bluuebunny/crossref_metadata_2025 huggingface dataset:
Design of Combined Buffer on a High-precision Weapon
Authors: Zhang L , Liu JB , Wang W , Liu Y , Zhang YT
Published: May 2023

Taking the buffer of a high-precision sniper weapon as the research object, according to its technical and tactical performance and buffer requirements, this article focuses on the design of the grooved variable hydraulic damper and anti-forward spring buffer by adopting hydraulic spring combination buffer technology. Using MATLAB mathematical simulation software, the recoil force model was constructed, and the simulation calculation was performed. In the light of calculation results, on the basis of modifying and improving the design parameters of the buffer, the actual shooting test of the buffer has been carried out. The test results show that the buffer can effectively reduce the peak value of recoil resistance while ensuring the shooting accuracy of sniper weapons, thereby reflecting the design of the buffer has achieved the expected effect. The test results verify the principle of the combined buffer, which provides certain reference significance for the design of other large-caliber sniper weapons.
Study on General Technology of Smart Floating Munition
Authors: Li Wang , Fei Tong , Kun Zhang , Xiaolei Li
Published: May 2023

In order to cope with the increasingly severe air defense threat and the problem of low cost-effectiveness ratio of traditional air defense missiles, this paper presents an overall scheme of smart floating munition, a small air defense weapon featuring low cost and high cost-effectiveness ratio, which can be used in batches. The composition and working principle of this weapon system are introduced, and the main technologies involved and solutions are discussed in detail. It can be used as a weapon supplement for Chinese military’s specific airspace blockade in the future.
Study on the Application of Ultrasonic Nondestructive Testing Method for Residual Stress of Autofrettaged Barrel
Authors: He Q , Gao X K , Zhou C J
Published: May 2023

Gun barrel under high bore pressure in the process of gun launching. The tangential stress was produced by autofrettaged technology, which can greatly improve the bearing capacity of barrel. The ultrasonic nondestructive testing method was used to design the residual stress testing device of barrel bore. The tangential residual stress of 125 mm barrel at certain depth from the inner surface was measured. The finite element model considering hydraulic autofrettage and finish machining of inner and outer surface of barrel was established, and the simulation data was compared with test data. It showed that the two methods have fine consistency. This technology can be applied to the residual stress detection of gun barrel in the total life cycle, and accumulate valuable data for improving barrel safety.
Numerical Investigation on the Interaction between Rocket Jet and Supersonic Inflow
Authors: Zhu Liang , Song Jun , Hu Bowen , Xu Ze
Published: May 2023

For the problem of interaction between rocket gas jet and supersonic inflow, this paper has investigated the relevant flow field characteristics by numerical simulation. Firstly, a computational program was developed using high-resolution schemes to solve complex supersonic flow field, which solves the Navier-Stokes equations based on a multi-block structural grid using finite volume method as well as k − ω SST turbulence model. Then, a classical experiment was conducted to validate the developed code. Results show that the rocket jet strongly interacts with the supersonic inflow that results in complex wave structure. The nozzle inlet mass flow rate has an important influence on the interaction. When the mass flow rate is in a low level, flow separation and shock train occur in the divergent region, leading to violent oscillation of flow. With the mass flow rate of nozzle inlet increasing, the rocket gas expands continuously after passing the nozzle outlet and the rocket jet would induce more complex shocks.
Experimental Study on the Damage Performance of the Zr-based Amorphous Alloy Jet against Steel Target
Authors: Cui Ping , Shi Dongmei , Wang Deshi , Zhang Xingze , Li Zhuang , Fu Dikun
Published: May 2023

To study the damage performance of the Zr-based amorphous alloy jet against metal target, the static explosive experiments were conducted with the simulated target of 45# steel in comparison with the copper jet. As shown by the experimental results, the depth of penetration (DOP) of the amorphous alloy jet declines with the stand-off distance after it reaches a level higher than 3.0 charge diameter (CD). Under the same conditions, the DOP of the amorphous alloy jet is less than that of the copper jet, and no plugging is found during penetration of the steel target. Moreover, the perforation area of the amorphous alloy jet increases with the stand- off distance. With a large stand-off, the amorphous alloy jet appears to be dispersed and granular during flight, forming the group of erosion holes on the target plate rather than a huge single perforation. Evident chemical reactions took place during the penetration of the amorphous alloy jet. The combined damage effects of both the penetration and explosion allows the shaped charge to obtain larger perforations, while exerting an adverse impact on the DOP as well.
Effect of Sintering Temperature on Room Temperature Microstructure of TiB Reinforced Titanium Matrix Composite
Authors: Wang Q. , Zhang Z.H. , Su T.J. , Li X.Y. , Zhang S.Z. , He J.Y. , Liu L.J. , Jia X.T.
Published: May 2023

In this paper, the 3.5 vol.%TiB reinforced TC4 (Ti6Al4V) matrix composites were successfully fabricated using a mechanical ball milling and spark plasma sintering. The sintering temperature, sintering pressure and holding time were 700 °C~1100 °C, 40 MPa and 5 min, respectively. The 3.5 vol.% TiB/ TC4 matrix composites. The relative density of 3.5 vol.% TiB/TC4 composites increases with the increase of sintering temperature, and reaches saturation when the sintering temperature is 900 °C. The size of α-Lamellae increases from 1.47 μm to 2.44 μm with the increase of sintering temperature. The aspect ratio of TiB whiskers first increase and then decreases along with the solution time extending.
On Manufacturing Process of Guided Rocket Fairing
Authors: Gao Yuan , Zhao Xiaogang , Sun Jianbang , Nan Guangzhi , Guo Zhiwei , Zhang Ping’an
Published: May 2023

This paper proposes a manufacturing technology plan based on the combination of 3D printing and precision cutting for a certain projectile fairing part with a thin-walled cavity structure. By holistically taking into account the process and design requirements, on the one hand, the process structure required for 3D printing and precision cutting is incorporated into the original design plan to improve the manufacturability of parts; on the other hand, the comprehensive research of the process plan, processing strategy, process equipment can solve the manufacturing difficulties during the product development, which not only ensures the realization of the lightweight product design structure, but also meets the requirements of the precision assembly and product usage.
Research Progress in Improving the Load Bearing Capacity of Composite Rocket Motor Cases
Authors: Meng Xiangwu , Zheng Zhicai , Xiao Yachao , Wang Zhizeng , Chen Yan , Wang Ming , Chang Yan
Published: May 2023

The paper summarizes research progress in ways to improve the load bearing capacity of composite motor cases. It especially sheds light on research progress in the selection of case materials, reinforcement technologies, experimental study and finite element analysis, layer sequence optimization, and hybrid fiber design for boosting the internal and external load bearing capacity of solid rocket motors’ composite cases.
Experimental Simulation of Dynamic Compression Properties of CFRP Cylinders under High Launch Overload
Authors: Wang W , Wang XC , Chen CX , Zhao H , Gao B , Zhang B , Feng JC , Peng G
Published: May 2023

Abstract.To explore the mechanical behavior of carbon fiber reinforced plastics (CFRP) under high launch overload, this study presents a laboratory loading technological method for chamber-pressure curve simulation under high launch overload using a Φ100 mm-diameter split-Hopkinson pressure bar (SHPB) device. On this basis, experiments are carried out to study the dynamic compression properties and failure modes of CFRP cylinders. The results show that applying a load changing in a similar way to the chamber pressure-temperature (P-T) curve to the specimens using a large-diameter SHPB device is an effective technical means to simulate the behavior evolution of CFRP cylinders under high launch overload. Through load testing and simulation, it is found that CFRP cylindrical members have a dynamic compressive strength of 611 MPa, and the maximum force and weight overload of 893 kN and 9023 g respectively, and failure strain between 0.5% and 0.6%. As a structural member, CFRP cylinders exhibit high rigidity and good resistance to high overload.
Research on Multiscale Structure, Component and Properity of Meretrix Lusoria Shell
Authors: Duan TT , Xu XY , Qu FZ , Guo Y , Yan SQ , Wang LL , Ruan GG , Wang JH , Xin PX , Huang YS , Wang L , Wang DG , Li N , Zheng W
Published: May 2023

This research was carried out with focus on the multi-scale structure of meretrix lusoria shell. In mesoscopic, meretrix lusoria shell contains three layers; the thickness of different layers is 0.6mm, 0.8mm and 0.7mm respectively. Compared to mesoscopic structure, the microstructure also has three layers, it refers to cuticle, prismatic layer and nacre. The cuticle is composed of a great number of particles, and its main composition is protein.The prismatic layer is composed of stagger structure. The inner layer presents orthogonal-sheets arrangement. This microstructure might show a special enhanced effect for the whole shell. The different inorganic layers’ crystal is same, which is aragonite. The mechanical properties of Meretrix lusoria shell are excellent, its elastic modulus was the same order of magnitude of high strength glass fiber composites. From this research will provide the theoretical basis for designing and producing bioinspired composite materials.
Influence of Polyurea Packaging Material on Anti-explosion Performance of a Fuze
Authors: Wen Q , Chang TX , Yu SR , Wang GY , Wang YS
Published: May 2023

Polyurea coating has excellent anti-explosion performance. In order to solve the problem of sympathetic detonation of a fuze, a polyuria-coated packaging barrel is designed. ANSYS software is used to simulate the sympathetic detonation test to verify the anti-explosion performance of the packaging barrel. The shock wave and explosion products produced from explosion are obviously hindered. The packaging barrel and the fuze body are damaged but the booster of the fuze is not detonated. The maximum pressure of selected elements in booster is 13.0 GPa, which is less than the initiation pressure of TATB in the booster. The acceptor fuze is not sympathetically detonated. A sympathetic detonation test is carried out and the results are consistent with the simulation.
Study on Interfacial Properties of Carbon Nanotube Modified Epoxy Resin/T1000 Carbon Fiber Composites
Authors: Xiao YC , Ma YD , Zheng ZC , Meng XW , Wang M , Wang Q , Chen Y
Published: May 2023

This study was made on domestic T1000 carbon fiber to investigate its surface condition, precursor, multifilament, fiber/resin contact angle, fiber/resin interfacial shear strength and interlaminar shear strength. Analysis was carried out to examine the surface physical state of domestic T1000 carbon fiber, the micro-scale interfacial properties and mechanical properties of the composites. The results show that domestic T1000 grade carbon fiber has no inherent characteristic defects such as visible bumps, rough edges or grooves on its surface. It can obtain higher tensile strength. The fiber/resin interfacial test shows that carboxylated carbon nanotubes are well dispersed in the epoxy resin matrix by physical method. The mixed resin matrix has good wettability on carbon fibers and the contact angle of the composite interface decreases. The interfacial shear strength of SYT65 carbon fibers/resin increases by 10.6%, and the interlaminar shear strength increases by 15.7%. Toray T1000 carbon fiber/resin interfacial shear strength increases by 6.1%, and interlaminar shear strength increases by 14.1%. Compared with Toray T1000, the resin system used in this study is more compatible with SYT65 carbon fiber, which can give full play to the mechanical properties of SYT65 carbon fiber.
Preparation and Properties of PBO Nanofiber Membranes via Electrospinning and Thermal Conversion
Authors: Xu XY , Duan TT , Guo Y , Wang JH , Yan SQ , Wang LL , Ruan GG , Wang L , Huang YS , Li N , Wang DG , Xin PX , Zheng W
Published: May 2023

In this study, Polybenzoxazole (PBO) nanofiber membranes are prepared by applying a three-step process, including synthesis of the electrospinning precursor with ortho-hydroxyl, electrospinning, and thermal conversion. Electrospinning is conducted at 10 kV with a distance of 10 cm and the solution concentration is 17.8% (w/v). Different flow rates are adopted to prepare polymer nanofiber membranes and test their properties. At the rate of 0.5 μL/min and 1 μL/min, uniform and compact films with nanofibers are obtained. The high-temperature transition from the precursor to PBO is then investigated systematically. Thermal treatment at 420°C is needed for complete cyclodecarboxylation conversion from the precursor to PBO. Diameters of the fibers in the as-prepared PBO nanofiber membrane are within the range of 120-130 nm. The membrane shows high thermal stability with the decomposition temperature of 619.8°C in N2 and 513.6°C in air respectively, presenting a promising application prospect in high-temperature areas.
Study on the Flexible Erosion Reducing Additive Containing Silicon and Boron
Authors: Fan W , Zhu W F , Gao P , He X M , Wang J B
Published: May 2023

In view of the severe erosion and wear of gun barrels, we first briefly introduce the research status of erosion reducing additives in this article. Based on these analyses, polydimethylsiloxane (PDMS)-Na2B4O7 additive and PDMS-H3BO3 additive are designed and prepared. These two additives are very flexible and can be folded or bent in any direction. After that, the erosion reducing performance of paraffin wax (PW)-TiO2 additive, PDMS-Na2B4O7 additive and PDMS-H3BO3 additive are studied through the vented vessel test. The results show that the erosion reducing performance of PDMS-Na2B4O7 additive and PDMS-H3BO3 additive is better than that of PW-TiO2 additive. But PDMS-Na2B4O7 additive cannot be completely burned and there are residues at the loading position of additives. PDMS-H3BO3 additive can provide the best erosion reducing performance and without residues. Therefore, PDMS-H3BO3 additive is selected for further research. The effect of granularity of H3BO3 on the erosion reducing performance is studied and compared with PW-TiO2 additive. The results show that the erosion reducing rate of PDMS-H3BO3-500 mesh additive and PDMS-H3BO3-3000 mesh additive is increased by 6.24% and 6.46%, respectively, compared with PW-TiO2 additive. PDMS-H3BO3-3000 mesh additive can provide better erosion reducing performance. But the granularity of H3BO3 has no obvious effect on the erosion reducing performance.
Optimizing the Anti-stab Performance of Fiber Composites by Using Ceramic Particle Reinforcements
Authors: Wei Rubin , Zhang Hui , Zong Hao , Dong Bin , Wang Xiaowei , Zhai Wen
Published: May 2023

Fiber reinforced composite is widely used in current stab-proof equipment, the high performance and light weight have always been pursued for a long time. The present study optimizes the anti-stab performance of fiber composites by using silica and silicon carbide ceramic particle reinforcements. The anti-stab performance of different composite processes and composite structures were characterized. Silica particle reinforcements were added to the fiber fabric in the form of a shear thickening fluid (STF). Quasi-static puncture tests results revealed that the puncture force of the fiber composite prepared by STF dilution process was significantly higher than that of the sample prepared without dilution. Under the same areal density, the puncture force of the sample with a dilution ratio of 1:2 had been improved by 79.9% higher than that of pure fiber fabrics. Silicon carbide particle reinforcements were added to the fiber fabric in the form of particles/epoxy resin coating. After coated with SiC particles, the aramid fiber fabric not only greatly improves the puncture force, but also significantly increases the wear of the tool. The dynamic puncture test results further showed that the SiC coated / STF aramid plain weave fabrics exhibited excellent stab-resistant performance.
Effects of Self-heating Process on the Mechanical Properties and Energy Consumption in Molding of Carbon Fiber/Epoxy Composites
Authors: Wang ZY , Chen G , Wang QF , Chong L , Yu QQ , Wu ZQ , Wang Z
Published: May 2023

In order to increase the molding efficiency of carbon fiber composites and reduce their energy consumption in molding and manufacturing costs, this study explores the self-heating molding process of carbon fiber composites and investigates the uniformity of temperature distribution of carbon fiber/epoxy (CF/EP) composites. Besides, the mechanical properties, molding efficiency and energy consumption of CF/EP composite laminates are studied, and the comparison with the conventional hot compression molding process is conducted. The results show that the fixing mode of the electrodes greatly affects the heating rate and temperature uniformity-specifically, the use of bolted pressure plates leads to a faster heating rate and a more uniform temperature distribution than the use of conductive adhesive tape. During the self-heating process, the temperature difference inside the prepreg stack of CF/EP composite laminates was found less than 5°C. Compared with the CF/EP composite laminates molded by hot compression, those molded by self-heating exhibited an increase in tensile strength by 14.9%, compressive strength by 14.2%, interlaminar shear strength by 2.5%, tensile modulus by 11.6%, and flexural modulus by 11.1%, except for bending strength that showed no significant improvement. The self-heating molding process showed a heating rate of 5-10 times higher than the hot compression molding process, consumed only about 6.8% of the energy that the latter required, and increased the molding efficiency by 32%.
New Trends in Ballistic UHMWPE UD Fabric
Authors: Wang JH , Guo Y , Su YX , Xu XY , Duan TT , Wang LL , Yan SQ , Ruan GG , Xin PX , Wang L , Li N , Huang YS , Zheng W
Published: May 2023

Ultra-high molecular weight polyethylene unidirectional fabric (hereinafter referred to as UHMWPE UD fabric) composite material is a ballistic composite material with excellent performance. Aiming to improve the ballistic property of UD fabric composite, this paper introduces the new trends both in polyethylene fiber broadening technology and UHMWPE UD fabric resin system; in view of the low heat resistance and poor resistance of UHMWPE UD fabric, the application and development of functionalized UHMWPE UD fabric composite are discussed. Finally, a new type of molecular ballistic composite material is proposed, which has a micro-structure obviously different from that of the conventional UHMWPE UD fabric composite.
Development of Methods for Determining Molecular Weights of Epoxy Resin
Authors: Hou QQ , Liu X , Gong W , Xu F , Zhang WS , Dong YZ , Xun QN , Ji KJ
Published: May 2023

Molecular weight, as one of the characteristic indexes of the intrinsic structure of epoxy resin, has a decisive impact on the curing process of epoxy resin, the structure of cured products and even the properties of composites. It is an important indicator for the quality evaluation of epoxy resin. This paper introduces various instrumental analysis techniques for molecular weight testing, including gel permeation chromatography, nuclear magnetic resonance spectroscopy, vapor pressure osmometry and mass spectrometry, and also compares and reviews the principles, characteristics, applications, and problems of each method, and finally looks into the research prospects.
Effect of Different Si Target Currents on Performance of Magnetron Sputtering Wear Resistant Coatings
Authors: Liu D , Shen YL , Wang EL , Meng C , Liu J , Shen QM
Published: May 2023

In order to ameliorate the properties of the coating material on the surface of the key moving parts of artillery, the influence of different Si target currents on microstructure and mechanical performances of magnetron sputtering TiAlMoSiN coating was studied. The phase structure of the coating, microstructure, coating adhesion, friction and wear properties were characterized, respectively. The deposited TiAlMoSiN coatings were mainly composed of TiN phase, Mo2N phase, amorphous Si3N4 phase and amorphous AlN phase. A typical columnar nano-multilayer structure was formed on the TiAlMoSiN coating after magnetron sputtering process. When the Si target current reached 1.0A, the coating hardness was supreme, valued 32.6 GPa. Along with the addition of the Si target current, the hardness and the bonding strength between the coatings and 45 steel substrates declined. As the Si target current was 1.5 A, TiAlMoSiN coating has the lowest friction coefficient and wear rate. Moreover, it was found out the coating with Si target current at 1.0A had shown the optimal surface properties.
Numerical Simulations of Reactive Material Double-Layered Liner Shaped Charge Penetrating Steel Target
Authors: He Suo , Chen Ting-hao , Sun Tao , Guo Huan-guo
Published: May 2023

The jet formation and penetration behaviors of shaped charge with a reactive material double-layered liner (RM-DLL) are presented in this paper based on the AUTODYN-2D code. Numerical results show that the wall thickness ratio of the RM-liner to the metal liner has a significant influence on the formation and penetration characteristics of composite jet. As the wall thickness ratio increases, the tip velocity of composite jet, the pressure on the RM-liner, and the temperature of RM-elements decrease. The effect of the wall thickness ratio on the penetration performance of RM-DLL shaped charges against steel targets significantly depends on the RM-initiation delay time (τ). The penetration depth (PD) of the composite jet with titanium liner into the steel target is limited. In the case of the RM-tungsten liner, the RM-mass following into the penetration crater is very small. In the case of the RM-copper liner, the penetration capability of composite jet is well matched with the mass of follow-thru RMs. Compared with the PD, the standoff has a more significant impact on the RM-mass entering the penetration hole.
Progress in the Preparation Methods of Poly (P-Phenylene Benzodioxazole)
Authors: Liu W , Guo C , Zhang DB , Chen XD , Peng XY
Published: May 2023

Poly (p-phenylene benzodioxazole) is an aromatic liquid crystalline polymer. Because of its unique rigid structure, high strength, high modulus, high temperature resistance and excellent chemical stability, it has broad application prospects in aerospace, ballistic resistance, fire protection and reinforcement materials. This paper summarizes several routes and methods for the preparation of PBO polymers, such as the terephthalic acid method, the AB monomer polymerization method, the TD complex salt method, and explains the development direction of the preparation of PBO polymers.
Ballistic Performance of Protection Structures Using Fiber Composites as Matrix Armor
Authors: Guo Y , Wang JH , Xu XY , Duan TT , Yan SQ , Wang DG , Xin PX , Wang L , Huang YS , Li N
Published: May 2023

The protective performance of a composite structure composed of the composite layer (FC composite) as the matrix armor and the ballistic ceramic layer as the faceplate against Type 53 7.62 mm Armor-Piercing Incendiary (API) is studied. FC composite is used as the hybrid fiber layer mainly containing carbon fiber, and the ballistic ceramic layer is respectively made of three kinds of ballistic ceramics: alumina, silicon carbide and boron carbide. The results show that the weight of boron carbide ceramic is 14% ~ 30% less than that of alumina ceramic and 10% ~ 24% less than that of silicon carbide ceramic under equal thickness of the FC composite substrate. The lowest total areal density is 44 kg/m2 when the bearing capacity of the armored vehicle is basically satisfied.
Study on Batch Deep-hole Drilling Technology of Carbon Fiber Reinforced Plastics
Authors: Shao M , Kong GQ , Wang K , Li DY , Yu QB , An ZH , Yao W , Liu XF
Published: May 2023

To meet assembly requirements, carbon fiber reinforced plastics (CFRP) generally require mechanical processing, of which the most common form is drilling. As a result of the increasing quantity of use and growing structural complexity of CFRP, the demand for batch high-precision hole making is becoming increasingly urgent. However, existing research is mostly focused on the small-batch and small-thickness drilling of samples. With a customized PCD drill bit, this study investigates the effects of large-batch drilling on the failure forms of the drill bit and the quality of holes drilled. The results show that (1) chip adhesion is of great importance to the failure of the drill bit in the process of batch hole making; (2) fluid cutting facilitates the cooling, lubrication, and chip removal of the bit, thereby dramatically reducing tool wear; (3) dry cutting leads to micro hole expansion so that the holes drilled have a slightly larger diameter than the drill bit; and (4) the addition of support plates at the exit position can effectively avoid defects such as exit tear and delamination.
Numerical Simulation of Triple-Layer Reactive Composite EFP Formation and Penetrating Interval Target
Authors: Wang Shi-peng , Ji Peng-yuan , He Suo , Cai Yi-qiang , Zheng Yuan-feng
Published: May 2023

In order to study the formation and penetration behavior of triple-layer reactive composite EFP, numerical simulation method is used to describe the formation and penetration process, and reveals the influence of blasting height on the formation and penetration. The numerical simulation results show that the formation process of the reactive composite EFP includes impact, boost and stretching flight stages. The impact stage: under the impact of detonation wave and detonation product, the outer, middle and inner liners collide with each other, kinetic energy exchange occurs during the process, and finally they are adhered to each other. The boost stage: the detonation wave and detonation products continue to promote the overall flight of EFP, and they begin to disappear gradually. The stretching flight stage: after the external impetus disappeared, the reactive composite EFP continues to fly by its own inertia and gradually stretches. The blasting height has a great influence on the formation and penetration behavior of reactive composite EFP. The results have certain reference significance for the study of triple-layer reactive composite EFP.
Research on the formation behavior of PTFE/Al reactive explosively formed projectile
Authors: Su Cheng-hai , Xiao Yan-wen , Sun Tao , Zheng Yuan-feng
Published: May 2023

Based on AUTODYN-3D finite element analysis platform, the SPH algorithm is used to simulate the forming characteristics of Al/PTFE reactive Explosively Formed Projectile (EFP). The evolution behaviors and distribution of morphology, velocity, density, and temperature field during the reactive EFP were analyzed. Numerical simulation results show that Al/PTFE reactive shaped charge can form stable reactive EFP, and the overall density of reactive EFP decreases with the extension of the forming time, and the density of reactive EFP is much lower than the initial density of reactive liner. When the reactive EFP is in the state of freely flying, the high temperature region mainly concentrates on the tail of the reactive EFP, the bottom of the reactive liner and the fracture flying zone, and the high temperature region proportion is significantly affected by the explosive type, the curvature radius of the reactive liner and the wall thickness of the reactive liner.
Ubiquitiformal Characterization on Meso-structure of Granular Composite Materials
Authors: Ju YB , Liu HT , Li EK , Yu F
Published: May 2023

A ubiquitiformal approach to characterize the mesostructure feature of granular composite materials is developed, and the complexity of a granular composite material is determined by its particle size distribution. To verify the validity, the ubiquitiform model for concrete is proposed and examined. It is found that the calculated numerical results of the complexity and PSD are in good agreement with the previous experimental data. Moreover, by using the ubiquitiform model, an analytical expression of the equivalent Young’s modulus for the concrete is obtained, it is also found that the numerical results are in good agreement with the previous experimental data.
Impact of Raw Phenyl Silicone Rubber Parameters on ethod Vulcanized Phenyl Silicone Rubber
Authors: Li H , Liu FB , Li B , Liu P , Sun ZY , Du HT , Du MX , Ma WD , Sun GH
Published: May 2023

Based on the structure of raw phenyl silicone rubber and performance of vulcanized rubber, the properties of raw and vulcanized phenyl silicone rubber are tested in this study. The relationship between raw rubber parameters and the influence of raw rubber properties on the performance of vulcanized rubber are also analyzed. Conclusions are as follows: (1) The viscosity average molecular weight of the raw silicone rubber measured by Ubbelohde viscometer and gel permeation chromatography (GPC) mdiffers relatively greatly, with the result of Ubbelohde viscometer higher than that of GPC. (2) The glass transition temperature of raw silicone rubber is significantly affected by the molar content of phenyl chain (phenyl content) in its structure. In a good linear relationship with phenyl content, it increases as the phenyl content increases. (3) The static glass transition temperature of raw rubber measured by differential scanning calorimetry (DSC) is 0-15 °C lower than the dynamic glass transition temperature measured by dynamic thermo-mechanical analyzer (DMA). (4) Mooney viscosity increases with the increase of the viscosity average molecular weight of raw rubber. (5) As phenyl content rises from 20 % to 40 %, the damping peak loss factor of vulcanized rubber increases from 0.4 to 0.7 and the damping peak temperature increases from -90 °C to -40 °C. (6) As the molar content of vinyl chain (vinyl content) is raised from 0.1 % to 0.6 %, the hardness of vulcanized rubber is boosted from 45 to 65, and the tensile strength decreases from 12 MPa to 6 MPa. (7) With the increase of vinyl content from 0.1 % to 0.4 %, the tear strength of vulcanized rubber decreases from 45 kN/m to 25 kN/m. (8) The vinyl content has an obvious impact on the damping performance of vulcanized rubber at high temperatures. When vinyl content increases from 0.1 % to 0.5 %, the damping property of the vulcanized rubber under high temperature drops from 0.25 to 0.1. (9) The compression set of vulcanized rubber decreases with the increase of vinyl content of raw rubber.
Study on the Test and Evaluation Technology for Multi-weapon Actual Combat Effectiveness in Multi-domains
Authors: Wu J P , Ren M , Liu M F , Liao M , Yan Z G , Lv H P , Sun W P
Published: May 2023

In view of the new characteristics and demands presented in the actual combat training assessment of our troops in recent years, such as fast attack of weapons and ammunitions, wide attack range, multi-bomb attack multi-target, low missing test rate, giving the assessment results quickly, etc., the disadvantages of the current attack effectiveness and evaluation system are analyzed. In this paper, multi-aperture integration optical measuring station, radar and unmanned aerial vehicle (UAV) three-dimensional measurement technology, higher adaptive broadband transmission technology, measurement and control network based on cloud computing technology are explored. The aim is to promote the current single projectile effectiveness test system to multi-weapon combat effectiveness test and evaluation system, which will improve the training level of our troops rapidly.
Discussion On Low-cost Design of Ammunition Electrical System
Authors: Hang Xu , yang Zhang , Hongxing Zheng , Fei Zuo , Xiaowen Xi , Shi He
Published: May 2023

Facing the demands of future battlefield, it is necessary to realize the low-cost design of missiles to meet the large demand for small missiles in the future battlefield. Based on this condition, this paper systematically studies the low-cost optimization design of missile safety scheme and the implementation of the low-cost design of cable network, and puts forward the scheme that can achieve the low-cost design of ammunition electrical system.
Disturbance Observer based Dynamic Surface Sliding Mode Control for Manipulator Arm with Adaptive RBF Networks
Authors: Zhou G Z , Zou Q , Shao S C
Published: May 2023

For the rotation position control of automatic loading manipulator arm with uncertain problems of load change and external disturbances, an adaptive radial basis function networks (RBF) dynamic surface sliding mode control (DSMC) strategy based on disturbance observer (DOB) is proposed. The value of the external disturbance, which is estimated by the DOB on line, is added to the output of the proposed controller for feedforward compensation. The dynamic performance of the controller is ensured by introducing the adaptive RBF networks while the stability of the controller is verified by designing the Lyapunov function. Comparison between the results of the proposed control strategy and those of the conventional sliding mode control (SMC) shows that the controller has better dynamic tracking characteristics, steady-state accuracy and strong robustness under load changes.
Research on Technology of Low-cost Flight Control Components for Intelligent Ammunition
Authors: Li Ding , Jing-zhu Xie , Yao Pu
Published: May 2023

The flight control component is a complex embedded computer system integrating navigation solution, control calculation and rudder control calculation, which is the core component of intelligent ammunition flight control system. Through the analysis and comparison of the hardware interface and operational capability requirements of flight control components of different guidance systems, the results show that the guidance system is the key factor affecting the overall structure of flight control components, then summarize the typical embedded processor type and peripheral interface mode in product performance and cost, and propose the design process and design principle of low-cost flight control components of intelligent ammunition.
Application of Artificial Intelligence in Spacecraft Ground Testing
Authors: Bo Zang , Lei Zang , Xin Chang
Published: May 2023

With the accelerated application of new-generation information technologies, developed countries have implemented digitalization strategies to gain a competitive advantage in the digital era. Artificial intelligence (AI) is widely used in a wide range of modern industries. Our country has put increasing emphasis on AI technologies, and our aerospace industry is being more digitalized. This study focuses on the application prospects of AI in spacecraft ground testing. It aims to build smart labs driven by products and discusses how to integrate AI into the process of quality supervision, instability prediction, situational awareness analysis for equipment, and optimization of knowledge-driven product design, thus digitalizing spacecraft ground tests.
Application of Intelligent Inspection Units in Improving the Safety of Large Thermal Test Systems
Authors: Xin Chang , Bo Zang , Yang Wang , Wenhao Xu , Kuang Liu
Published: May 2023

To ensure the success of space launch, large-scale thermal testing at the ground system level must be conducted for spacecraft products to verify their design, performance and quality. Such tests have the characteristics of high technical difficulty, high safety risks, complex supporting equipment, and long test cycles. So it is of great significance to improve the safety and reliability of large thermal test systems to ensure successful verifications of the spacecrafts. This paper focuses on the application of integrating artificial intelligence technology with the safety of large thermal test systems, and discusses improving the safety of large-scale thermal testing by using mobile intelligent inspection units, fixed intelligent inspection units, digital diagnosis, and situation prediction.
Is it possible to reach a sustainable change in Science Teaching at primary schools? A plan for achieving it
Authors: Nicolás-Castellano C , Limiñana R , Menargues A , Martínez-Torregrosa J
Published: May 2023

One of the great challenges of recent decades, which has been the subject of much debate and research, is how to bridge the gap between science education research and school practice. To address this issue, we have reviewed and analysed in depth the characteristics that in-service teacher training programmes should have in order to be effective and of high quality. In this paper, we present a professional development programme to achieve the desired didactic change in science teaching at schools. This programme is organized into phases that can be evaluated by measurable indicators to determine its success or failure. In addition, in order to assess the sustainability of change in a school (or group of teachers), we have incorporated the theory of critical mass in social change, which has received recent empirical support.
Implementing the use of Energy Bar Charts in the framework of an Early Physics approach
Authors: Bologna V , Leban S P , Longo F , Peressi M , Sorzio P
Published: May 2023

Introductory college courses use the Multiple Representations (MR) method for teaching/learning energy processes. It helps students understand concepts which are challenging to learn, like energy, and to solve related problems. Although this method is well-recognised in the context of Physics Education and researchers, it is less known by high school teachers because of its limited use in Physics textbooks. We report a recent experience where we accompanied teachers in their Pedagogical Content Knowledge (PCK) revision and in the building of an innovative way of teaching using conceptual fragmentation. The assessment confirmed the teaching efficiency of using Multiple Representations tools such as Energy Bar Charts.
Effect of electrokinetic treatment time on energy consumption and salt ions removal from clayey soils
Authors: Hussain Abdul Ahad , Kamran Kashif , Hina Maryam , Ishaq Mubashera , Naz Muhammad Y , Bashir Shahid , Sarwar Nadeem , Quazi Moinuddin Mohammed
Published: May 2023

Electrokinetics effectively removes contaminants, but its field-scale applications are limited mainly due to its high energy cost. In previous studies, the energy consumption was determined either by changing the soil’s specimens initial salt concentration while keeping the treatment time fixed or by changing the treatment time and keeping the same initial salt concentrations for all the specimens. Since both the initial salt concentration and treatment time are important parameters in determining reclamation cost, therefore, in this study, the soil specimens intentionally contaminated with different concentrations of sodium chloride (NaCl), i.e., varying from 3.7 to 15.5 g kg−1, were exposed to a constant DC electric field of 1 V cm−1for different time durations, i.e., varying from 6 to 72 h. The results show that electroosmotic flow (EOF) was directed from the anode to the cathode and higher for specimens contaminated with relatively low salt concentration, i.e., up to 7.6 g kg−1. Therefore, for these specimens, due to the combined effect of electroosmosis and electromigration, the removal of Na+was higher than the Cl−. However, for the specimen contaminated with a higher salt concentration, i.e., 15.5 g kg−1, the Cl−removal exceeded Na+due to the marginalization of EOF. Regardless of initial salt concentration, the electroosmotic flow and salt ions removal rates decreased with increasing treatment time, which might be attributed to the development of acidic and alkaline environments in soil. The collision of acidic and alkaline fronts resulted in a large potential gradient in a narrow soil region of pH jump, diminishing it everywhere else. This nonlinearity in the electric potential distribution in soil reduced the EOF and electromigration of salt ions.
A silver nanoparticle (AgNP)-loaded Bi2Se3 topological insulator p-n heterojunction photodiode for a near-infrared (NIR) photodetector
Authors: Elangovan Vinoth , Vaiyapuri Vijay , R Aysha Parveen , Jayaram Archana , Santhanakrishnan Harish , Mani Navaneethan
Published: May 2023

Near-infrared (NIR) photons are expanding advanced applications in optoelectronics. However, while 2D materials like graphene offer an attractive route for NIR photodetection, the alternative for high-performance NIR detection is still evolving. Hence, solution-processed n-Bi2Se3
/p-Si-based 2D heterojunction photodiodes have been fabricated here and used for high-performance NIR detection. Further, we report high photoresponsivity of 248 mA W−1 at 1100 nm, high external quantum efficiency of 22, 23 and 28% for Ag-loaded (at 5, 7.5 and 10%) Bi2Se3 and good stability. The chemical states of Bi2Se3 and Ag are detected using the core-level spectra of x-ray photoelectron spectroscopy. Photoresponse I–V characteristics are investigated under both dark and illumination; the high photocurrent achieved for Ag-loaded Bi2Se3 and the increase in the forward photocurrent under both dark and bright conditions are reported. The temporal photoresponse curve confirms the good stability (photoswitching behavior) and reproducibility with a response time of 0.74 s and a decay time of 0.18 s. Therefore, these unique performance and device parameters of a manufactured photodiode strongly recommend as a potential heterojunction photodiode for an NIR photodetector.
The effect of configurational entropy on acoustic emission of P2-type layered oxide cathodes for sodium-ion batteries
Authors: Dreyer Sören L , Zhang Ruizhuo , Wang Junbo , Kondrakov Aleksandr , Wang Qingsong , Brezesinski Torsten , Janek Jürgen
Published: May 2023

Sodium-ion batteries (SIBs) see intensive research and commercialization efforts, aiming to establish them as an alternative to lithium-ion batteries. Among the reported cathode material families for SIBs, Na-deficient P2-type layered oxides are promising candidates, benefiting from fast sodium diffusion and therefore high charge/discharge rates. However, upon sodium extraction at high potentials, a transition from the P2 to O2 phase occurs, with the corresponding change in cell volume resulting in particle fracture and capacity degradation. A possible solution to this is to increase configurational entropy by introducing more elements into the transition-metal layer (so-called high-entropy concept), leading to some kind of structural stabilization. In this work, the acoustic emission (AE) of a series of P2-type layered oxide cathodes with increasing configurational entropy [Na0.67(Mn0.55Ni0.21Co0.24)O2, Na0.67(Mn0.45Ni0.18Co0.24Ti0.1Mg0.03)O2 and Na0.67(Mn0.45Ni0.18Co0.18Ti0.1Mg0.03Al0.04Fe0.02)O2] is recorded during SIB operation and correlated to the materials properties, namely change in c lattice parameter and cracking behavior. A structure-property relationship between entropy, manifested in the extent of phase transition, and detected AE is derived, supported by the classification of signals by peak frequency. This classification in combination with microscopy imaging allows to distinguish between inter- and intragranular fracture. Relatively more intergranular and less intragranular crack formation is observed with increasing configurational entropy.
Bearing fault diagnosis based on improved cepstrum under variable speed condition
Authors: Wang Jian , Sun Yongjian , Wang Wei
Published: May 2023

The speed of rolling bearing often varies in actual operation process, the fault diagnosis of variable speed bearing is particularly important. In this paper, the definition of local maximum peak value of cepstrum is proposed, which can be used to extract variable speed features. And a variable speed bearing fault diagnosis method based on improved cepstrum is proposed. The proposed method could extract fault feature without tachometer and resampling. At first, the Local maximum peaks of the original cepstrum are extracted. Then, the corresponding thresholds of the peaks are calculated and determined one by one. Finally, the feature extraction is completed according to the thresholds. At the same time, this paper verified the feature extraction results under three different variable speed conditions, including acceleration, deceleration, and acceleration before deceleration. The experiments results show that the proposed method has higher accuracy (99.08%) and less running time than the other spectral analysis methods, which demonstrates the accuracy, rapidity and effectiveness. This proposed method provides a novel idea for fault diagnosis under condition of variable speed.
Evaluation of physical, mechanical and sliding wear properties of in-situ AB-TiC composite: a comparison with NAB alloy
Authors: Rathod S , Srivastava Yogesh , Kiragi Vinayaka R , Patnaik Amar
Published: May 2023

The purpose of the present study is to evaluate the physical, mechanical and sliding wear properties/response of cast in-situ aluminium bronze (AB)-TiC [(Cu10Al3Fe)5TiC] composite and compare with cast nickel aluminium bronze (NAB) [Cu10Al5Ni5Fe] alloy. Sliding wear tests were conducted in dry and partially lubricant conditions using a pin-on-disc machine. A test material in the form of pin was evaluated against a rotating heat-treated EN-31 steel disc. Wear loss, frictional heating and friction coefficient properties were examined. The NAB alloy showed higher tensile strength (32.7%), compressive strength (7.68% at room temperature. and 4.18% at 500 °C), hardness (8.78%) and density (3.17%), whereas thermal conductivity of the AB-TiC composite was found 4.89% higher than NAB alloy. In dry sliding condition, composite outperformed NAB alloy in terms of wear resistance up to a critical applied load and/or sliding speed. Beyond this point, the wear behavior altered. Increasing sliding speed caused to reduce wear transition load. While friction coefficient showed mixed trend. Under lubricated wear test conditions, AB-TiC composite displayed considerably higher wear resistance (50.08%, 44.41% & 51.55%) and friction coefficient (26.37%, 40.75% & 14.96%) than the NAB alloy when tested in only oil, oil with 100 μm graphite and oil with 7–10 μm graphite respectively. Arrival of seizure in general caused significantly higher wear loss and temperature rise. In addition, it caused large adhesion of the specimen material to the disc surface. The reported wear behaviour of the samples has been validated using the features of wear surfaces and subsurface regions. The latter also permitted to comprehend the working wear processes. The analysis significantly shows good impacts of the oil lubrication (with and without solid particles) in terms of decreasing wear rate, frictional heating, and friction coefficient. Formation of steady lubricating film/layer was reported to be responsible for the better wear performance of the samples. Furthermore, irrespective of material composition and microstructure there exists a precise set of test parameters (e.g. load and speed) leading to optimal wear performance wherein the beneficial impacts of load bearing capability, thermal stability of various phases predominates.