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二维线弹性偏微分方程的格林函数傅里叶算子求解方法

GREEN'S FUNCTION FOURIER OPERATOR FOR TWO-DIMENSIONAL LINEAR ELASTIC PARTIAL DIFFERENTIAL EQUATIONS

  • 摘要: 线弹性理论是连续介质力学中最基础且应用最广泛的理论框架之一. 本文针对二维线弹性偏微分方程在非均质材料和任意边界条件下的高效求解需求, 提出了一种格林函数傅里叶算子(Green's Function Fourier Operator, GFFO)方法, 将微分算子的物理结构与格林函数的数学本质同时嵌入神经网络架构. 首先, 将输入函数经傅里叶级数展开进入频域空间, 在该空间中格林函数核及其偏导数被显式参数化为一组可学习的复数乘子. 对于自伴微分方程, 在频域核中强制嵌入Hermitian对称性; 对于非齐次边界条件下格林函数平移不变性的丧失, 通过增强频域核矩阵的稀疏性学习予以自适应近似. 基于频域截断将可学习积分核压缩为与网格无关的有限维参数集, 并设计了GFFO-linear、GFFO-lift和GFFO-ResMLP三种算子学习架构以适应不同复杂程度的求解需求. 通过二维复合材料代表性体积单元(Representative Volume Element, RVE)和混合边界条件弹性板两个典型算例进行验证. 结果表明, GFFO在逼近精度、计算效率和泛化能力三方面均优于对比方法, 且具备清晰的物理可解释性, 为线弹性力学问题的快速求解与参数化分析提供了新途径.

     

    Abstract: Linear elasticity theory constitutes one of the most fundamental and extensively applied theoretical frameworks in continuum mechanics, serving as the cornerstone for analyzing deformation, stress distribution, and mechanical response in a vast range of engineering materials and structures. Despite its long-standing maturity, the efficient and accurate numerical solution of two-dimensional linear elastic partial differential equations (PDEs) remains a persistent challenge, especially for problems involving highly heterogeneous materials with complex microstructural configurations and for structures subjected to arbitrary, non-trivial boundary conditions. To address this pressing need, this paper proposes a novel computational paradigm termed the Green's Function Fourier Operator (GFFO) method, which uniquely integrates both the physical structure of the underlying differential operators and the profound mathematical essence of Green's functions directly into the architecture of neural networks. The proposed approach begins by expanding the input functions into Fourier series, thereby mapping the original physical-space representation into the frequency domain, where the Green's function kernel together with its associated partial derivatives are explicitly parameterized as a set of learnable complex-valued multipliers. For self-adjoint differential equations, which constitute a broad and important class of problems in elasticity, Hermitian symmetry is strictly enforced within the frequency-domain kernel, ensuring that the learned operator faithfully preserves the intrinsic spectral properties of the true physical system. Furthermore, to properly handle non-homogeneous boundary conditions under which the translation invariance of Green's functions is inevitably lost, the method introduces an adaptive approximation strategy based on enhancing sparsity learning of the frequency-domain kernel matrix. Additionally, by exploiting frequency-domain truncation, the learnable integral kernel is effectively compressed into a finite-dimensional parameter set that is completely independent of the underlying computational grid, substantially reducing both the number of trainable parameters and the associated training cost. To accommodate solution problems of varying complexity, three distinct operator-learning architectures are carefully designed and implemented, namely GFFO-linear, GFFO-lift, and GFFO-ResMLP. The effectiveness of the proposed method is comprehensively validated through two representative numerical examples: a two-dimensional composite Representative Volume Element (RVE) characterized by heterogeneous microstructures, and an elastic plate subjected to mixed boundary conditions. Extensive experimental results consistently demonstrate that GFFO outperforms existing comparison methods across three critical dimensions—approximation accuracy, computational efficiency, and generalization capability—while simultaneously retaining clear physical interpretability owing to its explicit Green's function structure. This work therefore provides a novel, efficient, and physically grounded pathway for the rapid solution and parametric analysis of linear elasticity problems in computational mechanics and engineering applications.

     

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