Defensive Weapons Research Articles

Discovery and Reconstruction of the Remains of the Beacon-Equipped Hollow Enemy Towers along the Ming Great Wall

Hollow Enemy Towers, as iconic structures of the Ming Great Wall, are renowned for their roles in defense surveillance, weapon storage, and firearm operation. Recent studies have indicated that certain Hollow Enemy Towers along the Ji Town section of the Ming Great Wall also serve the function of Beacon Towers for beacon signaling. However, previous studies have not definitively determined if these towers were distinctively marked, nor have they provided a comprehensive account of their current distribution and original historical appearance. This paper initially examined the historical documentation of white lime markings employed on the outer walls of certain Hollow Enemy Towers, which served as Beacon Towers during the middle and late Ming periods. Utilizing multidisciplinary methodologies, this research identified remains of lime markings of the Beacon-Equipped Hollow Enemy Towers along the Ji Town section of the Ming Great Wall, illustrating their extensive distribution. We analyzed the material composition and construction techniques of the lime mortar. This analysis clarifies the scope of lime plastering on the exterior walls of these towers and offers a point of reference for restoring their original historical appearance. The results make a significant supplement to the types of signaling structures on the Great Wall, enriching existing understanding of the original appearance of the Great Wall’s historical landscape.

МАГИЧЕСКОЕ ОРУЖИЕ ГЕРОЕВ ЭПОСА «НАРТЫ»

The article examines the archaic cult of the god of iron and the patron saint of metal Tlepsh, the emergence of metallurgy, the creation of the first weapons and armor made of metal, which are reflected in the Adyghe heroic epic Narts. The relevance of the article is due to the fact that the heroic epic Narts is almost not considered in the scientific literature as a source of information for the study of objects and tools, the creation of the first weapon, the addition of a complex of weapons and armor of horsemen. The purpose of the study is to compare the weapons of the heroes of the Nart epic, endowed with magical properties, having certain qualitative characteristics, technological features of manufacture, with the materials of archaeological sites of the Northwestern Caucasus. To achieve these goals, a comparative historical research method was used to determine the features of the origin and composition of various types of offensive and defensive weapons, reflecting the stages of development of blacksmithing and weapons production in a historical context. The transformation of the Chthonic «fire» god into the patron saint of iron and blacksmithing of the nart Tlepsha translates in the legends of the Nart epic the historical and economic prerequisites for the origin of metalworking in the Early Iron Age, the creation of the first tools and weapons of the sleds, which became models for creating the best defensive and offensive weapons in Eurasia. The archaeological sites of the Northwestern Caucasus confirm the continuous development of metallurgy and metalworking since ancient times and the creation of highly artistic bronze, gold, and silver products. The initiated research on this topic has a long–term perspective and requires continued work on the study of the original texts of the Adyghe heroic epic «Narts» for comparison with archaeological artifacts found in the Northwestern Caucasus.

Crystal structure of blue laccase BP76, a unique termite suicidal defense weapon

Aging workers of the termite Neocapritermes taracua can defend their colony by sacrificing themselves by body rupture, mixing the externally stored blue laccase BP76 with hydroquinones to produce a sticky liquid rich in toxic benzoquinones. Here, we describe the crystal structure of BP76 isolated from N.taracua in its native form. The structure reveals several stabilization strategies, including compact folding, glycosylation, and flexible loops with disulfide bridges and tight dimer interface. The remarkable stability of BP76 maintains its catalytic activity in solid state during the lifespan of N.taracua workers, providing old workers with an efficient defensive weapon to protect their colony.

Monitoring of Immune Memory by Phenotypical Lymphocyte Subsets Identikit: An Observational Study in a Blood Donors' Cohort.

The cross-talk between the innate and adaptive immune response represents the first defense weapon against the threat of pathogens. Substantial evidence has shown a relationship between immune phenotype lymphocytes and COVID-19 disease severity and/or implication in susceptibility to SARS-CoV-2 infection. Recently, belonging to ABO blood groups has been investigated as a correlation factor to COVID-19 disease. This pilot study investigated lymphocyte typing in a cohort of blood donors to understand the underlying mechanism in SARS-CoV-2 infection linked to the blood group. The study cohort consisted of 20-64-year-old subjects, without comorbidities, from both sexes, who were COVID-19 vaccinated with previous or no infection history. Whole blood samples, collected at A.O.R.N. Sant'Anna and San Sebastiano Hospital (Campania Region), were processed by multiparametric cytofluorimetric assay, to characterize CD4+ helper and CD8+ cytotoxic T cell CD3+ subpopulations. The CD45RA, CCR7, CD27, CD28, CD57 and PD-1 markers were investigated to delineate the peripheral T-cell maturation stages. Differences were detected in ABO blood types in CD3+, CD4+ gated on CD3+, CD8+ and CD8+ gated on CD3+ percentage. These results contribute to identifying a memory cell "identikit" profile in COVID-19 disease, thus leading to a useful tool in precision medicine.

Ame-miR-1-3p of bee venom reduced cell viability through the AZIN1/OAZ1-ODC1-polyamines pathway and enhanced the defense ability of honeybee (Apis mellifera L.).

Bee venom serves as an essential defensive weapon for bees and also finds application as a medicinal drug. MicroRNAs (miRNAs) serve as critical regulators and have been demonstrated to perform a variety of biological functions. However, the presence of miRNAs in bee venom needs to be confirmed. Therefore, we conducted small RNA sequencing and identified 158 known miRNAs, 15 conserved miRNAs and 4 novel miRNAs. It is noteworthy that ame-miR-1-3p, the most abundant among them, accounted for over a quarter of all miRNA reads. To validate the function of ame-miR-1-3p, we screened 28 candidate target genes using transcriptome sequencing and three target gene prediction software (miRanda, PITA and TargetScan) for ame-miR-1-3p. Subsequently, we employed real-time quantitative reverse transcription PCR (qRT-PCR), Western blot and other technologies to confirm that ame-miR-1-3p inhibits the relative expression of antizyme inhibitor 1 (AZIN1) by targeting the 3' untranslated region (UTR) of AZIN1. This, in turn, caused ODC antizyme 1 (OAZ1) to bind to ornithine decarboxylase 1 (ODC1) and mark ODC1 for proteolytic destruction. The reduction in functional ODC1 ultimately resulted in a decrease in polyamine biosynthesis. Furthermore, we determined that ame-miR-1-3p accelerates cell death through the AZIN1/OAZ1-ODC1-polyamines pathway. Our studies demonstrate that ame-miR-1-3p diminishes cell viability and it may collaborate with sPLA2 to enhance the defence capabilities of honeybees (Apis mellifera L.). Collectively, these data further elucidate the defence mechanism of bee venom and expand the potential applications of bee venom in medical treatment.

Transforming Escalation to Negotiation: Rethinking Confidence-Building Measures (CBMs) in the Ongoing Russia-Ukraine War

There have been several pieces of literature on the current war between Russia and Ukraine but little emphasis has been placed on transforming the growing escalation into negotiation. In this study, I discuss the causalities that surround the current war between the Russian Federation and Ukraine from different prisms. Various justifications and other indices which provide the likelihood of escalation to a nuclear conflict were touched. Also, I assessed, if at all, there was politics behind the supplies of ‘defensive weapons’ and other military aid to the warring parties. I propose an urgent arms control treaty not only between the United States and Russia but should also include China as the emerged third force, and other minor nuclear powers. Although, the Confidence Building Measures (CBMs) are mostly prominent before a complex conflict is transformed into conventional war, thus, this study suggests the roles the CBMs can still play in the current war. As such, the study relies on relevant written sources which make the study qualitative in nature.

Autonomous Steerable Ram-Air Type Load Parachute System Desıgn And Alternatıve Trajectory Algorıthm

The required supplies should be delivered by air to places that cannot be reached by land or sea. However, air resupply requires a runway on which the aircraft can land. In order to eliminate this need, the airdrop method is used. Airdrop is a commonly used replenishment method in both humanitarian aid operations and military operations where necessary. The most important limitations of airdrop replenishment are that the cargo may be affected by the wind and fall into undesirable areas and that the aircraft is vulnerable to enemy air defense systems. In today's cross-border operations, airdrops are necessary to ensure that troops can reach the supplies they need. GPS-guided, steerable parachutes can be used for high-altitude, long-distance airdrop by protecting the aircraft from enemy air defense weapons and preventing the payload from being blown away by the wind or into the hands of undesirable persons. In this study, the design of the system required by the Turkish Armed Forces is made, the command and control unit is created and the trajectory tracking algorithm is presented.

Melee weapons and defensive weapons of the nomads of Central Asia in the early Modern period

Melee weapons and defensive weapons of the nomads of Central Asia in the early Modern period

The theory of high hazard (HHT) based on grounded theory method and theories integration

PurposeOrganizations working in high-hazard environments contribute significantly to modern society and the economy, not only for the valuable resources they hold but also for the indispensable products and services they provide, such as power generation, transportation and defense weapons. Therefore, the main purpose of this study is to develop a framework that outlines future research on systems safety and provides a better understanding of how organizations can effectively manage hazard events.Design/methodology/approachIn this research, we developed the high hazard theory (HHT) and a theoretical framework based on the grounded theory method (GTM) and the integration of three established theoretical perspectives: normal accident theory (NAT), high reliability theory (HRT) and resilience engineering (RE) theory.FindingsWe focused on the temporal aspect of accidents to create a timeline showing the progression of hazard events and the factors contributing to safety and hazards in organizations. Given the limitations of the previous theories in providing a coherent explanation of hazard event escalation in high-hazard organizations (HHOs), we argue that the highlighted theories can be more complementary than contradictory regarding their standpoints on disasters and accident prevention.Practical implicationsA proper appreciation of the hazard nature of organizations can help reduce their susceptibility to failure, prevent outages and breakdowns of systems, identify areas for improvement and develop strategies to enhance performance.Originality/valueBy developing HHT, we contribute to systems safety research by developing a new, refined theory and enrich the theoretical debate. We also expand the understanding of scholars and practitioners about the characteristics of organizations working in high-hazard environments.

When ASFV Infection Meets the cGAS-STING Signaling Pathway

The African swine fever virus (ASFV) has the ability to infect both wild boars and domestic pigs, regardless of their breeds or ages, often resulting in a mortality rate of 100%. Host innate immunity is the most important defense weapon against invasion of pathogenic microbial infection. cGAS-STING signaling pathway is one of the greatest discoveries of the twenty-first century, which is crucial in host’s innate immune response. Recent studies have found that the interaction between cGAS/STING pathway and ASFV plays a key role during ASFV infection. At the same time, ASFV has also evolved different strategies to evade the killing of the host cGAS/STING pathway and promote its survival. Here, we review the latest progress in the interaction between ASFV infection, cGAS/STING pathways, and their related molecular mechanisms, aiming to provide new ideas for further research on the pathogenesis of ASFV, the development of vaccines and therapeutic drugs.

Regulation of the PFK1 gene on the interspecies microbial competition behavior of Saccharomyces cerevisiae

Saccharomyces cerevisiae is a widely used strain for ethanol fermentation; meanwhile, efficient utilization of glucose could effectively promote ethanol production. The PFK1 gene is a key gene for intracellular glucose metabolism in S. cerevisiae. Our previous work suggested that although deletion of the PFK1 gene could confer higher oxidative tolerance to S. cerevisiae cells, the PFK1Δ strain was prone to contamination by other microorganisms. High interspecies microbial competition ability is vital for the growth and survival of microorganisms in co-cultures. The result of our previous studies hinted us a reasonable logic that the EMP (i.e., the Embden-Meyerhof-Parnas pathway, the glycolytic pathway) key gene PFK1 could be involved in regulating interspecies competitiveness of S. cerevisiae through the regulation of glucose utilization and ethanol production efficiency. The results suggest that under 2% and 5% glucose, the PFK1Δ strain showed slower growth than the S288c wild-type and TDH1Δ strains in the lag and exponential growth stages, but realized higher growth in the stationary stage. However, relative high supplement of glucose (10%) eliminated this phenomenon, suggesting the importance of glucose in the regulation of PFK1 in yeast cell growth. Furthermore, during the lag growth phase, the PFK1Δ strain displayed a decelerated glucose consumption rate (P < 0.05). The expression levels of the HXT2, HXT5, and HXT6 genes decreased by approximately 0.5-fold (P < 0.05) and the expression level of the ZWF1 exhibited a onefold increase in the PFK1Δ strain compared to that in the S. cerevisiae S288c wild-type strain (P < 0.05).These findings suggested that the PFK1 inhibited the uptake and utilization of intracellular glucose by yeast cells, resulting in a higher amount of residual glucose in the medium for the PFK1Δ strain to utilize for growth during the reverse overshoot stage in the stationary phase. The results presented here also indicated the potential of ethanol as a defensive weapon against S. cerevisiae. The lower ethanol yield in the early stage of the PFK1Δ strain (P < 0.001) and the decreased expression levels of the PDC5 and PDC6 (P < 0.05), which led to slower growth, resulted in the strain being less competitive than the wild-type strain when co-cultured with Escherichia coli. The lower interspecies competitiveness of the PFK1Δ strain further promoted the growth of co-cultured E. coli, which in turn activated the ethanol production efficiency of the PFK1Δ strain to antagonize it from E. coli at the stationary stage. The results presented clarified the regulation of the PFK1 gene on the growth and interspecies microbial competition behavior of S. cerevisiae and would help us to understand the microbial interactions between S. cerevisiae and other microorganisms.Key points• PFK1Δ strain could realize reverse growth overshoot at the stationary stage• PFK1 deletion decreased ethanol yield and interspecific competitiveness• Proportion of E. coli in co-culture affected ethanol yield capacity of yeast cells

Analysis of the state of development of the issue of protection of critical infrastructure facilities using engineered munitions

The Russian-Ukrainian war at the stage of full-scale invasion has shown that one of the most difficult tasks of ensuring the survivability of troops and the functioning of critical infrastructure is to protect them from high-precision weapons, namely cruise and ballistic missiles and unmanned aerial vehicles.&#x0D; The experience of warfare shows that the existing domestic air defense systems do not fully defeat air targets, while highly effective foreign-made air defense systems are supplied in insufficient quantities, and the created mobile fire groups to destroy air targets are not always effective. In these circumstances, it is advisable to consider new integrated approaches to the use of various types of weapons in the active defense of troops and critical infrastructure against air attack.&#x0D; The complex construction of a system of active defense of troops and critical infrastructure against air attack is possible with the use of several types of weapons. Based on the analysis of the enemy's use of missiles of various classes and Shahed-type attack unmanned aerial vehicles, the paper proposes the use of engineered munitions as one of the means of defeating moving air targets that fly low at low speed. The use of special engineered ammunition will make it possible to increase the range of low-flying air targets and increase the likelihood of their defeat. This will improve the effectiveness of the existing system of protecting troops and critical infrastructure from air attack.&#x0D; The paper analyzes the use of air attack weapons of the Russian Federation against troops and critical infrastructure facilities of Ukraine, substantiates proposals on the expediency of using engineered ammunition as an element of building a system of active protection of troops and critical infrastructure facilities from air attack, and presents their principle of operation and possible applications.

Implementation of the Modernization Policy of the Main Equipment of the National Maritime Defense Weapon System

This study explores the implementation of the Navy's main weapon system modernization policy in the context of meeting the Minimum Essential Forces (MEF) Phase II for the 2015-2019 period, whose main focus is to overcome threats to national security. The purpose of the study is to explain the implementation process of the Navy's defense equipment modernization policy related to MEF and analyze policy factors that affect the results of its implementation. Using defense policy data and theory, the study identified obstacles such as budget constraints, differences in understanding between policy actors, less optimal supervision, and the role of the defense industry that has not been maximized. Document evaluation, interviews, and monitoring by defense experts show that the main constraint is not just related to limited resources, but rather to the imbalance of political will of policy actors. Consistency of implementation, commitment to transparency, accountability, and improvement of resource capabilities through priority scale and empowerment of the defense industry require the support of political will. The contribution of this research includes the development of political science, particularly in the context of defense and security politics. The results can be a reference for future researchers who are interested in understanding the issue of defense equipment modernization. The successful implementation of this policy is expected to have a significant impact on national defense and national security policies, with the support of political will identified as the main key to minimizing conflicts of interest and increasing the effectiveness of MEF implementation, maintaining national security.

THE OPERATION DESERT STORM AND THE PATRIOT MISSILE DEFENSE SYSTEM [4] -THE PATRIOT’S INDIRECT SUCCESS

According to Raytheon, the manufacturer of the Patriot system. The Patriot’s success was certainly a political one. Saudi Arabia could not possibly be on the same side of Israel if Israel counter-attacks Iraq. Because of this political complication, the US provided Israel with the defensive weapon such as the Patriot system. Thus, regardless of the Patriot’s defense effectiveness, the US was able to limit Israel’s military action to directly counter-attack Iraq. In this way, the US could keep the allied forces together, sustaining the US policy in the middle east.

한국의 對폴란드 교역 특성과 통상전략 분석

Purpose: This study derives Korea's trade strategy toward Poland and selects promising items exported to the Polish market after analyzing the macroeconomic trend and major industries in Poland and trade-investment relations between Korea and Poland.&#x0D; Research design, data, and methodology: This paper makes use of KITA statistics on trade and investment relations between Korea and Poland as well as a SWOT analysis of the Polish market.&#x0D; Results: Promising export items for the Polish market are electric battery anode material, defense industry products and weapons, semiconductors, synthetic resins, batteries and storage batteries, plastic products, measurement control analyzers, other machinery, transport and unloading machinery, and textile and chemical machinery.&#x0D; Conclusions: Poland should be established as a production/sales/producer service hub linking Western Europe to Eastern Europe, Russia, and the CIS region over the long term, taking advantage of opportunity factors such as geographic location and an excellent manufacturing base, high-quality inexpensive labor, and the government's active FDI promotion policy. In particular, the Polish government has recently been increasing the purchase of self-propelled artillery, tanks, and fighter jets, so Korea should quickly revise the Export-Import Bank of Korea Act to expand financial support in order to facilitate contracts with Poland for weapons.

Effects of Secondary Metabolites of Rice on Brown Planthopper and Its Symbionts.

The brown planthopper Nilaparvata lugens (Stål) (BPH) is a main rice pest in China and many other Asian countries. In the control of BPH, the application of insect-resistant rice has proven to be quite effective. Secondary metabolites are essential weapons in plants' defense against phytophagous insects. Studies have found that differences in the content of secondary metabolites play a crucial role in determining whether rice exhibits resistance or susceptibility to BPH. Simultaneously, symbionts are essential to the BPH. Nevertheless, there is limited research on the impact of secondary metabolites on the symbionts within BPH. Therefore, investigating the influence of secondary metabolites on both BPH and their symbionts is significant for the control of BPH. In this experiment, newly emerged female adults of BPH were fed artificial diets containing 10 different secondary metabolites. The results indicated that methyl jasmonate had inhibitory effects on the survival rate, weight gain, and reproductive capacity of BPH. Using qPCR methods, it was discovered that the number of symbiotic fungi (Ascomycetes symbionts) within BPH significantly decreased under methyl jasmonate stress. In conclusion, this experiment has preliminarily revealed the inhibitory effects of methyl jasmonate on BPH and its symbionts, demonstrating its potential for controlling BPH.

India’s Quest for Defence Indigenisation: A Case Study of the Indian Navy

India, like all major military powers, has been making sustained attempts at indigenously meeting its defence requirements. However, when one looks at the macro picture, it is apparent that the country has had limited successes in inducting defence platforms or weapon systems that are indigenously designed, tested, manufactured and inducted into the military. There have been some exceptions to this like the HF-24 Marut fighter jet, the Light Combat Aircraft Tejas, the Main Battle Tank Arjun, Leander class frigates, Indigenous Aircraft Carrier Vikrant, Kolkata and Vishakhapatnam class destroyers and the Arihant nuclear submarine. While these examples only prove the general rule, they also point out India’s relative success in creating domestic capacity to build naval platforms. As India embarks on the path of Atmanirbharta (self-reliance), it is crucial for the political and military decision-makers to understand what, why and how the above-mentioned projects, particularly the naval ones, became successful, so that their success can be replicated elsewhere. The article attempts to understand the reasons behind the Navy’s successes. These successes have been the result of an institutionalised—as opposed to an individual-centric—approach by the Navy to create in-house design capabilities, organisational structure, planning procedure, capacity building efforts and linkages with other stakeholders like naval Defence Public Sector Units, Defence Research and Development Organisation and other scientific establishments and industry. This has made the Indian Navy more successful as compared to the other two services of the Indian military when it comes to designing, testing, constructing and inducting indigenous naval platforms.

The Role of Hematopoietic Stem Cells in Lung Cancer Response to Radiation Therapy

Non-small cell lung carcinoma (NSCLC) comprises approximately 85% of all lung cancer cases in the United States. We demonstrated that after radiation therapy (RT), bone marrow-derived hematopoietic stem and progenitor cells (HSPCs) are recruited to the NSCLC tumor microenvironment (TME). These HSPCs seemed to positively affect tumor regrowth as their numbers directly correlated with regrowth rates. The TME is comprised of tumor tissue, stromal cells, immune cells, bone marrow-derived cells, and extra cellular matrix (ECM) proteins and has emerged as one of the predominant defensive weapons with which cancer can resist various forms of therapeutic intervention. The ability of tumor-associated HSPCs to maintain hematopoietic potency in tumors suggested a prominent role of these cells in tumor physiology, however; what was missing was a mechanistic understanding of: 1) how HSPCs participate in tumor growth post-RT and 2) how HSPCs are maintained within tumors. To answer these questions, we established NSCLC tumors in mice using Lewis Lung Carcinoma (LLC) cells and assessed tumor-associated HSPCs activity and molecular changes in the TME following RT. We observed that RT induces the TME to produce colony stimulating factor (CSF)-1, a factor that promotes the differentiation of HSPCs into tumor supportive M2-macrophages. Adoptive transplantation of dsRed labeled HSPCs into tumor bearing mice followed by RT directly showed the differentiation of HSPCs into M2-macrophages and a concomitant increase in the regrowth of tumors post-RT. Use of a therapeutic inhibitor of the CSF-1 receptor (GW2580) prevented HSPC differentiation in to M2-macrophages and significantly decreasing regrowth rates. We next assessed how tumor-associated HSPCs maintain their hematopoietic potency within the TME. Analysis of tumors demonstrated high expression levels of the laminin 5-1-1 isoform, which is known to bind CD49f (integrin alpha 6), a marker of functional HSPCs. Tumors exposed to RT demonstrated significantly reduced expression of both laminin 5-1-1 and CD49f. When bound, CD49f inhibits phosphorylation of focal adhesion kinase (FAK) resulting in maintenance of pluripotent stem cells. Analysis of tumor-associated HSPCs demonstrated significantly higher levels of phosphorylated FAK following tumor exposure to RT. Since RT induces HSPC differentiation in to M2-macophages, this observation suggests that tumor-associated HSPC functionality is maintained through the interaction between laminin 5-1-1- and CD49f. The identification of single HSPCs that differentiated in to M2-macrophages and which expressed phosphorylated FAK supports this conclusion. Taken together, this data province's evidence of a mechanism wherein RT disrupts laminin 5-1-1/CD49f interactions releasing tumor-associated HSPCs from maintenance signals. Concomitantly, RT induces the production of CSF-1 within the TME, which induces these “released” HSPCs to differentiate into tumor supportive M2-macrophages and promote tumor regrowth post-RT. Overall, these studies define a new understanding of tumor biology in which HSPCs are significant mediators of tumor response to RT. These findings also identify new cellular and molecular pathways to target in the treatment of NSCLC to achieve more optimal clinical outcomes.

Defensive armament of the Hunnu

The article analyzes the findings of protective equipment made in the archaeological monuments of the Hunnu culture on the territory of Transbaikalia and Mongolia. The description of the main features of horn and iron plates is given, their images are shown. The origin of various elements of armor plating and the period of their existence are considered. Reconstructions of the armours and helmets of the Hunnu have been created with the involvement of fully preserved analogues. The Hunnic warriors used lamellar and scaly cuirass, poncho, and robe armor, as well as lamellar helmets with a closed dome and an open top. The leading role of the Hunnu in the development of iron armor in Central Asia is noted. The appearance of new details of lamellar armor with an original system of six holes and a plate shape borrowed from scaly armor was revealed in the Hunnu. These plates were borrowed by other nomads and the Chinese. It is concluded that the level of development of defensive means allowed the Hunnu to form independent units of armored cavalry. More complete types of armour and helmets, including those of imported origin, were probably owned by commanders (representatives of the nobility). Ordinary warriors used armor of a lightweight design, where in addition to iron, less resistant materials (horn, leather, wood) were also used. Despite the fact that the Hunnu armored cavalry did not yet have sufficient penetrating power in the confrontation with the Chinese infantry, their experience in the development of defensive weapons proved useful for the subsequent evolution of armor among the Nomads.

Investigation on the microstructures, mechanical properties and impact initiation characteristics of Al/PTFE reactive materials reinforced by TiH2 particles

Aluminum/Polytetrafluoroethylene (Al/PTFE) is a representative energetic material, which can be used in many fields including defense weapon fragments, insensitive penetrator or oil-well perforation. However, the insufficient mechanical strength of traditional ingredient has seriously restricted its penetration ability, and traditional additives improve its compressive strength at the expense of reactivity. Hence, innovative component design and advanced manufacturing technology should be applied to Al/PTFE composite. In this investigation, TiH2 as a new reinforcement is introduced into Al/PTFE to improve both strength and reactivity. Quasi-static and dynamic compressive tests were conducted, and the impact reaction process was recorded by high-speed camera. The results shown Al/PTFE/TiH2 composites are all elasto-plastic materials, significant strain hardening and strain rate hardening phenomenon were observed. The compressive strength increased first and then decreased with increase in TiH2 content, reached the maximum of 185.1 MPa at the strain rate of 5000 s−1 when TiH2 content was 30 %, which increased by 30.4 % compared to traditional Al/PTFE. A newly-developed drop-weight device was used to quantitatively characterize reactivity, and the reaction efficiency reached 8.2 % when TiH2 content was 30 %, increased by 43.2 % compared to Al/PTFE. The formation of oriented PTFE nano-fibers was considered the important strengthening mechanism. The established Johnson–Cook model was agreed well with experimental results. Combining the results of thermogravimetry-differential scanning calorimetry (TG-DSC) tests with X-ray diffraction (XRD) analysis of reaction residues, the reaction mechanism was clarified. The impact initiation reaction was in a mechano-chemical manner and the reactivity was speculated to be the results of multiple actions between Al/PTFE and TiH2.