Crack-line and edge Green's functions for stress intensity factors of inclined edge cracks

Fretting loads on the surfaces of structural components can cause accelerated growth of short cracks. The rate of growth will depend on the combined stress intensity factor resulting from both remote and local loading. Many stress intensity factor solutions are available for remote loading, but solutions for arbitrary fretting loads are not. In...

Dual boundary element analysis of pin-loaded lugs

This paper describes an application of the dual boundary element method to pin-loaded lug problems in linear elastic fracture mechanics analysis. The dual equations of the method are the displacement and the traction boundary integral equations. When the displacement equation is applied on one of the crack surfaces and the traction equation on...

Waveforms in fretting fatigue

The magnitudes am directions of the frictional forces must be considered in any fracture mechanics analysis of crack growth under fretting fatigue conditions. A simple nonlinear friction model has been developed which relates the waveforms of the frictional forces to those of the applied forces when fretting occurs. It is shown that the...

Crack-line Green's functions for finite bodies

Crack-line Green's functions are obtained for cracks in various twodimensional configurations. The boundary element method, coupled with a singular field model of the crack tip, has been used to solve the initial elasticity problem. The Green's functions can be used to obtain the stress intensity factors for cracks in arbitrary stress fields...

Stress intensity factors for periodic radial cracks in a rotating disc

Stress intensity factors have been derived for periodically distributed radial cracks in rotating discs; both internal and edge cracks have been studied. It is shown that in general as the number of cracks increases, there is a shielding effect which lowers the stress intensity factors.

A database for compounding stress intensity factors

The compounding method enables stress intensity factors to be evaluated for complex geometrical configurations using the known results of simpIer ancillary configurations. Implementation of the method on a computer system requires that a data file of known results be available, and that a program be written to compound solutions from that data...

An improved compounding method for calculating stress intensity factors

The compounding methods for calculating stress intensity factors for complex geometrical configurations are re-examined. It is shown that techniques which were developed specifically for problems involving localized loads, eg a pin-loaded hole with a crack at its edge, can also be used when the loading is remote from the crack. When this is done...

Stress intensity factors for cracks at fastener holes

The compounding technique, a method for obtaining stress intensity factors for complex geometrical configurations from those for simple configurations, is applied to cracks at the edges of the holes in a row of fastener holes. The holes are assumed to be loaded on their perimeters; the original technique requires modification in order to...

Stress intensity factors for cracks at loaded holes-effect of load distribution

Stress intensity factors are evaluated for a radial crack at the edge of a circular hole subjected to a localized radial or tangential force on its perimeter. These factors can be used as Green's functions to determine the stress intensity factor when an arbitrary load distribution acts on the hole perimeter. Both the accuracy and ease-of-use of...

Stress intensity factors for cracks at loaded holes

A method is described for obtaining the opening-mode and sliding-mode stress intensity factors for the tip of a crack at the edge of a circular hole with arbitrary loads on its perimeter. The method involves the solutions of a singular integral equation which arises from expressing the equations of elasticity in terms of Mellin transforms. In...

Fatigue lifetimes for cracks at a double row of holes

Comparisons have been made of the stress intensity factors in single and double rows of cracked fastener holes. It is found that for a model configuration with cracks of equal size the stress intensity factor is less when a given number of fasteners is arranged in a double row. This results in slower rates of fatigue crack growth and longer...

Energy dissipated during stable crack growth in aluminium alloy 2024-T3

Experimental studies have been made of the resistance to stable crack growth (R-curve) in centrally cracked thin sheet specimens of aluminium alloy 2024-T3; the specimens were subjected to uniaxial tensile loads perpendicular to the cracks. The elastic and the plastic work associated with the R-curve were measured for two different loading...

Crack propagation in fatigue: some experiments with DTD 507A aluminium alloy sheet

Fatigue crack propagation rates have been measured in 16 swg sheets of this aluminium alloy using stress levels of 8800 ±7200 psi, 4400 ±3600 psi and 13,200 ±10,800 psi. The scatters in crack initiation times and crack rates were determined. Varying the panel length/width ratio from 1.2 to 4.75 was found to have little effect on crack rate. A...

Elastic yield zones round a crack tip: comparison of exact and approximate elastic theories

The elastic yield zones are calculated and compared, using both an approximate and the exact stress analysis for a crack in an infinite sheet. The 'effective crack length' for use in Fracture Toughness Tests is obtained, together with the maximum width of the elastic yield zone and the width at the crack tip.

Stress-strain relations for some dislocation models

It is shown that the basic model of the exhaustion theory of transient creep(2-4) is unable to account for certain observed phenomena. Several more complex models are proposed and studied.