用3D变分自编码器提取材料微观结构指纹,实现高效性能预测。
3D variational autoencoder for fingerprinting microstructure volume elements
- 通过映射到晶体学基本域,提升三维晶向数据的编码效率与训练收敛性。
- 在256维隐空间下,测试集平均取向误差仅3×10⁻²,重建精度高。
- 适用于不同织构、晶粒尺寸的微观结构,可替代耗时的晶体塑性模拟。
微观结构量化是建立材料结构-性能关系的关键步骤。基于机器学习的图像处理方法已优于传统技术,被广泛应用于微观结构量化。本文提出一种3D变分自编码器(VAE),用于编码包含体素化晶向数据的微观结构体积元(VEs)。通过将晶向空间映射至晶体学基本域进行预处理,实现连续损失函数,加速训练收敛。模型对随机织构的等轴多晶微观结构体积元进行编码,测试集上相对平均取向误差为3×10⁻²,隐空间维度为256。模型在纹理、晶粒尺寸和长宽比超出训练分布的微观结构上仍具有良好泛化能力。通过将训练集中的体积元作为晶体塑性(CP)模拟的初始构型,获取各应变增量下的体积平均应力响应,并将微结构指纹(低维隐空间参数)与应力记录一同存储,训练全连接神经网络以构建从指纹到应力响应的代理模型。该指纹代理模型在未见测试数据上实现2.75 MPa的相对均方误差,准确捕捉微观结构对CP应力响应的影响。
原文摘要 · Abstract (English)
Microstructure quantification is an important step towards establishing structure-property relationships in materials. Machine learning-based image processing methods have been shown to outperform conventional image processing techniques and are increasingly applied to microstructure quantification tasks. In this work, we present a 3D variational autoencoder (VAE) for encoding microstructure volume elements (VEs) comprising voxelated crystallographic orientation data. Crystal symmetries in the orientation space are accounted for by mapping to the crystallographic fundamental zone as a preprocessing step, which allows for a continuous loss function to be used and improves the training convergence rate. The VAE is then used to encode a training set of VEs with an equiaxed polycrystalline microstructure with random texture. Accurate reconstructions are achieved with a relative average misorientation error of 3x10^-2 on the test dataset, for a continuous latent space with dimension 256. We show that the model generalises well to microstructures with textures, grain sizes and aspect ratios outside the training distribution. Structure-property relationships are explored through using the training set of VEs as initial configurations in various crystal plasticity (CP) simulations. Microstructural fingerprints extracted from the VAE, which parameterise the VEs in a low-dimensional latent space, are stored alongside the volume-averaged stress response, at each strain increment, to uniaxial tensile deformation from CP simulations. This is then used to train a fully connected neural network mapping the input fingerprint to the resulting stress response, which acts as a surrogate model for the CP simulation. The fingerprint-based surrogate model is shown to accurately predict the microstructural dependence in the CP stress response, with a relative mean-squared error of 2.75 MPa on unseen test data.
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