An analysis of the mechanics and statistics of brittle crack initiation

✍ Scribed by F. A. McClintock; F. Zaverl

• Publisher: Springer Netherlands
• Year: 1979
• Tongue: English
• Weight: 656 KB
• Volume: 15
• Category: Article
• ISSN: 1573-2673
• DOI: 10.1007/bf00037827

✦ Synopsis

Analytical and numerical methods were developed to find how brittle macro-crack formation depends on the distribution of mean strength and critical stress intensity factors of grain boundary segments. The distributions were assumed to increase as some power of the excess of the strength above a lower limit. (For the first micro-crack, these give an asymptotic extreme value distribution of the third kind.) As expected, macro-crack initiation and final instability occur sooner with increasing coefficient of variation and with increasing size of part. The major discovery was that micro-cracking occurs at a lower fraction of the maximum strength in large parts than in small test specimens. Hence acoustic emission will be more practical in the field than observed in laboratory tests. Also, the load for first cracking is over-conservative by large factors where there is a high coefficient of variation in the grain boundary strengths, and the lower limit of strength approaches zero.