Mixed mode fracture characterization of hydroxylapatite-titanium alloy interface.
Cantilever beam and four-point bend specimen geometries were used to experimentally determine the critical energy release rates for a plasma sprayed hydroxylapatite-titanium alloy (HA-Ti alloy) interface. A locus of energy release rates as a function of crack tip phase angle was determined where a 0 degree phase angle represented tensile opening (mode I) loading and a 90 degree phase angle represented in-plane shear (mode II) loading. Energy release rates were found to increase substantially with an increase in phase angle. An energy release rate of 0.108 N/mm was determined for a phase angle of 0 degrees (mode I). Energy release rates of 0.221, 0.686, and 1.212 N/mm were determined for phase angles of 66 degrees, 69 degrees, and 72 degrees, respectively. The experimental data was matched to a phenomenological model for which crack propagation depended on mode I loading alone indicating that crack propagation at the Ha-Ti alloy interface is dominated by the mode I loading component. Therefore, regions of HA coated implants that experience compressive or shear loading across the HA-Ti alloy interface may be much less likely to debond than regions that experience tensile loading.
Mann
K A
KA
Department of Orthopedic Surgery, SUNY Health Science Center, Syracuse 13210, USA.
Edidin
A A
AA
Kinoshita
R K
RK
Manley
M T
MT
D000497:Alloys; D001672:Biocompatible Materials; D017886:Durapatite; D050723:Fractures, Bone; D006801:Humans; D006882:Hydroxyapatites; D008433:Mathematics; D008961:Models, Structural; D013314:Stress, Mechanical; D014025:Titanium
D000497:Alloys; D001672:Biocompatible Materials; D006882:Hydroxyapatites; C098170:hydroxyapatite-titanium alloy; D017886:Durapatite; D014025:Titanium