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arXiv 2103.12282math.NAcs.NA
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基于Padé展开的高阶隐式时间积分格式

High-order implicit time integration scheme based on Padé expansions

University of New South Wales(新南威尔士大学)

Chongmin Song, Sascha Eisenträger

摘要:

本文提出了一种求解瞬态和波传播问题的单步高阶隐式时间积分方法。它是由状态空间中一阶常微分方程的矩阵指数解的Padé展开式构造的。利用多项式因式分解和部分分式的有理函数的技术,并通过解耦的位移和速度矢量的解决方案,开发了一个计算效率高的计划。新算法的一个重要特点是不需要直接求质量矩阵的逆。本文从$M$阶对角Padé展开出发,发展了一个$2M$阶时间步进格式。这里,精度每提高两个阶数,就需要求解一个额外的实数或复数稀疏方程组。这些系统在复杂性上与标准Newmark方法相当,即,有效系统矩阵是静态刚度、阻尼和质量矩阵的线性组合。结果表明,二阶格式与Newmark常平均加速度法(通常也称为梯形法则)是等价的。所提出的时间积分器已在MATLAB中实现,使用内置的直接线性方程求解器。在这篇文章中,数值例子具有近一百万自由度。与普通的二阶时间积分格式相比,具有较高的精度和效率。MATLAB实现可根据请求从作者或GitHub存储库(待添加)获得。

英文摘要:

A single-step high-order implicit time integration scheme for the solution of transient and wave propagation problems is presented. It is constructed from the Padé expansions of the matrix exponential solution of a system of first-order ordinary differential equations formulated in the state-space. A computationally efficient scheme is developed exploiting the techniques of polynomial factorization and partial fractions of rational functions, and by decoupling the solution for the displacement and velocity vectors. An important feature of the novel algorithm is that no direct inversion of the mass matrix is required. From the diagonal Padé expansion of order $M$ a time-stepping scheme of order $2M$ is developed. Here, each elevation of the accuracy by two orders results in an additional system of real or complex sparse equations to be solved. These systems are comparable in complexity to the standard Newmark method, i.e., the effective system matrix is a linear combination of the static stiffness, damping, and mass matrices. It is shown that the second-order scheme is equivalent to Newmark's constant average acceleration method, often also referred to as trapezoidal rule. The proposed time integrator has been implemented in MATLAB using the built-in direct linear equation solvers. In this article, numerical examples featuring nearly one million degrees of freedom are presented. High-accuracy and efficiency in comparison with common second-order time integration schemes are observed. The MATLAB-implementation is available from the authors upon request or from the GitHub repository (to be added).

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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