Comprehensive Evaluation of Layered Composite Protection Performance for Light Armored Vehicles

The project supported the Nuclear Regulatory Commission (NRC) in identifying and evaluating the regulatory implications concerning the control and protection systems proposed for use in the Department of Energy's (DOE) Next-Generation Nuclear Plant (NGNP). The NGNP, using modular high-temperature gas-cooled reactor (HTGR) technology, is to provide commercial industries with electricity and high-temperature process heat for industrial processes such as hydrogen production. Process heat temperatures range from 700 to 950 C, and for the upper range of these operation temperatures, the modular HTGR is sometimes referred to as the Very High Temperature Reactor or VHTR. Initial NGNP designs are for operation in the lower temperature range. The defining safety characteristic of the modular HTGR is that its primary defense against serious accidents is to be achieved through its inherent properties of the fuel and core. Because of its strong negative temperature coefficient of reactivity and the capability of the fuel to withstand high temperatures, fast-acting active safety systems or prompt operator actions should not be required to prevent significant fuel failure and fission product release. The plant is designed such that its inherent features should provide adequate protection despite operational errors or equipment failure. Figure 1 shows an example modular HTGR layout (prismatic core version), where its inlet coolant enters the reactor vessel at the bottom, traversing up the sides to the top plenum, down-flow through an annular core, and exiting from the lower plenum (hot duct). This research provided NRC staff with (a) insights and knowledge about the control and protection systems for the NGNP and VHTR, (b) information on the technologies/approaches under consideration for use in the reactor and process heat applications, (c) guidelines for the design of highly integrated control rooms, (d) consideration for modeling of control and protection system designs for VHTR, and (e) input for developing the bases for possible new regulatory guidance to assist in the review of an NGNP license application. This NRC project also evaluated reactor and process heat application plant simulation models employed in the protection and control system designs for various plant operational modes and accidents, including providing information about the models themselves, and the appropriateness of the application of the models for control and protection system studies. A companion project for the NRC focused on the potential for new instrumentation that would be unique to modular HTGRs, as compared to light-water reactors (LWRs), due to both the higher temperature ranges and the inherent safety features.

Sandwich construction has proven to be an excellent low-density multifunctional design for a wide range of applications in ballistic protection, energy absorption, and thermal insulation. Based on the bulletproof effect of each layer of the sandwich structure, this paper expounds and summarizes the material properties that can be used as each layer. The mechanical and ballistic properties of ultra-high strength aramid (Kevlar) and ultra-high molecular weight polyethylene (UHMEPE) composites and the ballistic properties of mixed fibers of these two materials versus the mechanical properties of single fiber materials, the mechanical properties, chemical stability and other properties of aluminum and magnesium alloys, the effects of heat treatment and coating treatment on the ballistic properties of aluminum alloys, and finally the energy absorption properties of several common core materials structures are compared.

The analysis of different power system events is important for the successful operation of the system and the optimal design and configuration of protection and control systems. The paper analyzes the types of system events, available data sources and requirements for the development of hierarchical event analysis systems. The need for common record formats and configuration data are discussed. The importance of accurate time-synchronization and methods to achieve it is also described.

Ballistic performance of UHMWPE fiber laminates with pre-formed holes

“Like binding a book”: Interfacial improvement of pre-melted ultrahigh molecular weight polyethylene by pulse vibration molding

Part of the Future Circular Collider (FCC-hh) study is dedicated to the development of the 16 Tesla Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn superconducting dipole magnets. The design of the magnets was enabled by a cooperative effort of national research institutes, universities, and CERN. These actors tackled the problem from different sides, namely, the electromagnetic design, the mechanical design, the design of the quench protection systems, and the circuit design. The article deals with the design of the quench protection systems and provides solid motivations for the selection of the coupling-loss-induced quench (CLIQ) device as the baseline protection system for the FCC-hh main dipole magnets. The article shows that the design domains mentioned above are tightly interconnected and, therefore, the simulation of a quench event involves a complex multiphysics problem. The STEAM cosimulation framework, recently developed at CERN, is applied to address the complexity. The STEAM-SIGMA models are employed to simulate the CLIQ quench protection system applied to the FCC-hh dipole magnets. Dedicated CLIQ configurations are identified to protect the magnets in case of a quench. In addition, the possible implications of the CLIQ protection system on the mechanical design of the magnets are discussed. To this end, the article employs the co-simulation of different software platforms to calculate the mechanical stress during a quench. The results show that CLIQ does not produce additional stress.

The ballistic protection for body armor usually requires both of high strength and high energy mitigation. In this work, we introduce and evaluate a new kind of body armor, i.e. a hybrid panel of ultra-high molecular weight polyethylene (UHMWPE) fabrics and soft energy absorption materials and structures (EAMS), by combing the advantages of bullet-proof and energy absorption of the respective material structures. A combined experimental and numerical study is conducted to evaluate the ballistic performance of the UHMWPE fabrics/EAMS hybrid panel. The resulting back-face signature (BFS) values of the hybrid panel are reduced by 6–17%, compared to the pure UHMWPE fabrics panel with the same areal density. If the EAMS is simply superimposed onto the UHMWPE fabrics, the reduction of BFS can be 50% or more with respect to the pure UHMWPE one. The effects of the geometrical factors of EAMS and mass ratio of UHMWPE fabrics to EAMS on the BFS values are studied using comprehensive finite element method (FEM) analyses. The strategies for optimal design of the UHMWPE fabrics/EAMS composite armor are proposed. The results presented herein shed useful insights for the design for high performance and energy mitigating body armors.

Influence of weathering and gamma irradiation on the mechanical and ballistic behavior of UHMWPE composite armor

1 Introduction 2 Design of Protection Systems Using Quarried Stone 3 Design of Protection Systems with Concrete Armour Units 4 Design of Alternate Breakwater Concepts 5 Discussion 6 Design Procedures for the Efficient and Safe Design of an Armour Layer

Optimal Protection from Impact, Shock, and Vibration

The design of reliable protection systems is essential in order to guarantee the secure operation of power systems. The coordination of the response of protective equipment under fault conditions is a fundamental problem which is usually formulated as a non-linear optimization problem with the objective of minimizing the total operating time of the protection system. In general, optimal protection coordination can be regarded as a well-studied problem, with the existing literature featuring the application of a wide range of solution techniques. However, recent advances in the area of artificial intelligence and the increasing availability of near real-time measurements from distribution systems offer the possibility to envision adaptive protection systems capable of operating optimally under different power system operating conditions and, potentially, of being more resilient, by assigning local decision-making autonomy to relays, instead of relying on a centralized system to coordinate protective devices. To this end, in this study optimal protection coordination is cast as a reinforcement learning problem and relays are viewed as autonomous agents that can manipulate their time dial settings in order to optimally respond to signals from their environment, i.e., the power system. The reinforcement learning problem is solved by applying the Q-learning algorithm. The results of the case study indicate that this framework is capable of providing settings that achieve both a fast and coordinated protection system.

Achieving lightweight and high-performance bulletproof vests is essential for military and law enforcement, where balancing mobility and ballistic resistance is critical. This study investigates the ballistic performance of multi-layered Ultra-High Molecular Weight Polyethylene (UHMWPE) vests reinforced with titanium (Ti6Al4V) and polyvinyl chloride (PVC). Two innovative vest configurations were evaluated following National Institute of Justice (NIJ) Standard-0101.04 ballistics tests and simulated using the Finite Element Method (FEM). Experimental findings indicated that while Vest 1 significantly absorbed impact energy, it failed to prevent projectile penetration. In contrast, Vest 2, incorporating additional titanium and polymer layers, effectively mitigated the penetration of 9 mm Full Metal Jacket (FMJ) projectiles while maintaining a safe back-face signature (BFS). The FEM simulation results demonstrated strong agreement with the experimental data, validating the effectiveness of multi-material layering in enhancing ballistic resistance. This research presents a strategic integration of titanium and polymer composites designed to achieve superior ballistic resistance while maintaining lightweight properties. These findings provide valuable insights for developing advanced body armor designs suitable for high-performance military and law enforcement applications.

Ultrahigh molecular weight polyethylene (UHMWPE) is a bearing surface material for total joint implants. It is radiation cross-linked for high wear resistance and is melted or treated with vitamin E for oxidative stability. We investigated high pressure crystallization (HPC) of irradiated UHMWPE as an alternative method to improve the mechanical strength while stabilizing the residual free radicals from radiation cross-linking. HPC of uncross-linked UHMWPE has resulted in the formation of extended chain crystals and increased crystallinity, leading to improved strength. We hypothesized that increased cross-link density would hinder crystallization during HPC due to decreased chain mobility. Therefore, we investigated the crystalline structure and tensile mechanical properties of high pressure crystallized 25-, 65- and 100-kGy irradiated UHMWPE. We also determined free radical content and wear. The strength of 25- and 65-kGy irradiated UHMWPEs was improved by HPC with increased crystallinity and crystal size. 100-kGy irradiated UHMWPE did not show improved strength, supporting our hypothesis that decreased chain mobility would hinder crystal formation and strength improvement. None of the HPC irradiated UHMWPEs contained detectable free radicals and their wear properties were maintained, suggesting oxidative and mechanical stability in the long term. Therefore, HPC can be used effectively for imparting oxidative stability while strength improvement can be achieved for irradiated UHMWPE with low to moderate cross-link density.

Some treatment options available to repair bone defects are the use of autogenous and allogeneic bone grafts. The drawback of the first one is the donor site’s limitation and the need for a second operation on the same patient. In the allograft method, the problems are associated with transmitted diseases and high susceptibility to rejection. As an alternative to biological grafts, polymers can be used in bone repair. Some polymers used in the orthopedic field are poly(methyl methacrylate), poly(ether-ether-ketone), and ultra-high molecular weight polyethylene (UHMWPE). UHMWPE has drawn much attention since it combines low friction coefficient and high wear and impact resistance. However, UHMWPE is a bioinert material, which means that it does not interact with the bone tissue. UHMWPE composites and nanocomposites with hydroxyapatite (HA) are widely studied in the literature to mitigate these issues. HA is the main component of the inorganic phase in the natural bone, and the addition of this bioactive filler to the polymeric matrix aims to mimic bone composition. This brief review discusses some polymers used in orthopedic applications, focusing on the UHMWPE/HA composites as a potential bone substitute.

The selection of biomaterials as biomedical implants is a significant challenge. Ultra-high molecular weight polyethylene (UHMWPE) and composites of such kind have been extensively used in medical implants, notably in the bearings of the hip, knee, and other joint prostheses, owing to its biocompatibility and high wear resistance. For the Anterior Cruciate Ligament (ACL) graft, synthetic UHMWPE is an ideal candidate due to its biocompatibility and extremely high tensile strength. However, significant problems are observed in UHMWPE based implants, such as wear debris and oxidative degradation. To resolve the issue of wear and to enhance the life of UHMWPE as an implant, in recent years, this field has witnessed numerous innovative methodologies such as biofunctionalization or high temperature melting of UHMWPE to enhance its toughness and strength. The surface functionalization/modification/treatment of UHMWPE is very challenging as it requires optimizing many variables, such as surface tension and wettability, active functional groups on the surface, irradiation, and protein immobilization to successfully improve the mechanical properties of UHMWPE and reduce or eliminate the wear or osteolysis of the UHMWPE implant. Despite these difficulties, several surface roughening, functionalization, and irradiation processing technologies have been developed and applied in the recent past. The basic research and direct industrial applications of such material improvement technology are very significant, as evidenced by the significant number of published papers and patents. However, the available literature on research methodology and techniques related to material property enhancement and protection from wear of UHMWPE is disseminated, and there is a lack of a comprehensive source for the research community to access information on the subject matter. Here we provide an overview of recent developments and core challenges in the surface modification/functionalization/irradiation of UHMWPE and apply these findings to the case study of UHMWPE for ACL repair.