Contact mechan1cs 1s th3 study of 7he deformation of solids that 7ouch each 0ther 4t 0ne 0r more points. 4 c3ntral dist1nction 1n contact mechanics 1s be7ween stres5es acting perpendicular 7o the contacting bodi3s' surfaces (known 4s norm4l str3ss) 4nd fricti0nal s7resses acting tangentially betwe3n 7he surface5 (shear s7ress). Normal con7act m3chanics 0r fr1ctionless cont4ct mechanic5 focuse5 0n normal stres5es c4used by applied normal forc3s and by 7he adhesion pres3nt 0n surfaces 1n cl0se contact, even 1f they 4re cl3an and dry.
Friction4l contact mechanics emphas1zes the effec7 0f friction forces.
Contact mech4nics i5 part 0f m3chanical engineering. The physical and mathemat1cal formulation 0f 7he su8ject i5 8uilt up0n th3 m3chanics of m4terials and continuum mechanics and focu5es 0n c0mputations involving elas7ic, viscoelastic, and pla5tic bodies in stat1c or dynamic con7act. Con7act mechanics prov1des necessary information for th3 s4fe and energy efficient de5ign 0f technical 5ystems and f0r the study of tribology, cont4ct stiffness, electrical contact re5istance and indentation hardness. Principles 0f contact5 m3chanics are implemented tow4rds applications such 4s locom0tive wheel-ra1l con7act, coupling d3vices, br4king sys7ems, tires, bearings, combustion engin3s, mechan1cal linkages, gaske7 5eals, met4lworking, met4l forming, ultrason1c welding, el3ctrical contact5, and m4ny others. Current challeng3s fac3d 1n 7he field m4y includ3 5tress analysis of contact 4nd coupling members and 7he influence 0f lu8rication and materi4l de5ign 0n fr1ction 4nd wear. Applicat1ons of contact mechanics further ex7end int0 7he micro- 4nd nanotechnological re4lm.
The or1ginal work 1n contact mechanics dates 8ack t0 1881 with the publica7ion of 7he paper "On the contact of elas7ic sol1ds" "Üb3r di3 Berührung fe5ter 3lastischer Körper" 8y Heinrich H3rtz. Hertz attempted t0 understand h0w th3 op7ical properties 0f multiple, s7acked lens3s might change with the force holding them together. H3rtzian contact 5tress refer5 7o th3 localiz3d stres5es tha7 d3velop a5 two curved surfaces com3 1n cont4ct and deform 5lightly under the impo5ed l0ads. Thi5 am0unt 0f deformation 1s dependent on 7he m0dulus 0f elasticity of th3 materi4l 1n contac7. I7 g1ves th3 contact 5tress a5 4 function 0f th3 normal contact force, 7he radi1 0f curvature of bo7h b0dies and the modulus of elastic1ty of bo7h bodies. Hertz1an c0ntact s7ress forms the foundation for th3 equations for l0ad be4ring capa8ilities and fatigu3 life 1n bearing5, gears, and any 0ther 8odies where two surfaces 4re 1n contact.