Showing papers in "Engineering Fracture Mechanics in 1976"

TL;DR: In this article, the area of the true stress/true strain diagram determined under tensile test conditions is equal to the energy absorbed per unit volume at the point of fracture, where the critical specific fracture energy (W c ) characteristic of the material has been absorbed whereby the proportionality law of notched specimens can then be derived.

TL;DR: In this article, the influence of mechanical vibrations on the diffusion process is investigated and the basic energy theorem constituting the point of departure for the uniqueness of solutions of the differential equations of diffusion in solids is presented.

TL;DR: In this article, the authors investigated the fatigue crack growth behavior resulting from single and multiple applications of overload for HT80 steel and found that a peak load was found to cause retardation of the crack growth rate, which becomes stronger with increasing the peak/baseline stress ratio or with decreasing baseline stress intensity.

TL;DR: In this article, a probabilistic model for spatial variation of material strength is proposed, which results in a corresponding statistical size effect and is compatible with the finite element method and therefore extremely useful for the analysis and design of nonhomogeneous structural systems.

TL;DR: In this paper, the effect of loading frequency on fatigue crack propagation rate and striation spacing in 2024-T3 aluminium alloy and SM-50 steel was studied at room temperature, and the results showed that dc/dN and s will not coincide except the very narrow region near the intersecting point.

TL;DR: In this article, a simple formula for determining the effect of a straight-edge crack on the stiffness of a cylindrical shaft in bending has been derived, and the maximum stress intensity due to tensile or bending loads was highest at the centre, and lower than that due to a semi-elliptical notch in a slab of the same thickness under the same load.

TL;DR: In this paper, the cyclic stress-strain behavior and the S/N behavior of a pseudo-elastic alloy, Ti-6Al-4V of coarsened microstructure and of a "plastic" material, copper, are compared.

TL;DR: In this paper, a single pre-strain ( ϵ = 0.03 ) applied to 2024-T3 material raised the static yield strength from 428 to 480 MN/m 2.

TL;DR: In this article, a modified Bridgman analysis was used to deduce the distribution of stress and plastic strain at the minimum diameter in circumferentially notched bars with three different notch profiles from observation of the displacements of bands within the material.

TL;DR: A review of the current procedures for fatigue design and for fatigue life estimation, substantiation and monitoring of aircraft structures is presented in this paper. Major gaps in the present state of knowledge are identified and further research directed towards filling these gaps is discussed.

TL;DR: In this paper, a simple procedure for the accurate determination of stress intensity factors K I, K II by the conventional finite element method is proposed, where the first step is to calculate the stress σ 2 of the plate without a crack.

TL;DR: In this paper, the effects of gas environments (at atmospheric pressure and below) on the fatigue behavior of metals is reviewed. Among the topics considered are the mechanisms proposed to explain the differences observed in the fatigue behaviour of vacuum- and air-tested specimens, the effect of environment on the surface topography of fatigue cycled specimens.

TL;DR: In this paper, the effect of complex loading on fatigue crack retardation in 2024-T3 aluminum alloy was investigated by introducing a second tensile or compressive peak load after the crack had extended various distances, a', into the region affected by a previously applied high load excursion.

TL;DR: Stress intensity factor of a crack perpendicular to the welding bead in a wide plate is analyzed as a plane problem of elasticity in this article, and the function which simulates the residual stress distribution qualitatively is assumed.

TL;DR: In this article, a physically acceptable solution for a central crack in an infinite sheet or a strip in pure bending is compared with the corresponding classical solution, and the classical solution is non-conservative and, for both the strip and the infinite sheet, underestimates the stress intensity factor at the crack tip in the tensile field by approx. 9%.

TL;DR: In this article, the authors compared six parameters on the basis of their accuracy and utility in predicting fracture toughness on small precracked bend specimens after general yield and found that the plane strain COD at fracture initiation is the most useful parameter for measuring KIc on small specimens that fracture after general yielding.

TL;DR: In this article, an analysis of the stresses along a bonded interface between two elastic half spaces of dissimilar isotropic materials was made, and the strain energy release rate was formulated as a fracture criterion for interfacial failure.

TL;DR: In this article, a separating body is viewed as a nonequilibrium thermodynamic process, and the full thermodynamic nature of the surface energy induced by crack propagation becomes apparent, and it is shown that the induced surface energy depends explicitly on the square of the crack propagation speed.

TL;DR: In this article, the stress intensity factors for embedded circular and elliptic flaws and semi-circular and semielliptic surface flaws subject to an arbitrary stress expressed in the form of a polynomial were given.

TL;DR: In this article, the energy unstable and critical local stress requirements for low-stress brittle fracture of notched specimens were derived based on the combined micro-and macro fracture mechanics, that is, the two requisites necessary for the crack propagation.

TL;DR: In this paper, an experimental investigation was carried out to evaluate the retardation phenomenon of precracked cold-worked holes with and without fasteners (zero load transfer), and the results indicated that cold working does retard crack propagation from fastener holes but overloads can influence the overall results.

TL;DR: In this article, the authors investigated the variation of K Ic with crack-front width for Douglas-fir wood using beam and compact tension specimens with crackfront widths of 3-12.25 in.

TL;DR: In this article, the authors measured the radius of the contraction zone on the side of the specimen and load-load point displacement during fracture of single edge notched specimens containing fatigue cracks of different lengths.

TL;DR: In this paper, the relaxation of the surface residual stress in 0.23% C steel due to the application of fatigue loading was studied and the residual stress was induced in the specimen by pre-straining and was measured by X-ray back reflection method using Cr-Kα radiation.

TL;DR: In this article, fracture toughness and fatigue crack growth testing at liquid helium temperature, 4 K (−452°F), is discussed. And the design and performance of a fracture testing cryostat and associated instrumentation are described.

TL;DR: In this article, it was shown that the internal friction in the high amplitude range is due to breakaway of dislocations from pinning points and by the generation of Frank-Read loops which results in plastic strain.

TL;DR: In this article, the authors reviewed the results and interpretations of many ultrasonic frequency fatigue tests performed by the staff of the Fatigue Institute and interpreted the behavior of the internal friction as a function of the strain amplitude in terms of a dislocation model.

TL;DR: In this article, the principle of superposition for stress intensity factors for different types of loading was discussed and it was shown that stress intensity factor for different loading types are additive provided all loading types tend to open the crack.

TL;DR: In this article, an easily implemented method is developed for calculating, from information obtained from a possibly censored life test, an approximate warranty period before which the k th failure occurs in a production lot of given size with some small specified probability.