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1.
卞梁  王肖钧  章杰 《爆炸与冲击》2009,29(6):607-612
针对传统光滑粒子法在计算高速碰撞问题时会出现近邻粒子逸出核函数影响域而产生数值破坏这一缺陷,提出了一种根据粒子间距变化自动添加、合并粒子的SPH自适应粒子分布算法。采用该方法对Taylor碰撞和超高速碰撞问题进行了数值模拟,结果表明,该方法可以有效地消除计算中出现的数值破坏,提高计算精度。  相似文献   

2.
高速碰撞中的有限元方法及其应用   总被引:13,自引:2,他引:11  
讨论了连续介质力学守恒方程的有限元离散方法,针对高速碰撞的物理特点,提出了数值计算中所应重视的问题及其有效的解决办法。文中给出的典型算例说明本方法对各类高速碰撞问题的数值模拟计算是十分有用和成功的。  相似文献   

3.
超高速碰撞问题的三维物质点法   总被引:2,自引:0,他引:2  
马上  张雄  邱信明 《爆炸与冲击》2006,26(3):273-278
简要介绍了物质点法(material point method)的离散原理,通过引入Johnson-Cook材料模型和Mie-Gruneisen状态方程,将其用于超高速碰撞问题的分析中,并编制了相应三维物质点法程序MPM3D。该方法避免了拉格朗日格式因网格畸变产生的数值困难,也克服了欧拉格式材料界面跟踪问题以及因非线性对流扩散项而引起的数值困难。利用该程序对Taylor杆高速碰撞问题和空间碎片防护超高速碰撞问题进行了数值模拟,所得数值结果与实验结果基本吻合,验证了程序的正确性,说明了物质点法在分析超高速碰撞问题时相对于有限元法的优势。  相似文献   

4.
简要介绍了三维动力学分析软件MSC/DYTRAN的功能,基本特征,以及在数值计算领域如:浅滩水下爆破,弹丸高速碰撞,成型装药等问题中的应用,并给出了部分算例。  相似文献   

5.
《力学学报》2012,44(1)
通过建立弹塑性碰撞动态子结构模型,推导了模态坐标下的控制方程,提出了模拟柔性结构碰撞激发弹塑性波传播的动态子结构方法,并对其中的主模态的存在性和主模态截断的收敛性进行了证明.通过对柔性杆纵向碰撞和柔性梁横向碰撞两个算例的计算,并将计算结果与理论解和三维动力有限方法计算结果进行了对比,验证了该方法的数值收敛性和计算碰撞弹塑性波传播的有效性.  相似文献   

6.
三维显式有限元程序及炸药冲击起爆应用   总被引:1,自引:0,他引:1  
冲击和爆炸数值模拟在军事工程和民用领域都应用广泛。基于显式有限元理论,本文介绍了自主研发的三维冲击和起爆流体动力学程序。该程序的功能包含了材料本构、状态方程、炸药反应速率方程和接触碰撞算法,能够模拟复杂条件下结构冲击和炸药起爆问题。由于采用面向对象的编程方法,程序结构相对简单并且容易修改。首先,进行了Taylor杆碰撞数值模拟,并将计算结果与实验结果以及DYNA2D结果进行了比较;接着,基于Lee-Tarver点火增长模型,模拟了冲击加载下裸炸药和带壳炸药的冲击起爆问题。计算结果表明,三维程序计算结果与实验值和商业软件结果都非常吻合,该程序能够较准确地模拟三维结构的冲击和炸药起爆问题。同时,基于面向对象开发的三维计算程序实现了模块化功能,易于后续开发,为冲击和爆炸计算程序的开发提供了参考。  相似文献   

7.
大面积金属板材304L/Q235B的爆炸焊接过程涉及炸药爆轰、金属板材的高速碰撞和塑性变形等。采用有限元法计算模拟这个问题时,网格单元会发生扭曲畸变现象,导致计算精度下降,甚至出现单元负体积而使计算终止,并且炸药爆轰形成气体产物飞散过程也很难模拟。为了能模拟大面积金属板材的爆炸焊接整个过程并获得合理的技术工艺参数,采用物质点法进行三维数值模拟分析。物质点法作为一种无网格法,在模拟冲击动力学问题中主要采用显式积分算法。通过将拉格朗日质点单元与固定的欧拉背景网格相结合,可以实现爆炸焊接的复板与基板的高速碰撞、炸药滑移爆轰、金属板面的塑性变形过程的数值模拟,并给出爆炸复合板材的形变、有效塑性应变和复板与基板的碰撞速度的计算结果。采用物质点法模拟的复合板材变形与爆炸焊接实验结果基本一致。计算复板与基板的碰撞速度这个重要的物理参数时,物质点法与Richter理论公式的相对误差不超过13%。数值计算和实验结果表明,物质点法在数值精度和计算效率方面具有优势,物质点法是研究金属焊接爆炸问题的一种有效数值方法。  相似文献   

8.
通过建立弹塑性碰撞动态子结构模型, 推导了模态坐标下的控制方程, 提出了模拟柔性结构碰撞激发弹塑性波传播的动态子结构方法, 并对其中的主模态的存在性 和主模态截断的收敛性进行了证明. 通过对柔性杆纵向碰撞和柔性梁横向碰撞两个算例的计 算, 并将计算结果与理论解和三维动力有限方法计算结果进行了对比, 验证了该方法的数值 收敛性和计算碰撞弹塑性波传播的有效性.  相似文献   

9.
两自由度振动系统的斜碰撞分析   总被引:3,自引:0,他引:3  
韩维  胡海岩  金栋平 《力学学报》2003,35(6):723-729
研究斜碰撞振动系统动力学的一个关键问题是对系统在碰撞前后的状态进行合理描述和正确计算.针对两弹性体斜碰撞问题,基于瞬间碰撞假设,提出了采用步进冲量来分析和求解斜碰撞前后的状态关系;并以弹簧摆和振子组成的两自由度斜碰撞振动系统为例,具体介绍了该算法如何实现.用解析方法讨论了该系统在斜碰撞过程中可能出现的各种力学现象,将冲量步进算法得到的数值解与解析结果进行对比,取得了完全一致的结果.该数值方法能适应多种斜碰撞问题的计算.  相似文献   

10.
爆炸与冲击问题的大规模高精度计算   总被引:1,自引:0,他引:1  
爆炸与冲击问题的数值模拟在国防和民用安全领域具有重要的工程实用价值.由于爆炸与冲击问题是一个多物质在高应变率、高温及高压条件下的强非线性的瞬态动力学问题,给数值模拟带来了很多的困难,为此,针对爆炸与冲击问题数值模拟中的一些关键和难点问题开展了研究.提出了三维非线性双曲守恒系统的伪弧长自适应网格算法,分析了算法的实现过程,数值结果表明该算法有效地提高了冲击波强间断处的分辨率.发展了针对气相爆轰数值模拟的附加龙格-库塔方法,对非线性对流项进行显示计算,化学反应源项进行半隐式计算,有效地解决了源项引起的刚性问题,计算结果表明该算法可以准确地捕捉和描述爆轰波的复杂结构和典型特征.针对三维工程实际物理问题中的大规模计算需求,给出了三维多物质流体动力学欧拉数值方法的并行化方法,开发了三维爆炸与冲击问题并行计算程序,并给出了针对该并行程序的测试方法.上述工作有利地解决了爆炸与冲击问题大规模、高精度计算中的一些难题.最后,开展了大口径聚能射流侵彻混凝土靶问题的数值模拟和实验研究,通过典型爆炸与冲击工程问题的计算验证了所研究数值方法的有效性.  相似文献   

11.
聚能装药的欧拉数值模拟   总被引:2,自引:0,他引:2  
用二维有限差分欧拉程序MEPH2Y模拟了聚能装药的作用过程,包括爆轰波的形成、传播及与其他介质的相互作用,高温高压下射流(或射弹)的形成、延展、减压、断裂,射流(或射弹)对靶的侵彻及靶的成坑和动态响应等过程。介绍了程序所用的数学模型、数值方法,以及模拟的部分问题与实验结果的比较。结果表明,数值模拟结果与实验结果符合较好。  相似文献   

12.
SUMMARY

Analysis/design calculations of transonic flow are discussed and several improvements are made. The nonisentropic potential method is used to calculate the inviscid transonic flow analysis problem instead of the traditional potential method. An inverse integral 3D boundary layer method is used to calculate the boundary layer in the viscous transonic flow analysis problem. The viscous/inviscid interaction calculations are carried out by a semi-inverse coupling scheme. In design problem calculations, an improved residual-correction method is used. Three individual methods are combined in a global algorithm and computing code. The improvements speed up the convergence, increase applicability and computational efficiency. Some numerical results are given to illustrate that the present method provides an effective engineering tool of high accuracy and efficiency in three dimensional transonic analysis and design situations.  相似文献   

13.
In this paper, a least‐square weighted residual method (LSWRM) for level set (LS) formulation is introduced to achieve interface capturing in two‐dimensional (2D) and three‐dimensional (3D) problems. An LSWRM was adopted for two semi‐discretized advection and reinitialization equations of the LS formulation. The present LSWRM provided good mathematical properties such as natural numerical diffusion and the symmetry of the resulting algebraic systems for the advection and reinitialization equations. The proposed method was validated by solving some 2D and 3D benchmark problems such as those involving a rotating slotted disk, the rotation of a slotted sphere, and a time‐reversed single‐vortex flow and a deformation problem of a spherical fluid. The numerical results were compared with those obtained from essentially non‐oscillatory type formulations and particle LS methods. Further, the proposed LSWRM for the LS formulation was coupled with a splitting finite element method code to solve the incompressible Navier–Stokes equations, and then, the collapse of a 3D broken dam flow was well simulated; in the simulation, the entrapping of air and the splashing of the surge front of water were reproduced. The mass conservation of the present method was found to be satisfactory during the entire simulation. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

14.
This paper describes a new class of three‐dimensional finite difference schemes for high‐speed turbulent flows in complex geometries based on the high‐order monotonicity‐preserving (MP) method. Simulations conducted for various 1D, 2D, and 3D problems indicate that the new high‐order MP schemes can preserve sharp changes in the flow variables without spurious oscillations and are able to capture the turbulence at the smallest computed scales. Our results also indicate that the MP method has less numerical dissipation and faster grid convergence than the weighted essentially non‐oscillatory method. However, both of these methods are computationally more demanding than the COMP method and are only used for the inviscid fluxes. To reduce the computational cost for reacting flows, the scalar equations are solved by the COMP method, which is shown to yield similar results to those obtained by the MP in supersonic turbulent flows with strong shock waves. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

15.
This paper uses a fourth‐order compact finite‐difference scheme for solving steady incompressible flows. The high‐order compact method applied is an alternating direction implicit operator scheme, which has been used by Ekaterinaris for computing two‐dimensional compressible flows. Herein, this numerical scheme is efficiently implemented to solve the incompressible Navier–Stokes equations in the primitive variables formulation using the artificial compressibility method. For space discretizing the convective fluxes, fourth‐order centered spatial accuracy of the implicit operators is efficiently obtained by performing compact space differentiation in which the method uses block‐tridiagonal matrix inversions. To stabilize the numerical solution, numerical dissipation terms and/or filters are used. In this study, the high‐order compact implicit operator scheme is also extended for computing three‐dimensional incompressible flows. The accuracy and efficiency of this high‐order compact method are demonstrated for different incompressible flow problems. A sensitivity study is also conducted to evaluate the effects of grid resolution and pseudocompressibility parameter on accuracy and convergence rate of the solution. The effects of filtering and numerical dissipation on the solution are also investigated. Test cases considered herein for validating the results are incompressible flows in a 2‐D backward facing step, a 2‐D cavity and a 3‐D cavity at different flow conditions. Results obtained for these cases are in good agreement with the available numerical and experimental results. The study shows that the scheme is robust, efficient and accurate for solving incompressible flow problems. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

16.
钝感炸药点火增长模型的欧拉数值模拟   总被引:1,自引:0,他引:1  
在自主研发的二维多介质欧拉弹塑性流体力学程序中,通过引入点火增长的反应率模型以及炸药 减敏模型,借助网格自适应技术,研究钝感炸药的冲击点火、直径效应以及死区形成等爆轰现象。数值模拟结 果表明,该程序能够正确模拟平面爆轰波的爆速、CJ状态、vonNeumann尖点等爆轰参数;并能够较好模拟炸 药的直径效应。另外,通过引入考虑减敏效应的反应率模型,能较好地模拟钝感炸药的死区形成过程。  相似文献   

17.
钨珠对铝、钢靶侵彻的数值研究与分析   总被引:2,自引:0,他引:2  
本文应用MEPH程序数值模拟了击靶速度小于3km/s的4mm的钨珠对铝靶、钢靶的侵彻,并对计算所得的结果进行了理论分析,与有关实验比较。对弹丸的形状、靶材厚度对穿深的影响也给出了一部分结果。  相似文献   

18.
本文所提算法适用于二维和三维多介质流体力学两步欧拉数值方法中输运计算的混合网格(包括自由面网格)界面处理。在一个混合网格中,界面被近似地看作直线(二维)或平面(三维)。整个方法分为三步:(1)第一步,用混合网格周围的八个网格的介质面积份额(二维)或二十六个网格的介质体积份额(三维)确定界面的法线方向;第二步,用混合网格的本身的介质面积份额(二维)或体积份额(三维)确定界面的方程(位置);第三步,用此直线方程求出通过网格边界的流以及下一时刻网格的面积份额(二维)或体积份额(三维)。最后给出了用此方法所做的一些数值计算及与SLIC算法的比较。  相似文献   

19.
This paper applies the finite‐volume method to computations of steady flows of viscous and viscoelastic incompressible fluids in complex two and three‐dimensional geometries. The materials adopted in the study obey different constitutive laws: Newtonian, purely viscous Carreau–Yasuda as also Upper‐Convected Maxwell and Phan‐Thien/Tanner differential models, with a Williams–Landel–Ferry (WLF) equation for temperature dependence. Specific analyses are made depending on the rheological model. A staggered grid is used for discretizing the equations and unknowns. Stockage possibilities allow us to solve problems involving a great number of degrees of freedom, up to 1 500 000 unknowns with a desk computer. In relation to the fluid properties, our numerical simulations provide flow characteristics for various 2D and 3D configurations and demonstrate the possibilities of the code to solve problems involving complex nonlinear constitutive equations with thermal effects. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

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