1 / 16

Modeling Static Friction of Rubber-Metal Contact

Modeling Static Friction of Rubber-Metal Contact. MANE 6960 Friction & Wear of Materials Katie Sherrick. Introduction. Most laws of friction are based on metal-metal contact Elastomer-metal contacts do not have the same friction properties as traditional friction laws would indicate

nevaeh
Download Presentation

Modeling Static Friction of Rubber-Metal Contact

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Modeling Static Friction of Rubber-Metal Contact MANE 6960 Friction & Wear of Materials Katie Sherrick

  2. Introduction • Most laws of friction are based on metal-metal contact • Elastomer-metal contacts do not have the same friction properties as traditional friction laws would indicate • Differences in elastomer-metal contact friction are due primarily to the viscoelastic nature of the elastomer

  3. Single-Asperity Contact

  4. Contact Pressure: Elastic-Rigid P Hertzian Contact δ G = shear modulus (sphere) a = contact radius

  5. Viscoelasticity • Rubber and elastomeric materials are viscoelastic in behavior  exhibit both viscous and elastic properties when undergoing deformation • Time-dependent strain

  6. SLS Model • Standard Linear Solid (Zener) More accurate than the Kelvin or Maxwell models for elastomeric materials Accounts for both creep and stress relaxation

  7. Normal Viscoelastic-Rigid Single Asperity Contact • Correspondence principle  elastic solution is used to obtain viscoelastic

  8. Tangential Loading If tangential load Q is applied to the normally-loaded asperity couple, the distribution of shear stresses is per Mindlin: P δ c is radius of the stick zone Q Limiting displacement for an asperity couple: Q = μP

  9. Static Friction Force

  10. Model Validation Static Friction Force as a function of Normal Approach (δn)

  11. Multi-Asperity Contact Mechanics • Contact between rubber-like material and metal is simulated for the load-controlled case • The asperity interactions depend on surface roughness parameters (Greenwood & Williamson) • Average summit radius β • Standard deviation of summit heights σ • Summit density ηs

  12. Multi-Asperity Modeling • Depending on compression of each asperity couple, each individual couple is either: • Partial slip • Full slide • A critical asperity height is calculated: d = surface separation σ= std. dev of summit heights δt = tangential displacement

  13. Multi-Asperity Modeling • All contacts with a height larger than scr are in partial slip regime • The total friction force is a summation of the full slide and partial slip regimes: Friction force for viscoelastic contact are calculated by substituting the appropriate operator for G in this equation Φ(s) is the normalized Gaussian asperity height distribution

  14. Multi-Asperity Modeling • When Fpartially-slip = 0, all asperities in contact are in full slide  max friction force is reached • Calculated using either the load-controlled or displacement-controlled single-asperity contact models

  15. Multi-Asperity Results Material Properties Effect of Surface Roughness Model results are comparable to experimental values at low pressures

  16. Questions?

More Related