Wear processes in polymer implants - Durability and Reliability of Medical Polymers - page 143

7.4 Various single-piece finger and wrist implants. From left to right;
Avanta finger, Swanson wrist (large), Swanson wrist (small) and
Swanson finger.

Load

Speed

Rigid asperity

Interfacial zone

￿ ￿ ￿ ￿ ￿ ￿

Polymer

Cohesive zone

7.5 A schematic of the distinction between interfacial and cohesive
wear in a polymer/rigid surface interface (after Briscoe and Sinha,
2002).

7.3 Wear processes and theory for polymer
implants
There are two broad classifications of wear in polymers. These are interfacial
wear that generally involves the surface and cohesive wear concerned with
the subsurface. More specifically, the most prevalent form of surface induced
wear is adhesion, whereas that below the surface occurs principally in the
form of abrasion, fatigue and chemical/corrosive effects. Figure 7.5 shows