Influence of high-velocity impact on metals

The work is devoted to investigation of metals’ behavior under shock loading. The materials under investigation were copper, aluminum, lead, titanium, titanium alloys and different steels. Microstructure investigations have been carried out using optical microscopy. The strength behavior was investigated with the help of a microhardness device. Comparison of the spherical action of waves and uniaxial shock loading for the aforementioned metals has been done.     

Study concerning the penetration of high-velocity fine particles into various materials

Results are shown of a study concerning the penetration of fine particles (size range from a few microns to a few tens of microns) moving at a velocity up to 16 km/sec into barriers made of plastic materials (thickness up to a few microns), brittle materials, or soft materials.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 22, No. 3, pp. 499–504, March 1972.     

Evaluation of the resistance of materials of obstacles to high-velocity penetration by a wedge-shaped striker

The strength constituent of resistance in penetration of a wedge-shaped striker into an obstacle with a velocity of more than 2 km/sec was evaluated. The relationship of resistance to depth of penetration was obtained. The depth of penetration of a worn wedge-shaped striker into an obstacle of 20 steel was calculated. Satisfactory agreement of the calculated data with the experimental was obtained.Translated from Problemy Prochnosti, No. 7, pp. 48–51, July, 1992.     

High-speed penetration of a thin plate into a metal strip

The article presents experimental data on the penetration of a thin copper plate into a strip of steel and titanium alloy. It shows The effect of the width of the strip on the depth of penetration connected with the effect of unloading waves from the lateral surfaces of the strip and the nucleation of a crack at the bottom of the formed crater.Translated from Problemy Prochnosti, No. 8, pp. 45–48, August, 1992.     

Powder bombardment of a metal plate: Superdeep penetration

Superdeep penetration data (mass transfer) have been used in a model based on the assumption that particle-obstacle interaction is plastic.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 61, No. 1, pp. 41–45, July, 1991.     

Resistance of brittle solids to high-velocity projectile penetration at the initial stage of impact

It is established that single-crystalline brittle materials exhibit a lower resistance to the penetration of hard projectiles as compared to analogous polycrystalline targets with the same composition and standard mechanical properties. This difference is explained by the fact that single crystals, in contrast to polycrystalline materials, exhibit a significant decrease in hardness in the initial stage of impact as compared to the value measured under standard conditions.     

板间距对铝板多冲击结构高速撞击防护性能影响的试验研究

为了研究板间距变化对铝板多冲击结构高速撞击损伤与防护特性的影响,采用二级轻气炮发射铝球弹丸对具有不同板间距的双层、三层、四层和五层铝板结构进行了高速撞击试验,弹丸直径分别为3.97 mm、5 mm和6.35 mm,撞击速度为1.72~4.88 km/s,撞击角度为0°。结果表明:在铝球弹丸的弹道段撞击速度区间,板间距变化对铝板多冲击结构的高速撞击防护性能无显著影响;在铝球弹丸的破碎段撞击速度区间,对于相同的总防护间距,具有不同板间距的铝板多冲击结构的高速撞击防护性能存在明显差异;基于该试验数据定义的三层、四层和五层铝板结构的板间距因子,可为具有高效抗高速撞击能力的铝板多冲击结构的板间距设计提供依据。     

Studies on the properties of high-velocity oxy-fuel thermal spray coatings for higher temperature applications

Materials operating at high temperatures in corrosive media suffer erosion-corrosion wear, oxidation, and hot corrosion. Among various methods used for the protection of the surfaces against degradation, we can especially mention the technology of application of coatings by high-velocity oxy-fuel spraying, which gives coatings which high strength and hardness, low (less than 1%) porosity, and high erosion-corrosion and wear resistances. The characteristics of the coatings and their protective properties are presented. The role of some high-velocity oxy-fuel coatings in the protection of metals and alloys against degradation at high temperatures in various media is demonstrated. Published in Fizyko-Khimichna Mekhanika Materialiv, Vol. 41, No. 6, pp. 80–95, November–December, 2005.     

Mathematical model of the process of thermal destruction of polymer materials under intense thermal effects

It is proposed to describe heat- and mass-transfer processes in decomposing materials by taking into account both the chemical and physical transformations and the phase transition temperatures.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 53, No. 5, pp. 774–781, November, 1987.     

Influence of composition and process parameters on the thermal spray deposition of UHMWPE coatings

Ultra-high molecular weight polyethylene (UHMWPE) has remarkable properties in the bulk state and has substantial potential for use as a protective coating on metals. However, the molecular architecture responsible for these exceptional properties also causes difficulties in the formation of coatings by thermal spraying. This paper studies the effect of molecular weight, particle size and the influence of the addition of low-molecular weight binders on the structure and properties of combustion flame sprayed coatings. The flow of splats for each UHMWPE polymer and blends of selected polyethylenes was characterized by microstructural analysis and the performance of the resulting coatings evaluated by mechanical testing. A computational model was developed to calculate the temperature profiles of in-flight particles and to simulate the behaviour of particles during deposition. The model was applied to the polyethylene system and the experimental results show that the composition, the particle size and the process parameters are important factors in the optimization of coating quality.     

Influence of rapid thermal annealing on the process of aluminum induced crystallization of amorphous Si

The effects of annealing methods on the crystallization process and microstructure of polycrystalline silicon (poly-Si) films obtained by aluminum-induced crystallization (AIC) of amorphous Si (a-Si) films were comparatively investigated. Glass/Al/a-Si structures were annealed by rapid thermal annealing (RTA) and conventional furnace at 500 °C for different times in Ar. As compared to furnace annealing, AIC of a-Si films annealed by RTA possesses a shorter period of nucleation time, a higher nucleation density and reduces the process time to form continuous poly-Si films. It is revealed that the continuous Si films obtained by both RTA and conventional furnace annealing are polycrystalline in nature, exhibiting good microstructures with Raman peaks at 518 cm^?1 and full-width at half-maximums of 6.43–6.48 cm^?1.     

Influence of fluctuations of the heat-transfer coefficient on the temperature and thermal stresses in a plate quenched in a vibrating fluidized bed of a disperse material

The influence of fluctuations of the heat-transfer coefficient on the evolution of the temperature and thermal-stress fields in a plate is analyzed.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 46, No. 5, pp. 825–829, May, 1984.     

爆破拆除烟囱倒塌过程中风效应影响研究

在烟囱爆破拆除倒塌过程中,不同形式的风可使烟囱产生顺风向效应及横风向效应。横风向效应又包括横风向旋涡脱落及共振效应、横风向空气动力失稳。烟囱在风的长期作用下会发生失稳倾斜。本文揭示了爆破拆除过程中烟囱由于风振影响而发生倾斜、失稳的机理,分析了不同风向的三类风效应对爆破拆除时烟囱倒塌方向发生偏移的影响。根据分析计算结果可得,纵向风振影响最为显著,静力风效应影响相对较小,横向风振产生影响随机性较强。同时作者得出了爆破拆除烟囱时考虑风效应影响需采取的相应技术手段和措施。     

The influence of plate hardness on the ballistic penetration of thick steel plates

This investigation describes and analyses the experimental results pertinent to the penetration of steel plates of varying hardness in the range HV295–HV520 and of thickness 20 and 80 mm by ogive-shaped 20-mm-diameter projectiles over the velocity range 300–800 m s⁻¹. All the tests were carried out at normal impact angle, i.e. zero obliquity. The experimental results presented include the variation of depth of penetration, crater volume, lip height, bulge height and diameter, plugged length and diameter and specific energy absorption capacity with impact velocity for tests on each plate of a given hardness and thickness. Selected data and observations relating to the plastic zone size and shape surrounding the penetrating projectile, incidence and extent of adiabatic shear band (ASB) formation and plate spalling have also been presented. These experimental data have been interpreted in terms of the appropriate penetration mechanisms like ductile hole formation, bulging followed by star cracking, ASB-induced shear plugging, etc., and also by making use of the fact that the projectile undergoes substantial deformation when penetrating the harder plates (HV450 and HV520). It is also demonstrated that the resistance to penetration and hence the mechanism of penetration is very much dependent on whether the penetration occurs under plane strain or plane stress conditions. For example, ASB-induced plugging occurs only under plane stress conditions while projectile deformation is dominant only under plane strain conditions even in harder plates.     

热环境对基础激励作用下纤维增强树脂基复合薄板振动特性的影响

采用理论与实际相结合的方式,研究了热环境对纤维增强树脂基复合薄板振动特性的影响。首先,建立了基础激励作用下纤维增强树脂基复合薄板在热环境中的解析模型,推导获得了固有频率、模态振型、振动响应及阻尼比的解析表达式,并给出了热环境下复合薄板振动特性的求解流程。然后,搭建了热环境下该类型复合薄板结构的振动测试系统,并以TC500碳纤维/树脂薄板为研究对象进行了实际测试。以相应的测试结果为例,研究发现,当温度从20℃上升到200℃时,复合薄板的模态振型基本不发生改变,固有频率降低幅度在2.3%~36.6%之间,振动响应幅值增大范围约为15.3%~58.4%,且阻尼性能也呈现增大的趋势,例如相对于常温下的阻尼结果,当温度上升到200℃时,其前6阶模态阻尼比的增大程度在13.9%~56.4%之间。另外,经过对比理论和测试获得的不同温度下的固有频率、模态振型、振动响应及阻尼结果可知,两者吻合较好,进而验证了解析分析方法及其结果的正确性。      

Turbulent thermal boundary layer on a flat plate with a thermally insulated section

The influence of an initial adiabatic section on the heat transfer coefficient is studied on the assumption that the heat transfer law is expressed in the form St=A/Re _T ^**m Prⁿ. In addition, the temperature distribution on a thermally insulated wall is obtained when heat transfer occurs over the initial section.