Experimental study of the friction and wear behaviour of a polymer disc/primer coating combination used in ball‐joints by means of large‐scale testing

The surfaces of a heavily loaded ball‐joint were initially covered with a sliding spray, and suffer wear. A solution is found by incorporating ultra high molecular weight polyethylene (UHMWPE) discs with a carbon fibre/epoxy reinforced ring as sliding material into the chairs of the structure. The ball side is covered with a zinc phosphate primer coating. For design purposes the local static and dynamic behaviour of the hybrid UHMWPE discs in contact with steel or Zn‐coated counterfaces should be large‐scale tested in terms of their loading capacity, low friction and wear resistance. Also the influence of creep and wear on friction is examined. After the large‐scale verification tests in laboratory, a good correlation is found with a test in the field. Copyright © 2006 John Wiley & Sons, Ltd.     

Finite element analysis on local yield map and critical maximum contact pressure for yielding in hard coating with an interlayer under sliding contact

Micro-crack in the hard coating initiates usually from the local yield position. To prevent the crack to occur, the most important criterion is to satisfy the condition that the von Mises stress is less than the yield strength of material. In this paper, the local yield map showing the yielding position are introduced by using the finite element method and the criterion. The critical maximum contact pressures for yielding at the different positions were calculated by using the coating thickness, friction coefficient and the yield strength, where a critical range of yield strength ratio for the transition of yielding positions was found for 0.40.5. When the yield strength ratio is less than the range, yielding initiates from the interlayer and when the ratio is larger than the range, yielding initiates at the surface for high friction coefficient and in the base for low friction coefficient.