycle and their clinical relevance. Through this summary, we also address the need for re-assessing clinical strategies targeting ATR as a cancer therapy based on these newly discovered roles for ATR. Full article

Ensuring military and police personnel protection is vital for urban security. However, the impact response mechanism of the UHMWPE laminate used in ballistic helmets and vests remains unclear, making it hard to effectively protect the head, chest, and abdomen. This study utilized 3D-DIC technology to analyze UHMWPE laminate’s response to 9 mm lead-core pistol bullets traveling at 334.93 m/s. Damage mode and response characteristics were revealed, and an effective numerical calculation method was established that could reveal the energy conversion process. The bullet penetrated by 1.03 mm, causing noticeable fiber traction, resulting in cross-shaped failure due to fiber compression and aggregation. Bulge transitioned from circular to square, initially increasing rapidly, then slowing. Maximum in-plane shear strain occurred at ±45°, with values of 0.0904 and −0.0928. Model accuracy was confirmed by comparing strain distributions. The investigation focused on bullet-laminate interaction and energy conversion. Bullet’s kinetic energy is converted into laminate’s kinetic and internal energy, with the majority of erosion energy occurring in the first four equivalent sublaminates and the primary energy change in the system occurring at 75 μs in the fourth equivalent sublayer. The results show the damage mode and energy conversion of the laminate, providing theoretical support for understanding the impact response mechanism and improving the efficiency of protective energy absorption. Full article

A military helicopter is easily attacked by bullets in a battlefield environment. The composite blade is the main lifting surface and control surface of the helicopter. Its ballistic performance directly determines the vulnerability and survivability of the helicopter in the battlefield environment. To study the ballistic performance of the composite helicopter blade, the damage characteristics of the impacted composite rotor blade are obtained by experiments. A numerical simulation model is established by applying Abaqus software to predict the blade ballistic damage. The three-dimensional progressive damage failure model is used to analyze the ballistic damage under the experimental conditions. The effectiveness and accuracy of the numerical simulation model are verified through a comparison with the experimental results. The ballistic damage of composite blades under three experimental conditions was investigated. The results show that the ballistic damage type of composite blade mainly includes delamination, fiber breakage, and foam collapse. The damage to the composite material at the position of bullet incidence is mainly local shear fracture, while the damage to the composite material at the exit position is mainly fiber tensile fracture. The ballistic damage size of the composite blade is closely related to the ballistic position, incident angle, and structure characteristics along the ballistic path. The larger the incident angle, the smaller the ballistic damage size of the blade. The greater the structural stiffness of the structure near the exit, the greater the damage size of the exit. The numerical simulation model presented in this paper can provide a reference for research on the ballistic performance of composite helicopter blades. Full article

Polymethyl methacrylate (PMMA) polymer is widely used in various fields today. In order to reveal the structural impact performance of PMMA materials in underwater engineering thoroughly, this paper firstly proposed a simplified plate model for a spherical shell hull under concentrative impact loading. Then, to simulate the hyper-elastic material properties of PMMA in the impact process, the Johnson–Cook constitutive model and damage failure model were adopted. And the least squares method was used to confirm accurately the J–C constitutive and damage failure model parameters of PMMA through material test data. Moreover, the dynamic process of the steel bullet impacting the PMMA plate structure was analyzed by the finite element software ABAQUS. The calculation results show that the numerical simulation results in this paper have a good convergence, and the residual velocities at different initial velocities and thicknesses of plates are in good agreement with the experimental test data. Therefore, the feasibility and accuracy of the impact analysis of PMMA structures based on J–C constitutive and damage failure models in this paper are verified accordingly. Finally, based on the presented finite element model, the structure response and the variation of residual velocity of the bullet with the PMMA plate thickness was analyzed in depth; that is, the results show that the residual velocity of the bullet has a certain linear relationship with the thickness, even in an underwater environment, and even in an underwater environment will increase both with a thicker structure or a higher pressure. Full article

Enhancing the impact resistance performance of carbon fiber-reinforced polymer (CFRP) laminates stands as a prominent research focus among various nations. Existing studies have shown a tendency towards arbitrary selection of the inter-ply helix angle values in CFRP laminates, which is accompanied by a limited number of samples representing the chosen helix angles. However, existing studies have shown a relatively random selection of spiral angle values between CFRP laminates, and the sample size of selected spiral angles is limited, posing certain limitations. In order to tackle this problem, we have employed a systematic arrangement of combinations to select the optimal helix angle for CFRP laminates. Inspired by the biological structures of Bouligand, we have sequentially chosen 19 distinct sets of helix angles, aiming to overcome the inherent limitations and enhance the research outcomes in this field. In this study, we established 19 finite element models to investigate the behavior of Bouligand-inspired CFRP composite panels under high-velocity bullet impact. The models were created by selecting 19 sets of helix angles within the range of 0 to 90° with a 5° interval. The results show that the energy absorption of the Bouligand layer-stacking composite plate is better than that of the conventional plate. The optimal spiral angles of the CFRP laminate are 25° and 30°, and the energy absorption characteristics of the laminate are the best at these angles. The impact resistance is also the best at these angles. The energy absorption of the Bouligand layer-stacking composite plate is 396% higher in absorbed internal energy and 361% higher in absorbed kinetic energy compared to the conventional layer-stacking composite plate, significantly improving the ballistic performance of the CFRP bulletproof material and providing a reference for the design of individual protection equipment. Full article

The nacre has excellent impact resistance performance, and it is attracting attention in the field of aerospace composite research. Inspired by the layered structure from nacre, semi-cylindrical nacre-like composite shells of brittle silicon carbide ceramic (SiC) and aluminum (AA5083-H116) were established. Two types of tablet arrangements (regular hexagonal and Voronoi polygons) of the composites were designed, and the same size of ceramic and aluminum shell were established for the impact resistance analyzed numerically. In order to better compare the resistance performance of the four types of structures under different impact velocity, the following parameters were analyzed including energy variation, damage characteristic, bullet residual velocity, and semi-cylindrical shell displacement. The results show that the semi-cylindrical ceramic shells have higher rigidity and ballistic limit, but the severe vibration after impact causes penetrating cracks, and the whole structure failure occurred eventually. The nacre-like composites have higher ballistic limits than semi-cylindrical aluminum shells, and the impact of bullets only causes local failure. In the same conditions, the impact resistance of regular hexagons is better than Voronoi polygons. The research analyzes the resistance characteristic of nacre-like composites and single materials, and provides a reference for the design of nacre-like structures. Full article

Poly(p-phenylene terephthalamide) (PPTA) and ultra-high-molecular-weight polyethylene (UHMWPE) are high-performance polymer materials largely used for body armor applications. Although composite structures from a combination of PPTA and UHMWPE have been created and described in the literature, the manufacture of layered composites from PPTA fabrics and UHMWPE films with UHMWPE film as an adhesive layer has not been reported. Such a new design can provide the obvious advantage of simple manufacturing technology. In this study, for the first time, we prepared PPTA fabrics/UHMWPE films laminate panels using plasma treatment and hot-pressing and examined their ballistic performance. Ballistic testing results indicated that samples with moderate interlayer adhesion between PPTA and UHMWPE layers exhibited enhanced performance. A further increase in interlayer adhesion showed a reverse effect. This finding implies that optimization of interface adhesion is essential to achieve maximum impact energy absorption through the delamination process. In addition, it was found that the stacking sequence of the PPTA and UHMWPE layers affected ballistic performance. Samples with PPTA as the outermost layer performed better than those with UHMWPE as the outermost layer. Furthermore, microscopy of the tested laminate samples showed that PPTA fibers exhibited shear cutting failure on the entrance side and tensile failure on the exit side of the panel. UHMWPE films exhibited brittle failure and thermal damage at high compression strain rate on the entrance side and tensile fracture on the exit side. For the first time, findings from this study reported in-field bullet testing results of PPTA/UHMWPE composite panels, which can provide important insights for designing, fabricating, and failure analysis of such composite structures for body armors. Full article

The accidental release of toxic gases leads to fire, explosion, and acute toxicity, and may result in severe problems for people and the environment. The risk analysis of hazardous chemicals using consequence modelling is essential to improve the process reliability and safety of the liquefied petroleum gas (LPG) terminal. The previous researchers focused on single-mode failure for risk assessment. No study exists on LPG plant multimode risk analysis and threat zone prediction using machine learning. This study aims to evaluate the fire and explosion hazard potential of one of Asia’s biggest LPG terminals in India. Areal locations of hazardous atmospheres (ALOHA) software simulations are used to generate threat zones for the worst scenarios. The same dataset is used to develop the artificial neural network (ANN) prediction model. The threats of flammable vapour cloud, thermal radiations from fire, and overpressure blast waves are estimated in two different weather conditions. A total of 14 LPG leak scenarios involving a 19 kg capacity cylinder, 21 tons capacity tank truck, 600 tons capacity mounded bullet, and 1350 tons capacity Horton sphere in the terminal are considered. Amongst all scenarios, the catastrophic rupture of the Horton sphere of 1350 MT capacity presented the most significant risk to life safety. Thermal flux of 37.5 kW/ m² from flames will damage nearby structures and equipment and spread fire by the domino effect. A novel soft computing technique called a threat and risk analysis-based ANN model has been developed to predict threat zone distances for LPG leaks. Based on the significance of incidents in the LPG terminal, 160 attributes were collected for the ANN modelling. The developed ANN model predicted the threat zone distance with an accuracy of R² value being 0.9958, and MSE being 202.9061 in testing. These results are evident in the reliability of the proposed framework for safety distance prediction. The LPG plant authorities can adopt this model to assess the safety distance from the hazardous chemical explosion based on the prior forecasted atmosphere conditions from the weather department. Full article