共查询到20条相似文献,搜索用时 31 毫秒
1.
文章将刚塑性/刚粘塑性流动理论与再生核质点方法(RKPM)相结合,提出了基于刚塑性/刚粘塑性不可压缩材料的无网格RKPM法,进一步拓展了无网格RKPM法的应用范围。分别采用边界奇异权法和修正的罚函数法处理本质边界条件和体积不可压缩条件,推导了金属塑性成形过程无网格RKPM法数值模拟的刚度方程,给出了关键算法。对平面应变镦粗过程进行了数值模拟,并将模拟结果与刚塑性有限元体积成形商品化软件Deform 2D计算结果作了比较,二者吻合良好,表明了该文方法的正确性和有效性。 相似文献
2.
3.
将无网格方法引入三维金属体积成形分析,在给出基于刚塑性流动理论的三维无网格再生核质点方法及其基本理论方程的基础上,为了提高分析系统的通用化和自动化,采用网格法来描述任意形状的三维模具型腔曲面,给出了三维无网格法数值模拟系统中动态接触边界自动处理的非线性接触算法,实现了任意模具形状的三维体积成形过程的无网格法数值模拟。对上模为半球形的三维立方体塑性变形过程进行了数值模拟,并与三维刚塑性有限元体积成形商品软件Deform3D的计算结果作了比较,验证了本文方法的正确性。 相似文献
4.
H.Y. Wen X.H. Dong X.Y. Ruan 《金属学报(英文版)》2006,19(2):79-84
A meshfree method based on reproducing kernel approximation and point collocation is presented for analysis of metal ring compression. The point collocation method is a true meshfree method without the employment of a background mesh. It is shown that, in a point collocation approach, the remesh problem because of the mesh distortion in FEM (finite element method) and the low efficiency in Galerkin-based meshfree method are avoided. The corrected kernel functions are introduced to the stabilization of free-surface boundary conditions. The solution of symmetric ring compression problem is compared with a conventional finite element solution, and reasonable results have been obtained. 相似文献
5.
6.
7.
8.
9.
10.
11.
In this article, the elastic-plastic finite element formulations using dynamic explicit time-integration schemes are proposed
for numerical analysis of automotive body panel stamping processes. A general formulation of finite element simulation for
complex sheet forming processes with arbitrarily shaped tools is briefly introduced. In finite element simulation of automotive
body panel stamping processes, the robustness and stability of computation are important requirements since the computation
time and convergency become major points of consideration besides the solution accuracy due to the complexity of geometry
and boundary conditions. For analyses of more complex cases with larger and more refined meshes, the explicit method is more
time effective than the implicit method, and it has no convergency problem and has the robust nature of contact and friction
algorithms, although the implicit method is widely used because of excellent accuracy and reliability. The elastic-plastic
scheme is more reliable and rigorous, while the rigid-plastic scheme requires short computation time. The performance of the
dynamic explicit algorithms is investigated by comparing the simulation results of forming of complex-shaped automotive body
parts, such as a fuel tank and a rear hinge, with the experimental results. It has been shown that dynamic explicit schemes
provide quite similar results to the experimental results. It is thus shown that the proposed dynamic explicit elastic-plastic
finite element method enables an effective computation for complicated automotive body panel stamping processes. 相似文献
12.
采用刚塑性材料假设,建立了刚塑性无网格伽辽金方法。利用变换法施加本质边界条件;采用反正切摩擦模型描述摩擦力边界,在局部坐标系下施加摩擦力边界条件;采用Newton-Raphson迭代方法求解刚度方程。对于挤压过程而言,当高径比较大时,可被近似为稳态流动。由于口模内速度变化梯度较大,采用最小二乘近似节点控制方法来控制近似效果。根据建立的刚塑性无网格伽辽金方法对正向、反向和复合挤压过程等进行了稳态分析,并与刚塑性有限元软件Deform模拟结果进行了相应的比较,验证了无网格伽辽金方法分析结果的正确性。 相似文献
13.
三维有限元模拟技术在金属塑性成形中的应用 总被引:8,自引:1,他引:8
金属塑性成形过程是一个非常复杂的弹塑性大变形过程,有限元法是用于金属成形过程模拟中一种有效的数值计算方法。本文概括地介绍了弹塑性、弹粘塑性、刚塑性、刚粘塑性四种有限元法,系统地讨论了有限元模拟中的关键技术,即几何模型的建立、单元类型的选择、网恪的划分与重划分、接触和摩擦问题等技术,并结合实例说明了三维有限元模拟在金属塑性成形领域中的具体应用。最后,基于现存问题提出了自己的见解。 相似文献
14.
Y.G. Dong W.Z. Zhang J.F. Song 《金属学报(英文版)》2007,20(1):49-58
In alloy bar rolling process, the component of alloyed steel influenced the spread coefficient greatly, therefore, the component influence coefficient m of different alloyed steel has been determined firstly to calculate the maximum spread. Then the curvature radius of stress free surface and the "critical point on the contact boundary" have been solved, the surface profile of outgoing workpiece has been obtained. Furthermore, the formula of the equivalent contact section area has been proposed and the mean roll radius has been calculated. The bar rolling experiment and the rigid-plastic FEM (finite element method) simulation have been carried out to verify the novel approach. Compared with experimental data and simulation results, the novel approach can be used in setting processing parameter and design of finishing groove. 相似文献
15.
塑性有限元在金属轧制过程中应用的进展 总被引:2,自引:0,他引:2
介绍了塑性有限元在金属轧制领域中应用的发展历程和新进展,包括:刚塑性有限元理论及应用研究;弹塑性有限元在轧制过程分析中的进展;用于轧制过程建模的快速有限元;元胞自动机与有限元结合进行轧制过程多尺度综合模拟;利用晶体塑性有限元研究轧制过程中取向织构;轧制过程中裂纹和夹杂物演变的有限元模拟.最后对今后的发展趋势做了展望. 相似文献
16.
17.
18.
运用一种基于全量理论的多步有限元方法计算分析了金属体积成形过程.该方法针对刚塑性不可压缩材料,在静力平衡条件下以约束变分原理通过最小化近似塑性势能进行有限元求解.多步模拟在各中间构形的虚拟滑动约束下沿变形路径进行分步迭代计算,考虑了接触和变形历史,能够快速模拟较复杂的体积成形问题.运用该方法对几个典型金属体积成形过程进行了正向一步和多步数值模拟,将计算结果与增量有限元法计算结果进行了比较.结果表明:在计算金属体积成形过程中,基于全量理论的多步有限元模拟能够在大大缩短计算时间的同时获得与增量法计算结果相比偏差小于10%的计算结果. 相似文献
19.
As a new attempt, equal channel angular extrusion (ECAE) of nickel–titanium shape memory alloy (NiTi SMA) tube was investigated by means of process experiment, finite element method (FEM) and microscopy. NiTi SMA tube with the steel core in it was inserted into the steel can during ECAE of NiTi SMA tube. Based on rigid-viscoplastic FEM, multiple coupled boundary conditions and multiple constitutive models were used for finite element simulation of ECAE of NiTi SMA tube, where the effective stress field, the effective strain field and the velocity field were obtained. Finite element simulation results are in good accordance with the experimental ones. Finite element simulation results reveal that the velocity field shows the minimum value in the corner of NiTi SMA tube, where severe shear deformation occurs. Microstructural observation results reveal that severe plastic deformation leads to a certain grain orientation as well as occurrence of substructures in the grain interior and dynamic recovery occurs during ECAE of NiTi SMA tube. ECAE of NiTi SMA tube provides a new approach to manufacturing ultrafine-grained NiTi SMA tube. 相似文献