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ABAQUS中用户材料子程序UMAT的开发主要解决两方面的问题：本构模型的建立和积分算法的选择。 本文主要研究非线性材料的UMAT实现方法，并重点研究其迭代算法部分，目前，用户材料子程序UMAT的迭代算法主要是常刚度法，常刚度法的优点在于算法原理较简单，程序编写较方便，缺点是当遇到复杂非线性材料时，其迭代次数较多，收敛速度也较慢，在这个情况下，本文采取的是一种迭代次数较少且收敛速度较快的切线刚度法，具体就是采用FORTRAN语言编制了基于Von-Mises模型的接口程序,并采用切线刚度算法，通过与ABAQUS自带本构关系计算的结果相比较，验证其正确性。(This paper studies the user subroutine UMAT of ABAQUS development methods, the use of FORTRAN language isotropic hardening material model of the interface program, studied the effects of such material is extremely elastic-plastic constitutive relation method. This article UMAT tightly around the secondary development of technology, the first principle of its interface detail, and then for the theory of nonlinear finite element incremental stiffness of the regular tangent stiffness method and the theory of algorithms to do an in-depth analysis of deduced a regular tangent stiffness and rigidity of the law of the specific expression of algorithm theory, and then the preparation of the two algorithms, respectively, of the UMAT program, and finally the establishment of a specific model checking, bringing with ABAQUS elasto-plastic constitutive relation of the calculated results compared to verify the correctness of the two.)

用有限差分法求解雷诺方程，提供了一段简介的MATLAB程序(Reynolds equation using the finite difference method, the period of introduction MATLAB program)

说明：  给定四个数（1--13），判经过四则运算后能否得到结果24，若能，输出表达式。 (Given the number four (1- 13), after sub after four computing results can be 24, if the output expression.)

圆面上的点到圆心的距离 圆面上的点到圆心的距离 圆面上的点到圆心的距离 圆面上的点到圆心的距离(Round surface of the distance from point to circle center point of the surface of the distance to the center circle to the center point of the surface of the distance from the surface point to the center circle distance)

说明：  用matlab实现的有限元工具箱，有平面空间梁单元，杆单元，实体单元等。(achieved using Matlab Toolbox FEM, graphic space beam elements, rod elements, entities modules.)

模拟电场中的等势线，利用计算机数学软件MATLAB模拟仿真真空中自由电荷，电偶极子，带电细棒，尖端导体等附近静电场电场线及等势线分布图型(Equipotential line in simulated electric field)

数学中计算曲线积分 数学工具中常用到这样的方法(Calculated curve integral mathematics math tools commonly used in such a way)

牛顿迭代求根法和牛顿-steffensen加速法(Newton method for root-solving problems. Newton-Steffenson is also included.)

用C语言编写的Fluent UDF实例，包含Adjust宏，profile宏等八个实例教程，快速上手(The UDF is for computational fluid dynamics software Fluent, it concludes the Profile.c,the Adjust.c)

说明：  LM莱文博格马夸特优化算法，python语言(this is a file of LM algorithm which was wroten by python language)