Proceedings of SerbiaTrib '13

Serbian TribologySocietySERBIATRIB ‘1313 th International Conference onTribologyKragujevac, Serbia, 15 – 17 May 2013Faculty of Engineeringin KragujevacTRIBOLOGY ASPECT OFRUBBER SHOCK ABSORBERS DEVELOPMENTMilan Banić 1 , Dušan Stamenković 2 , Miloš Milošević 3 , Aleksandar Miltenović 41 Faculty of Mechanical Engineering, University of Niš, Serbia, banic@masfak.ni.ac.rs2 Faculty of Mechanical Engineering, University of Niš, Serbia, dusans@masfak.ni.ac.rs3 Faculty of Mechanical Engineering, University of Niš, Serbia, mmilos@masfak.ni.ac.rs4 Faculty of Mechanical Engineering, University of Niš, Serbia, amiltenovic@yahoo.comAbstract: Rubber is a very flexible material with many desirable properties which enable its broad use inengineering practice. Rubber or rubber-metal springs are widely used as anti-vibration or anti-shockcomponents in technical systems. Rubber-metal springs are usually realized as a bonded assembly, howeverespecially in shock absorbers, it is possible to realize free contacts between rubber and metal parts. Inprevious authors research it was observed that friction between rubber and metal in such case have asignificant influence on the damping characteristics of shock absorber. This paper analyzes the developmentprocess of rubber or rubber-metal shock absorbers realized with free contacts between the constitutive parts,starting from the design, construction, testing and operation, with special emphasis on the development ofrubber-metal springs for the buffing and draw gear of railway vehicles.Keywords: rubber friction, rubber-metal spring, shock absorber, product development.1. INTRODUCTIONRubber or rubber-metal springs are widely usedin industry as anti-vibration or anti-shockcomponents giving many years of service. Theyhave several advantages in respect to metal springs(lower price, easier installation, lower mass,reduced corrosion, no risk of fracture and no needfor lubrication) [1]. However, they have one majordisadvantage reflected in insufficiently reliableservice life caused by rubber fatigue.Those elements are well established to controlvertical and lateral movements. Nowadays, themore demanding operating environment has madethe design of such components more challengingthan ever before. In addition to the design of therubber part itself the interface between the part andthe structure is also important.The properties of the rubber-metal spring aremainly influenced by a rubber compound. Rubbercompounds are generally composed of a baserubber (e.g. natural rubber), filler (e.g. carbonblack) and a curing agent (e.g. sulphur). Additionalcomponents may include antioxidants, adhesionagents, flame retardant agents and special processenhancingchemical additives. Common physicalproperties of rubber compounds are affected byevery ingredient of a rubber recipe independently ofor dependently on each other. The mixing andcuring process is also critical in determining theseproperties. Improving one compound propertyalways results in changing other properties, forbetter or for worse. Noted fact makes developmentof elastomeric based products a very complicatedtask. Up to appearance of modern computer aidedtools, the development of those products relied onlyon previous experience of the designer and trial anderror procedure. Such approach was inefficient,expensive and time consuming because it requirediterative procedure combined with excessiveexperimental testing to achieve desired mechanicalproperties.Rubber-metal springs are usually realized as abonded assembly, however especially in shockabsorbers, it is possible to realize free contactsbetween rubber and metal parts. In that case,connections between rubber blocks and metal platesare realized by applying pressure and resultingstatic friction. During the load cycle of the shockabsorber, apart the energy dissipation in rubber,286 13 th International Conference on Tribology – Serbiatrib’13