An empirical stress-intensity factor equation for the surface crack

Plane strain crack toughness testing of high strength metallic materials.

Vibration of cracked structures: A state of the art review

The paper presents an energetic approach useful to predict of the static and fatigue behavior of components weakened by sharp re-entrant corners. Despite the fact that stresses and strain energy density tend toward infinity at the point of singularity, the energy in a small volume of material surrounding the notch tip has obviously a finite value and such a value is thought of as the entity that controls the failure. The energy, averaged in a volume of radius R (which depends on the material properties), is a precise function of the Notch Stress Intensity Factors and is given in closed form for plane stress and plane strain conditions, the material being thought of as isotropic and linear elastic. The method is validated taking into account experimental data already reported in the literature, concerning both static tests carried out on polymethyl metacrylate (PMMA)and Duraluminium specimens and fatigue tests on welded joints and notched components in structural steels. As a matter of fact, the method proposed here is the re-formulation, on one hand, of some recent area/volume criteria (in which averaged values of the maximum principal stress are used to predict component fatigue limits) and, on the other, of N-SIF-based criteria, where the Notch Stress Intensity Factors are thought of as the parameters that control static and fatigue failures.

A finite-volume-energy based approach to predict the static and fatigue behavior of components with sharp V-shaped notches

The finite element method is now recognized as a general approximation process which is applicable to a variety of engineering problems—structural mechanics being only one of these. Boundary solution procedures have been introduced as an independent alternative which at times is more economical and possesses certain merits. In this survey of the field we show how such procedures can be utilized in conventional FEM context.

The coupling of the finite element method and boundary solution procedures

Solutions are given for several plane elastostatic problems of plates having a V-notch on one edge, and subjected to a variety of boundary conditions. The effect of the magnitude of the V-notch angle and specimen geometry on stress intensity factors KI and KII are obtained for unloaded notch surfaces. There is less than one percent difference in opening mode I stress intensity factor in going from a zero degree notch angle to a 30 degree notch angle.

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Plane elastostatic analysis of V-notched plates

Stress-Intensity Factors for a Single-Edge-Notch Tension Specimen by Boundary Collocation of a Stress Function

: A boundary-value-collocation procedure was used in conjunction with the Williams stress function to determine values of the stress-intensity factor K for single edge cracks of various depths in specimens subjected to pure bending. The results are of use in connection with K(sub Ic) fracture toughness tests, which utilize rectangular-section crack-notch beam specimens loaded in four-point bending, and are in good agreement with published results derived from experimental compliance measurements. The results are expressed in convenient, compact form in terms of the dimensionless quantity Y(exp 2)=K(exp 2)B(exp 2)W(exp 3)/M(exp 2), which is a function of relative crack depth a/W only, where B and W are the specimen width and thickness and M is the applied bending moment. On the assumption that the condition for a valid K(sub Ic) test is that the maximum nominal stress at the crack tip should not exceed the yield strength of the material, the K(sub Ic) measurement capacity of bend specimens was estimate as a function of a/W. The measurement capacity is proportional to the yield strength and to the square root of the specimen depth, and it is greatest for a/W in the range 0.2 to 0.3. Values of K for single-edge-notch specimens subjected to combined bending and tension were obtained by superposition of the present results and those of earlier work for specimens loaded in uniform tension. These values are of interest in connection with the use of single-edge-notch specimens that are off-center pin-loaded in tension. It is shown that the K(sub Ic) measurement capacity of such specimens is not very sensitive to the eccentricity of loading.

Stress-Intensity Factors for Single-Edge-Notch Specimens in Bending or Combined Bending and Tension by Boundary Collocation of a Stress Function

Stress-intensity factors for three-point bending by boundary value collocation - structural dynamics

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Stress-Intensity Factors for Three-Point Bend Specimens by Boundary Collocation

Elastic displacements for edge cracked plate specimens used as crack extension indicator in plane strain fracture toughness measurements

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Bernard Gross

Papers

Plane elastostatic analysis of V-notched plates

Stress-Intensity Factors for a Single-Edge-Notch Tension Specimen by Boundary Collocation of a Stress Function

Stress-Intensity Factors for Single-Edge-Notch Specimens in Bending or Combined Bending and Tension by Boundary Collocation of a Stress Function

Stress-Intensity Factors for Three-Point Bend Specimens by Boundary Collocation

Elastic displacements for various edge-cracked plate specimens.