An Application of Microscopic Digital Image Correlation to Dental Materials
The mechanical properties of the human tooth have been of interest for many decades. While the strength and elastic modulus of these tissues have been examined in detail, comparatively few studies have been carried out on their fatigue and fracture behavior due to limitations posed by the small volume of available tissue, and consequent difficulties in applying standardized techniques to potentially hydrated and very small specimens. Although indentation fracture test eliminates the size constraints, a recent review has addressed the shortcomings of indentation fracture tests, particularly in regards to the load dependence. In this paper, fracture behavior of human dentin is studied by means of stable crack growth. Miniature compact tension (CT) specimens were machined from human teeth, as shown in Fig. 1. A portable motorized loading frame combined with a microscopic imaging system has been developed to document load and displacement field while the specimen is stressed, as shown in Fig. 2. Digital Image Correlation (DIC) was adopted to examine the mechanisms of crack growth resistance and near-tip displacement distribution for cracks in human dentin that are subjected to opening mode loads. According to the unique geometry of the dentin CT specimen (Fig. 1), the stress intensity distribution with crack growth could not be estimated using relationships provided by ASTM standards E399 or E647. Therefore, numerical models were developed to determine the stress intensity distribution as a function of crack length, opening load and specimen geometry.
KeywordsDisplacement Field Digital Image Correlation Crack Opening Displacement Crack Growth Resistance Curve Compact Tension
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