Crack Propagation in Double-Base Propellants
Abstract
Crack propagation tests were conducted on a composite modified doublebase CMDB) propellant with the use of center-cracked strip biaxial specimens. Constant strain rate tests were conducted at several temperatures (40 to 105 F) and crosshead rates (0.02 to 200 in./min) to define the crack initiation and propagation characteristics for monotonically increasing strain history. The tests were conducted at ambient, 250, and 500 psig pressure to evaluate the effect of pressure on initiation and crack velocity. A second series of tests was conducted to evaluate the effect of a prestrain damage history on crack propagation. In the second series, the samples (without precut cracks) were initially prestrained to 15 to 25 percent and held for a period of time to induce material damage. After load release and sufficient recovery time, cracks were inserted in the specimens and they were then pulled to failure at a constant strain rate. Similar tests were conducted on round, notched tensile samples to define the critical stress intensity factor (Klc) and to provide a comparison between uniaxial and biaxial fraction initiation. Schapery's viscoelastic fracture theory was used to evaluate the crack velocity data under constant strain rate conditions. One important result of the study was the finding that the crack velocity depended rather strongly on imposed strain level.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1976
- Accession Number
- ADA040954
Entities
People
- D. T. Wang
- S. W. Beckwith