Fatigue crack propagation behavior

Total interpenetration of chains (X approaches Rg) is not necessary to achieve complete strength when M > M and x < 7). However, a word of caution while complete strength may be obtained in terms of critical fracture measures such as G c and A lc, the durability, measured in sub-critical fracture terms, such as the fatigue crack propagation rate da/AN, may be very far from its fully healed state at r. We have shown that while the weld toughness A lc increases linearly with interdiffusion depth X as K f. X, the fatigue crack propagation behavior of partially healed welds behaves as [1]... 

Although the constant AKpvalues applied had different amplitudes the fatigue crack propagation behavior is quite similar for the three polymers. They all show... 

Gallagher, J. P., and Wei, R. P., Corrosion Fatigue Crack Propagation Behavior in Steels, Corrosion Fatigue Chemistry, Mechanics and Microstructure, NACE-2 (1972), 409. 

L. A. James, Fatigue—Crack Propagation Behavior of Inconel 718, HEDL-TME 75-80, Hanford Engineering Development Laboratory, Richland, Washington (1975). 

Connelly GM, Rimnac CM, Wright TM, Hertzberg RW, Manson JA (1984), Fatigue crack propagation behavior of ultrahigh molecular weight polyethylene J Orthop Res, 2, 119-125. 

Figure 1. Fatigue crack propagation behavior of neat resins.

Choe, H., Chen, D., Schneibel, J.H. et al., 2001, Ambient to high temperature fracture toughness and fatigue crack propagation behavior in a Mo 12Si 8.5B intermetallic, Intermetallics 9 319. 

Source H.H. Smith, RS. Kullen, and D.J. Michel, Fatigue Crack Propagation Behavior ofTitanium Alloys6242Sand5621SatBevatedTemperature, Metall. Trans. A, Vol 19A, April 1988, p 881 -885... 

O Connor, B.P.D., Plumtree, A. Fatigue crack propagation behavior and damage accumulation relationships in an aluminum alloy. In Fracture Mechanics 19th Symposium, ASTM STP 969, pp. 787-799 (1988)... 

James, L.A. Fatigue crack propagation behavior of pressure vessel steels. Bulletin 194, Welding Research Council NY (1974)... 

Studies have reported subtle differences in the morphology and fatigue crack propagation behavior of extruded versus compression molded UHMWPE. For example. 

However, researchers from Berkeley observed no significant difference in the fatigue crack propagation behavior of virgin (unsterilized) UHMWPE when comparing 500ppm, lOOOppm, and SOOOppm concentrations with unstabiUzed controls [41]. Thus, the precise mechanism for the hypothesized improvement in mechanical properties (if any) for vitamin-E-blended materials below 5000 ppm remains to be confirmed and more fully elucidated in the literature. 

Work by Schapery, Saxena, Wilhams, and others details the analysis of cracks in creeping, strain rate dependent materials, and provides a predictive basis for the apparently brittle nature of FCP in UHMWPE [43-48]. Particularly usefid are the models developed by Schapery and Wilhams, which directly link the intrinsic, constitutive viscoelastic relaxation behavior of the material to the advance of a stable crack tip [46,48]. The power of these models is the predictive nature of the mechanics in relating ECP dynamics to the material s viscoelastic behavior that is eashy measured in a simple one-dimensional creep test The elementary consequences of the models result in the static mode fatigue crack propagation behavior that is observed in UHMWPE, and thus potentially provide a first-principles explanation of the fatigue and fracture behavior by the material. 

---