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Novel fracture toughness test using a notchless triangular prism (NTP) specimen
N D Ruse1, T Troczynski, M I MacEntee
1University of British Columbia, Vancouver, Canada.
Journal of Biomedical Materials Research
|August 1, 1996
Summary
A new notchless triangular prism (NTP) test specimen was developed to determine fracture toughness in materials and adhesive interfaces. This method offers a simpler, more reproducible alternative to standard techniques, showing good correlation with existing methods.
Area of Science:
- Materials Science
- Mechanical Engineering
- Fracture Mechanics
Background:
- Accurate fracture toughness measurement is crucial for material and adhesive interface reliability.
- Existing methods, like the chevron-notched short rod (CNSR) specimen, often require complex notching procedures.
- A need exists for a simplified, yet reliable, fracture toughness testing method.
Purpose of the Study:
- To develop and validate a novel test specimen, the notchless triangular prism (NTP), for fracture toughness determination.
- To compare the performance of the NTP specimen with the standard CNSR specimen.
- To assess the applicability of the NTP test for bulk materials and adhesive interfaces.
Main Methods:
- Development of the notchless triangular prism (NTP) test specimen, designed for easy and reproducible machining without initial notching.
- Finite element analysis (FEA) to compare stress distribution in NTP and CNSR specimens under tensile loading.
- Calibration study using poly(methyl methacrylate) (PMMA) to correlate NTP and CNSR fracture toughness values.
- Testing of various dental materials and an adhesive interface using the NTP method.
Main Results:
- FEA confirmed similar stress distributions between NTP and CNSR specimens.
- Excellent correlation was observed between NTP and CNSR fracture toughness values for PMMA.
- NTP testing yielded fracture toughness values comparable to literature data for dental materials and adhesive interfaces.
- Observed fracture patterns indicated plane strain conditions, and crack arrest in most specimens suggested a stable testing procedure.
Conclusions:
- The notchless triangular prism (NTP) test is a valid and reliable method for determining fracture toughness.
- The NTP specimen offers a simpler and more reproducible alternative to traditional methods for materials and adhesive interfaces.
- This new method facilitates the assessment of fracture mechanics in diverse material systems, including dental applications.