共查询到20条相似文献,搜索用时 62 毫秒
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《振动与冲击》2017,(11)
为了解高强铝合金对动能杆的抗侵彻性能,在一级轻气炮上开展了直径5.98 mm的平头刚性弹侵彻6mm厚7A04-T6铝合金靶板的打靶试验,撞击速度范围为73.9~446.5 m/s。获得了弹体贯穿靶板后的剩余速度以及靶板的断裂行为,通过拟合初始-剩余速度数据得到了弹道极限。同时,在ABAQUS/Explicit中建立了三维有限元模型对打靶试验进行了数值计算,7A04-T6的力学行为通过Johnson-Cook本构模型和修正的Johnson-Cook断裂准则描述。试验结果表明,7A04-T6高强铝合金靶板在平头弹撞击下发生剪切冲塞,塞块表面有明显裂纹产生,弹道极限为156.0 m/s,剪切冲塞可在撞击速度不低于约0.90倍弹道极限时形成。数值仿真发现,有限元计算可成功再现靶板的剪切冲塞及冲塞表面的断裂;预报的弹道极限为168.8 m/s,比试验结果高约9%;撞击速度不低于0.92倍弹道极限时靶板发生剪切冲塞破坏,与试验结果十分接近。 相似文献
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《振动与冲击》2018,(21)
UHMWPE板抗侵彻性能优异但在实际使用过程中需切割成一定尺寸后再拼接安装,半穿甲导弹内爆后形成的高速破片侵彻UHMWPE板时弹着点位置具有随机性。利用数值仿真方法研究破片着靶点位置、破片速度、破片长径比对拼接的UHMWPE板抗侵彻性能的影响。结果表明:破片开始侵彻UHMWPE板时,UHMWPE板在弯矩和剪应力共同作用下出现纤维剪切破坏;随着破片继续侵彻,UHMWPE板主要受到弯矩作用发生纤维拉伸断裂破坏并伴随有严重的分层现象;当破片侵彻两块拼接的UHMWPE板速度较低(小于1 000 m/s)时,拼接的UHMWPE板存在明显的抗弹薄弱区,薄弱区域的范围大约为3倍的弹径;当破片侵彻四块拼接板时,可将靶板划分为薄弱,次薄弱及正常区域。考虑到半穿甲导弹产生破片的大小和安装工艺的方便性,认为UHMWPE板拼接安装时,拼接缝两侧10 cm范围内作为抗弹薄弱区域,需要加固。 相似文献
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介绍存储测试系统的研制情况,阐述存储测试系统的工作原理和安装过程中的冲击隔离方法,并将其用于空气炮的内弹道加速度测量.采用碰靶时的接电技术测出了飞行体以300m/s的速度侵彻混凝土靶板时的加速度,并用存储测试系统对飞行体以600m/s的速度侵彻混凝土靶板时的加速度进行了探索性的测量,给出了初步测试结果. 相似文献
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现有的尖头弹侵彻金属靶板的弹道极限计算模型往往需要大量的试验数据和靶板材料的动态性能参数,且没有考虑侵彻速度对侵彻效果的影响,这给工程应用带来了很大的不便和误差。基于这一问题,考虑速度效应和靶板材料参数对侵彻的影响,结合流体动力学原理与动态空穴膨胀理论,分别提出了双模式和单模式侵彻模型。双模式侵彻模型的侵彻过程可分为两个阶段:流体动力变形阶段和塑性变形阶段,当侵彻速度小于靶材产生流体动力变形的临界速度时,侵彻进入塑性变形阶段,根据功能原理,建立了计算弹道极限的解析模型;单模式侵彻模型仅考虑塑性变形阶段。解析模型计算的弹道极限与弹道试验结果吻合的较好,且模型中不涉及弹道试验数据和靶板材料的动态性能参数,易于迅速求解,便于工程应用,可用于对延性金属靶板抗尖头弹侵彻能力的评估。 相似文献
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研究93W钨合金破片对铝合金靶板的弹道极限(V50)影响规律,对战斗部毁伤元威力设计具有重要意义。通过弹道冲击试验获取了钨合金立方体破片、球形破片在90°着角的情况下,对4 mm 2024铝靶的侵彻弹道极限(V50)。基于数值模拟与试验结果的一致性,分析了钨合金破片形状、质量对V50的影响规律。结果表明:两种形状破片的侵彻V50均随着破片质量的增加而减小;在90°着角时,立方体破片的侵彻V50较低于球形破片,且两者V50差值随着破片质量的增大而增大。其中,立方体破片由于着靶姿态的变化导致V50存在着波动区间,随着破片质量增加,V50的波动区间相对增加,且立方体破片侵彻V50小于球形破片V50的概率也随之增加。 相似文献
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针对抗破片侵彻用新型钢/芳纶纤维叠层复合结构优化设计,基于4 mm钢板+12 mm芳纶纤维叠层复合结构、5 mm钢板+10 mm芳纶纤维叠层复合结构抗7.5 g FSP型破片弹道极限速度试验分析,进行了同工况下破片侵彻叠层复合结构的数值仿真计算;在验证数值仿真模型基础上,开展了7.5 g与10.0 g破片对4 mm、5 mm钢板叠加6~16mm芳纶纤维板组合成复合结构侵彻数值仿真,获得了相应的弹道极限速度;根据试验现象和数值仿真结果进行了钢/芳纶纤维叠层复合结构抗破片侵彻机理分析;根据此类复合结构的防护特点,以结构最小面密度为目标函数,建立了适用一定破片质量和撞击速度范围的结构参数优化设计模型;采用所提方法进行了抗撞击速度为1100 m/s的10.0 g破片侵彻的钢/芳纶纤维复合结构实例设计,通过试验验证了优化设计方法的合理性和实用性。 相似文献
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《International journal for numerical methods in engineering》2018,113(9):1488-1506
In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method. 相似文献
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Standards are the basis for production enterprises to organize production ex-factory inspection trade 《中国标准化(英文版)》2008,25(1):24-25
Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.…… 相似文献
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A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa. 相似文献
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On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.…… 相似文献
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Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß. 相似文献
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C. Qihong W. Zhan‐Wen J. Yi J. Yehua L. Fei F. Hanguang 《Materialwissenschaft und Werkstofftechnik》2014,45(7):582-590
In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M2(B,C), (W,Mo)2(B,C), M3(B,C), M23(B,C)6 type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm2. The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K1 mill housing of bar mill. 相似文献
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Dimiter Hadjistamov 《材料科学与工程:中英文B版...》2019,(2):56-65
The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ... 相似文献
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Kyo-Hong CHOI Kwon-Koo CHO Gyu-Bong CHO Hyo-Jun AHN Ki-Won KIM Yoo-Young KIM 《材料科学与工程学报》2007,25(6):886-891
Several researches have been reported about the characteristic of β-Ga2O3 nanowires which was synthesized on nickel oxide particle. But indeed, recent researches about synthesis of β-Ga2O3 nanowires on oxide-assisted transition metal are limited to nickel or cobalt oxide catalyst. In this work, Gallium oxide (β-Ga2O3 ) nanowires were synthesized by a simple thermal evaporation method from gallium powder in the range of 700 - 1000℃ using the iron, nickel, copper, cobalt and zinc oxide as a catalyst, respectively. The β-Ga2O3 nanowires with single crystalline without defects were successfully synthesized at the reaction temperature of 850, 900 and 950℃ in all the catalysts. But optimum experimental condition in synthesis of nanowires varied with the kind of catalyst. As increasing synthesis temperature,the morphology of gallium oxide nanowires changed from nanowires to nanorods, and its diameter increased. From these results, we could be proposed that the growth mechanism of β-Ga2O3 nanowires was changed with synthesis temperature of nanowires. Microstructure and morphology of Synthesized nanowire was characterized by HR-TEM, FE-SEM, EDX and XRD. 相似文献
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Cubic boron nitride(c-BN) film was deposited on a Si (100) substrate by the RF-magnetron sputtering.The mainly problems for fabrication of c-BN films are the low purity and high intrinsic compressive stress. In order to solve the two problems, the c-BN film with the buffer interlayer was deposited on the substrate which had been implanted with nitrogen and/or boron ions. The results show: the implantation of nitrogen ions can obviously increase c-BN content and reduce the internal stress slightly; while the implantation of boron shows no obvious improvement to the content of c-BN, which can reduce the internal stress in the film obviously. In addition, it is suggested that the implantation of nitrogen and boron shows the best result, which not only can increase the content of c-BN, but also reduce the internal stress in the c-BN film obviously. 相似文献