Fracture Mechanics Study of Sliding Contacts in Glassy Polymers

Recently, there has been some concerns regarding the use of polymer based composite materials in lieu of metallic restorative materials. Our efforts are targeted towards polymers used in dental restorative materials which behave in a brittle manner. The material currently under investigation is a possible replacement for metallic dental restorative materials. In this study, we seek to develop a finite element elasto-plastic model of cylinder micro-indentation and sliding contact as a means of eventually modelling the pin-on-disc wear test, used to cause fatigue wear. ADINA 6.1 commercial finite element package was used to perform this task. The primary objective of this paper is to study the distribution of the stresses and the corresponding strain behavior around the contact area in order to edify crack phenomena. To achieve this objective, sliding contact and fracture mechanics have been combined into a current plain stress vertical surface and horizontal subsurface crack analyses. The behavior of both of these cracks under different loading and material properties are fully investigated. The results so far show that, at certain loads, the crack tip locations, and specimen material properties such as elasticity or elastoplasticity can strongly effect the crack tip’s behavior for both of these cracks. The results also show that the initial crack position strongly influences both the stress field and the crack propagation direction.