To investigate the effects of silicon formulations on the cold tolerance of rice seedlings,Song Japonica 16(not cold tolerant)and Dongnong 427(cold tolerant)rice varieties were used as test materials and four differen...To investigate the effects of silicon formulations on the cold tolerance of rice seedlings,Song Japonica 16(not cold tolerant)and Dongnong 427(cold tolerant)rice varieties were used as test materials and four different types of silicon formulations,Si-50-G,Si-60-G,Si-T-G,and Si-E-G,were applied as foliar sprays at the seedling stage,and a control group CK(equal amount of distilled water)was set up.One week after the first silicon spray,two types of rice were subjected to low-temperature stress treatments at day/night temperatures of 12℃/10℃for 2,4,6,and 8 days.The effects of different silicon formulations on the chlorophyll,proline(Pro)and soluble sugar contents as well as superoxide dismutase(SOD),peroxidase(POD)and catalase(CAT)activities of rice seedlings under low-temperature stress were compared to find out the effects of silicon formulations on the cold tolerance of rice seedlings.The results showed that silicon formulations could significantly increase the chlorophyll content of rice seedling leaves,with Si-50-G being the most effective,with a significant increment of 40.17%compared to the CK at 2 days of low temperature.Four silicon formulations significantly increased the proline content and soluble sugar content of rice leaves at low temperature for 4-8 days.For Song Japonica 16,the most significant increment in leaf POD activity was observed in Si-E-G treatment at 2,4 and 8 days of temperature stress,with 73.58%,20.95%and 217.24%increases compared to the CK,respectively.For 4 and 6 days of temperature stress,the most significant increase in CAT activity was observed in Si-E-G treatment,with 25.70%and 75.78%increases compared to the CK,respectively.For Dongnong 427,the Si-60-G treatment showed the highest increase in leaf SOD activity for 4 and 8 days of temperature stress,with significant increases of 58.15%and 82.76%compared to the CK,respectively,and the Si-E-G treatment showed the highest increase in leaf POD activity for 2 and 8 days of temperature stress,with significant increases of 97.75%and 245.10%compared to the CK,respectively.It showed that the spraying of silicon formulations could significantly enhance the cold tolerance of rice.This study provided a scientific basis for the rational use of silicon formulations to enhance cold tolerance in rice and had important theoretical and practical significance for ensuring sustainable high and stable rice yields in Heilongjiang Province,as well as for the development of silicon fertilizers.展开更多
Continuous carbon fiber reinforced silicon carbide(C/SiC)composites are often subjected to low-velocity impacts when utilized as structural materials for thermal protection.However,research on in-plane impact damage a...Continuous carbon fiber reinforced silicon carbide(C/SiC)composites are often subjected to low-velocity impacts when utilized as structural materials for thermal protection.However,research on in-plane impact damage and multiple impact damage of C/SiC composites is limited.To investigate the in-plane impact damage behavior of C/SiC composites,a drop-weight impact test method was developed for strip samples,and these results were subsequently compared with those of C/SiC composite plates.Results show that the in-plane impact behavior of C/SiC strip samples is similar to that of C/SiC composite plates.Variation of the impact load with displacement is characterized by three stages:a nearly linear stage,a severe load drop stage,and a rebound stage where displacement occurs after the impact energy exceeds its peak value.Impact damage behavior under single and multiple impacts on 2D plain and 3D needled C/SiC composites was investigated at different impact energies and durations.Crack propagation in C/SiC composites was studied by computerized tomography(CT)technique.In the 2D plain C/SiC composite,load propagation between layers is hindered during impact,leading to delamination and 90°fiber brittle fracture.The crack length perpendicular to the impact direction increases with impact energy increases,resulting in more serious 0°fiber fracture and a larger area of fiber loss.In the 3D needled C/SiC composite,load propagates between the layers during impact through the connection of needled fibers.The fibers continue to provide substantial structural support,with notable instances of fiber pull-off and debonding.Consequently,the impact resistance is superior to that of 2D plain C/SiC composite.When the 3D needled C/SiC composite undergoes two successive impacts of 1.5 J,the energy absorption efficiency of the second impact is significantly lower,accompanied by a smaller impact displacement.Moreover,the total energy absorption efficiency of these two impacts of 1.5 J is lower than that of a single 3.0 J impact.展开更多
Aseries of [(Fe_(0.6)Co_(0.2)Ni_(0.2))_(0.75-0.03x)B_(0.2)Si_(0.05+0.03x)]_(96)Nb_(4) amorphous alloy composite coatings were prepared by adjusting the silicon content(x=0,1,2,3,4,5,and 6)and their microstructures and...Aseries of [(Fe_(0.6)Co_(0.2)Ni_(0.2))_(0.75-0.03x)B_(0.2)Si_(0.05+0.03x)]_(96)Nb_(4) amorphous alloy composite coatings were prepared by adjusting the silicon content(x=0,1,2,3,4,5,and 6)and their microstructures and tribological properties were investigated by laser cladding technique.Additionally,the effect of Si on the glass forming ability(GFA)of the layers was understood.Results show that an appropriate Si content can refine the microstructure of the FeCoNiBSiNb laser cladding layers and improve the mechanical and tribological properties.The hardness of the coating layer increases monotonically with the Si content.At the Si content of 4.8at%(x=0),the coating layer exhibits a relatively low hardness(734.2HV 0.1).Conversely,at the silicon content of 13.44at%(x=3),the coating layer exhibits the highest hardness(1106HV 0.1).The non-crystalline content and tensile strength exhibit an initial increase,followed by a subsequent decrease.At x=2,the coating exhibits its maximum fracture strength(2880 MPa).However,when x>2,the fracture strength of the coating decreases with an increase in x.Conversely,with an increase in Si content,the wear volume loss initially decreases and then increases.At a Si content of 10.56at%(x=2),the coating exhibits the highest non-crystalline content(42%),the highest tensile strength(2880 MPa),and the most favorable dry friction performance.展开更多
The boundness and compactness of products of multiplication,composition and differentiation on weighted Bergman spaces in the unit ball are studied.We define the differentiation operator on the space of holomorphic fu...The boundness and compactness of products of multiplication,composition and differentiation on weighted Bergman spaces in the unit ball are studied.We define the differentiation operator on the space of holomorphic functions in the unit ball by radial derivative.Then we extend the Sharma's results.展开更多
An energetic binder based on hydroxyl-terminated polybutadiene(HTPB),doped with different ratios of nitrocellulose(NC)(10%,20%,30%,and 50%),was developed to study the effect of NC doping on the thermal decomposition b...An energetic binder based on hydroxyl-terminated polybutadiene(HTPB),doped with different ratios of nitrocellulose(NC)(10%,20%,30%,and 50%),was developed to study the effect of NC doping on the thermal decomposition behavior of a composite propellant(CP)comprising ammonium nitrate(AN)as an oxidizer and magnesium(Mg)as a fuel.Optimization of the propellant formulation was conducted using Chemical Equilibrium with Applications-National Aeronautics and Space Administration(CEA-NASA)software,which demonstrated an increase in specific impulse by 12.09 s when the binder contained 50%NC.Fourier-transform infrared spectroscopy(FTIR)analysis confirmed the excellent compatibility between the components,and density measurements revealed an increase of 6.4%with a higher NC content.Morphological analysis using optical microscopy showed that NC doping improved the uniformity and compactness of the surface,reduced cavities,and achieved a more homogeneous particle distribution.Differential scanning calorimetry(DSC)analysis indicated a decrease in the decomposition temperature of the propellant as the NC content increased,while kinetic studies revealed a 48.68%reduction in the activation energy when 50%NC was incorporated into the binder.These findings suggest that the addition of NC enhances combustion efficiency and improves overall propellant performance.This study highlights the potential of the new HTPB-NC energetic binder as a promising approach for advancing solid propellant technology.展开更多
The rising concern over electromagnetic (EM) pollution is re-sponsible for the rapid progress in EM interference (EMI) shielding and EM wave absorption in the last few years, and carbon materials with a large sur-face...The rising concern over electromagnetic (EM) pollution is re-sponsible for the rapid progress in EM interference (EMI) shielding and EM wave absorption in the last few years, and carbon materials with a large sur-face area and high porosity have been investigated. Compared to other car-bon materials, biomass-derived carbon (BC) are considered efficient and eco-friendly materials for this purpose. We summarize the recent advances in BC materials for both EMI shielding and EM wave absorption. After a brief overview of the synthesis strategies of BC materials and a precise out-line of EM wave interference, strategies for improving their EMI shielding and EM wave absorption are discussed. Finally, the existing challenges and the future prospects for such materials are briefly summarized.展开更多
Plant roots are widely known to provide mechanical reinforcement to soils against shearing and further increase slope stability.However,whether roots provide reinforcement to loess cyclic re-sistance and how various f...Plant roots are widely known to provide mechanical reinforcement to soils against shearing and further increase slope stability.However,whether roots provide reinforcement to loess cyclic re-sistance and how various factors affect roots reinforcement during seismic loading have rarely been studied.The objective is to conduct a series of cyclic direct simple shear tests and DEM numerical simulation to investigate the cyclic behaviour of rooted loess.The effects of initial static shear stress and loading frequency on the cyclic resistance of root-soil composites were first investigated.After that,cyclic direct simple shear simulations at constant volume were carried out based on the discrete element method(PFC^(3D))to investigate the effects of root geome-try,mechanical traits and root-soil bond strength on the cyclic strength of rooted loess.It was discovered that the roots could effectively improve the cyclic resistance of loess.The cyclic resistance of the root-soil composite decreases with the increase of the initial shear stress,then increases,and improves with the increase of the frequency.The simulation result show that increases in root elastic modulus and root-soil interfacial bond strength can all enhance the cyclic resistance of root-soil composites,and the maximum cyclic resistance of the root-soil composite was obtained when the initial inclination angle of the root system was 90°.展开更多
Metal phosphides have been studied as prospective anode materials for sodium-ion batteries(SIBs)due to their higher specific capacity compared to other anode materials.However,rapid capacity decay and limited cycle li...Metal phosphides have been studied as prospective anode materials for sodium-ion batteries(SIBs)due to their higher specific capacity compared to other anode materials.However,rapid capacity decay and limited cycle life caused by volume expansion and low electrical conductivity of phosphides in SIBs remain still unsolved.To address these issues,GeP_(3) was first prepared by high-energy ball milling,and then Ketjen black(KB)was introduced to synthesize composite GeP_(3)/KB anode materials under controlled milling speed and time by a secondary ball milling process.During the ball milling process,GeP_(3) and KB form strong chemical bonds,resulting in a closely bonded composite.Consequently,the GeP_(3)/KB anodes was demonstrated excellent sodium storage performance,achieving a high reversible capacity of 933.41 mAh·g^(–1) at a current density of 0.05 A·g^(–1) for a special formula of GeP_(3)/KB-600-40 sample prepared at ball milling speed of 600 r/min for 40 h.Even at a high current density of 2 A·g^(–1) over 200 cycles,the capacity remains 314.52 mAh·g^(–1) with a retention rate of 66.6%.In conclusion,this work successfully prepares GeP_(3)/KB anode-carbon composite for electrodes by high-energy ball milling,which can restrict electrode volume expansion,enhance capacity,and improve cycle stability of SIBs.展开更多
As a negative electrode material for lithium-ion batteries,silicon monoxide(SiO)suffers from dramatic volume changes during cycling,causing excessive stress within the electrode and resulting in electrode deformation ...As a negative electrode material for lithium-ion batteries,silicon monoxide(SiO)suffers from dramatic volume changes during cycling,causing excessive stress within the electrode and resulting in electrode deformation and fragmentation.This ultimately leads to a decrease in cell capacity.The trends of volume expansion and capacity change of the SiO/graphite(SiO/C)composite electrode during cycling were investigated via in situ expansion monitoring.First,a series of expansion test schemes were designed,and the linear relationship between negative electrode expansion and cell capacity degradation was quantitatively analyzed.Then,the effects of different initial pressures on the long-term cycling performance of the cell were evaluated.Finally,the mechanism of their effects was analyzed by scanning electron microscope.The results show that after 50 cycles,the cell capacity decreases from 2.556 mAh to 1.689 mAh,with a capacity retention ratio(CRR)of only 66.08%.A linear relationship between the capacity retention ratio and thickness expansion was found.Electrochemical measurements and scanning electron microscope images demonstrate that intense stress inhibits the lithiation of the negative electrode and that the electrode is more susceptible to irreversible damage during cycling.Overall,these results reveal the relationship between the cycling performance of SiO and the internal pressure of the electrode from a macroscopic point of view,which provides some reference for the application of SiO/C composite electrodes in lithium-ion batteries.展开更多
Affected by the geological characteristics of coal bearing strata in western mining areas of China,the double soft composite roof has low strength and poor integrity,which is prone to induce disasters such as large de...Affected by the geological characteristics of coal bearing strata in western mining areas of China,the double soft composite roof has low strength and poor integrity,which is prone to induce disasters such as large deformation and roof collapse.Four-point bending tests were conducted on anchored double-layer rock beams with different pre tightening force and upper/lower rock strength ratios(Ⅰ/Ⅱ)based on the digital speckle correlation method(DSCM).The research results indicate that the instability process of anchored roof can be divided into stages of elastic deformation,crack propagation,alternating fracture,and failure collapse.The proportion of crack propagation and alternating fracture processes increased with the increase of pre-tightening force and Ⅰ/Ⅱ.The pre-tightening force can suppress the sliding of the upper/lower rock interface,and delay the initiation and propagation of cracks.As Ⅰ/Ⅱ increases,the failure mode changes from tensile failure steel strip to shear failure anchor rod.Steel strip can improve the continued bearing effect of anchored roof during crack propagation and alternating fracture processes.展开更多
The design of unmanned aerial vehicles(UAVs)revolves around the careful selection of materials that are both lightweight and robust.Carbon fiber-reinforced polymer(CFRP)emerged as an ideal option for wing construction...The design of unmanned aerial vehicles(UAVs)revolves around the careful selection of materials that are both lightweight and robust.Carbon fiber-reinforced polymer(CFRP)emerged as an ideal option for wing construction,with its mechanical qualities thoroughly investigated.In this study,we developed and optimized a conceptual UAV wing to withstand structural loads by establishing progressive composite stacking sequences,and we conducted a series of experimental characterizations on the resulting material.In the optimization phase,the objective was defined as weight reduction,while the Hashin damage criterion was established as the constraint for the optimization process.The optimization algorithm adaptively monitors regional damage criterion values,implementing necessary adjustments to facilitate the mitigation process in a cost-effective manner.Optimization of the analytical model using Simulia Abaqus~(TM)and a Python-based user-defined sub-routine resulted in a 34.7%reduction in the wing's structural weight after 45 iterative rounds.Then,the custom-developed optimization algorithm was compared with a genetic algorithm optimization.This comparison has demonstrated that,although the genetic algorithm explores numerous possibilities through hybridization,the custom-developed algorithm is more result-oriented and achieves optimization in a reduced number of steps.To validate the structural analysis,test specimens were fabricated from the wing's most critically loaded segment,utilizing the identical stacking sequence employed in the optimization studies.Rigorous mechanical testing revealed unexpectedly high compressive strength,while tensile and bending strengths fell within expected ranges.All observed failure loads remained within the established safety margins,thereby confirming the reliability of the analytical predictions.展开更多
The compression and energy absorption properties of foam geopolymers increase stress wave attenuation under explosion impacts,reducing the vibration effect on the structure.Explosion tests were conducted using several...The compression and energy absorption properties of foam geopolymers increase stress wave attenuation under explosion impacts,reducing the vibration effect on the structure.Explosion tests were conducted using several composite structure models,including a concrete lining structure(CLS)without foam geopolymer and six foam geopolymer composite structures(FGCS)with different backfill parameters,to study the dynamic response and wave dissipation mechanisms of FGCS under explosive loading.Pressure,strain,and vibration responses at different locations were synchronously tested.The damage modes and dynamic responses of different models were compared,and how wave elimination and energy absorption efficiencies were affected by foam geopolymer backfill parameters was analyzed.The results showed that the foam geopolymer absorbed and dissipated the impact energy through continuous compressive deformation under high strain rates and dynamic loading,reducing the strain in the liner structure by 52%and increasing the pressure attenuation rate by 28%.Additionally,the foam geopolymer backfill reduced structural vibration and liner deformation,with the FGCS structure showing 35%less displacement and 70%less acceleration compared to the CLS.The FGCS model with thicker,less dense foam geopolymer backfill,having more pores and higher porosity,demonstrated better compression and energy absorption under dynamic impact,increasing stress wave attenuation efficiency.By analyzing the stress wave propagation and the compression characteristics of the porous medium,it was concluded that the stress transfer ratio of FGCS-ρ-579 was 77%lower than that of CLS,and the transmitted wave energy was 90%lower.The results of this study provide a scientific basis for optimizing underground composite structure interlayer parameters.展开更多
The advancement of planar micro-supercapacitors(PMSCs)for micro-electromechanical systems(MEMS)has been significantly hindered by the challenge of achieving high energy and power densities.This study addresses this is...The advancement of planar micro-supercapacitors(PMSCs)for micro-electromechanical systems(MEMS)has been significantly hindered by the challenge of achieving high energy and power densities.This study addresses this issue by leveraging screen-printing technology to fabricate high-performance PMSCs using innovative composite ink.The ink,a synergistic blend of few-layer graphene(Gt),carbon black(CB),and NiCo_(2)O_(4),was meticulously mixed to form a conductive and robust coating that enhanced the capacitive performance of the PMSCs.The optimized ink formulation and printing process result in a micro-supercapacitor with an exceptional areal capacitance of 18.95 mF/cm^(2)and an areal energy density of 2.63μW·h/cm^(2)at a current density of 0.05 mA/cm^(2),along with an areal power density of 0.025 mW/cm^(2).The devices demonstrated impressive durability with a capacitance retention rate of 94.7%after a stringent 20000-cycle test,demonstrating their potential for long-term applications.Moreover,the PMSCs displayed excellent mechanical flexibility,with a capacitance decrease of only 3.43%after 5000 bending cycles,highlighting their suitability for flexible electronic devices.The ease of integrating these PMSCs into series and parallel configurations for customized power further underscores their practicality for integrated power supply solutions in various technologies.展开更多
This paper focuses on the high-temperature tensile failure mechanism of RTM(resin transfer moulding)-made symmetric and asymmetric composite T-joints.The failure modes as well as the load-displacement curves of symmet...This paper focuses on the high-temperature tensile failure mechanism of RTM(resin transfer moulding)-made symmetric and asymmetric composite T-joints.The failure modes as well as the load-displacement curves of symmetric(three specimens)and asymmetric(three specimens)composite T-joints were determined by tensile tests at room and high temperatures.Progressive damage models(PDMs)of symmetric and asymmetric composite T-joints at room and high temperatures were established based on mixed criteria,and the result predicted from the aforementioned PDMs were compared with experimental data.The predicted initial and final failure loads and failure modes are in good agreement with the experimental results.The failure mechanisms of composite T-joints at different temperatures were investigated by scanning electron microscopy.The results reveal that while the failure mode of asymmetric T-joints at high temperatures resembles that at room temperature,there is a difference in the failure modes of symmetric T-joints.The ultimate failure load of symmetric and asymmetric T-joints at elevated temperatures increases and reduces by 18.4%and 4.97%,albeit with a more discrete distri-bution.This work is expected to provide us with more knowledge about the usability of composite T-joints in elevated temperature environments.展开更多
The use of ultra-high molecular weight polyethylene(UHMWPE)composite in the design of lightweight protective equipment,has gained a lot of interest.However,there is an urgent need to understand the ballistic response ...The use of ultra-high molecular weight polyethylene(UHMWPE)composite in the design of lightweight protective equipment,has gained a lot of interest.However,there is an urgent need to understand the ballistic response mechanism and theoretical prediction model of performance.This paper explores the ballistic response mechanism of UHMWPE composite through experimental and simulation analyses.Then,a resistance-driven modeling method was proposed to establish a theoretical model for predicting the bulletproof performance.The ballistic response mechanism of UHMWPE composite encompassed three fundamental modes:local response,structural response,and coupled response.The occurrence ratio of these fundamental response modes during impact was dependent on the projectile velocity and laminate thickness.The bulletproof performance of laminate under different response modes was assessed based on the penetration depth of the projectile,the bulging height on the rear face of the laminate,the thickness of remaining sub-laminate,and residual velocity of the projectile.The absolute deviations of bulletproof performance indicator between theoretical value and experimental value were well within 11.13%,demonstrating that the established evaluation model possessed high degree of prediction accuracy.展开更多
Basalt fibers/7075 aluminum matrix composites were studied to meet the demand of aluminum alloy drill pipes for material wear resistance.The composites with different basalt fiber additions were prepared by hot presse...Basalt fibers/7075 aluminum matrix composites were studied to meet the demand of aluminum alloy drill pipes for material wear resistance.The composites with different basalt fiber additions were prepared by hot pressed sintering and hot extrusion.The mechanical properties as well as friction and wear properties of the composites were studied by microstructure analysis,tensile experiments,friction and wear experiments.The results showed that basalt fibers were oriented and uniformly distributed and led to local grain refinement in the alloy matrix.The hardness and elongation of the composites were improved.The friction coefficient of the composites increased and then decreased,and the maximum wear depth and wear amount decreased,then increased,then decreased again with the growth of basalt fiber addition.Meanwhile,the inclusion of basalt fibers mitigated the uneven wear of the extruded 7075 aluminum alloy.The value of wear depth difference of 7075-0.2BF was the smallest,and that of 7075-2.0BF was close to it.The maximum wear depth and wear volume the 7075-0.2BF and 7075-2.0BF were also the smallest.The inhibition of uneven wear by basalt fibers enhanced of wear resistance for 7075 aluminum alloy,which has reference significance for improving the performance of aluminum alloy drill pipes.展开更多
In this paper,a type of reinforcing structure for composite shell with single and through hole is presented.The experimental tests for the composite shells without hole,with single hole and reinforced structure,with t...In this paper,a type of reinforcing structure for composite shell with single and through hole is presented.The experimental tests for the composite shells without hole,with single hole and reinforced structure,with through hole and reinforced structure subjected to hydrostatic pressure were carried out by the designed experimental test system.The mechanical responses of the composite shells under hydrostatic pressure are obtained by the high-speed camera and strain measurement.The results show that the entire deformation process of the shell can be divided into three:uniform compression,"buckling mode formation"and buckling.The"buckling mode formation"process is captured and reported for the first time.For the composite shell with single hole,the proposed reinforcing structure has a significant reinforcement effect on the shell and the buckling capacity of the shell is not weaker than the complete composite shell.For the composite shell with through hole,sealing effect can be achieved by the proposed reinforcing structure,but the buckling capacity of the shell after reinforcement can only reach 77%of the original buckling capacity.展开更多
This study represents an important step forward in the domain of additive manufacturing of energetic materials.It presents the successful formulation and fabrication by 3D printing of gun propellants using Fused Depos...This study represents an important step forward in the domain of additive manufacturing of energetic materials.It presents the successful formulation and fabrication by 3D printing of gun propellants using Fused Deposition Modeling(FDM)technology,highlighting the immense potential of this innovative approach.The use of FDM additive manufacturing technology to print gun propellants is a significant advancement due to its novel application in this field,which has not been previously reported.Through this study,the potential of FDM 3D-printing in the production of high-performance energetic composites is demonstrated,and also a new standard for manufacturability in this field can be established.The thermoplastic composites developed in this study are characterized by a notably high energetic solids content,comprising 70%hexogen(RDX)and 10%nitrocellulose(NC),which surpasses the conventional limit of 60%energetic solids typically achieved in stereolithography and light-curing 3D printing methods.The primary objective of the study was to optimize the formulation,enhance performance,and establish an equilibrium between printability and propellant efficacy.Among the three energetic for-mulations developed for 3D printing feedstock,only two were suitable for printing via the FDM tech-nique.Notably,the formulation consisting of 70%RDX,10%NC,and 20%polycaprolactone(PCL)emerged as the most advantageous option for gun propellants,owing to its exceptional processability,ease of printability,and high energetic performance.展开更多
To explore the design criteria for composite charges and reveal the intrinsic relationship between the detonation wave propagation in composite charges and the overall energy distribution of shock waves,this study ana...To explore the design criteria for composite charges and reveal the intrinsic relationship between the detonation wave propagation in composite charges and the overall energy distribution of shock waves,this study analyzes the propagation and interaction processes of detonation waves in composite charges with different structural dimensions and explosive combinations. It also investigates the spatial distribution characteristics of the resulting shock wave loads. Based on dimensional analysis theory, a theoretical analysis of the shock wave overpressure distribution in free air fields is conducted. Utilizing the derived dimensionless function relationships, the hydrocode AUTODYN is employed to investigate the effects of charge structure parameters and explosive combinations on the internal overdriven detonation phenomena and the distribution of shock wave loads. It is found that the overdriven detonation phenomenon in the inner layer of composite charges increases the strength of the axial detonation wave,thereby enhancing the intensity of the primary end wave formed upon refraction into the air, which affects the distribution characteristics of the shock wave overpressure. Research has shown that increasing the thickness ratio and detonation velocity ratio of composite charges is beneficial for exacerbating the phenomenon of overdriven detonation, improving the primary end wave intensity and axial overpressure. This gain effect gradually weakens with the propagation of shock waves. When overdriven detonation occurs inside the composite charge, the detonation pressure first increases and then decreases. The Mach reflection pressure of the composite charge with a larger aspect ratio is attenuated to a greater extent. In addition, as the aspect ratio of the composite charge increases, the shock wave energy gradually flows from the axial direction to the radial direction. Therefore, as the aspect ratio of the composite charge increases, the primary end wave intensity and axial overpressure gradually decrease.展开更多
Investigating the influence of radiation on glass fibre composites is essential for their use in space and aerospace environment.Gaining insight into the damage mechanisms caused by gamma irradiation,can improve the s...Investigating the influence of radiation on glass fibre composites is essential for their use in space and aerospace environment.Gaining insight into the damage mechanisms caused by gamma irradiation,can improve the safety and resilience of structures.This paper is aimed at investigating the failure mode and damage of gamma-irradiated repurposed pultruded glass fibre-reinforced polyester subjected to lowvelocity impact using three types of non-destructive techniques.Three sets of differently layered configurations(CRC,WCRW,W2CR2C)consisting of chopped(c),roving(r),and weaved(w)fibre-reinforced polyester are applied in this study.Drop hammer test is applied to evaluate the low-impact resistance properties of Gamma-irradiated composite at 100 kGy,500 kGy,and 1000 kGy.Preliminary flexural and hardness tests are conducted to further assess the behaviour of irradiated polymer composites.Further,the damage modes associated with the low-impact test are characterised using infrared thermography,flat panel digital radiography,and microscope observation.The results show that the composites irradiated with various doses display good impact resistance at 20 J,presenting minor damages in the form of dents on the surface.The irradiated CRC and WCRW display best impact resistance at 500 kGy,while W2CR2C at 1000 kGy.This shows that the layering sequence of reinforcement fibre can influence the impact resistance of irradiated composites.Apart from that,the application of non-destructive techniques show different damage mechanisms in the form resin cracks,yarn splitting/fracture,and matrix splitting when the composites are exposed at high and low irradiation doses.These findings offer valuable data for the defence industry,particularly in the areas of repair,maintenance,and the development of new materials.展开更多
基金the National Natural Science Foundation of China(31471440)。
文摘To investigate the effects of silicon formulations on the cold tolerance of rice seedlings,Song Japonica 16(not cold tolerant)and Dongnong 427(cold tolerant)rice varieties were used as test materials and four different types of silicon formulations,Si-50-G,Si-60-G,Si-T-G,and Si-E-G,were applied as foliar sprays at the seedling stage,and a control group CK(equal amount of distilled water)was set up.One week after the first silicon spray,two types of rice were subjected to low-temperature stress treatments at day/night temperatures of 12℃/10℃for 2,4,6,and 8 days.The effects of different silicon formulations on the chlorophyll,proline(Pro)and soluble sugar contents as well as superoxide dismutase(SOD),peroxidase(POD)and catalase(CAT)activities of rice seedlings under low-temperature stress were compared to find out the effects of silicon formulations on the cold tolerance of rice seedlings.The results showed that silicon formulations could significantly increase the chlorophyll content of rice seedling leaves,with Si-50-G being the most effective,with a significant increment of 40.17%compared to the CK at 2 days of low temperature.Four silicon formulations significantly increased the proline content and soluble sugar content of rice leaves at low temperature for 4-8 days.For Song Japonica 16,the most significant increment in leaf POD activity was observed in Si-E-G treatment at 2,4 and 8 days of temperature stress,with 73.58%,20.95%and 217.24%increases compared to the CK,respectively.For 4 and 6 days of temperature stress,the most significant increase in CAT activity was observed in Si-E-G treatment,with 25.70%and 75.78%increases compared to the CK,respectively.For Dongnong 427,the Si-60-G treatment showed the highest increase in leaf SOD activity for 4 and 8 days of temperature stress,with significant increases of 58.15%and 82.76%compared to the CK,respectively,and the Si-E-G treatment showed the highest increase in leaf POD activity for 2 and 8 days of temperature stress,with significant increases of 97.75%and 245.10%compared to the CK,respectively.It showed that the spraying of silicon formulations could significantly enhance the cold tolerance of rice.This study provided a scientific basis for the rational use of silicon formulations to enhance cold tolerance in rice and had important theoretical and practical significance for ensuring sustainable high and stable rice yields in Heilongjiang Province,as well as for the development of silicon fertilizers.
基金Aeronautical Science Foundation of China(2021Z057053001)。
文摘Continuous carbon fiber reinforced silicon carbide(C/SiC)composites are often subjected to low-velocity impacts when utilized as structural materials for thermal protection.However,research on in-plane impact damage and multiple impact damage of C/SiC composites is limited.To investigate the in-plane impact damage behavior of C/SiC composites,a drop-weight impact test method was developed for strip samples,and these results were subsequently compared with those of C/SiC composite plates.Results show that the in-plane impact behavior of C/SiC strip samples is similar to that of C/SiC composite plates.Variation of the impact load with displacement is characterized by three stages:a nearly linear stage,a severe load drop stage,and a rebound stage where displacement occurs after the impact energy exceeds its peak value.Impact damage behavior under single and multiple impacts on 2D plain and 3D needled C/SiC composites was investigated at different impact energies and durations.Crack propagation in C/SiC composites was studied by computerized tomography(CT)technique.In the 2D plain C/SiC composite,load propagation between layers is hindered during impact,leading to delamination and 90°fiber brittle fracture.The crack length perpendicular to the impact direction increases with impact energy increases,resulting in more serious 0°fiber fracture and a larger area of fiber loss.In the 3D needled C/SiC composite,load propagates between the layers during impact through the connection of needled fibers.The fibers continue to provide substantial structural support,with notable instances of fiber pull-off and debonding.Consequently,the impact resistance is superior to that of 2D plain C/SiC composite.When the 3D needled C/SiC composite undergoes two successive impacts of 1.5 J,the energy absorption efficiency of the second impact is significantly lower,accompanied by a smaller impact displacement.Moreover,the total energy absorption efficiency of these two impacts of 1.5 J is lower than that of a single 3.0 J impact.
文摘Aseries of [(Fe_(0.6)Co_(0.2)Ni_(0.2))_(0.75-0.03x)B_(0.2)Si_(0.05+0.03x)]_(96)Nb_(4) amorphous alloy composite coatings were prepared by adjusting the silicon content(x=0,1,2,3,4,5,and 6)and their microstructures and tribological properties were investigated by laser cladding technique.Additionally,the effect of Si on the glass forming ability(GFA)of the layers was understood.Results show that an appropriate Si content can refine the microstructure of the FeCoNiBSiNb laser cladding layers and improve the mechanical and tribological properties.The hardness of the coating layer increases monotonically with the Si content.At the Si content of 4.8at%(x=0),the coating layer exhibits a relatively low hardness(734.2HV 0.1).Conversely,at the silicon content of 13.44at%(x=3),the coating layer exhibits the highest hardness(1106HV 0.1).The non-crystalline content and tensile strength exhibit an initial increase,followed by a subsequent decrease.At x=2,the coating exhibits its maximum fracture strength(2880 MPa).However,when x>2,the fracture strength of the coating decreases with an increase in x.Conversely,with an increase in Si content,the wear volume loss initially decreases and then increases.At a Si content of 10.56at%(x=2),the coating exhibits the highest non-crystalline content(42%),the highest tensile strength(2880 MPa),and the most favorable dry friction performance.
基金Supported by Natural Science Foundation of Guangdong Province in China(2018KTSCX161)。
文摘The boundness and compactness of products of multiplication,composition and differentiation on weighted Bergman spaces in the unit ball are studied.We define the differentiation operator on the space of holomorphic functions in the unit ball by radial derivative.Then we extend the Sharma's results.
文摘An energetic binder based on hydroxyl-terminated polybutadiene(HTPB),doped with different ratios of nitrocellulose(NC)(10%,20%,30%,and 50%),was developed to study the effect of NC doping on the thermal decomposition behavior of a composite propellant(CP)comprising ammonium nitrate(AN)as an oxidizer and magnesium(Mg)as a fuel.Optimization of the propellant formulation was conducted using Chemical Equilibrium with Applications-National Aeronautics and Space Administration(CEA-NASA)software,which demonstrated an increase in specific impulse by 12.09 s when the binder contained 50%NC.Fourier-transform infrared spectroscopy(FTIR)analysis confirmed the excellent compatibility between the components,and density measurements revealed an increase of 6.4%with a higher NC content.Morphological analysis using optical microscopy showed that NC doping improved the uniformity and compactness of the surface,reduced cavities,and achieved a more homogeneous particle distribution.Differential scanning calorimetry(DSC)analysis indicated a decrease in the decomposition temperature of the propellant as the NC content increased,while kinetic studies revealed a 48.68%reduction in the activation energy when 50%NC was incorporated into the binder.These findings suggest that the addition of NC enhances combustion efficiency and improves overall propellant performance.This study highlights the potential of the new HTPB-NC energetic binder as a promising approach for advancing solid propellant technology.
基金Anusandhan National Research Foundation (ANRF), Department of Science & Technology (DST), New Delhi, India under Ramanujan award (SB/S2/RJN-159/2017)。
文摘The rising concern over electromagnetic (EM) pollution is re-sponsible for the rapid progress in EM interference (EMI) shielding and EM wave absorption in the last few years, and carbon materials with a large sur-face area and high porosity have been investigated. Compared to other car-bon materials, biomass-derived carbon (BC) are considered efficient and eco-friendly materials for this purpose. We summarize the recent advances in BC materials for both EMI shielding and EM wave absorption. After a brief overview of the synthesis strategies of BC materials and a precise out-line of EM wave interference, strategies for improving their EMI shielding and EM wave absorption are discussed. Finally, the existing challenges and the future prospects for such materials are briefly summarized.
文摘Plant roots are widely known to provide mechanical reinforcement to soils against shearing and further increase slope stability.However,whether roots provide reinforcement to loess cyclic re-sistance and how various factors affect roots reinforcement during seismic loading have rarely been studied.The objective is to conduct a series of cyclic direct simple shear tests and DEM numerical simulation to investigate the cyclic behaviour of rooted loess.The effects of initial static shear stress and loading frequency on the cyclic resistance of root-soil composites were first investigated.After that,cyclic direct simple shear simulations at constant volume were carried out based on the discrete element method(PFC^(3D))to investigate the effects of root geome-try,mechanical traits and root-soil bond strength on the cyclic strength of rooted loess.It was discovered that the roots could effectively improve the cyclic resistance of loess.The cyclic resistance of the root-soil composite decreases with the increase of the initial shear stress,then increases,and improves with the increase of the frequency.The simulation result show that increases in root elastic modulus and root-soil interfacial bond strength can all enhance the cyclic resistance of root-soil composites,and the maximum cyclic resistance of the root-soil composite was obtained when the initial inclination angle of the root system was 90°.
基金National Natural Science Foundation of China Young Scientist Fund(22105120)Shaanxi Province Qin Chuangyuan“Scientist+Engineer”Team Construction Project(2024QCY-KXJ-127)。
文摘Metal phosphides have been studied as prospective anode materials for sodium-ion batteries(SIBs)due to their higher specific capacity compared to other anode materials.However,rapid capacity decay and limited cycle life caused by volume expansion and low electrical conductivity of phosphides in SIBs remain still unsolved.To address these issues,GeP_(3) was first prepared by high-energy ball milling,and then Ketjen black(KB)was introduced to synthesize composite GeP_(3)/KB anode materials under controlled milling speed and time by a secondary ball milling process.During the ball milling process,GeP_(3) and KB form strong chemical bonds,resulting in a closely bonded composite.Consequently,the GeP_(3)/KB anodes was demonstrated excellent sodium storage performance,achieving a high reversible capacity of 933.41 mAh·g^(–1) at a current density of 0.05 A·g^(–1) for a special formula of GeP_(3)/KB-600-40 sample prepared at ball milling speed of 600 r/min for 40 h.Even at a high current density of 2 A·g^(–1) over 200 cycles,the capacity remains 314.52 mAh·g^(–1) with a retention rate of 66.6%.In conclusion,this work successfully prepares GeP_(3)/KB anode-carbon composite for electrodes by high-energy ball milling,which can restrict electrode volume expansion,enhance capacity,and improve cycle stability of SIBs.
基金supported by the Fundamental Research Funds for the Central Universities(WK2090000055)Anhui Provincial Natural Science Foundation of China(2308085QG231).
文摘As a negative electrode material for lithium-ion batteries,silicon monoxide(SiO)suffers from dramatic volume changes during cycling,causing excessive stress within the electrode and resulting in electrode deformation and fragmentation.This ultimately leads to a decrease in cell capacity.The trends of volume expansion and capacity change of the SiO/graphite(SiO/C)composite electrode during cycling were investigated via in situ expansion monitoring.First,a series of expansion test schemes were designed,and the linear relationship between negative electrode expansion and cell capacity degradation was quantitatively analyzed.Then,the effects of different initial pressures on the long-term cycling performance of the cell were evaluated.Finally,the mechanism of their effects was analyzed by scanning electron microscope.The results show that after 50 cycles,the cell capacity decreases from 2.556 mAh to 1.689 mAh,with a capacity retention ratio(CRR)of only 66.08%.A linear relationship between the capacity retention ratio and thickness expansion was found.Electrochemical measurements and scanning electron microscope images demonstrate that intense stress inhibits the lithiation of the negative electrode and that the electrode is more susceptible to irreversible damage during cycling.Overall,these results reveal the relationship between the cycling performance of SiO and the internal pressure of the electrode from a macroscopic point of view,which provides some reference for the application of SiO/C composite electrodes in lithium-ion batteries.
基金Project(SDAST2024QT060)supported by the Young Talent of Lifting Engineering for Science and Technology in Shandong,ChinaProjects(52304136,52304149,52204093)supported by the National Natural Science Foundation of China+1 种基金Project(ZR2022ME165)supported by the Shandong Provincial Natural Science Foundation,ChinaProject(2023YD02)supported by the Key Project of Research and Development in Liaocheng,China。
文摘Affected by the geological characteristics of coal bearing strata in western mining areas of China,the double soft composite roof has low strength and poor integrity,which is prone to induce disasters such as large deformation and roof collapse.Four-point bending tests were conducted on anchored double-layer rock beams with different pre tightening force and upper/lower rock strength ratios(Ⅰ/Ⅱ)based on the digital speckle correlation method(DSCM).The research results indicate that the instability process of anchored roof can be divided into stages of elastic deformation,crack propagation,alternating fracture,and failure collapse.The proportion of crack propagation and alternating fracture processes increased with the increase of pre-tightening force and Ⅰ/Ⅱ.The pre-tightening force can suppress the sliding of the upper/lower rock interface,and delay the initiation and propagation of cracks.As Ⅰ/Ⅱ increases,the failure mode changes from tensile failure steel strip to shear failure anchor rod.Steel strip can improve the continued bearing effect of anchored roof during crack propagation and alternating fracture processes.
基金supported by the Istanbul Technical University Office of Scientific Research Projects(ITUBAPSIS),under grant MYL-2022-43776。
文摘The design of unmanned aerial vehicles(UAVs)revolves around the careful selection of materials that are both lightweight and robust.Carbon fiber-reinforced polymer(CFRP)emerged as an ideal option for wing construction,with its mechanical qualities thoroughly investigated.In this study,we developed and optimized a conceptual UAV wing to withstand structural loads by establishing progressive composite stacking sequences,and we conducted a series of experimental characterizations on the resulting material.In the optimization phase,the objective was defined as weight reduction,while the Hashin damage criterion was established as the constraint for the optimization process.The optimization algorithm adaptively monitors regional damage criterion values,implementing necessary adjustments to facilitate the mitigation process in a cost-effective manner.Optimization of the analytical model using Simulia Abaqus~(TM)and a Python-based user-defined sub-routine resulted in a 34.7%reduction in the wing's structural weight after 45 iterative rounds.Then,the custom-developed optimization algorithm was compared with a genetic algorithm optimization.This comparison has demonstrated that,although the genetic algorithm explores numerous possibilities through hybridization,the custom-developed algorithm is more result-oriented and achieves optimization in a reduced number of steps.To validate the structural analysis,test specimens were fabricated from the wing's most critically loaded segment,utilizing the identical stacking sequence employed in the optimization studies.Rigorous mechanical testing revealed unexpectedly high compressive strength,while tensile and bending strengths fell within expected ranges.All observed failure loads remained within the established safety margins,thereby confirming the reliability of the analytical predictions.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.52378401,12202494)the Fundamental Research Funds for the Central Universities(Grant No.30922010918)。
文摘The compression and energy absorption properties of foam geopolymers increase stress wave attenuation under explosion impacts,reducing the vibration effect on the structure.Explosion tests were conducted using several composite structure models,including a concrete lining structure(CLS)without foam geopolymer and six foam geopolymer composite structures(FGCS)with different backfill parameters,to study the dynamic response and wave dissipation mechanisms of FGCS under explosive loading.Pressure,strain,and vibration responses at different locations were synchronously tested.The damage modes and dynamic responses of different models were compared,and how wave elimination and energy absorption efficiencies were affected by foam geopolymer backfill parameters was analyzed.The results showed that the foam geopolymer absorbed and dissipated the impact energy through continuous compressive deformation under high strain rates and dynamic loading,reducing the strain in the liner structure by 52%and increasing the pressure attenuation rate by 28%.Additionally,the foam geopolymer backfill reduced structural vibration and liner deformation,with the FGCS structure showing 35%less displacement and 70%less acceleration compared to the CLS.The FGCS model with thicker,less dense foam geopolymer backfill,having more pores and higher porosity,demonstrated better compression and energy absorption under dynamic impact,increasing stress wave attenuation efficiency.By analyzing the stress wave propagation and the compression characteristics of the porous medium,it was concluded that the stress transfer ratio of FGCS-ρ-579 was 77%lower than that of CLS,and the transmitted wave energy was 90%lower.The results of this study provide a scientific basis for optimizing underground composite structure interlayer parameters.
基金supported by the Shanxi Province Central Guidance Fund for Local Science and Technology Development Project(YDZJSX2024D030)the National Natural Science Foundation of China(22075197,22278290)+2 种基金the Shanxi Province Key Research and Development Program Project(2021020660301013)the Shanxi Provincial Natural Science Foundation of China(202103021224079)the Research and Development Project of Key Core and Common Technology of Shanxi Province(20201102018).
文摘The advancement of planar micro-supercapacitors(PMSCs)for micro-electromechanical systems(MEMS)has been significantly hindered by the challenge of achieving high energy and power densities.This study addresses this issue by leveraging screen-printing technology to fabricate high-performance PMSCs using innovative composite ink.The ink,a synergistic blend of few-layer graphene(Gt),carbon black(CB),and NiCo_(2)O_(4),was meticulously mixed to form a conductive and robust coating that enhanced the capacitive performance of the PMSCs.The optimized ink formulation and printing process result in a micro-supercapacitor with an exceptional areal capacitance of 18.95 mF/cm^(2)and an areal energy density of 2.63μW·h/cm^(2)at a current density of 0.05 mA/cm^(2),along with an areal power density of 0.025 mW/cm^(2).The devices demonstrated impressive durability with a capacitance retention rate of 94.7%after a stringent 20000-cycle test,demonstrating their potential for long-term applications.Moreover,the PMSCs displayed excellent mechanical flexibility,with a capacitance decrease of only 3.43%after 5000 bending cycles,highlighting their suitability for flexible electronic devices.The ease of integrating these PMSCs into series and parallel configurations for customized power further underscores their practicality for integrated power supply solutions in various technologies.
基金supported by the Natural Science Foundation of Shanghai(Grant No.24ZR1401700)Fundamental Research Funds for the Central Universities(Grant No.2232022D-28)the Young Elite Scientists Sponsorship Program by the China Association for Science and Technology(Grant No.2016QNRC001).
文摘This paper focuses on the high-temperature tensile failure mechanism of RTM(resin transfer moulding)-made symmetric and asymmetric composite T-joints.The failure modes as well as the load-displacement curves of symmetric(three specimens)and asymmetric(three specimens)composite T-joints were determined by tensile tests at room and high temperatures.Progressive damage models(PDMs)of symmetric and asymmetric composite T-joints at room and high temperatures were established based on mixed criteria,and the result predicted from the aforementioned PDMs were compared with experimental data.The predicted initial and final failure loads and failure modes are in good agreement with the experimental results.The failure mechanisms of composite T-joints at different temperatures were investigated by scanning electron microscopy.The results reveal that while the failure mode of asymmetric T-joints at high temperatures resembles that at room temperature,there is a difference in the failure modes of symmetric T-joints.The ultimate failure load of symmetric and asymmetric T-joints at elevated temperatures increases and reduces by 18.4%and 4.97%,albeit with a more discrete distri-bution.This work is expected to provide us with more knowledge about the usability of composite T-joints in elevated temperature environments.
基金supported by the National Key Research and Development of China(Grant No.2022YFB4601901)the National Natural Science Foundation of China(Grant No.12122202)。
文摘The use of ultra-high molecular weight polyethylene(UHMWPE)composite in the design of lightweight protective equipment,has gained a lot of interest.However,there is an urgent need to understand the ballistic response mechanism and theoretical prediction model of performance.This paper explores the ballistic response mechanism of UHMWPE composite through experimental and simulation analyses.Then,a resistance-driven modeling method was proposed to establish a theoretical model for predicting the bulletproof performance.The ballistic response mechanism of UHMWPE composite encompassed three fundamental modes:local response,structural response,and coupled response.The occurrence ratio of these fundamental response modes during impact was dependent on the projectile velocity and laminate thickness.The bulletproof performance of laminate under different response modes was assessed based on the penetration depth of the projectile,the bulging height on the rear face of the laminate,the thickness of remaining sub-laminate,and residual velocity of the projectile.The absolute deviations of bulletproof performance indicator between theoretical value and experimental value were well within 11.13%,demonstrating that the established evaluation model possessed high degree of prediction accuracy.
基金Project(2021YFC2900200)supported by the National Key Research and Development Project of ChinaProject(20230203114SF)supported by the Key Research and Development Project of Jilin Province,China。
文摘Basalt fibers/7075 aluminum matrix composites were studied to meet the demand of aluminum alloy drill pipes for material wear resistance.The composites with different basalt fiber additions were prepared by hot pressed sintering and hot extrusion.The mechanical properties as well as friction and wear properties of the composites were studied by microstructure analysis,tensile experiments,friction and wear experiments.The results showed that basalt fibers were oriented and uniformly distributed and led to local grain refinement in the alloy matrix.The hardness and elongation of the composites were improved.The friction coefficient of the composites increased and then decreased,and the maximum wear depth and wear amount decreased,then increased,then decreased again with the growth of basalt fiber addition.Meanwhile,the inclusion of basalt fibers mitigated the uneven wear of the extruded 7075 aluminum alloy.The value of wear depth difference of 7075-0.2BF was the smallest,and that of 7075-2.0BF was close to it.The maximum wear depth and wear volume the 7075-0.2BF and 7075-2.0BF were also the smallest.The inhibition of uneven wear by basalt fibers enhanced of wear resistance for 7075 aluminum alloy,which has reference significance for improving the performance of aluminum alloy drill pipes.
基金supported by the Ningbo Major Research and Development Plan Project(Grant No.2024Z135)the Natural Science Basic Research Program of Shaanxi Province(Grant No.2024JC-YBMS-322)+1 种基金China Postdoctoral Science Foundation(Grant No.2020M673492)National Natural Science Foundation of China(Grant No.51909219)。
文摘In this paper,a type of reinforcing structure for composite shell with single and through hole is presented.The experimental tests for the composite shells without hole,with single hole and reinforced structure,with through hole and reinforced structure subjected to hydrostatic pressure were carried out by the designed experimental test system.The mechanical responses of the composite shells under hydrostatic pressure are obtained by the high-speed camera and strain measurement.The results show that the entire deformation process of the shell can be divided into three:uniform compression,"buckling mode formation"and buckling.The"buckling mode formation"process is captured and reported for the first time.For the composite shell with single hole,the proposed reinforcing structure has a significant reinforcement effect on the shell and the buckling capacity of the shell is not weaker than the complete composite shell.For the composite shell with through hole,sealing effect can be achieved by the proposed reinforcing structure,but the buckling capacity of the shell after reinforcement can only reach 77%of the original buckling capacity.
基金supported by a grant from the Ministry of Research, Innovation and Digitization, UEFISCDI, Grant Nos. PN-IIIP2-2.1-PED-2021-1890, PN-IV-P6-6.3-SOL-2024-2-0254 and PNIV-P7-7.1-PTE-2024-0517, within PNCDI Ⅳ.
文摘This study represents an important step forward in the domain of additive manufacturing of energetic materials.It presents the successful formulation and fabrication by 3D printing of gun propellants using Fused Deposition Modeling(FDM)technology,highlighting the immense potential of this innovative approach.The use of FDM additive manufacturing technology to print gun propellants is a significant advancement due to its novel application in this field,which has not been previously reported.Through this study,the potential of FDM 3D-printing in the production of high-performance energetic composites is demonstrated,and also a new standard for manufacturability in this field can be established.The thermoplastic composites developed in this study are characterized by a notably high energetic solids content,comprising 70%hexogen(RDX)and 10%nitrocellulose(NC),which surpasses the conventional limit of 60%energetic solids typically achieved in stereolithography and light-curing 3D printing methods.The primary objective of the study was to optimize the formulation,enhance performance,and establish an equilibrium between printability and propellant efficacy.Among the three energetic for-mulations developed for 3D printing feedstock,only two were suitable for printing via the FDM tech-nique.Notably,the formulation consisting of 70%RDX,10%NC,and 20%polycaprolactone(PCL)emerged as the most advantageous option for gun propellants,owing to its exceptional processability,ease of printability,and high energetic performance.
基金funded by the National Natural Science Foundation of China(Grant No. 12302437)Jiangsu Provincial Natural Science Foundation (Grant No.SBK2023045424)。
文摘To explore the design criteria for composite charges and reveal the intrinsic relationship between the detonation wave propagation in composite charges and the overall energy distribution of shock waves,this study analyzes the propagation and interaction processes of detonation waves in composite charges with different structural dimensions and explosive combinations. It also investigates the spatial distribution characteristics of the resulting shock wave loads. Based on dimensional analysis theory, a theoretical analysis of the shock wave overpressure distribution in free air fields is conducted. Utilizing the derived dimensionless function relationships, the hydrocode AUTODYN is employed to investigate the effects of charge structure parameters and explosive combinations on the internal overdriven detonation phenomena and the distribution of shock wave loads. It is found that the overdriven detonation phenomenon in the inner layer of composite charges increases the strength of the axial detonation wave,thereby enhancing the intensity of the primary end wave formed upon refraction into the air, which affects the distribution characteristics of the shock wave overpressure. Research has shown that increasing the thickness ratio and detonation velocity ratio of composite charges is beneficial for exacerbating the phenomenon of overdriven detonation, improving the primary end wave intensity and axial overpressure. This gain effect gradually weakens with the propagation of shock waves. When overdriven detonation occurs inside the composite charge, the detonation pressure first increases and then decreases. The Mach reflection pressure of the composite charge with a larger aspect ratio is attenuated to a greater extent. In addition, as the aspect ratio of the composite charge increases, the shock wave energy gradually flows from the axial direction to the radial direction. Therefore, as the aspect ratio of the composite charge increases, the primary end wave intensity and axial overpressure gradually decrease.
基金funded by Universiti Tenaga Nasional(UNITEN),Malaysia for supporting this research under the Dato'Low Tuck Kwong International Grant,project code 20238002DLTKsupport for this work from the Ministry of Higher EducationMalaysia through the Higher Institution Center of Excellence(HICoE 2023-JPT(BPKI)1000/016/018/34(5))program+2 种基金supported by Tenaga Nasional Berhad(TNB)and UNITEN through the BOLD Refresh Postdoctoral Fellowships under Grant J510050002-IC-6 BOLDREFRESH2023-Centre of ExcellencePrince Sultan University for their supportIndustrial Technology Division,Malaysian Nuclear Agency for their support in this research work.
文摘Investigating the influence of radiation on glass fibre composites is essential for their use in space and aerospace environment.Gaining insight into the damage mechanisms caused by gamma irradiation,can improve the safety and resilience of structures.This paper is aimed at investigating the failure mode and damage of gamma-irradiated repurposed pultruded glass fibre-reinforced polyester subjected to lowvelocity impact using three types of non-destructive techniques.Three sets of differently layered configurations(CRC,WCRW,W2CR2C)consisting of chopped(c),roving(r),and weaved(w)fibre-reinforced polyester are applied in this study.Drop hammer test is applied to evaluate the low-impact resistance properties of Gamma-irradiated composite at 100 kGy,500 kGy,and 1000 kGy.Preliminary flexural and hardness tests are conducted to further assess the behaviour of irradiated polymer composites.Further,the damage modes associated with the low-impact test are characterised using infrared thermography,flat panel digital radiography,and microscope observation.The results show that the composites irradiated with various doses display good impact resistance at 20 J,presenting minor damages in the form of dents on the surface.The irradiated CRC and WCRW display best impact resistance at 500 kGy,while W2CR2C at 1000 kGy.This shows that the layering sequence of reinforcement fibre can influence the impact resistance of irradiated composites.Apart from that,the application of non-destructive techniques show different damage mechanisms in the form resin cracks,yarn splitting/fracture,and matrix splitting when the composites are exposed at high and low irradiation doses.These findings offer valuable data for the defence industry,particularly in the areas of repair,maintenance,and the development of new materials.
