SEDL / STP / STP1296-EB / STP16257S

Analysis of Fatigue Crack Growth in Pin-Loaded Lug Joints under Inelastic Deformations

Prakash, RV
National Aerospace Laboratories, Bangalore,

Raju, KN
National Aerospace Laboratories, Bangalore,

Satish Kumar, K
Indian Institute of Science, Bangalore,

Dattaguru, B
Indian Institute of Science, Bangalore,

Ramamurthy, TS
Indian Institute of Science, Bangalore,

Pages: 15    Published: Jan 1997

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Abstract

Results of an experimental program on fatigue crack growth in an interference fit lug joint and numerical estimation of relevant fracture parameters to correlate the experimental data are presented in this paper. Fatigue crack growth rates of naturally initiating cracks were estimated fractographically as a function of crack length for lug joints fitted with different levels of interference. The fracture parameters to correlate the crack growth behavior were estimated using a two-dimensional materially nonlinear contact stress finite element analysis. A path-independent integral, Δ T^p* computed for incremental loads and summed up (I) during cyclic loading was used as an elasto-plastic fracture parameter. Correlation of the experimental crack growth data and the evaluated range of ΔT resulted in a power law similar to the Paris equation. Further, the fatigue crack growth (FCG) rate was evaluated using the relationship between low cycle fatigue (LCF) parameters and the fracture parameter, ΔT, as estimated. These are in good agreement with the experimental results.