Stress-Transfer Micromechanics For Fiber Length with a Photocure Vinyl Ester Composite.
The objective was to test how increasing fiber length above the critical length would influence mechanical properties and fracture crack propagation. Micromechanics considering fiber/matrix stress-transfer was used to evaluate the results in addition to a shear debonding volume percent correction term necessary for the final analysis. Fiber lengths of 0.5, 1.0, 2.0, 3.0, and 6.0 mm with 9 μm diameters were added into a photocure vinyl ester particulate-filled composite at a uniform 28.2 vol%. Mechanical flexural testing was performed using four-point fully articulated fixtures for samples measuring 2 × 2 × 50 mm3across a 40 mm span. Fiber length correlated with improved mechanical properties for flexural strength, modulus, yield strength, strain, work of fracture, and strain energy release,p< 0.001. In addition, sample fracture depth significantly decreased with increasing fiber lengths,p< 0.00001. All mechanical properties correlated significantly as predictors for fracture failure,p< 0.000001, and as estimators for each other,p< 0.0001. The stress-transfer micromechanics for fiber length were improved upon for strength by including a simple correction factor to account for loss of fiber volume percent related to cracks deflecting around debonded fiber ends. In turn, the elastic property of modulus was shown to exhibit a tendency to follow stress-transfer micromechanics.
Department of Biomedical Engineering, School of Engineering, University of Alabama at Birmingham, Birmingham, Alabama.
Richard C
RC
Petersen
Department of Biomedical Engineering, School of Engineering; Department of Surgery, School of Medicine; Division of Biomaterials, School of Dentistry, University of Alabama at Birmingham, Birmingham, Alabama.
Jack E
JE
Lemons
Division of Biomaterials, School of Dentistry, and Department of Biomedical Engineering, School of Engineering, University of Alabama at Birmingham, Birmingham, Alabama.
Michael S
MS
McCracken