Dynamic Fracture Behavior of Structural Materials.
Abstract
The goals of this research program are first to develop and apply procedures for obtaining more accurate measures of dynamic fracture initiation and propagation toughness, and then to establish the relationship between them. The dynamic initiation toughness K sub Id will be obtained by applying short pulse loads to SEN specimens and using minimum-time crack instability criteria. The dynamic propagation toughness K sub Id will be obtained by measuring the temperature histories in material near the tip of a fast running crack. During the first research year, a Charpy impact machine was modified to produce a well-defined tensile pulse in a SEN specimen. Flat-topped pulses of a shape suitable for K sub Id determinations were obtained that had rise times of about 18 microseconds and durations of 50 microseconds and 100 microseconds. A high-spatial-resolution temperature measuring instrument, based on laser thermoprobe concepts, was constructed and evaluated for use in K sub ID determinations for fast running cracks. By monitoring the change in intensity of a monochromatic light beam passing through a thin CdS film, we could measure the temperature of the film substrate to 0.25 cover a range of 150 C. Thus the technique appears suitable for dynamic fracture investigations.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 1982
- Accession Number
- ADA119182
Entities
People
- D. A. Shockey
- J. H. Giovanola
Organizations
- SRI International