Fatigue cracks analysis

Alisha Hutson, Ted Nicholas, Reji John Fretting fatigue crack analysis in Ti-6AI-... 

Eracture mechanics concepts can also be appHed to fatigue crack growth under a constant static load, but in this case the material behavior is nonlinear and time-dependent (29,30). Slow, stable crack growth data can be presented in terms of the crack growth rate per unit of time against the appHed R or J, if the nonlinearity is not too great. Eor extensive nonlinearity a viscoelastic analysis can become very complex (11) and a number of schemes based on the time rate of change of/have been proposed (31,32). 

In a recent study, Saintier et al. ° investigated the multiaxial effects on fatigue crack nucleation and growth in natural mbber. They found that the same mechanisms of decohesion and cavitation of inclusions that cause crack nucleation and crack growth in uniaxial experiments were responsible for the crack behavior in multiaxial experiments. They studied crack orientations for nonproportional multiaxial fatigue loadings and found them to be related to the direction of the maximum first principal stress of a cycle when material plane rotations are taken into account. This method accounts for material rotations in the analysis due to the displacement of planes associated with large strain conditions. 

Brocklehurst [37] has written an exhaustive review of the early work (prior to 1977) on fracture in polycrystalline graphite. Much of this work focused on the fracture behavior of nuclear graphites. In most investigations considered, conventional fracture mechanics tests and analysis were performed for macroscopic cracks. LEFM provided an adequate criterion for failure. Additionally, results on work of fracture, strain energy release rate, and fatigue crack propagation were reported. 

J. C. Newman, FASTRAN-2 A fatigue crack growth structural analysis program, NASA-TM-104,159, (NASA Langley Research Center, 1992)... 

Westwood, H.J., Lee, W.K., Corrosion-Fatigue Cracking in Fossil-Fueled Boilers, Corrosion Cracking, Proc. in the International Conf. on Fatigue, Corrosion Cracking, Fracture Mechanics and Failure Analysis, ASM, Salt Lake City, UT, pp. 23-34, 1986. 

Altstadt V, Keiter S, Renner M, Schlarb A (2000) Accelerated evaluation of environmental ageing monitored by fatigue crack growth experiments. In Cardon AH, Fuduka H, Reifsnider KL, Verchery G (eds) Recent developments in durability analysis of composite systems. Balkema, Rotterdam, pp 195-209... 

This combined analysis of AoA and Ar, therefore establishes that the main cracks that nucleate close to the contact edge correspond to predominantly tensile fatigue cracks. This conclusion remains valid whatever the contact condition (partial slip or gross slip). In addition, the distribution of within the contact plane is of interest (Fig. 15). The maximum amplitude... 

In the case of a cracked component a crack analysis should be run to verify that the crack is a high cycle fatigue failure. An instrumented operational test of the component will identify the frequencies of high vibration levels causing the problem. 

Wei, R. P., and Brazill, R. L., An Assessment of A-C and D-C Potential Systems for Monitoring Fatigue Crack Growth, in Fatigue Crack Growth Measurement and Data Analysis, ASTM STP 738, S. J. Hudak, Jr., and R. J. Bucci, eds., American Society for Testing and Materials, Philadelphia, PA (1981), 103-119. 

Fig. 1.21 Longitudinal corrosion fatigue cracks in preexisting notches of copper tubes in a subcooler [54]. http //www.corroslonlab.com/Failure-Analysis-Studies/30038.corrosion-fatlgue-cu-tube. htm. Photo provided courtesy of Corrosion Testing Laboratories, inc., Newark, DE.

H. Nakajima, T. Shoji, M. Kikuchi, H. Nitsuma, M. Shindo, Detecting acoustic emission during cyclic crack growth in simulated BWR environments, in S.J. Hudak, R.J. Bucci (Eds.), Fatigue Crack Growth Measurement and Data Analysis, ASTM STP 738, ASTM International, West Conshohocken, PA, 1981, pp. 139—162. 

E. Tada, K. Noda, S. Kuma, T. Tsuru, Monitoring of corrosion fatigue cracking using harmonic analysis of current responses induced by cyclic stressing, J. Jpn. Inst. Met. 63 (1999) 1075—1082. 

The fatigue crack growth rate test results on AMg6 aluminum alloy at 4 K, 76 K, and room temperature, are summarized in Figs. 3,4, and 5, respectively. The Paris power law [ ] is used as the basis for empirical analysis of the data... 

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