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...

Cracks are dangerous and frequently observed defects in steel structures. Therefore, the understanding of the mechanism of crack is very important to structure safety. Although the mechanism of static crack has been widely studied by researchers, the mechanism of dynamic crack has been left out and seldom been discussed. In this paper, a modeling method for acoustic emission (AE) source of dyna...

Despite decades of study, the atomic-scale mechanisms of fatigue crack growth remain elusive. Here we use the coupled atomistic–discrete dislocation method, a multiscale simulation method, to examine the influence of dislocation glide resistance on near-threshold fatigue crack growth in an aluminum alloy. The simulations indicate that the threshold increases with an increase in dislocation glid...

Very high cycle fatigue (VHCF) tests were carried out under variable amplitude loading for TC21 titanium alloy. The first level of was set as 950 MPa close to yield strength, and the second low determined between 435 500 where cracks initiated at specimen subsurface constant amplitude. results indicate that high/low stress block significantly reduced cumulative life amplitude, crack initiation ...

The effect of uniaxial tensile stress on the atomic structure and relief subsurface layer molybdenum ribbons has been studied. destruction Mo (100) face with formation crystallites was revealed near crack tip. At same time, block structures are found to rotate both in lateral plane its perpendicular plane. surface ribbon is fragmented into sections, which associated at different scales. With a ...

Crack: The tests were performed using Crack version 1.0 beta 18. Crack is a description logic system with both TBox and ABox, using the logic ALCRIFO. Crack reasoning procedures are based on a sound and complete tableaux algorithm 1].

Mixed-mode dynamic crack growth behavior in a compositionally graded particle filled polymer is studied experimentally and computationally. Beams with single edge cracks initially aligned in the direction of the compositional gradient and subjected to one-point eccentric impact loading are examined. Optical interferometry along with high-speed photography is used to measure surface deformations...

To advance the understanding of metallic materials for structural components at cryogenic temperatures, a review previous studies on mechanical properties austenitic stainless steels, titanium alloys, aluminum and copper alloys is presented herein. In particular, evaluation strength toughness balance intends to clarify key differences between these facilitate better alloy design potentially bol...

We use computer simulations to study the behavior of sharp and blunted cracks in various f.c.c. metals. We find that in models representing platinum and gold a sharp crack is stable with respect to the emission of a dislocation from the crack tip, whereas for all other metals studied the sharp crack is unstable. This result cannot be explained by existing criteria for the intrinsic ductile/brit...

Precracked and notched specimens were used to investigate the fracture mechanism of a bainite steel at low temperature. The critical fracture event was studied using metallographic sectioning method. The results showed that the critical cleavage event was different in the precracked and the notched specimens. At -196C, all specimens fractured at lower-shelf region without any ductile crack grow...