Toshiyuki Meshii

Application of -Stress to Predict the Lower Bound Fracture Toughness for Increasing the Test Specimen Thickness in the Transition Temperature Region

This work was motivated by the fact that although fracture toughness of a material in the ductile-to-brittle transition temperature region exhibits the test specimen thickness (TST) effect on , frequently described as , experiences a contradiction that is deduced from this empirical formulation; that is, = 0 for large TST. On the other hand, our previous works have showed that the TST effect on could be explained as a difference in the out-of-plane constraint and correlated with the out-of-plane -stress. Thus, in this work, the TST effect on for the decommissioned Shoreham reactor vessel steel A533B was demonstrated from the standpoint of out-of-plane constraint. The results validated that was effective for describing the decreasing tendency. Because the Shoreham data included a lower bound for increasing TST, a new finding was made that successfully predicted the lower bound of with increasing TST. This lower bound prediction with conquered the contradiction that the empirical predicts = 0 for large TST.

Maximum Stress Intensity Factor for a Circumferential Crack in a Finite-Length Thin-Walled Cylinder under Transient Radial Temperature Distribution

Transient stress intensity factor of an axisymmetric circumferential crack in a finite-length, thin-walled and edges rotation-restrained cylinder, which is suddenly cooled inside from uniform temperature distribution was formulated. Then the effects of various structural parameters and heat transfer conditions on the value were studied. The maximum transient stress intensity factor in a thermal cycle showed a tendency to decrease monotonously when crack length was varied to become longer than a specific value. Furthermore, the maximum transient stress intensity factor for an infinite cylinder length was smaller than that for a specific length when cylinder length was varied.

Stress intensity factor for a circumferential crack in a finite-length thin to thick-walled cylinder under an arbitrary biquadratic stress distribution on the crack surfaces

Abstract This paper presents the development of a practical method, by using prepared tabulated data, to calculate the mode I stress intensity factor (SIF) for an inner surface circumferential crack in a finite-length cylinder. The crack surfaces are subjected to an axisymmetric stress with an arbitrary biquadratic radial distribution. The method was derived by applying the authors’ weight function for the crack. This work is based on the thin shell theory and the Petroski–Achenbach method. Our method is valid over a wide range of mean radius to wall thickness ratio, R m / W ⩾1, and for relatively short cracks with a / W ⩽0.5. The difference between the SIF obtained by our method for the geometry and that from finite element analysis is within 5%. The method we developed describes the effect that cylinder length gives on the SIF. This effect needs to be considered for cylinders shorter than non-dimensional cylinder length βH ⩽5.

CLOSED FORM STRESS INTENSITY FACTOR FOR AN ARBITRARILY LOCATED INNER CIRCUMFERENTIAL SURFACE CRACK IN A CYLINDER SUBJECTED TO AXISYMMETRIC BENDING LOADS

Abstract In this paper, the stress intensity factor for an inner circumferential surface crack in a hollow cylindrical shell under axisymmetric bending loads is studied. The closed-form equations of stress intensity factor and inclination angles at the cylinder edges were derived. These equations can appropriately evaluate the effects of cylinder length and crack location on the stress intensity factor. The validity of these equations was illustrated by comparing solutions with numerical ones. The results showed that the stress intensity factor increases as the cylinder length decreases, and as the crack gets near the cylinder edge.

Closed form stress intensity factor of an arbitrarily located inner-surface circumferential crack in an edge-restraint cylinder under linear radial temperature distribution

Abstract Closed form stress intensity factor of an arbitrarily located inner-surface circumferential crack in an edge-restraint cylinder under linear radial temperature distribution was derived based on the theory of cylindrical shell and compliance. The effects of cylinder length, crack position and edge restraint on the stress intensity factor can be evaluated by the equation. According to the numerical examples of the equations, the stress intensity factor showed its maximum when the crack was located at the midpoint of its length, and a tendency to decrease as the crack length became larger than a specific value.

Stress Intensity Factor of a Circumferential Crack in a Thick-Walled Cylinder Under Thermal Striping

This paper tries to explain the interesting field data that indicate a surface axisymmetric circumferential crack inside a hollow cylinder (circumferential crack) shows tendency toward crack arrest, when the temperature of the fluid inside the cylinder experiences sinusoidal fluctuation (thermal striping). For this purpose, transient stress intensity factor (SIF) range of a circumferential crack in a finite-length thick-walled cylinder with rotation-restrained edges, under thermal striping, was analyzed. It was assumed that the fluid temperature changes sinusoidally and that heat transfer coefficient is constant. First an analytical temperature solution for the problem was obtained and it was combined with our SIF evaluation method derived based on superposition principle and Duhamels analogy. Then we defined the maximum SIF range as the maximum value of the SIF range during thermal striping and studied the characteristic change of this maximum SIF range with the variation of crack depth to explain the crack arrest tendency. Results showed that the maximum SIF range under thermal striping decreases monotonously when crack depth is varied to become deeper than a specific value, which corresponds to the crack arrest tendency.

Stress intensity factor error index for finite element analysis with singular elements

An error index for the stress intensity factor (SIF) obtained from the finite element analysis results using singular elements is proposed. The index was developed by considering the facts that the analytical function shape of the crack tip displacement is known and that the SIF can be evaluated from the displacements only. The advantage of the error index is that it has the dimension of the SIF and converges to zero when the actual error of the SIF by displacement correlation technique converges to zero. Numerical examples for some typical crack problems, including a mixed mode crack, whose analytical solutions are known, indicated the validity of the index. The degree of actual SIF error seems to be approximated by the value of the proposed index.

Stress Intensity Factor Evaluation of a Circumferential Crack in a Finite Length Thin-Walled Cylinder for Arbitrarily Distributed Stress on Crack Surface by Weight Function Method

A weight function to evaluate the stress intensity factor (SIF) of a circumferential crack, subjected to arbitrarily distributed stress on the crack surfaces, in a finite length thin-walled cylinder was derived based on the closed form SIF equation previously developed by the authors. It is easy to evaluate the effects of structural parameters and stress distribution on the SIF with this weight function. Numerical examples confirmed the validity of the weight function. These examples showed that the effect of cylinder length on the SIF is quite large.

Analytical Approach to Crack Arrest Tendency Under Cyclic Thermal Stress for an Inner-Surface Circumferential Crack in a Finite-Length Cylinder

This paper presents a study of the crack arrest tendency under cyclic thermal stress for an inner-surface circumferential crack in a finite-length cylinder with its edges rotation-restrained, when the inside of the cylinder is cooled from uniform temperature distribution. The effects of structural parameters and heat transfer condition on the maximum transient SIF for the problem were investigated with the formerly developed systematical evaluation methods. Then, a tentative value of threshold stress intensity range ΔK th being assumed as well as Paris law, the evaluation of crack length for crack arrest under cyclic thermal stresses was carried out. Finally, a map to find the crack arrest point for a cylinder with mean radius to wall thickness ratio R m /W=I and a specific length H under various heat transfer conditions could be originated. From the map, it was predicted that when the heat transfer coefficient and/or initial wall-coolant temperature differences become large enough, the nondimensional crack arrest length saturates to a specific value and is no longer affected by those conditions.

Stress intensity factor of an arbitrarily located circumferential crack in a thin-walled cylinder with axisymmetrically loaded ends

Abstract A simplified method has been developed to approximately calculate the stress intensity factor of a circumferential crack in a thin-walled cylinder with ends subjected to axisymmetric radial and bending loads, based on the theory of cylindrical shell and method similar to Rice and Levy’s line spring method. The effects of cylinder length and crack location on the value can be evaluated by this method. The numerical results for the problem with the ends subjected to a pair of axisymmetric bending loads showed the necessity of considering the effects of cylinder length and crack location on the stress intensity factor for the problem.