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中文核心期刊

基于有限元法的微凸体侧碰及摩擦系数预测模型

A PREDICTION MODEL FOR SHOULDER CONTACT AND FRICTION COEFFICIENT OF ASPERITY BASED ON FINITE ELEMENT METHOD

  • 摘要: 在微观层面, 摩擦现象可视为微凸体间的碰撞过程. 基于有限元法建立了U71MnG单对半球形微凸体的碰撞模型, 深入研究了微凸体侧碰偏移量对碰撞过程中法向力和切向力的影响. 为准确预测微凸体侧碰过程中切向力与法向力的关系, 构建了法向力和切向力与干涉量、偏移量及碰撞过程之间的非线性映射模型. 鉴于有限元计算过程耗时较长, 仅选取部分代表性算例进行有限元分析, 其余算例由训练后的BP神经网络(Back Propagation Neural Network , BPNN)进行预测. 进一步采用物理信息约束的星鸦优化算法(Physics-Informed Nutcracker Optimization Algorithm, PINOA)对BPNN的超参数进行了优化, 从而有效避免了神经网络的过拟合现象, 并显著提高了模型的预测精度. 研究结果表明, 在干涉量取10%、15%、20%、25%和30%R的五种工况下, 单对微凸体的切向力、法向力及其摩擦系数随干涉量增大而增大; 在相同干涉量下, 随偏移量增大, 单对微凸体的摩擦系数呈现下降趋势. 最后将微凸体的侧碰碰撞模型通过统计学模型推广至宏观表面, 获得可用于实际表面摩擦系数预测的函数表达式. 该建模过程与机器学习耦合框架在较短的计算时间内实现了对微凸结构接触响应的高精度预测, 为宏观表面摩擦行为的设计与预测提供了可操作的路径.

     

    Abstract: At the micro level, the friction phenomenon can be viewed as a collision process between asperities. A collision model for a pair of hemispherical asperities made of U71MnG was established based on the finite element method (FEM). This study extensively examined the impact of the lateral offset of asperities on the normal and tangential forces during the collision process. To accurately predict the relationship between the tangential and normal forces during the lateral collision of asperities, a nonlinear mapping model was constructed, relating normal and tangential forces to interference, offset, and the collision process. Given that the finite element computation is time-consuming, a subset of representative cases was analyzed using FEM, while the remaining cases were predicted by a trained Back Propagation Neural Network (BPNN). Additionally, hyperparameters of the BPNN were optimized using the Physics-Informed Nutcracker Optimization Algorithm (PINOA), effectively preventing overfitting and significantly improving the model's predictive accuracy. The results show that under five interference levels of 10%, 15%, 20%, 25%, and 30% R, the tangential force, normal force, and the corresponding friction coefficient for a single asperity increase with interference. At a fixed interference level, the friction coefficient decreases with increasing offset distance. Finally, the shoulder-contact collision model of the asperity was mapped to macroscopic surfaces using a statistical model, yielding a functional expression suitable for predicting real-world surface friction coefficients. The propose modeling framework coupled with machine learning achieves high-fidelity predictions of asperity contact responses within a relatively short computation time, providing a practical pathway for the design and prediction of friction behavior.

     

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