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基于潜在变量概率空间的随机多孔材料力学行为全概率分析方法

A FULL PROBABILISTIC ANALYSIS APPROACH FOR THE MECHANICAL BEHAVIOR OF RANDOM POROUS MATERIALS BASED ON LATENT VARIABLE PROBABILITY SPACE

  • 摘要: 随机多孔材料微观结构的不确定性经由物理规律的驱动传播到宏观响应不确定性。在此过程中,微观结构空间不确定性的充分描述需要引入高维联合概率密度函数,且需与非线性跨尺度传播互相耦合,为宏观性能的不确定性量化带来了严峻的挑战。为此,本研究提出了一种基于变分自动编码器和概率密度演化理论的数据-物理双驱动的不确定性分析框架,实现了单轴受压下随机多孔微观结构不确定性向宏观均匀化应力-应变响应不确定性的传播。首先利用数据驱动的变分自编码器将复杂高维微观结构映射到低维潜在空间,并以低维潜在变量的概率分布近似表征其高维空间不确定性。这不仅实现了高维随机变量的有效降维,且保留了微观结构的关键概率分布特征。随后,在潜在变量的概率空间中采样,并解码映射回原像素空间,以重建微观结构样本。进一步地,基于物理驱动的概率密度演化理论与潜在变量的概率空间中的确定性采样,将高维不确定性问题转换为一组确定性偏微分方程的求解,最终给出随机多孔材料均匀化应力-应变曲线的全概率演化过程。结果表明,对于64维的潜在概率空间,仅需1000次确定性分析便可达到20000次蒙特卡洛模拟计算的精度,验证了该方法的高效性与准确性。上述策略融合了数据驱动与物理驱动的各自优势,为复杂材料系统的不确定性分析提供了一种创新可行的解决方案。

     

    Abstract: Uncertainty in the microstructure of random porous materials propagates to the uncertainty of macroscopic responses through fundamental physical laws. This process requires a comprehensive description of the spatial uncertainty at the microscopic level, which involves the introduction of a high-dimensional joint probability density function. Additionally, the uncertainty need to be coupled with nonlinear multi-scale propagation, which creates significant challenges for the uncertainty quantification of macroscopic material performance. To address this issue, this study proposes a data-physics dual-driven uncertainty analysis framework integrating variational autoencoders and probability density evolution theory, and achieves the propagation of microstructural uncertainty to homogenized stress-strain response uncertainty under uniaxial compression. Initially, a data-driven variational autoencoder (VAE) is used to map the complex, high-dimensional microstructure to a low-dimensional latent space. In this space, the spatial uncertainty is represented by the probability distribution of the latent variables. This method effectively reduces the dimensionality of high-dimensional random variables while preserving the key probabilistic characteristics of the microstructure. Afterward, sampling is performed in the probability space of the latent variables, and the samples are then decoded back to the original pixel space to reconstruct the microstructure. This enables the generation of new microstructure samples that reflect the uncertainty in the original material system. Moreover, based on a physics-driven theory of probability density evolution,

     

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