Showing papers in "Engineering Fracture Mechanics in 1974"

TL;DR: In this paper, the authors applied cyclic stresses with stress ratio R = 0.65 to sheet specimens of aluminium which have an initial crack inclined to the tensile axis at angles of 30°, 45°, 72° or 90°.

TL;DR: In this paper, a design rationale for materials which contain flaws caused by metallurgical inclusions, fabrication and erection overloads, and fatigue cracking is outlined for materials that contain flaws.

TL;DR: In this paper, a Ti-6Al-4V titanium alloy was used to study the effect of crack closure on crack growth and showed that crack closure is not the sole cause for delay.

TL;DR: In this paper, a critical combination of hydrogen concentration and stress will develop at the edge of the plastic enclave, and this will produce an incremental crack growing from the edge to the crack tip.

TL;DR: In this article, a detailed discussion of the development of fatigue-crack growth "laws" is presented, which are then generalized to three forms, viz. da/dN = C 1 (S a ) (1) da/DN = c 2 S(a) n (2) da /dN= C 3 f(K) n(3) Examples of the use of these crack growth "law" and the knowledge of fracture mechanics are presented to illustrate the application of fatiguecrack growing concepts to: Predict life; establish greater reliability; select materials:

TL;DR: In this article, a criterion for predicting the growth of three-dimensional cracks is developed on the basis of the strain energy density concept which has been used successfully for treating two-dimensional crack problems.

TL;DR: In this paper, the fracture toughness of a number of cemented carbide alloys have been determined using a wedge-impact method for precracking; the materials were of WC-Co type with cobalt content ranging from 6 to 25 wt-% and mean carbide grain size between 1.0 and 3.3 μ m.

TL;DR: In this paper, the accuracy of several crack propagation equations published in recent years are tested on crack propagation behavior of fourteen metallic materials and four equations based on different crack propagation models yield reasonably good approximations of measured behaviour.

TL;DR: In this article, the influence of intermittent overloads on fatigue crack growth in polymethylmethacrylate, a transparent polymer, was investigated and it was found that a significant tensile load was required to displace the portions of the crack surfaces which were initially closed.

TL;DR: In this article, the authors measured the dynamic stress-intensity factor about the tip of a rapidly moving crack in polymethylmethacrylate (PMMA) using ultra-high speed photographic techniques to record the photoelastic patterns produced around the crack tip.

TL;DR: In this paper, an approximate method is proposed for the analysis of unidirectional, filamentary composite materials having slit notches perpendicular to the fibers and subjected to tension parallel to the fiber.

TL;DR: In this paper, the topography of the stretched zone was measured from stereo electron micrographs and the width of the stretch zone appeared to be in the order of magnitude of the ligament spacing in Krafft's model.

TL;DR: In this article, an empirical crack growth rate model based on the change in crack extension force, Δℷ, was proposed and its relation to current ΔK models is discussed and observations on the fatigue surface morphology presented.

TL;DR: In this article, a method for determining approximate stress intensity factors is presented, and the accuracy of the method is assessed using three widely differing configurations for which alternative solutions are available, and an approximate solution is then obtained to a configuration for which no alternative solution exists.

TL;DR: In this article, a limited number of cold expansion and interference fit fastener systems were evaluated to determine their capability to retard the growth of cracks emanating from fastener holes, and the results showed that a cold expansion or properly installed interference-fit fastener system significantly retards the development of preexisting cracks.

TL;DR: In this article, the authors measured dynamic stress intensity factors, crack velocities and branching angles in Homalite-100 sheets of 1/8in. and 3/8-in. thickness.

TL;DR: The dual integral I is path independent, and is expressible as the rate of decrease of potential energy Q for stress field as well as lower bounds of integrals obtained by variational principles.

TL;DR: In this paper, crack growth was observed under variable amplitude loading, during high stress-amplitude cycles, associated with 45°-mode cracking, whereas the crack front orientation was still at an angle of 90°.

TL;DR: In this paper, the authors developed a general theory for the determination of the structure in the vicinity of the tip of a crack within an isotropic elastic solid, based on the presence of a Barenblatt-type zone, in which cohesive stresses act, thereby allowing nonlinear behaviour to he taken into account.

TL;DR: In this paper, the authors investigated the effect of partially debonded infinite stringer on the stress intensity at the crack tip and solved the integral equation, obtained from the continuity of displacements along the line where the stringer and the plate are bonded.

TL;DR: In this article, a cyclic crack propagation relationship based on the stress intensity factor concept, which can be successfully utilised for both types of materials, has been found, and the possible modified forms of such a relationship in terms of strain energy release rate, the crack tip yielding and the crack opening displacement concepts are also indicated.

TL;DR: A technique known as the Taylor Series Correction Method (TSCM) for extracting the stress intensity factor from photoelastic data is reviewed in this article, where the Sneddon-Srivastav solution for a line crack in a finite width plate is demonstrated as the crack tip approaches the free edge.

TL;DR: In this paper, an incremental solution is presented for plane strain conditions, the cylindrical inclusion being assumed rigid, while the matrix obeys the Mises yield criterion and its associated flow rule and has a very small or zero linear work-hardening characteristic.

TL;DR: In this article, it was shown that the stage of multiplication and growth preceding the propagation of the final macro-crack and following a very short stage of formation of point-defects represents the principal engineering aspect of fatigue except when, as the result of the preexistence of a dominant local defect or stress-concentration, the fatigue life is completely determined by the propagating crack.

TL;DR: In this article, the authors used caustics for the study of the validity of the Dugdale-Barenblatt model for the solution of the stress-distribution in cracked plates made of elastic-plastic materials.

TL;DR: In this paper, a laser speckle method was used to investigate the in-plane displacements around crack tips in single edge crack tensile specimens made of Araldite CT 200.

TL;DR: In this article, photoelastic measurements on centrally notched sheets of polycarbonate have been used to confirm the elastic stress field around the yielded zone predicted by the Dugdale model.

TL;DR: In this paper, an edge-cracked specimen of commercially available polymethylmethacrylate (PMMA) having about triple thickness in a region surrounding a segment of the prospective fracture path have been loaded in the extensional mode.

TL;DR: In this paper, the effect of mean stress on fatigue crack propagation and on the critical fatigue crack size associated with sudden fast fracture in center-notched plate specimens of a rail steel under pulsating loading was studied.

TL;DR: In this paper, the Elber closure model was applied to HP-9Ni-4Co-30C steel heat treated to three strength levels and it was concluded that the constant amplitude crack growth rate is dependent on the strength level of the material.