TITLE:
A Finite Element Study of Crack Behavior for Carbon Na-notube Reinforced Bone Cement
AUTHORS:
Kaveh PourAkbar Saffar, Ahmad Raeisi Najafi, Manssour H. Moeinzadeh, Leszek J. Sudak
KEYWORDS:
Bone Cement; Carbon Nanotube; Finite Element; Crack Propagation; Stress Intensity Factor
JOURNAL NAME:
World Journal of Mechanics,
Vol.3 No.5A,
August
23,
2013
ABSTRACT: Polymethylmethacrylate (PMMA) bone cement is a polymeric material
that is widely used as a structural orthopedic material. However, it is not
an ideal material for bone grafting due to its fragility. Carbon nanotubes
(CNTs) have been introduced in order to reinforce PMMA resulting in a composite
material which exhibits improved tensile properties, increased fatigue
resistance and fracture toughness. This improvement is potentially due to
bridging and arresting cracks as well as absorption of energy. In this study, a
two-dimensional finite element model is presented for the fracture
analysis of PMMA-CNT composite material. Instead of the classical single fiber
model, the present work considers an ensemble of CNTs interacting with a
pre-existing crack. Casca is used to produce a two dimensional mesh and the
fracture analysis is performed using Franc 2D. The model is
subjected to uni-axial loading in the transverse plane and the interaction
between the crack and CNTs is evaluated by determining the stress
intensity factor in the vicinity of the crack tips. The effects of geometric
parameters of the CNTs and the material structural heterogeneity on crack
propagation trajectory are investigated. Furthermore, the effects of CNT
diameter, wall thickness and elastic mismatch between the matrix and the
nanotubes on crack growth are studied. The results illustrate that the CNTs
repel cracks during loading as they act as barriers to crack growth. As a
result, the incorporation of CNTs into PMMA reduces crack growth but more
importantly increases the fracture resistance of bone cement.