Normal contact stiffness

File:Contacting surfaces.jpg

Normal contact stiffness is a physical quantity related to the generalized force displacement behavior of rough surfaces in contact with a rigid body or a second similar rough surface.{{Cite journal |last=Persson |first=B.N.J. |date=2006 |title=Contact mechanics for randomly rough surfaces |url=http://dx.doi.org/10.1016/j.surfrep.2006.04.001 |journal=Surface Science Reports |volume=61 |issue=4 |pages=201–227 |doi=10.1016/j.surfrep.2006.04.001 |arxiv=cond-mat/0603807 |bibcode=2006SurSR..61..201P |issn=0167-5729}}{{Cite journal |last1=Zhai |first1=C. |last2=Gan |first2=Y. |last3=Hanaor |first3=D. |last4=Proust |first4=G. |last5=Retraint |first5=D. |date=2016 |title=The Role of Surface Structure in Normal Contact Stiffness |url=http://link.springer.com/10.1007/s11340-015-0107-0 |journal=Experimental Mechanics |language=en |volume=56 |issue=3 |pages=359–368 |doi=10.1007/s11340-015-0107-0 |issn=0014-4851}} Specifically it is the amount of force per unit displacement required to compress an elastic object in the contact region. Rough surfaces can be considered as consisting of large numbers of asperities.{{Cite book |last1=Bowden |first1=Frank Philip |title=The friction and lubrication of solids |last2=Tabor |first2=David |date=2008 |publisher=Clarendon Pr |isbn=978-0-19-850777-2 |edition=Repr |series=Oxford classic texts |location=Oxford}} As two solid bodies of the same material approach one another, the asperities interact, and they transition from conditions of non-contact to homogeneous bulk behaviour, with changes in the contact area.{{Cite journal |last1=Jacobs |first1=Tevis D. B. |last2=Martini |first2=Ashlie |date=2017-11-01 |title=Measuring and Understanding Contact Area at the Nanoscale: A Review |url=https://asmedigitalcollection.asme.org/appliedmechanicsreviews/article/doi/10.1115/1.4038130/367044/Measuring-and-Understanding-Contact-Area-at-the |journal=Applied Mechanics Reviews |language=en |volume=69 |issue=6 |doi=10.1115/1.4038130 |bibcode=2017ApMRv..69f1101J |issn=0003-6900}} The varying values of stiffness and true contact area at an interface during this transition are dependent on the conditions of applied pressure and are of importance for the study of systems involving the physical interactions of multiple bodies including granular matter, electrode contacts, and thermal contacts, where the interface-localized structures govern overall system performance by controlling the transmission of force, heat, charge carriers or matter through the interface.{{Cite journal |last1=Zhai |first1=Chongpu |last2=Hanaor |first2=Dorian |last3=Gan |first3=Yixiang |date=2017 |title=Contact stiffness of multiscale surfaces by truncation analysis |url=https://linkinghub.elsevier.com/retrieve/pii/S0020740317311591 |journal=International Journal of Mechanical Sciences |language=en |volume=131-132 |pages=305–316 |doi=10.1016/j.ijmecsci.2017.07.018}}