bluuebunny/crossref_metadata_2025_split huggingface dataset:
Exhausted jet caused the deformation of front metal seal covers in a multiple launch rocket system
Authors: Liu Z P , Zhao J X , Ma G J , Gao X F , Jiang L 
Published: July 2020

Abstract
During the launch tests of a Multiple Launch Rocket System (MLRS), the front metal seal covers on unlaunched tubes had plastic deformation and felled to the ground. More seriously, the rocket exhausted jet directly caused damage to some of the unlaunched rockets projectiles. As the rocket exhausted jet impinged on the cover, high temperature and high pressure jet caused plastic deformation of the covers. So the temperature and pressure of exhausted jet acting on the surface of the cover were measured. Then pressure data were used to estimate the strain of front cover on adjacent launch tube caused only by pressure. And temperature data were used for thermal stress analysis of the cover. Furthermore, the triaxial strain curves of the cover were obtained during a flight test in which a 252-mm diameter rocket projectile was launched from the MLRS. The results demonstrated that plastic deformation of the covers is mainly due to the thermal deformation caused by the high temperature, which provided guidance for optimal design of front seal covers. No plastic deformation was found in the modified covers during subsequent launch tests of the MLRS.
Optimization of the specific kinetic energy of the pre-grooved stun grenade fragments based on HyperMesh, LS-DYNA and Matlab
Authors: Liu Xing-yu , Ren-jun Zhan , Yong-li Li 
Published: July 2020

Abstract
Large-scale fragments formed by packaging shell of stun grenade are easy to cause irreversible damage to human body in close range. In order to reduce the specific kinetic energy of shell fragments as much as possible, the pre-grooving method is proposed to optimize the safety of packaging shell. According to the process of fragment forming, flying and impacting, the shell breaking model, fragment dispersion model and average specific kinetic energy calculation model are established respectively. The non-grooved shell and inner grooved shell are simulated by the joint simulation method of HyperMesh, LS-DYNA and Matlab. The fragment mass distribution, initial velocity and average specific kinetic energy are obtained and compared. The results show that under the same main charge parameters, the mass distribution of fragments is more concentrated and the large mass fragments are less in the inner grooved shell than in the non-grooved shell; the average initial velocity of fragments in the inner grooved shell is lower than that in the non-grooved shell; the attenuation of average specific kinetic energy in the inner grooved shell is faster than that in the non-grooved shell, which is safer than that in the non-grooved structure.
Study on shock initiation of the charge covered by metal plate with penetrated notch
Authors: Chen X W , Wang J X , Tang K , Wang H F , Li Y B 
Published: July 2020

Abstract
To analyze the coupling damage effect of high-speed fragments and near-field strong shock wave on the covered charge, a theoretical model of the shock initiation of the charge covered by metal plate with defects was established. The defect of the covered plate was simplified as a penetration notch, and the evolution characteristics of the shock wave in the notch were analyzed theoretically. The critical condition of the explosive detonation was determined by combining the explosive initiation criterion and the shock wave evolution characteristics. Take TNT covered by steel plate with a penetrated notch as an example, the nonlinear finite element program was used to simulate the shock initiation process of pressed charge, and the validity of the numerical simulation was verified by experimental results. The influence of the intensity of the shock wave, the thickness of the covered metal plate as well as the geometrical characteristics of the penetrated notch on the shock initiation of the pressed charge were analyzed by combining the theoretical model and numerical simulation results. The relationship of the notch size of the covered plate and the detonation distance was obtained by fitting, and the parameters n and K of the critical initiation criterion were obtained by least squares method. The theoretical calculation results and the numerical simulation results are agree with each other well and show that, the covered metal plate is beneficial for the protection of the charge. The existence of notch will weaken the protective performance of the covered plate, and the shape and size of the notch are also important factors that will affect the critical detonation distance of the charge. For the pressed TNT with and without 45# steel covered plate with the thickness 3 millimeters, the critical detonation distance of non-contact explosion was 13 millimeters and 81 millimeters, respectively. For the covered plate with a cylindrical notch, the critical detonation distance of the pressed TNT increases with increase of the diameter of the covered plate. For the covered plate has a frustum notch, the critical detonation distance of the pressed TNT decreases with increase of the slope in normal reflection.
Internal explosion load distribution and strain response of ellipsoidal end cover of explosion containment vessel
Authors: Hu Y H , Gu W B , Liu J Q , Han Y M , Wang Z 
Published: July 2020

Abstract
As a kind of limitation device of explosive products and shock wave, explosion containment vessel is widely used in military and civil fields. Due to its own structural characteristics, Mach wave convergence and collision will occur near the pole of the end cover of the cylindrical explosion containment vessel, resulting in a great pressure jump and seriously affecting the strain response characteristics of the end cover. In this paper, by means of experiment and numerical simulation, the distribution of flow field inside the end cover was explored, and it was found that the initial load of the end cover pole included the first incident wave of internal explosion, convergent re-incident wave of central section and the Mach wave convergence wave. By analyzing the strain spectrum, it is found that the different frequencies are excited by loads at different locations, so that the energy distribution under each frequency of strain is different, resulting in differences of strain. These results can provide reference for the design of explosion containment vessel.
Vibration-intensity prediction of underwater blasting based on grey relational analysis and dimension theory
Authors: Wang Z X , Gu W B , Zhao S T , Yu L F , P C  , Xu Jinglin 
Published: July 2020

Abstract
In addition to the distance from the blasting center and the charge amount, the influence of the water depth of the blasting zone and the difference in elevation between the measuring points are non-negligible for the vibration intensity of underwater blasting. Hence, the conventional Sadov’s formula is no longer fully applicable for the vibration-intensity prediction of underwater blasting. Combined with the vibration data of underwater blasting projects, a grey relational analysis of the influencing factors for blasting-vibration intensity has been conducted. The obtained order of the influence degree, from high to low, is the charge amount, elevation of the measuring point, water depth of the blasting zone, and the distance from blasting center. A formula for vibration-intensity prediction that comprehensively considers the influencing factors was derived from dimension theory; this formula is similar to Sadov’s formula. The comparison of the two prediction results showed that the average error of the formula considering the water depth of the blasting zone and the difference in elevation was below 10%. This showed a significant improvement in the prediction accuracy, compared with the Sadov’s formula, indicating that this derived formula is applicable for the vibration-intensity prediction of underwater blasting on land measuring points.
The Mechanism of Liquid Dispersing from a Cylinder Driven by Central Dynamic Shock Loading
Authors: Li L , Lu X X , Ren X B , Ren Y J , Zhao Sh T , Yan X F 
Published: July 2020

Abstract
A systematic investigation on the mechanism of dynamic liquid dispersing process via theoretical and experimental approach is presented. Based on the experimental results, dynamic analysis, one-dimensional characteristics analysis and some numerical simulation are carried out. The stretching and shearing actions, spall fracture mechanism and characters of cavitation layered are explored. Then the thermodynamic non-equilibrium process, metastable liquid dispersing, cavitation generation and some multiscale mechanisms are revealed.
Theoretical calculation for overpressure of air shock wave of explosion induced reaction of reactive material case
Authors: Du N , Zhang X F , Xiong W , Wang J P , Chen H H , Huang B Y 
Published: July 2020

Abstract
In order to study the power of the air shock wave produced by the reactive material driven by explosion, the reaction behavior of the reactive material driven by explosion was analyzed by AUTODYN@ software, and the reaction law of the reactive material was obtained. Considering the chemical energy released by the reactive material, the calculation model of shock wave initial parameters is improved. Combined with dimensional analysis, the theoretical calculation model for overpressure of air shock wave generated by the reactive material driven by explosion is studied. The results show that, under the driving of explosion, the casing made of the reactive material does not react completely. The velocity of air shock wave produced by the charge with reactive material casing is higher than that of the charge with inert material casing. The predicted value of the theoretical calculation model is in good agreement with the experimental results, and the established model can well describe the attenuation law of the air shock wave overpressure generated by the reactive material driven by the explosion.
The effect of shell material and load coefficient on the expansion of shell driven by detonation
Authors: Wang X Y , Wang Sh Sh , Lu X 
Published: July 2020

Abstract
Detonation driven metal expansion and fragmentation is a complex transient nonlinear dynamic problem. The research on the influence of the materials and load coefficients on expansion driven by detonation can provide a basis for fragment velocity prediction and warhead design. The numerical simulation of detonation driving was studied, including the TNT charge with five kinds of materials and six kinds of load coefficient β values shells. The characteristics in detail which the experiment was difficult to reflect were obtained, and the influence of material properties and β value of metal shells on the fragment velocities were revealed. With the increase of the density of the material, the dissipative energy of the shock wave in the casing decreases, and the contribution of the shock wave loading to the velocity of the fragment increases. Meanwhile, the increase of the shell wall thickness and the corresponding decrease of β value lead to the increase of the internal dissipation energy of the shock wave in the casings, the decrease of the energy for the shell expansion acceleration and the decrease of the contribution to the fragment velocity.
Analysis of dynamic back face deformation of a body armor impact by a rifle bullet using 3D-DIC
Authors: Wen Y K , Zheng H , Zhang J B , Yan W M , Cui G Y , Xu Ch 
Published: July 2020

Abstract
Body armor that defeats the threat can still cause severe trauma by striking the thorax with its back face deformation (BFD). In this study, the 3D digital image correlation (DIC) technology was adopted to capture the dynamic BFD of a ceramic/UHMWPE body armor impact by a rifle bullet. The shape and size of the BFD time histories, deformation velocity, acceleration and line slices profile on armor back face were obtained. The maximum BFD height can reach to 34.3 mm within about 1.2 ms, and then slowly decreases to the static deformation height of about 24mm for the impact velocity 675.4 m/s. The maximum deformation velocity and acceleration are 129.9 m/s and 1.29e6 m/s^2, respectively.
FBG testing on inside strain capturing of concrete blocks subjected to hard projectiles penetration
Authors: Gao D C , Yao W J , Ren Y , Wang R , Wu Q , Feng J 
Published: July 2020

Abstract
This study evaluates the terminal ballistics and strain behaviors of normal strength concrete blocks penetrated by hard ogival-nosed projectiles. Fiber Bragg Gratings (FBG) sensors are utilized herein to measure the radial strain responses inside concrete target during penetration process. With precise location, a novel method of FBG sensors embedment inside concrete block is proposed. The penetration tests are conducted with ballistic gun whereby the FBG sensor reflected signals are recorded. Consequently, Holmquist–Johnson–Cook (HJC) model is used to describe the concrete material dynamic behaviors. The LS-Dyna numerical penetration model is validated by Depth of Penetration (DOP) prediction. The numerical radial strain inside concrete target matches well with the experimental data by FGB testing.
Numerical simulation of dynamic response of underwater supercavitating projectile structure based on after-effect enhancement of kinetic penetration
Authors: Li X , Yan P , Tan B , Zhao Y L , Liang W G 
Published: July 2020

Abstract
Aiming at the underwater supercavitating projectile, a damage mode of enhanced effect after kinetic penetration is proposed. The structure of energetic projectile with prefabricated breaking groove is designed, which can not only ensure the projectile strength in underwater motion, but also release the filling agent to the interior of the target through the projectile fracture when hitting the target. Based on ANSYS/LS-DYNA finite element analysis software, the equivalent model of supercavitating energetic projectile penetrating low-carbon steel shell of mine in three-phase domain is established. The dynamic response of the projectile in the stage of underwater motion and penetration is obtained by analyzing the force of the key parts of projectile and observing the deformation of the projectile structure. By changing the initial velocity and landing angle of the projectile, analyzing the law of velocity variation and penetration depth of the projectile, observing the deformation of the projectile structure and the phenomenon of the energetic agent disperation when penetrating the steel plate, the quantitative conclusion of the damage effect of the energetic projectile on the typical mine target under different working conditions is obtained. The research results have reference value for the structural design and power evaluation of underwater supercavitating energetic projectile.
Study on strain rate dependence and energy absorption characteristics of two aluminum alloys 7A62 and 7085
Authors: Wan M M , Wang Y L , Wu H L , Wang S L , Li B W , Mu X M 
Published: July 2020

Abstract
The dynamic compression properties of two aluminum alloys 7A62 and 7085 were tested using Split Hopkinson Pressure Bar (SHPB ) technique. The effects of strain rate on yield stress and dynamic energy absorption characteristics of the two materials were analyzed. The critical strain rate and the maximum energy absorbed before shear failure occurred of the two materials were given. The results showed that both the two materials show a strong strain rate dependence effect, and the yield stress increased with increasing strain rate. The aluminum alloy 7085 has a lower yield stress than 7A62 under the same strain rate level. But it has a better energy absorption characteristic than 7A62 for its good plasticity.
Dynamic response of fiber-composite-reinforced shell structure subjected to internal blast loading
Authors: Gan Y D , Wei D , Zhang Q M , Su J J , Long R R , Chen P W , Liang H Z 
Published: July 2020

Abstract
In this study, we report the analysis of a dynamic response process of a fiber-composite-reinforced shell when subjected to internal blast loading of different TNT equivalent by using a three-dimensional digital image correlation method. And it was compared with the dynamic response of the metal shell with the same TNT equivalent and the same surface density. We received the relationship between dynamic deformations and the sizes of the two shells under different TNT equivalence. Through comparison of the results, it was shown that the response process of the fiber-composite-reinforced shell was much more complex than that of the metal shell. Our experimental results suggest that the shock wave intensity, the material mechanical properties and the structure symmetry had important influences at different stages of the structural dynamic response. Fiber composites with high strength restricted the structural deformation extent and deformation rate. In addition, the interaction between fiber composite and metal liner reduced the probability of structural damage caused by the energy concentration. This work provides important insights for the design of cylindrical explosion vessels.
Microstructure and mechanical properties of AI/Fe micro-laminated composites fabricated by ultrasonic consolidation
Authors: Wang Y , Hou F M , Yang Q , Fan Z Y , Pan H Y , Xu H 
Published: July 2020

Abstract
Ultrasonic consolidation technology is a new method for preparing high-performance laminate composite materials. This rapid consolidation additive manufacturing technology provides a new idea for the integration of complementary functional laminated composite structures. It has great potential for preparation of new generation of complex laminated composite parts, broadening the application field of laminated composite material, and means an advanced 3D additive manufacturing technology for materials and structures. In this paper, it is aimed at Al/carbon steel and Al/Fe laminated composites systems with low cost and multilayer structures, Al/carbon steel and Al/Fe laminated composite samples were consolidated by ultrasonic consolidation process. And the Al/carbon steel and Al/Fe interfacial bonding were studied by SEM and EDS. The hardness and tensile properties of laminated composites were tested by mechanical properties together with the fracture morphology of each interface was studied.
Improving dimensional and surface quality of additive manufactured parts
Authors: Bruni C , Gianangeli C , Mancia T , Greco L , Pieralisi M 
Published: July 2020

Abstract
In modern manufacturing of polymer components the injection moulding represents the conventional way to get the desired shape respecting dimensional and surface requirements. But, such process plan requires the design of the tools and that of whole manufacturing process. A different choice could be done when the production consists of small batches or a single unit. In this case it is useful to realize the workpiece without tools taking into consideration the additive manufacturing technique. The limit of such flexible manufacturing technology is represented sometimes, in particular in working polymers such as ABS, by the difficulty to respect dimensional and surface requirements. The research activity to be presented involved the realization of cubic geometries in ABS by FDM (Fused Deposition Modeling). The staircase, the waviness and roughness of the surfaces were evaluated and quantified. The slight machining phase performed by front milling considered in the process plan allowed to reduce the staircase effect up to about zero and to reduce the waviness of about some decimals of millimeter to some hundredth of millimeter. The surface roughness was also improved. The methodology and the details are reported.
Study on microstructure control and performance optimization of ZCuPb20Sn5 alloy by rare earth la
Authors: Ren X Y , Zhang G W , Hong X , Sun F E 
Published: July 2020

Abstract
ZCuPb20Sn5 alloy is a cast lead-tin bronze alloy. Due to its high lead content, it has excellent comprehensive properties such as friction reduction and wear resistance, high fatigue strength, good thermal conductivity, and good wear resistance. It is widely used in automobiles, Aerospace industry and other fields. Therefore, this article selects ZCuPb20Sn5 alloy as the research object. By adding rare earth La to ZCuPb20Sn5 alloy solution, the metallographic structure and mechanical properties are observed, and the effect of rare earth La on the microstructure and properties of ZCuPb20Sn5 alloy material is analyzed. The results show that with the increase of La content, the tensile strength, elongation and hardness of lead-tin bronze alloys all increase first and then decrease. Without the addition of rare earth lanthanum, the tensile strength of lead-tin bronze can reach about 241.5 MPa. Adding different amounts of rare earth to the lead-tin bronze alloy can improve the tensile strength and elongation of the alloy. When 0.04 wt.% rare earth lanthanum is added, The strength and elongation reached the maximum. After several experiments, the tensile strength remained at about 267.1, the elongation remained at about 15.13%, the tensile strength increased by about 25.6 MPa, and the hardness remained at about 80 HB, with little increase.
The pre-hot dipping effects on the bimetal casting of nitriding steel sleeve into the Al-Si matrix
Authors: Xu H , Guo B X , Fan Z Y , Mao H K , Wang Y 
Published: July 2020

Abstract
Steel-aluminum composite material combine the excellent mechanical properties of steel such as high strength and good wear resistance with the advantages of lightweight aluminum for widely using in automobile engine block, gearbox and other car body structures. In this paper, a new process is used to cast the alloy steel sleeve into Al-Si alloy matrix for preparing aluminum engine block with steel cylinder liner. The process consists of three parts: the surface pre-treatment of steel, the hot-dipping melt and solid-liquid casting of steel with aluminum. Generally, the hot dipping melt should have lower melting point than the melting point of aluminum alloy, good temperature oxidation resistance and amount of solid solubility both with steel and aluminum. Giving consideration of such condition and cost, Zn´ Al and its alloys are used in present paper for learning the effect of hot dip coating melts on the interface properties of steel/aluminum at different times. After hot dipping, a coating formed on the surface of the steel bushing, which improves its wettability in the aluminum melt and the metallurgical bonding effect of the steel-aluminum interface. The microstructure, phase composition, growth kinetics and hardness distribution of the interface were analyzed by metallographic microscopy, scanning electron microscopy with EDS. The results show that the metallurgical bonding interface of steel/aluminum bimetal casting can be obtained by hot dipping. Hard-brittle diffusion layer produced by dipping pure Al is thicker than that produced by ZL101. Dipping pure zinc produces a dense intermetallic layer of 3-5 um and a large amount of dispersed phase of Al3FeZnx, and the bonding performance of such interface is better than the other two. The interface hardness of steel-aluminum bimetal casting obtained by hot dipping pure Al melt, ZL101 melt and pure Zn melt can reach 563.5HV, 528.3HV and 632.3HV, respectively.