Effect of Welded Stiffeners on Fatigue Crack Growth Rate
Abstract
The growth of large fatigue cracks was studied in welded, stiffened panels through the use of analytical, numerical, and experimental means. Large-scale testing was conducted by integrating welded, stiffened panels into a box girder configuration subjected to cyclic fatigue loading. The experiments show a decrease in the crack growth rate between stiffeners, which is attributed to compressive residual stress between stiffeners. Analytical modeling is performed based on superposition of linear elastic fracture mechanics, assuming a worst-case residual stress field representation. Numerical modeling is performed using finite element models, with temperature gradients simulating residual stresses, to calculate the J-Integral around the crack tip at different stages of crack development, and transforming the results into a propagation rate prediction. The two modeling techniques give similar results, validating the simpler analytical method. Either method can predict the results of the experiments conservatively with reasonable accuracy. Simple crack growth calculations that ignore the residual stress fields and the stiffeners give results that are too conservative by a factor of about three on the life. On the other hand, simple correction factors for the stiffeners give very unconservative results, also by a factor of about three.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1999
- Accession Number
- AD1210520
Entities
People
- Paul J. Pilarski
- Robert J. Dexter