热-力耦合作用下乏燃料剪切机运动副干摩擦行为研究

Dry Friction Behavior of Stainless Steel Kinematic Pair of Spent Fuel Shearing Machine under Thermal-mechanical Coupling

  • 摘要: 极端工况下乏燃料剪切机不锈钢滚轮运动副会出现卡死现象,滚动摩擦变为滑动摩擦,加之高辐照工况下难以润滑,导致轮轨运动副磨损严重。本文通过对经典Archard模型进行修正,建立了不锈钢干摩擦磨损的热-力耦合模型。对比试验表明,磨损预测的最大相对误差为9.34%,验证了所建立模型的有效性。利用本文所建模型研究了极限滑动工况下剪切滑车滚轮的摩擦行为。结果表明,随着滑动距离的增加,温度和Mises应力都呈先下降后上升的趋势,且对接触区域的影响范围逐渐扩大。本研究得到了滚轮磨损深度与滑动距离之间的定量映射规律,为提高乏燃料剪切机的可靠性提供理论依据。

     

    Abstract: The shearing machine is a key equipment in the spent fuel reprocessing system. The kinematic pair of the stainless steel roller in the shearing machine under extreme conditions will get stuck. Rolling friction becomes sliding friction and high radiation conditions make it difficult to lubricate, resulting in severe wear of the kinematic pair. Nowadays the research on dry friction of stainless steel kinematic pair is extremely scarce. Meanwhile, there is a lack of comprehensive design and maintenance methods in practical engineering applications. To overcome the above problem, the relevant research based on the experimental and simulated methods was conducted in this paper. Firstly, the classic Archard model was modified by defining the wear coefficient as a function of contact stress and sliding speed, and the numerical solution process was derived. The thermal-mechanical coupling model for stainless steel dry friction wear was established by simplifing the model as a two-dimensional problem. The above mentioned model was solved using the command stream of finite element software. Secondly, the dry sliding wear test of stainless steel kinematic pair was conducted. Compared with the experimental results, the maximum wear prediction error is 9.34%, which verifies the effectiveness of the established model. Meanwhile, the variation law of contact stress and temperature during the sliding process was analyzed. Due to the influence of wear and the frictional heat, the contact stress of the kinematic pair first decreases, then increases, and finally slowly decreases. The interaction between heat, contact stress, and wear affects each other. The influence mechanism of the three factors at different stages is constantly changing. Thirdly, the friction behavior of the pulley under extreme sliding conditions was studied using the above mentioned methods. The simulated results indicate that as the sliding distance increases, both temperature and Mises stress present earlier decrease and later increase trend. In addition, the scope of influence on the contact area is gradually expanding. During the reciprocating sliding process of the roller, the contact surface is subjected to cyclic loading and the plastic deformation will occur within the surface layer. As plastic deformation accumulates, the crack appears at a certain location on the contact surface and eventually leads to material falling off. Finally, The quantitative mapping law between the wear depth of the roller and the sliding distance is obtained, which provides a theoretical basis for improving the reliability of spent fuel shearing machines.

     

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