Courses - Fracture Analysis and Failure Prevention
of Glasses and Ceramics
June 11 - 15, 2018 (noon)
Engineers, scientists and technicians interested in strength and fracture-mechanics testing, fracture issues related to process development or control, failure analysis (during production, testing, or service), and failure prevention. Class limit of 18. Reserve Early!
This course covers the examination and interpretation of markings on fracture-exposed surfaces of glasses and polycrystalline ceramics, and the analysis of crack systems, i.e., fractography. Further, it covers using fractography in failure analysis, strength testing, and fracture-mechanics testing. The mechanisms by which fracture markings are produced will be explained, and the information provided by the markings (e.g., in estimating stress at failure, in making measurements for fracture toughness tests, will be emphasized. Observation and documentation techniques will be covered. The role of fracture analysis in failure prevention (i.e. ensuring mechanical reliability) is emphasized throughout the course. This is a hands-on course in which the students will view fractured glass and ceramic samples with stereographic optical microscopes and other tools.
The course is designed to meet the needs of people interested in glasses or ceramics. Most of the examples that will be examined by the participants early in the course will be glass specimens, since fracture markings are most clearly seen in glass. Ceramic examples and specimens will be covered in depth in the later days of the course. In-depth coverage will be provided on equipment, documentation, formal fractographic standards, and quantitative fractography, with an emphasis on determining the stress in the part at fracture. Ample time is devoted to covering grinding and machining flaws in glasses and ceramics, the fractography of polycrystalline and single crystal ceramics, fracture toughness determination, and Weibull strength correlations with fractographic analysis. Links between fractography and failure prevention are included in the discussions, case studies, and examples.
Fundamentals of fractography, explanations of fracture markings, examination of specimens, equipment for observation and documentation, fracture origins in glasses and ceramics, quantitative fractography in testing (strength, fracture mechanics) and failure analysis, examples of fracture in polycrystalline ceramics, and using fractography in failure prevention. Attendees may bring 1-2 specimens for after-class inspection. The course instructors will be available after class on Days 1, 2 and 4 for inspections of specimens. Attendees should bring a simple hand calculator and a laser pointer.
Schedule Outline: The course schedule is revamped this year and expanded to 4.5 days. Extensive hands-on examination of specimens is dispersed throughout the entire 4.5 days of the course.
- Days 1 and 2: Equipment and techniques, stress/strain basics, crack patterns (a first look), fracture markings (with hands-on examination of examples), fracture mechanics, stress corrosion, contact damage by particles, contact damage by grinding and machining, specimen reconstruction. (8:30 am-4:30 pm each day)
- Day 3: Thermal-shock origins in glass, glue chipping, common conditions of failure, fracture mirror constant (definition and measurement) (8:30 am-12:00 pm) Note: Class participants will have the opportunity to visit the Corning Museum of Glass the afternoon of Day 3. The course instructors will not be available the afternoon of Day 3 for inspection of specimens.
- Day 4: Further discussion of fracture mirrors, making and using replicas of fracture surfaces, fractographic standards, origins in ceramics, machining and grinding cracks in glasses and ceramics. (8:30 am-4:30 pm)
- Day 5: Single crystals, Weibull strength analysis and fractography, case studies (8:30 am-12:30 pm)
Dr. James Varner is a Professor of Ceramic Engineering Emeritus at Alfred University. He received his Ph.D. in Ceramics at Alfred University.
George Quinn is a recently retired Ceramic Engineer with the National Institute of Standards and Technology, Gaithersburg, MD. He received his BSME from Northeastern University.