|Statement||by J.J. Lee and W.N. Sharpe, Jr.|
|Series||NASA-CR -- 180315., NASA contractor report -- NASA CR-180315.|
|Contributions||Sharpe, William N., United States. National Aeronautics and Space Administration.|
|The Physical Object|
The behaviour of the short fatigue cracks less than a millimeter in length (short cracks) cannot be analysed by linear elastic methods because of large-scale plasticity effects. A number of modification to LEFM and new models have been introduced to correlate the behaviour of long and short fatigue cracks. Research on fatigue crack propagation of conventional and highly crosslinked UHMWPEs has confirmed a detrimental effect of increasing radiation-crosslinking levels on the resistance to crack inception and crack growth [5, 33, 35, 40–42]. Figure contains scatterbands of data from Baker et al. , indicating a continuous decrease in fatigue crack propagation performance with increasing. Crack closure is a phenomenon in fatigue loading, where the opposing faces of a crack remain in contact even with an external load acting on the material. As the load is increased, a critical value will be reached at which time the crack becomes closure occurs from the presence of material propping open the crack faces and can arise from many sources including plastic deformation or. The implications of crack closure on fatigue crack are considered. The experimental results show that crack closure cannot fully account for the effect of stress ratio, R, on crack growth, and that it cannot be regarded as the sole cause for delay. Key Words (Suggested by Author(s)) Fatigue crack growth Crack closure Ti-6Al-4V titanium File Size: 2MB.
An Analytical Investigation of Plasticity Induced Closure Involving Short Cracks. Closure Measurements on Short Fatigue Cracksjoojin. Mechanics of Fatigue Crack Closure ASTM STP Volume of ASTM special technical publication. Crack Closure. Crack closure plays a major role in several aspects of fatigue crack growth, including the effect of R ratio (there is less closure at higher R) and short cracks (which display less closure than long cracks for the same cyclic stress intensity). Also considered are a statistical approach to crack closure determination, the crack closure behavior of surface cracks under pure bending, closure measurements on short fatigue cracks, and crack. An automated interferometric displacement gage was used to monitor crack-mouth-opening behavior of naturally initiated small surface cracks in a series of titanium alloys having a range of microstructures and deformation characteristics. Findings indicate that the transient development of crack closure plays a significant role in the early propagation of small fatigue by:
Verreman Y. () Growth Rates and Closure Development of Short Fatigue Cracks at Notches and at Weld Toes. In: Pluvinage G., Gjonaj M. (eds) Notch Effects in Fatigue and Fracture. NATO Science Series (Series II: Mathematics, Physics and Chemistry), vol Cited by: 1. But small cracks growing in a notch stress field are predicted to have higher levels of crack closure . However, careful measurements of the closure levels of small cracks growing in strain. In materials science, fatigue is the weakening of a material caused by cyclic loading that results in progressive and localised structural damage and the growth of cracks. Once a fatigue crack has initiated, each loading cycle will grow the crack a small amount, typically producing striations on some parts of the fracture surface. The crack will continue to grow until it reaches a critical. Closure Effects on Crack Behavior-- investigates how fatigue crack closure, as an intrinsic feature of growing fatigue cracks, can have an influence on many different aspects of crack growth. Organized according to the particular class of closure and including a variety of both experimental and analytical/numerical techniques, STP is an.