Contact Area Evolution In Rough Surfaces: A Comprehensive X-Ray CT Study

Prof. Erik Johansson; Dr. Lars Nilsson; Prof. Maria Holm

Authors

Prof. Erik Johansson Department of Materials Science, KTH Royal Institute of Technology, Stockholm, Sweden
Dr. Lars Nilsson Department of Mechanical Engineering, Chalmers University of Technology, Gothenburg, Sweden
Prof. Maria Holm Department of Mechanical Engineering, Chalmers University of Technology, Gothenburg, Sweden

Keywords:

Real area of contact, Junction growth, Rough surfaces, X-ray computed tomography (X-ray CT)

Abstract

Understanding the contact behavior of rough surfaces is fundamental to predicting and controlling friction, wear, adhesion, and sealing in numerous engineering applications. A critical aspect of this behavior is the real area of contact, which is typically orders of magnitude smaller than the nominal contact area. Furthermore, under combined normal and tangential loading, the real area of contact can increase, a phenomenon known as junction growth. While theoretical models and numerical simulations have provided valuable insights into contact mechanics and junction growth, experimental validation, particularly for non-transparent materials and complex rough surfaces, remains challenging. This article presents a review of experimental investigations into the evolution of the real contact area and junction growth in rough contacts, with a specific focus on the application of X-ray computed tomography (X-ray CT). The principles of using X-ray CT for visualizing and quantifying the real contact area are discussed, along with typical experimental methodologies and findings. The analysis highlights the capability of X-ray CT to provide three-dimensional, non-destructive insights into the buried interface of rough contacts under various loading conditions, enabling a more direct experimental assessment of junction growth compared to traditional surface-based techniques. Challenges and future prospects of using X-ray CT and other advanced experimental methods for understanding rough contact behavior are also discussed.

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