Fatigue crack growth can be strongly influenced by crack closure, i. e., the contacting of the opposing faces of a fatigue crack above the minimum load in a loading cycle. This crack closure shields the crack tip from the full stress field, but different views are held regarding the extent of this shielding. The type of closure, whether it be plasticity-induced, or roughness-induced may also pl...

A new mixed-mode threshold stress intensity factor is developed using a critical plane-based multiaxial fatigue theory and the Kitagawa diagram. The proposed method is a nominal approach since the fatigue damage is evaluated using remote stresses acting on a cracked component rather than stresses near the crack tip. An equivalent stress intensity factor defined on the critical plane is proposed...

An assessment of the effects of microstructure on room temperature fatigue crack initiation and short crack propagation in a Ni-base superalloy is presented. The assessment was carried out on microstructural variants of U720Li, including as-received U720Li, U720Li-LG (large grain variant) and U720Li-LP (large intragranular coherent γ′ variant). Fatigue tests were carried out at room temperature...

The fatigue behavior of the unnotched and notched silicon carbide fiber-reinforced titanium/titanium aluminide hybrid laminated composite was investigated at room temperature. The evolution of microstructural damage and its effect on stiffness and strength degradation was quantified as a function of loading cycles and applied stress levels. Fatigue crack propagation behavior and damage mechanis...

We investigated the microstructural and fatigue characteristics on consolidated Japanese cedar called “ObiSugi (Cryptomeria japonicain)” fabricated by hot-pressing. Hot-press treatment was conducted at various conditions. Three point bending test, hardness test and plane bending fatigue test of consolidated wood were carried out to investigate mechanical properties. Flexural strength of consoli...

Increasing use of aluminum shape castings in automotive and aerospace industries has drawn great attention to fatigue properties of cast aluminum components. The fatigue resistance of aluminum castings strongly depends upon the presence of casting flaws and characteristics of microstructural constituents. The existence of casting flaws significantly reduces fatigue crack initiation life. In the...

Prediction of crack growth and fatigue life estimation of metals using linear/nonlinear acousto-ultrasound methods is an ongoing issue. It is known that by measuring nonlinear parameters, the relative accumulated fatigue damage can be evaluated. However, there is still a need to measure two crack propagation states to assess the absolute residual fatigue life. A procedure based on the measureme...

Fatigue crack growth is a complex process that involves interactions between many elements ranging across several length scales. This work provides an in-depth, experimental study of fatigue crack growth and the relationships between four of these elements: strain field, microstructure, crack path, and crack growth rate. Multiple data sets were acquired for fatigue crack growth in a nickel-base...

A reliable and cost effective two-phase methodology is proposed to predict crack propagation in generic two-dimensional structural components under complex fatigue loading. First, the fatigue crack path and its stress intensity factors are calculated in a specialized finite element software, using small crack increments. At each crack propagation step, the mesh is automatically redefined based ...

Step-loading fatigue tests have been conducted on two � -TiAl alloys with differing microstructures following quasi-static indentations intended to simulate assembly-related impact damage to lowpressure turbine blades. Fatigue tests were conducted at 600 �C using computer-controlled servohydrau­ lic loading at a frequency of 20 Hz. Reasonably good agreement was achieved between the fatigue data...