The characterization of critical levels of microstructural damage that can lead to fatigue-crack propagation under high-cycle fatigue loading conditions is a major concern for the aircraft industry with respect to the structural integrity of turbine engine components. The extremely high cyclic frequencies characteristic of in-flight loading spectra necessitate that a damage-tolerant design appr...

Using cold working fastener holes is a simple life enhancement procedure that strengthens metallic components by retarding crack growth around a hole. In the present paper, the residual stress field that is induced by the hole expansion process is obtained based on different material models namely elastic perfect plastic, isotropic hardening and kinematic hardening using three-dimensional finit...

Traditional separation methods for thick-walled metal tubes include turning and sawing, which suffer from wasted raw material low efficiency. In view of this, this paper proposes a new process using impact load to promote crack generation tube separation. Based on the principles radial repeated load, stress concentration effect fatigue fracture, rapid initiation stable expansion are promoted. a...

Three separate impact events were simulated (LS-DYNA ® ) based on experimental tests previously conducted [2] (i.e., the appropriate impact velocities assigned to the model projectile): i) a pre-fracture event (2.1 m/s); ii) a crack event (2.7 m/s); and iii) a fracture event (3.3 m/s). Two element sets were created in the locations of the experimental strain gauges (dorsal radial styloid and do...

Multi-layered systems used in automotive plain bearings show complex patterns of crack growth under service conditions. The studied architecture consists of a steel backing (1.8 mm), a compliant pure-aluminum interlayer (0.04 mm) and a lining of medium-strength aluminum alloy (0.38 mm). Previous experimental studies [1] with flat strip specimens of identical architecture under three point bendi...

*Correspondence: Alex Hansen, Department of Physics, Norwegian University of Science and Technology (NTNU), Høyskoleringen 5, NO-7491 Trondheim, Norway e-mail: [email protected] We investigate numerically the dynamics of crack propagation along a weak plane using a model consisting of fibers connecting a soft and a hard clamp. This bottom-up model has previously been shown to contain the comp...

The compliance technique has been used to monitor crack length during fracture and fatigue testing of materials. Difficulties arise when this technique is applied to anisotropic biological materials such as bone. In this tutorial, two different methods of analyzing compliance calibration data are described: the standard ASTM method and a new approach developed by the authors specifically for an...

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...

The thermal resistance of a bridged matrix crack in a fiber-reinforced ceramic composite is analyzed. The problem is cast in terms of a unit cell comprising an infinitely long composite cylinder with a single matrix crack perpendicular to the fiber axis. At the outset, it is demonstrated that the thermal resistance of such a crack can be represented by a simple circuit consisting of two paralle...