共查询到18条相似文献,搜索用时 109 毫秒
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弹靶侵彻仿真中材料参数对计算结果有着至关重要的影响。为寻求一套适用于弹靶侵彻仿真计算的材料参数拟合方法,借助前期开展的靶板材料动态力学性能试验、靶板材料断裂试验,通过不同拟合方法依次得到不同的JC本构模型及失效模型参数,依据试验建立有限元计算模型,将数值计算结果与试验结果进行对比。结果表明:(1)对于同一材料的力学性能试验,采用不同的拟合方法可得到不同的JC本构、JC失效参数,二者会对弹靶仿真结果造成一定影响;(2)在不考虑温度软化项的前提下,采用高应变率作为参考应变率进行拟合能更加准确地表征材料在高应变率下的应力-应变关系,更加适用于弹靶侵彻强瞬态、高应变率作用过程仿真;(3)对于同一JC本构模型,采用平均应力三轴度拟合的JC失效模型较采用初始应力三轴度拟合的JC失效模型所得战斗部剩余速度计算结果偏小,仅采用拉伸试件结果拟合的JC失效模型较采用扭转、拉伸试件结果拟合的JC失效模型所得战斗部剩余速度计算结果偏小。 相似文献
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研究了Rubin等人提出的基于Rankine卵形体速度势函数分析的侵彻模型。根据该侵彻模型的基本方法编制了计算程序,计算头部形状为锥形、卵形和球形的长杆弹体垂直碰撞靶板时的侵彻深度和穿透靶板后的剩余速度,分析侵彻模型对不同头部形状的长杆弹体的适用性。另外,利用该分析方法计算并分析了卵形头部长杆弹体对铝靶侵彻和穿透的缩比模型问题,用分析方法验证了无量纲侵彻深度和剩余速度相等的侵彻几何相似规律,同时得到了弹体减加速度与几何尺寸成反比的重要结论。最后对混凝土靶板的侵彻与穿透问题进行了尝试计算,得到了同实验基本一致的计算结果并对其进行了深入分析。 相似文献
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以长杆弹垂直侵彻半无限厚靶板为研究对象,分析了弹体最大侵彻深度与入射速度的关系,研究了弹体入射速度对侵彻最大深度的影响规律。研究表明:靶板的强度和界面效应使弹体在侵彻过程中存在一个临界速度,当入射速度大于临界速度时,弹体的侵彻才能通过开坑阶段进入准稳定阶段,它是造成当入射速度较小时侵彻深度随入射速度的提高而几乎不变或缓慢增加的主要原因;准稳定侵彻过程中弹体速度和侵彻速度基本不变,并且两者存在线性关系,这种关系只与弹体和靶板的材料性能有关,是造成当入射速度较大时侵彻深度随入射速度的提高呈快速线性增大的主要原因。 相似文献
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根据串联战斗部对混凝土目标的毁伤模式,将其前、后级的作用过程进行分解,结合前级对目标的预破坏,运用数值模拟分析了混凝土靶体预开孔对弹丸侵彻性能的影响,并通过实验进行了部分验证。结果表明:相同靶体开孔深度一定条件下,随着开孔数量的增加,弹丸的侵深逐渐增加,但当开孔数量增大到一定程度时,其对弹丸侵深的提高并不是很明显;当弹丸侵深未超过开孔深度时,随开孔数量增加,弹丸侵彻过载明显下降,而当弹丸侵深超过开孔深度后,开孔数量对弹丸侵彻过载的影响则不大。相同靶体开孔数量一定条件下,随着开孔深度的增加,弹丸的侵深逐渐增加;当弹丸侵深未超过开孔深度时,弹丸的侵彻过载出现明显的下降段,且开孔越深,下降段越长;而当弹丸侵深超过开孔深度后,开孔深度对弹丸侵彻过载的影响则不大。研究结果可为串联战斗部的前、后级优化设计提供参考。 相似文献
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采用光滑粒子流体动力学(SPH)方法对花岗岩靶板受碰撞侵彻的大应变、高应变率变形问题进行了数值模拟。为了描述弹目材料的非线性变形及破坏特性,对花岗岩靶板引入了Holmquist-Johnson-Cook(HJC)本构模型及损伤模型,对弹体引入含损伤的Johnson-Cook(J-C)本构方程和Grüneisen状态方程,靶板与弹体均离散成拉格朗日粒子。通过自编程序仿真计算0~4 m/s的着靶速度下花岗岩靶板的三维侵彻过程,对比分析了钢珠在不同弹体条件下的侵彻结果,在固体侵彻、半流体侵彻和流体侵彻的区域内拟合了侵彻深度随着靶速度的变化曲线。数值计算结果显示,侵彻深度随着靶速度的增加在固体侵彻区间(v01421 m/s)呈现递增趋势,在半流体侵彻区间(1421 m/s?v0?1700 m/s)呈现递减趋势,在流体侵彻区间(v0 1700 m/s)呈现递增趋势并逐渐趋于平滑,达到峰值。 相似文献
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屈明 《工程物理研究院科技年报》2003,(1):157-158
利用ANSYS/LSDYNA软件,弹丸采用弹塑性硬化材料模型,混凝土采用HJC材料模型,并利用以前对弹丸侵彻混凝土研究所得到的材料参数,对同截卵、尖卵两种头形且尺寸和重量都较大的弹丸侵彻混凝土的侵彻性能进行了数值模拟研究。由于弹靶尺寸特征相差较大,在现有计算条件下,给建模和分析带来了较大困难,为了能将计算规模控制在可求解的范围内,我们采用二维模型来分析研究弹丸的高速侵彻能力,采用三维模型来研究当弹丸带有—定攻角和着角时其在进入隧道段之前的行为。 相似文献
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建立了考虑损伤的求解靶板阻力的理论模型,以此来评估陶瓷靶板的抗侵彻能力;数值模拟了长杆弹侵彻氧化铝陶瓷靶的破坏特性,结合实验结果确定了氧化铝陶瓷本构模型中的材料参数。建立了聚能射流侵彻氧化铝陶瓷靶的计算模型,对射流的形成机理及氧化铝陶瓷靶的抗侵彻性能进行研究,讨论了药型罩的几何尺寸对所形成的射流速度及侵彻深度的影响。结果表明:药型罩的锥角和壁厚增大,射流速度减小,壁厚对射流速度梯度的影响较大;同样,药型罩的锥角对侵彻深度也有较大的影响。 相似文献
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Transient elastography in anisotropic medium: application to the measurement of slow and fast shear wave speeds in muscles 总被引:1,自引:0,他引:1
Gennisson JL Catheline S Chaffaï S Fink M 《The Journal of the Acoustical Society of America》2003,114(1):536-541
From the measurement of a low frequency (50-150 Hz) shear wave speed, transient elastography evaluates the Young's modulus in isotropic soft tissues. In this paper, it is shown that a rod source can generate a low frequency polarized shear strain waves. Consequently this technique allows to study anisotropic medium such as muscle. The evidence of the polarization of low frequency shear strain waves is supported by both numeric simulations and experiments. The numeric simulations are based on theoretical Green's functions in isotropic and anisotropic media (hexagonal system). The experiments in vitro led on beef muscle proves the pertinent of this simple anisotropic pattern. Results in vivo on man biceps shows the existence of slow and fast shear waves as predicted by theory. 相似文献
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Glassmaker NJ Hui CY Yamaguchi T Creton C 《The European physical journal. E, Soft matter》2008,25(3):253-266
New experimental results are presented about the final stage of failure of soft viscoelastic adhesives. A microscopic view
of the detachment of the adhesive shows that after cavity growth and expansion, well adhered soft adhesives form a network
of fibrils connected to expanded contacting feet which fail via a sliding mechanism, sensitive to interfacial shear stresses
rather than by a fracture mechanism as sometimes suggested in earlier work. A mechanical model of this stretching and sliding
failure phenomenon is presented which treats the fibril as a nonlinear elastic or viscoelastic rod and the foot as an elastic
layer subject to a friction force proportional to the local displacement rate. The force on the stretched rod drives the sliding
of the foot against the substrate. The main experimental parameter controlling the failure strain and stress during the sliding
process is identified by the model as the normalized probe pull speed, which also depends on the magnitude of the friction
and PSA modulus. In addition, the material properties, viscoelasticity and finite extensibility of the polymer chains, are
shown to have an important effect on both the details of the sliding process and the ultimate failure strain and stress.
Electronic supplementary material Appendix B is only available in electronic form at
and are accessible for authorised users. 相似文献
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Interpretation of the data often requires numerical simulations of the experiments and comparisons with the data. However, determination of an appropriate set of values for parameters in constitutive equations valid under shock and high strain rate loading remains one of the most difficult tasks for material model developers. Most researchers employ experimental data obtained under idealized stress/strain states in the model parameter calibration scheme. Since the dynamic response of materials is very complex, especially the failure response, the generality of the model parameters is highly questionable. For example, the fracturing of ceramic materials involves nucleation, propagation, and coalescence of microcracks under shock and impact. The dynamic deformation processes in ceramics include dynamic pore collapse, dislocation generation, twinning, and microcracking. When shocked above the Hugoniot elastic limit, the ceramic deformation becomes inelastic; therefore, the constitutive model formulation should consider modeling the effects of these various processes on the degradation of strength and stiffness of ceramic. This paper presents a brief summary of diagnostic measurements and modeling techniques associated with validation and verification of ceramic constitutive/damage models under high strain rate, shock, and penetration loading applications. 相似文献
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DeCamp MF Reis DA Cavalieri A Bucksbaum PH Clarke R Merlin R Dufresne EM Arms DA Lindenberg AM MacPhee AG Chang Z Lings B Wark JS Fahy S 《Physical review letters》2003,91(16):165502
We measure transient strain in ultrafast laser-excited Ge by time-resolved x-ray anomalous transmission. The development of the coherent strain pulse is dominated by rapid ambipolar diffusion. This pulse extends considerably longer than the laser penetration depth because the plasma initially propagates faster than the acoustic modes. X-ray diffraction simulations are in agreement with the observed dynamics. 相似文献
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Reis DA DeCamp MF Bucksbaum PH Clarke R Dufresne E Hertlein M Merlin R Falcone R Kapteyn H Murnane MM Larsson J Missalla T Wark JS 《Physical review letters》2001,86(14):3072-3075
Pump-probe time-resolved x-ray diffraction of allowed and nearly forbidden reflections in InSb is used to follow the propagation of a coherent acoustic pulse generated by ultrafast laser excitation. The surface and bulk components of the strain could be simultaneously measured due to the large x-ray penetration depth. Comparison of the experimental data with dynamical diffraction simulations suggests that the conventional model for impulsively generated strain underestimates the partitioning of energy into coherent modes. 相似文献
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A. S. Vlasov E. L. Zil’berbrand A. A. Kozhushko A. I. Kozachuk A. B. Sinani A. I. Slutsker V. I. Betekhtin S. S. Ordan’yan 《Technical Physics》2004,49(5):583-586
The kinetics of penetration of deformable striking rods into SiC ceramics with different void content is studied. The penetration
may be viewed as a two-stage process. At the first stage, the penetration rate is minimal and the rate of contraction of the
rod is maximal. At this stage, the penetration resistance of the ceramic is the highest. At the second (quasi-steady-state)
stage, the penetration kinetics is similar to the kinetics of penetration into a zero-strength medium and resistance to penetration
is largely inertial. At the first stage, the penetration resistance is shown to correlate with the hardness of the ceramic
and depend strongly on the void content. 相似文献