颗粒流润滑力链网络非均匀性及流态调控研究

Granular lubrication is a new lubrication method which can be used in extreme conditions, while the force chain network heterogeneity and flow control are the key obstacles remains unsolved in fully understanding granular lubrication theory. This project plans to start from the correlative control mechanisms of mesoscopic force chains，macroscopic constitutive and flow regime. Firstly, to study the force chain network heterogeneity of granular lubrication, by this way, the evolution rule of mesoscopic fabric for force chain networks will be systematic mastered. Then, this project intends to study the phase transformation mechanism, velocity sliding mechanism, self-diffusion characteristics and constitutive relations of granular lubrication, looking for proper 3D parameters to build granular lubrication phase diagram for guiding practice, besides, to establish stress-strain relation on the basis of coaxality and stress wave anisotropy. Finally, combining with tribological test results to compare with theory, important threshold value and criterion can be gained. With above achievements, granular lubrication theory and method for considering force chain network heterogeneity and flow control can be proposed. The research results will provide a new reference in tribological design, so as to promote the further development of granular lubrication theory.

颗粒流润滑是可应用在极端工况环境下的新型润滑方法，颗粒流润滑的力链网络非均匀性和流态调控是进一步完善颗粒流润滑理论亟需解决的关键问题。本项目拟从细观力链与宏观本构、流态的关联控制机制出发，研究颗粒流润滑系统力链网络的非均匀特性，掌握其力链网络细观织构的演变规律；进而探索颗粒流润滑的相态转变机制、速度滑移机制、自扩散特性和本构关系，寻找合适的三维参数，建立可以指导实践的颗粒流润滑相变图和构建以非共轴性、应力波动各向异性为基础的应力-应变关系。最后，结合摩擦学试验结果进行对比和验证，得到重要的判据和阈值，揭示相应的规律和控制方法，提出考虑力链网络非均匀性和流态调控的颗粒流润滑理论与方法。研究结果将为摩擦学设计提供新的借鉴，从而促进颗粒流润滑理论的进一步发展。

由于颗粒物质的离散性、颗粒流润滑流变的多样性以及力链演变的复杂性，导致颗粒流润滑状态下具体特殊且多样的动力学特性。通过力传输行为的试验研究，模拟分析颗粒流润滑状态下的动力学状态转变、力链演变、剪切膨胀特性、本构关系和相态转变机制，从一定程度上解释了颗粒流润滑的多尺度动力学机制，从而为完善颗粒流润滑理论提供了借鉴。. 通过剪切平行板间颗粒流润滑试验，研究了颗粒材料、颗粒尺寸、剪切速度和颗粒湿度对颗粒流润滑状态下力传输行为的影响。发现颗粒流润滑状态下的力传输路径主要决定于颗粒润滑介质之间的力链，从而揭示了颗粒流润滑时的力传递机制。. 结合接触分析和三体界面力学分析, 研究了颗粒流润滑的接触力分布规律、力链网络的演变规律及动力学状态、力链的分布及对颗粒流润滑系统的影响, 同时研究了润滑启动阶段剪切膨胀现象的变化规律，剪切膨胀的速度适应机制和压力适应机制，并在总结剪切速度和压力载荷对剪切膨胀影响的基础上分析得出了剪切膨胀现象的力学机制，阐明了压力载荷对颗粒流润滑的宏观流动、配位数和力链演变以及接触承载等动力学特性的影响规律，进而揭示了颗粒流润滑状态下的本构关系和相态转变机制。. 通过探索颗粒流润滑的相态转变机制、速度滑移机制、自扩散特性和本构关系，实现了细观力链与宏观本构、流态的有效关联。结合离散元方法，给出了考虑力链网络非均匀性和相变多样性的分析结果。针对平行板滑动摩擦副，并通过平行板颗粒流润滑的摩擦测试仪等摩擦学试验机对颗粒流润滑摩擦系数等参数进行了试验验证和修正。