传动件接触表面润滑及疲劳损伤机理研究

Transmission components are widely used in aerospace and automotive industries, however，they are often subject to wear and contact fatigue damages when they operate under heavy cyclic contact loading, especially in the presence of subsurface micro-defects such as inclusions. To alleviate such damages, lubricants are usually employed to prevent direct contact between two surfaces. However, the damage mechanisms of transmission components under lubrication conditions are still unclear and the mechanics model capable of predicting their reliability and life time is not available. Thus, the proposed project aims to develop a quantitative mechanics model to understand the contact fatigue and wear damage mechanisms of transmission components under elastohydrodynamic lubrication conditions, with the effects of surface roughness and subsurface micro-defects being taken into account. Based on this model, the surface wear and the subsurface micro-crack nucleation and propagation behaviors of the components can be analyzed and their remaining life time can be estimated. The quantitative mechanics model would be developed based on micromechanics, contact mechanics and computational fluid dynamics by integrating Eshelby' equivalent inclusion method, the distributed dislocation technique, the contact mechanics theory, the wear law and the fluid dynamics. Experimental methods including wear and contact fatigue testing, subsurface micro-defect detection, and surface profiling will be used not only to provide physical parameters for the mechanics model but also validate it. This study will not only enrich the knowledge of mechanics but also be of great significance for the design, manufacturing and maintenance of transmission components as well as for the selection and optimization of the lubricants.

传动件广泛应用于航空航天、汽车制造等领域， 但在周期性重载荷下，其表面磨损以及近表面疲劳断裂会导致零部件的性能降低甚至损毁，特别是当其近表面存在夹杂等微观缺陷。尽管润滑剂能缓解该类损伤及破坏，传动件接触表面在润滑条件下的疲劳损伤机理尚不明确，其可靠性及寿命预测还缺少完整的理论模型。本项目旨在建立传动件非光滑接触表面下含夹杂等缺陷时，在弹性流体动力润滑状态下的力学模型，分析其表面摩擦磨损，近表面裂纹形成与扩展以及由此导致传动件寿命的降低。该模型的建立基于微观力学、接触力学和计算流体力学，将综合运用Eshelby等效夹杂理论、分布位错法、接触算法、磨损理论、弹性流体动力学等方法。同时，摩擦疲劳损伤测试、近表面缺陷检测以及形貌分析等手段将被用来为模型提供可靠的物理参数以及实验验证。该研究将对传动件的设计制造、使用维护以及润滑油的选择产生非常重要的影响。

传动件广泛应用于航空航天、汽车制造等领域，但在周期性重载荷下，其表面磨损以及近表面疲劳断裂会导致零部件的性能降低甚至损毁，特别是当其近表面存在夹杂等微观缺陷。尽管润滑剂能缓解该类损伤及破坏，传动件接触表面在润滑条件下的疲劳损伤机理尚不明确，其可靠性及寿命预测还缺少完整的理论模型。. 本项目构建了基于微观力学的计算平台，通过综合运用Eshelby 等效夹杂理论、分布位错法、接触算法、磨损理论、弹性流体动力学等方法，精确预测了含夹杂、裂纹等微观缺陷的材料在各种摩擦接触情况下的应力场分布、接触面积和塑性变形等。研究发现，干摩擦接触条件下，裂纹的长度、深度和数量以及非同质夹杂的性质和数量分布对材料表面的变形和应力分布有明显的影响。应力集中现象容易发生在裂纹的尖端部位和夹杂的边缘处，从而引起塑性变形，并且受夹杂的性能和分布影响较大。在弹流润滑条件下，润滑油的厚度和压强分布受很多因素的影响，包括裂纹与夹杂的数量和分布、表面粗糙度、润滑油的流动速度以及接触模式的变化等，并最终影响了材料表面的变形。计算平台还成功分析了边界润滑或粘滑接触情况下应力分布以及材料近表面内缺陷对摩擦接触的影响。此外，计算平台精确计算了在多种工况条件下裂纹的应力强度因子，细致分析了裂纹尖端的塑性变形机制。同时，本项目进行了传动件材料的摩擦磨损实验，为理论计算的验证提供了基础。. 因此，开发的计算平台能够提供完整的理论模型，来精确预测摩擦接触情况下材料的变形。通过系统分析关键因素在复杂工况条件下对摩擦接触特性的影响，形成了关于理论预测的数据库，有助于深入理解摩擦与润滑过程中材料的微观力学问题，有助于澄清润滑条件下传动件材料的疲劳损伤机制、预测其使用寿命。