Crack Growth Analysis for Arbitrary Spectrum Loading. Volume 1. Results and Discussion
Abstract
This combined analytical and experimental study was undertaken to investigate fatigue crack growth interaction effects and to either modify existing crack growth retardation models or to develop new models. A test program was conducted on 2219-T851 aluminum and on Ti 6Al-4V titanium center cracked panel and compact tension specimens. A variety of loading conditions, including constant amplitude, single and multiple overloads, single and multiple periodic overloads, simplified block programs, compression, tension-compression and compression-tension sequences, was investigated. Loading variables included the relative magnitudes of overloads and baseline loads, frequency of occurrence of single and multiple periodic overloads, relative magnitude of compression spike loads and stress ratio. Simplified block program load variables included organizing the load layers as low-to-high, high-to-low or randomized loads, and the introduction of either a single overload cycle to each block or an occassional underload. Two multi-layer fighter spectrum tests were included. It was concluded that the crack closure concept could be used to explain a variety of crack growth interaction effects. An empirical mathematical model using this concept was developed and shown to yield reasonably accurate predictions of crack growth behavior for many loading sequences. This model was integrated into the cracks II digital computer program.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1974
- Accession Number
- ADA021700
Entities
People
- M. Creager
- P. D. Bell
Organizations
- Grumman