Multiple contact friction on laser-induced periodic surface structures (LIPSS)

激光诱导周期性表面结构上的多重接触摩擦 (LIPSS)

• 批准号: 454915637
• 负责人: Professor Dr. Gianaurelio Cuniberti, since 8/2021
• 金额: --
• 依托单位: Lehrstuhl für Oberflächen- und Grenzflächentechnologien
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/454915637?language=en
• 关键词: Multiple; contact; friction; laser; induced

This project aims to address a fundamental problem in materials science, i.e. the relation between the material and geometric properties of two solid surfaces and the kinetic friction variations recorded when the surfaces slide past each other in dry conditions. To this end we will make use of state-of-the-art preparation and characterization methods including femtosecond laser irradiation and advanced atomic force microscopy (AFM) techniques. Laser induced periodic surface structures (LIPSS) with different special periods, orientation and degrees of complexity will be the benchmark for friction force measurements with colloidal probes used as sliding objects. The materials addressed in the project will include metals (stainless steel), glasses (fused silica), polymers (PDMS, PVS, PMMA), and graphite (HOPG) which will allow to establish and analyse a significant collection of friction force signals. Due to the complexity of the problem (involving millions of atoms in the contact areas continuously ruptured and formed again) we will ignore phenomena occurring at the molecular scale, but rather treat the two bodies as a continuum and start from a statistical characterization (a) of the surface properties (morphology, stiffness and adhesion) before the contact is established and (b) of the time evolution of the friction under different loading conditions. The first series of data will be used as an input for numeric simulations based on the contact theory recently established by B.N.J. Persson. This theory is capable of predicting the real contact area corresponding to a given normal force from the power spectral density of the surface height. The second series of data will be compared with the friction force variations estimated with the Burridge-Knopoff model for earthquake dynamics. This pioneer model considers a series of blocks joined by springs and collectively dragged (elastically) by a larger object simulating a tectonic plate. In our case, the blocks correspond to the contact patches and the springs represent the stiffnesses of the “bridges” established through the bulk material joining two patches. The driving plate is the colloidal probe coupled to the AFM cantilever. As a result a complex pattern of overlapping stick-slip phases is expected, the average of which, divided by the applied normal load, is the friction coefficient. This will be interesting to test possible deviations from the Amonton’s theory, which has been recently discussed in the literature, and also find important multidisciplinary applications, e. g. in the development of artificial tactile sensors.

该项目旨在解决材料科学中的一个基本问题，即两个固体表面的材料和几何性质之间的关系，以及在干燥条件下表面相互滑动时记录的动摩擦变化。为此，我们将利用最先进的制备和表征方法，包括飞秒激光照射和先进的原子力显微镜（AFM）技术。激光诱导周期性表面结构（LIPSS）具有不同的特殊周期、取向和复杂程度，将成为胶体探针作为滑动物体进行摩擦力测量的基准。该项目涉及的材料将包括金属（不锈钢）、玻璃（熔融石英）、聚合物（PDMS、PVS、PMMA）和石墨（HOPG），这些材料将允许建立和分析大量的摩擦力信号。由于问题的复杂性（涉及接触区域中数百万个原子连续破裂并再次形成）我们将忽略分子尺度上发生的现象，而是将两个物体视为一个连续体，并从表面性质的统计表征开始。（形态、刚度和附着力）和（B）在不同载荷条件下摩擦的时间演变。第一系列的数据将被用作基于B.N.J. Escherson最近建立的接触理论的数值模拟的输入。该理论能够从表面高度的功率谱密度预测与给定法向力对应的真实的接触面积。第二个系列的数据将与摩擦力的变化估计与Burridge-Knopoff模型的地震动力学进行比较。这个先驱模型考虑了一系列由弹簧连接的块体，并被一个模拟构造板块的更大物体（弹性地）共同拖曳。在我们的例子中，块对应于接触片，弹簧代表通过连接两个片的散装材料建立的"桥"的刚度。驱动板是耦合到AFM悬臂梁的胶体探针。因此，预计会出现重叠粘滑阶段的复杂模式，其平均值除以所施加的法向载荷，即为摩擦系数。这对于测试与阿蒙顿理论的可能偏差将是有趣的，该理论最近在文献中进行了讨论，并且还发现了重要的多学科应用，例如。G.在人工触觉传感器的发展中。