DEVELOPMENT AND UTILIZATION OF A COMBINATION CRYOGENIC AND ELEVATED TEMPERATURE COMPLIANCE GAGE FOR DETERMINATION OF FRACTURE TOUGHNESS OF HIGH STRENGTH METALLIC MATERIALS
Abstract
The Fracture Mechanics approach and its limitations are discussed based upon a literature survey. A workable compliance gage enabling the measurement of plane strain K sub IC pop-in stress or load level and plane stress K sub C failure load as a function of compliance (deflection) from -320 to 600F in an air environment has been developed, designed, and constructed. The load-deflection readout instrumentation is compatible with commercially available X-Y recorders. The gage was calibrated at -320, 75, and 350F in an air environment. This was performed and accomplished by comparing experimentally determined results on 2024-T3 aluminum alloy with the Westergaard-Irwin theoretically derived compliance parameters that reflect compliance at the edges of a centrally cracked sheet or plate specimen. The compliance gage was used to determine the fracture toughness of 2024-T3 aluminum alloy at -320, 75, and 350F. The experimentally obtained compliance results were in agreement with the Westergaard-Irwin theoretically derived hypothesis involving a mathematical model and general theory of elasticity. It was also established from experimental test data and fracture mechanics analytical concepts that 2024-T3 aluminum alloy data at 75 and 350F (short time) use can be based on the evidences of gross plastic flow before failure. However, at -320F and below the design criteria with this alloy should be based upon the fracture toughness of the material and the severity of defects to avoid catastrophic failure under cryogenic service conditions.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1967
- Accession Number
- AD0819581
Entities
People
- Sidney O. Davis.
Organizations
- Air Force Research Laboratory