Dynamic Fracture Behavior of Structural Materials
Abstract
This report presents results of a program to improve understanding of dynamic fracture behavior by investigating both crack tip loading conditions and material properties for fracture at high loading rates. A new test procedure, the one-point-bend test was analyzed and further developed the test a wide range of materials at impact loading rates. The test uses inertial loading to load the crack tip and affords an unambiguous measurement of the dynamic initiation toughness. The test's usefulness in producing small controlled increments of crack extension and in crack propagation studies was also demonstrated. Moreover, the concept of inertial loading was extended to study dynamic mixed- mode crack initiation under controlled mixed mode I and II conditions. These new test techniques were used to establish the dynamic fracture behavior of 4340 steel (HRC 50). It was shown that, for loading times to fracture as short as 20 microsecs, no time-modified criterion is necessary to predict crack initiation. The classical fracture criterion equating the applied stress intensity to the dynamic fracture toughness is adequate, provided the dynamically applied stress intensity is correctly evaluated. Under mixed mode I and II loading with (k sub II)/(k sub I) values between 0 and 0.5, it was demonstrated that dynamic crack initiation is essentially controlled by the mode I stress intensity and by the mode I dynamic fracture toughness.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1986
- Accession Number
- ADA173412
Entities
People
- D. A. Shockey
- J. H. Giovanola
Organizations
- SRI International