Ballistic impact test of different-scale casings is an efficient way to demonstrate the casing containment capability at the preliminary design stage of the engine. For the sake of studying the titanium alloy TC4 casi...Ballistic impact test of different-scale casings is an efficient way to demonstrate the casing containment capability at the preliminary design stage of the engine. For the sake of studying the titanium alloy TC4 casing perfonnance, the ballistic tests of flat and curved simulation casing are implemented by using two flat blades of different sizes as the projectile. The impact mechanism and failure of the target are discussed. Impact of the projectile is a highly nonlinear transient process with the large deformation of the target. On the impact, failures of the flat casing and the subscale casing are similar, concluding two parts, the global dish- ing and localized ductile tearing. The main localized failure mode combines plugging （shear） and petaling （shear） if the projectile perforates or penetrates, while crater （shear） if the projectile rebounds. The ballistic limit equation is verified by the test data and the results show that this empirical equation could be a practical way to estimate the critical velocity.展开更多
The appearance of high-entropy alloys (HEAs) makes it possible for a material to possess both high strength and high ductility. It is with great potential to apply HEAs under extreme conditions such as in the penetrat...The appearance of high-entropy alloys (HEAs) makes it possible for a material to possess both high strength and high ductility. It is with great potential to apply HEAs under extreme conditions such as in the penetration process. In this paper, experiments of WFeNiMo HEA and tungsten heavy alloy (WHA) projectiles penetrating medium-carbon steel were conducted by using the ballistic gun and two-stage light-gas gun that can accelerate projectiles to impact velocities ranging from 1162 m/s to 2130 m/s. Depth of penetration (DOP) at elevated impact velocities of HEA and WHA projectiles were obtained firstly. Combined with the macroscopic and microscopic analysis of the residual projectiles, the transition of the penetration mode of the WFeNiMo HEA projectile was identified systemically. The experimental results indicated that the penetration mode of the HEA projectile changes from self-sharpening to mushrooming with the increase of impact velocity, while for the WHA projectile, the penetration mode is always mushrooming. The microstructure of the residual HEA projectiles showed that the phases tangle with each other and the morphology of the microstructure of the phases differs in the two penetration modes. Besides, the evolution of shear bands and fractures varies in the two modes. The evolution of the microstructure of HEAs causes the sharp-pointed nose to disappear and the HEA projectile ultimately becomes blunt as the impact velocity increases.展开更多
文摘Ballistic impact test of different-scale casings is an efficient way to demonstrate the casing containment capability at the preliminary design stage of the engine. For the sake of studying the titanium alloy TC4 casing perfonnance, the ballistic tests of flat and curved simulation casing are implemented by using two flat blades of different sizes as the projectile. The impact mechanism and failure of the target are discussed. Impact of the projectile is a highly nonlinear transient process with the large deformation of the target. On the impact, failures of the flat casing and the subscale casing are similar, concluding two parts, the global dish- ing and localized ductile tearing. The main localized failure mode combines plugging （shear） and petaling （shear） if the projectile perforates or penetrates, while crater （shear） if the projectile rebounds. The ballistic limit equation is verified by the test data and the results show that this empirical equation could be a practical way to estimate the critical velocity.
文摘高拱坝由于具有拱梁受力特性,其坝身往往较薄,而当薄拱坝坝后遭受侵彻爆炸打击时,高拱坝的安全将面临严峻的威胁。采用声固耦合方法模拟库水与大坝-地基动态耦合作用,光滑粒子流体动力学-有限元耦合方法(smoothed particle hydrodynamics-finite element method,SPH-FEM)模拟侵彻内部爆炸及大坝毁伤发展过程,建立了考虑混凝土高应变率效应的库水-坝体-爆炸耦合作用模型,研究了薄拱坝坝后遭受侵彻内部爆炸打击后的毁伤发展过程,探讨了坝后侵彻深度对薄拱坝坝身内部爆炸毁伤特性的影响,揭示了双曲拱坝上、下游几何特征对坝身侵彻爆炸破坏发展过程和毁伤机理。结果表明:高拱坝上、下游面的几何特征对大坝内部爆炸毁伤发展过程具有重要的影响;薄拱坝坝身遭受侵彻爆炸将对大坝安全构成严重威胁,且侵彻高拱坝中部破坏效应最大。
基金This work is funded by the National Natural Science Foundation of China(No.11790292)the NSAF Joint Fund(No.U1730101).
文摘The appearance of high-entropy alloys (HEAs) makes it possible for a material to possess both high strength and high ductility. It is with great potential to apply HEAs under extreme conditions such as in the penetration process. In this paper, experiments of WFeNiMo HEA and tungsten heavy alloy (WHA) projectiles penetrating medium-carbon steel were conducted by using the ballistic gun and two-stage light-gas gun that can accelerate projectiles to impact velocities ranging from 1162 m/s to 2130 m/s. Depth of penetration (DOP) at elevated impact velocities of HEA and WHA projectiles were obtained firstly. Combined with the macroscopic and microscopic analysis of the residual projectiles, the transition of the penetration mode of the WFeNiMo HEA projectile was identified systemically. The experimental results indicated that the penetration mode of the HEA projectile changes from self-sharpening to mushrooming with the increase of impact velocity, while for the WHA projectile, the penetration mode is always mushrooming. The microstructure of the residual HEA projectiles showed that the phases tangle with each other and the morphology of the microstructure of the phases differs in the two penetration modes. Besides, the evolution of shear bands and fractures varies in the two modes. The evolution of the microstructure of HEAs causes the sharp-pointed nose to disappear and the HEA projectile ultimately becomes blunt as the impact velocity increases.
