Which Asperity Scales Matter for True Contact Area? A Multi-Scale and Statistical Investigation

Details

• Personal Author:
  Jackson RL ; Jacobs TDB
• Description:
  The true contact area between two surfaces is only a small fraction of the apparent macroscopic contact area; it governs many interfacial properties such as friction and contact resistance and depends sensitively on roughness. However, for real-world multi-scale surface topography, it is not clear which size scales of roughness govern the true contact area. This study investigates true contact area for a real-world surface that has been characterized across all scales from Angstroms to centimeters. Elastic and elastic-plastic contact is investigated using both a multiscale framework and a statistical roughness model. The multiscale method is a rough-surface contact-modeling technique based on Archard's stacked scales from a spectrum of the surfaces, which has shown promise when compared to previous experimental and numerical results. In contrast, statistical models assume that the asperities follow a defined height distribution and are in contact when taller than the mean surface separation. The results show that even the smallest scales can have a significant influence on the contact area, especially when the contact is elastic. However, when the contact is elastic-plastic, the influence of smaller scales can be limited depending on the character of the roughness. For self-similar, fractal-like roughness across some scales, the pressure tends to saturate at those scales. This work also explores the inclusion of scale-dependent yield strength. Both the multiscale and statistical models predict that the inclusion of scale-dependent strength causes the predicted contact area of the elastic-plastic models to come into closer agreement with that of the elastic model, especially when a wider range of size scales are included. In addition, both types of models predict that below a certain scale, smaller asperities flatten under contact pressure and will no longer influence the predicted contact area. Taken together, this work helps to guide the accurate modeling of rough-surface contact, and provides insights into which scales can be modified to improve performance in manufactured components. [Description provided by NIOSH]
• Subjects:
  Occupational Health Safety
• Keywords:
  Author Keywords: Contact Contact Mechanics Mathematical Models Mechanical Properties Testing Roughness Rough Surfaces Surface Properties Topography
• ISSN:
  0167-6636
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Journal Article
• Place as Subject:
  Alabama ; OSHA Region 3 ; OSHA Region 4 ; Pennsylvania
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Volume:
  184
• NIOSHTIC Number:
  nn:20068410
• Citation:
  Mech Mater 2023 Sep; 184:104746
• Contact Point Address:
  R.L. Jackson, Department of Mechanical Engineering, Auburn University, Auburn, AL, 36849, USA
• Email:
  jackson@auburn.edu
• Federal Fiscal Year:
  2023
• Performing Organization:
  University of Pittsburgh
• Peer Reviewed:
  True
• Start Date:
  20210930
• Source Full Name:
  Mechanics of Materials
• End Date:
  20230929
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:d50e9f413cf34baf26b775d3eeec7860836ebbfc52344e73d75838b281f8d6024171b0d4727bef91272460c88d9efbb90861944f5dad8a50752d2150334e2fdd
• Download URL:
  https://stacks.cdc.gov/view/cdc/230568/cdc_230568_DS1.pdf
• File Type:
  [PDF - 4.46 MB ]