Modeling Pressure Vessel Toughness with Various Small Specimens
Abstract
Specimen configuration and size are often secondary considerations when performing fracture toughness tests. Typically the user will select a specimen geometry and size that are compatible with the material configuration, the type and size of the loading machine, and the devises that are available. In the work here, special consideration is given to identifying the best configuration for measuring the fracture toughness of an internally-loaded pressure vessel. The work utilizes the Bowie and Freese stress intensity factor, K, for a pressurized cylinder over a wide range of crack lengths and cylinder wall ratios, with K normalized by von Mises combined stresses and remaining ligament (K/sigma VM(w-a)(exp 1/2).. This normalized K, when compared to the normalized K for the single-edge notched bend, SEN(B), the compact tension, C(T), and the middle tension, M(T), clearly indicates that depending on the a/w ratio, each of the specimens provides an optimum location where it can be used to model the pressure vessel. For intermediate a/w, as recommended by ASTM Test Method for Plane-Strain Fracture Toughness of Metallic Materials (E399), all of the specimens investigated distinctly under-predict the actual toughness of the pressure vessel. For the case of the pressure vessel with a wall ratio (w) of two, an under-prediction in toughness of 35% is predicted for the SEN(B) and M(T) specimens, and a 47% under-prediction is predicted for the C(T) specimen (at a/w = 0.5). Experiments were conducted on ASTM A723 steel (yield strength = 1125 MPa) at a/w ratios of 0.2, 0.467, 0.6, and 0.8 for the SEN(B), C(T), and M(T) specimens.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 2001
- Accession Number
- ADA387581
Entities
People
- Charles Mossey
- Edward Troiano
- John H. Underwood
Organizations
- United States Army Armament Research, Development and Engineering Center