A Wedge Test for Quantifying Fully Plastic Fracture.
Abstract
A test using two wedges splitting a small, doubly grooved specimen allows measurement of stable, fully plastic crack initiation and growth under variable amounts of triaxiality. In wedge tests, 25 mm cubes of 1018 hot rolled steel in three different orientations exceeded the limit load predicted by plastic slip-line fields. The test gave crack tip initiation displacements of 0.7-0.8mm, regardless of orientation. Since microscopic examination of the fracture surfaces indicated that the wedges suppress blunting, the presence of non-zero initiation displacements suggests that a fracture process zone of finite thickness must be established before crack growth. During growth, a specimen with rolling direction normal to the crack plane had a crack growth ductility (minimum displacement per unit ligament reduction) of 0.006-0.009, compared to ductilities of 0.016-0.027 for specimens with rolling direction parallel to the crack front or parallel to the growth direction. The lower ductility with the crack normal to the rolling direction appears to be due to a smoother fracture surface without zigzagging between inclusion stringers.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 30, 1986
- Accession Number
- ADA168607
Entities
People
- Frank A. Mcclintock
- Sara J. Wineman
Organizations
- Massachusetts Institute of Technology