内燃机活塞组-缸套系统多尺度混合润滑建模、磨损规律及性能退化机理研究

For the piston assembly-liner system of internal combustion engines, the tribological performance is changing dynamically due to wear. However, it is still hard to predict the wear process of an engineering friction pair such as the piston assembly-liner system for the following two reasons. The first reason is that it is difficult to determine the interfacial lubrication and contact status because the multi-scale effects at the system interface. The second reason is that the wear coefficient of the presented wear models doesn't correspond to the dynamic changes of the interfacial contact status accurately. In this project, the wear process and the dynamic changing mechanism of the tribological performance of engineering friction pairs will be studied. During research the piston assembly-liner system will be selected as the study object. Firstly the modeling and numerical solving methods of the multi-scale mixed lubrication will be studied according to the multi-scale characteristics of the engineering tribological interface. Secondly the wear law will be studied to determine the wear coefficient at different contact status based on wear experiments and theoretical analysis. Then the dynamic changing process of the system performance and its mechanism will be studied based on a coupling analysis of the multi-scale mixed lubrication and the wear process. Some experiments will be conducted to verify and modify the presented theoretical methods. By this project the tribologial theory and the corresponding analysis methods towards to specific engineering friction pairs will be enriched. The results of this project will lay the foundations for the tribological design of the piston assembly-liner system to reach a prolonged wear life and improved tribological performance during the life-time.

由于磨损，内燃机活塞组-缸套摩擦副的摩擦学性能一直处于动态变化之中。然而磨损的预测仍是摩擦学界的难题，一是因为活塞组-缸套等工程摩擦副界面处的多尺度效应问题，导致界面处的润滑和接触状态难以精确确定；二是因为磨损预测模型中的磨损系数未能很好地反映界面处接触状态的动态变化。本项目将以内燃机活塞组-缸套摩擦副为对象，对系统磨损过程及摩擦学性能退化机理进行深入研究。首先针对摩擦副界面处的多尺度特点，研究多尺度混合润滑建模，以及降低计算自由度数的高效数值方法。然后基于实验和理论分析，研究活塞组-缸套系统复杂接触状态下的磨损系数取值规律。接下来基于多尺度混合润滑和磨损耦合分析，研究活塞组-缸套系统摩擦学性能的动态演变过程及退化机理，并开展实验对模型和方法进行验证和修正。本项目研究将丰富摩擦学理论及其面向工程摩擦副的分析方法，相关结果将为活塞组-缸套等摩擦副在寿命期内控制磨损、优化摩擦学性能提供依据。

内燃机仍然是船用和车用领域的主要动力装置。活塞组-缸套系统是内燃机的关键摩擦副，在复杂及苛刻工况下，其润滑性能和抗磨损性能是学术界和产业界关注的焦点。对该系统进行精确建模和摩擦学性能准确预测面临较大的困难，主要表现在两个方面。一是因为活塞组-缸套等工程摩擦副界面处存在多尺度效应问题，表面宏观结构、微观粗糙度以及介于二者之间的表面织构等对摩擦副的润滑和接触均具有不可忽略的影响，导致界面处的润滑和接触状态难以精确和高效率地确定；二是因为磨损预测模型中的磨损系数未能很好地反映界面处接触状态的动态变化。本项目以内燃机活塞组-缸套摩擦副为对象，首先针对摩擦副界面处的多尺度特点，研究了多尺度混合润滑建模，以及降低计算自由度数的高效数值方法。然后基于实验和理论分析，研究了载荷、温度、润滑油特性、速度等因素对系统磨损过程的影响。接下来基于多尺度混合润滑和磨损耦合分析，研究了活塞组-缸套系统的表面形貌及系统性能动态演变过程。通过本项目研究，得到的主要结果包括：基于多尺度均匀化方法，考虑表面多尺度效应，建立了内燃机活塞组-缸套系统的多尺度润滑和磨损分析方法，并形成了相关的分析工具；对某柴油机活塞组-缸套系统的表面形貌进行了多尺度摩擦学分析和设计改进，理论结果和试验验证均表明可以降低系统摩擦损失15%以上；表面形貌与润滑油特性的综合改进，可以有效提高抗磨损性能和降低系统的能量消耗。本项目研究丰富了摩擦学理论及其面向工程摩擦副的分析方法，相关结果将为活塞组-缸套等工程摩擦副在寿命期内控制磨损、优化摩擦学性能提供理论依据和工具支持。