Evaluation of KIc depending on sample size for ceramics

✍ Scribed by Bao Yiwang; Jin Zongzhe; Li Xiaorui

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 445 KB
• Volume: 48
• Category: Article
• ISSN: 0013-7944
• DOI: 10.1016/0013-7944(94)90145-7

✦ Synopsis

Ahatrac-The functional relationships between fracture toughness and sample size, and between fracture strength and sample size, for single-edge-notched-beam (SENB) specimens were derived. Experiments for size. effects of fracture toughness on Al,O, and Si,N, ceramics were carried out, and the results were identical with the theoretical ones. It is pointed out that the size effects of K,,, the size requirement as well as the requirement of proportional specimens are derived from the calculation formula of fracture toughness. The formula is invalid when the size of specimens used is smaller than the critical size. Theoretical and experimental results indicate that, under the critical size, fracture toughness size has a peak value which is about 20% higher than the real toughness value. The larger the specimen, the more reliable and more stable the measured toughness value. This study presents a useful means for error analysis of K,, measurement and for the evaluation of reliability of structural ceramics.