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基于机器学习软骨细胞的时间依赖性力学行为及本构参数反演

TIME-DEPENDENT MECHANICAL BEHAVIOR AND CONSTITUTIVE PARAMETER IDENTIFICATION OF CHONDROCYTES BASED ON MACHINE LEARNING

  • 摘要: 探究软骨细胞机械负载下的力学特性对于理解软骨细胞的正常和病理状态以及骨性关节炎的病因至关重要. 基于软骨细胞有限元计算模型的力学响应与其本构参数之间的高度复杂非线性, 本文提出了分别利用双向深度神经网络TW-Deepnets模型和随机森林RF模型并结合有限元方法来识别软骨细胞本构参数的两种反演方法. 首先, 建立了软骨细胞的无侧限压缩实验有限元模型, 收集MSnHS本构参数空间点与对应的有限元计算模型的压缩反作用力响应数据集. 其次, 结合贝叶斯超参数优化算法搭建了用于软骨细胞本构参数反求的TW-Deepnets模型和RF模型, 对有限元收集的数据进行训练, 并利用单个软骨细胞受到50%压缩程度下的实验数据对软骨细胞的MSnHS本构参数进行了反求. 最后, 通过与实验曲线的对比验证了所提出的反演方法的有效性, 并引入决定系数R2对两种模型的预测准确性进行了对比评估, 检验了模型对各本构参数的预测性能, 分析了MSnHS本构模型中各参数影响软骨细胞力学响应的重要性占比. 结果表明, 本研究提出的本构参数反演方法能够有效获取软骨细胞的本构参数值, 从而准确描述软骨细胞的时间依赖性力学特性, 该方法也可进一步推广到生物细胞在静态或动态负载条件下的复杂参数反演问题.

     

    Abstract: Research on the mechanical properties of chondrocytes under mechanical loading is crucial to understanding their normal and pathological states of chondrocytes and the etiology of osteoarthritis. Based on the highly complex nonlinear relationship between mechanical response and the constitutive parameters of the finite element method computational model of chondrocyte, two inversion methods were proposed to identify the MSnHS constitutive parameters of chondrocytes using the two-way deepnets (TW-Deepnets) model and random forest (RF) model, respectively, combined with the finite element method. Firstly, a three-dimensional finite element model was developed to simulate a stress relaxation unconfined compression test of a single cell. The spatial points of MSnHS constitutive parameters and corresponding finite element compression reaction force-response data were collected. Secondly, the TW-Deepnets model and RF model for chondrocyte parameter inversion were built by combining the Bayes hyperparameter optimization algorithm, and the data collected by the finite element method were trained by the machine learning models. Based on the experimental data of a single chondrocyte subjected to 50% compression, the MSnHS constitutive parameters of chondrocytes were reversed. Finally, the effectiveness of the proposed inversion methods were verified by comparison with the experimental curves from Nguyen, and the accuracy of the two methods was compared and evaluated by determinant coefficient R2. The proportion of the importance of each parameter in the MSnHS constitutive model to the mechanical response of chondrocytes was analyzed, and the prediction performance of the two models for each constitutive parameter were tested. The results show that TW-Deepnets model and RF model combined with finite element method are effective and accurate method to identify the MSnHS constitutive material parameters of chondrocytes, and the obtained constitutive parameters can describe the time-dependent mechanical properties of chondrocytes. This method can also be extended to the complex parameters inversion problem of biological cells under static or dynamic loading conditions.

     

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