Assessment of J-R Curves Obtained from Precracked Charpy Samples
Abstract
J-R curves were determined for five materials (7075-T651; 2024-T351; HY130; HY80; and A723, Class 1, Grade 4) using precracked Charpy samples and standard size C(T) and SE(B) samples. Crack growth in the Charpy samples was estimated using the load drop method of analysis of the load displacement trace, and crack extension in the C(T) and SE(B) specimens was determined using the electric potential method. The results show that physical crack extension in the larger sample was not well estimated by the Charpy sample results. However, if the crack extension is presented as relative crack growth (as a percentage of the uncracked ligament), the agreement between the two widely different specimen sizes is much better, although not exact. With the exception of the relatively brittle 7075-T651, the J corresponding to zero, one percent, and two percent crack growth was higher in the Charpy samples than in the larger samples. This was attributed to the inability of the load drop method to determine the exact location of the crack initiation. Although nonconservative, we believe the load drop method analysis of precracked Charpy data is adequate for quality control toughness testing provided that it is realized that JIc and J-R curves may be overestimated slightly.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1985
- Accession Number
- ADA161806
Entities
People
- J. A. Kapp
- M. I. Jolles
Organizations
- United States Army Armament Research, Development and Engineering Center