A study has been made of the fatigue-crack propagation properties of a series of laminated Nbreinforced Nb3Al intermetallic-matrix composites with varying microstructural scale but nominally identical reinforcement volume fraction (20 pct Nb). It was found that resistance to fatigue-crack growth improved with increasing metallic layer thickness (in the range 50 to 250 mm) both in the crack-divi...

Interest in extending the high cycle fatigue life of structures has increased in the last decade of the 20th century. Since a long fatigue life depends on keeping cyclic loads near or below the fatigue threshold, understanding near-threshold behavior is now all the more important. This paper reviews the status of the ‘threshold of fatigue’ and to a lesser extent its relation to the ‘fatigue lim...

This paper presents a new incremental formulation for predicting the curved growth paths of twodimensional fatigue cracks. The displacement and traction boundary integral equations (BIEs) are employed to calculate responses of a linear elastic cracked body. The Paris law and the principle of local symmetry are adopted for defining the growth rate and direction of a fatigue crack, respectively. ...

Ultrasonic methods have been implemented for in situ sizing of fatigue cracks near fastener holes. These techniques, however, only provide an estimate at the time of the measurement and cannot predict the remaining life of the structure. In contrast, statistical crack propagation approaches model the expected fatigue life based on worst-case fatigue process assumptions. The authors have recentl...

Due to cost and time limitations, experiments for fatigue crack growth are only feasible below certain cycle numbers. In this paper, it is investigated whether or not fatigue crack growth laws allow for an extrapolation of the statistics of the cycle number to reach a certain crack length from limited experimental data, and hence reduce costs.

A major part of fracture mechanics is concerned with studying the initiation and propagation of fatigue cracks. This typically requires constant monitoring of crack growth during fatigue cycles which necessitates automation of the whole process. If the rate of crack growth can be determined the experimenter can vary externally controlled parameters such as load level, load cycle frequency and s...

Residual compressive stress can improve fretting fatigue strength. In this paper, the effects of residual stress on fretting fatigue of Al 2024-T351 alloy specimens are studied using a numerical approach. The extended finite element method combined with the cyclic cohesive zone model is adopted to model fretting fatigue crack growth behavior. It is shown that residual stress changes the frettin...

The very high cycle fatigue behavior (10-10 cycles) of Ti-6246 has been investigated using ultrasonic fatigue techniques. In this regime of fatigue (0.4-0.6σYS), only certain microstructural regions are susceptible to fatigue damage accumulation, and lifetimes are related to the distribution of fatigue critical microstructural neighborhoods. Three distinct categories of crystallographic crack i...

Abstract: To ensure the rail transportations safety, evaluation of fatigue behavior of the rail steel is necessary. High cycle fatigue behaviour of a rail steel was the subject of investigation in this research using fracture mechanics. Finite element method (FEM) was used for analyzing the distribution of the stresses on the rail, exerted by the external load. FEM analysis showed that the ...

In this paper, three-dimensional modeling of the fatigue crack growth profiles was performed in a simple riveted lap joint. Simulation results showed that mode I was dominated on the one side of the plates and the crack straightly grew on this side, while the other side of the plates was in a mixed-mode condition and the crack propagation path was not straight on this side. Afterward, the fract...