Prof. Xu Minglong’s team from Xi’an Jiaotong University has published a study on stick-slip friction in Science Advances, titled "Frictional strength regulated by roughness alignment." The research addresses a key challenge in aerospace and high-end equipment fields: interface micro-nano roughness undermines the performance of stepwise stick-slip friction-driven actuators—a core technology for next-generation spacecraft ultra-stable platforms (listed by ESA and NASA) valued for high precision and radiation resistance.

The team tested surfaces with Gaussian and fractal roughness, adjusting the alignment angle of contact surfaces. Macro experiments showed optimal alignment boosted static friction strength by nearly an order of magnitude (vs. random contacts) while keeping dynamic friction coefficient stable. Via 3D X-ray computed tomography (3DXRCT), they observed stick-slip transitions and found key parameters followed the Generalized Extreme Value (GEV) distribution. They also introduced a contact fabric tensor to quantify matching (its anisotropy index predicts friction transition load) and built a model that revealed a strong negative linear correlation between anisotropy index and static friction strength, consistent with rate-and-state friction (RSF) theory.

The study offers new insights for high-precision friction actuators and a mechanical framework for precision manufacturing, seismic modeling, and bionic adhesion systems. Xi’an Jiaotong University is the first completing unit. PhD student Huang Shaoqi and Associate Professor Zhang Shuwen are co-first authors; Profs. Zhai Chongpu and Xu Minglong are corresponding authors. Funding came from the National Natural Science Foundation of China (Nos. 12472186, 12202342), with support from relevant state key laboratories and testing centers at the university.

https://www.science.org/doi/10.1126/sciadv.ady6779