Showing papers in "Engineering Fracture Mechanics in 1973"

TL;DR: In this paper, the authors re-examine some of the fundamental concepts of the classical theory of fracture and discuss the numerous inconsistencies and misconceptions that have not received attention, and apply the modified Griffith theory for ductile material.

TL;DR: In this paper, a dislocation model was developed compatible with this point of view, which yields a relation between the fracture strain and the volume fraction of the inclusions, which is the critical event in ductile fracture; it is immediately followed by spontaneous growth and coalescence of the voids.

TL;DR: In this article, the authors discuss the different aspects of the fatigue process in relation to the basic concepts of fracture mechanics and delimit the conditions under which this process approaches the model too closely for purposes of design.

TL;DR: In this article, a single-cycle peak overload was investigated in Ti-6Al-4V sheet and the recovery of an overloaded crack was linear with respect to the constant load amplitude cyclic stress intensity.

TL;DR: In this paper, the Neuber stress-concentration relation for notches in an elastic-plastic material subjected to shear loading was generalized for a crack in a finite plate subjected to tensile loading.

TL;DR: In this paper, the effect of fatigue crack retardation due to variable amplitude loading spectra was studied in 7075-T6511 aluminum alloy, where precracked compact tension specimens were subjected to single and multiple peak applications of overload stress intensity values and subsequently cycled at lower stress intensities.

TL;DR: In this paper, acoustic emissions of fatigue crack growth have been monitored and quantitatively correlated with growth rate and the applied range of stress intensity for high cycle fatigue of 2024-T851 aluminum alloy.

TL;DR: In this article, a theory of fracture mechanics is proposed in which attention is focused on the intensity of the energy field in the crack tip region and the strength or amplitude of this field is referred to as the energy-density factor, S. The difference between k and S is analogous to the difference between a scalar and vector quantity.

TL;DR: In this paper, the authors studied the crack propagation of Alclad sheet specimens under two types of random loading and under program loading with a very short period (40 cycles) and a longer period (20,000 cycles).

TL;DR: In this paper, the effect of load ratio on low crack growth rates and threshold stress conditions exhibited by five medium carbon steels has been studied and it was found that decreased values of R retarded crack growth to an increasing degree as a defined threshold for crack growth was approached.

TL;DR: In this paper, the authors presented a theoretical analysis of the stress intensity factor for the tension of a centrally cracked strip reinforced with stringers along its edges, based on the Laurent expansions of the complex stress potentials, and the perturbation technique was applied in determining their coefficients from the boundary conditions.

TL;DR: In this paper, a finite element analysis was used to determine numerically Rice's J -integral values in centrally notched plates of 4340 steel and the numerical values were compared with corresponding J-integral value using Dugdale model and antiplane strain model with a power law hardening of n = 0.3.

TL;DR: In this paper, heat outputs from plastic zones of fast running cracks in polymeric materials have been measured by means of thermocouples, and it was found that heat outputs increased with molecular weight and with crack velocity.

TL;DR: In this paper, a method to predict the residual strength of a cracked sheet structure is proposed, which takes full account of sheet-stringer interaction in the cracked region and a criterion for crack arrest is put forward.

TL;DR: In this paper, the fracture toughness of low alloy quenched and tempered steels with yield strengths over 200,000 psi can be improved by microstructural control by as much as 70 per cent.

TL;DR: In this paper, two thermomechanical treatments have been considered, one a high strength condition equivalent to the conventional T-6 treatment and the other an over-aged condition comparable to the T-73 treatment.

TL;DR: In this paper, the authors describe experimental results of crack propagation studies in part-through crack specimens and show that crack extension under cyclic loading is characterized during the loading cycle by the interaction of the crack with a surface wave.

TL;DR: In this article, a fracture mechanics model for cracks originating from the pores in the web-to-flange fillet weld is developed, and estimates of the stress-intensity factor are made that numerically describe the initial flaw condition.

TL;DR: The results of 22 different investigations of cyclic crack growth, principally on the 2024-T3 and 7075-T6 alloys, but including results for unalloyed and other 2-, 5-, 6-, and 7thousand series alloys have been examined and compiled with a view to separating metallurgical effects from other factors.

TL;DR: In this article, the influence of biaxial loading on plastic zone size and crack opening displacement has been examined, and the theoretical predictions are supported by a limited amount of experimental data.

TL;DR: In this article, a critical review of various fracture mechanics analytical methods for aircraft structural design is presented, including linear elastic fracture mechanics, which is applied to several types of built up structural components under spectrum loading conditions.

TL;DR: The rates of fatigue crack propagation of a cobalt base superalloy (HS 188) were measured at 75, 1112, 1400 and 1600°F as a function of the range of the stress intensity factor ΔK.

TL;DR: In this article, the applicability of the general yielding fracture mechanics concept of crack opening displacement is made in relation to the well established concepts of linear elastic fracture mechanics, and the nature of the relationship between fracture displacement and stress intensity factor is explored using the concepts of Linear Elasticity and model analyses proposed by Dugdale.

TL;DR: In this article, a crack sandwiched between two dissimilar media of infinite height is considered and the local intensification of the dynamic stresses due to the crack is analyzed for incident waves directed at an arbitrary angle.

TL;DR: In this paper, the authors investigated the relationship between K Ic and ordinary tensile material properties for four steels ranging in yield strength from 80 to 250 ksi (552-1720 MN/m 2 ).

TL;DR: In this article, a near tip strain criterion was proposed as a ductile fracture criterion to study the onset of slow growth of surface crack in two batches, B and C, of fully annealed 2024-0 aluminum alloy and HY-80 steel.

TL;DR: In this article, two models were investigated for their application to retardation behavior, namely, linear cumulative growth and Wheeler, and the results showed that the results appeared suitable for comparison with actual test results for diffusion-bonded Ti-6A1-4V and HP-9Ni-4Co steel at 0.3 and 0.2 carbon contents.

TL;DR: In this paper, the authors present the findings of an Advanced Research Projects Agency (ARPA) study, the overall objective of which was to develop a nondestructive testing technique to determine flaw criticality based on acoustic emission.

TL;DR: In this article, a model to predict the increase in critical flaw size or stable crack growth potential which can occur by the inclusion of ductile fibers in a brittle matrix is considered.