Investigation of Stress Intensity Factor for Overloaded Holes and Cold-Expanded Holes
Abstract
For life assessment of airframe components, it is important to understand how the residual stresses due to material yielding affect crack initiation or crack growth at holes. A key step in understanding such effects is the quantification of the Mode 1 stress intensity factor for cracks that may initiate subsequent to overloading. Here, a two-dimensional weight function approach is used to determine stress intensity factors for cracks in either tensile or compressive stress fields due to one of three mechanisms: remote tension overload, remote compression overload or hole cold expansion. The effect of subsequent remote loading is also considered. The key input is the stress distribution in the corresponding uncracked body along the prospective crack path. The key trends are investigated through many numerical examples for symmetrically-cracked holes in large steel and/or aluminium alloy plates. Cold expansion of finite-width plates representative of C-130 wing skin locations is also studied. For both remote overload cases, it is shown that, once the crack length is the same or larger than the initial yield zone, the stress intensity factors are the same as for the case without the initial overload. However, for cold-expanded holes, the beneficial reduction in stress intensity factor extends beyond the initial yield zone. Hence, the present work provides a greater depth of understanding of how typical residual stresses can affect key inputs into airframe life assessment.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 2012
- Accession Number
- ADA578051
Entities
People
- Manfred Heller
- Richard Callinan
- Robert Kaye
Organizations
- Defence Science and Technology Group