present work shows the numerical determination of fatigue crack opening and closure stress intensity factors of a C(T) specimen under variable amplitude loading using a finite element method. A half compact tension C(T) specimen, assuming plane stress constraint was used by finite element method covering the effects in two-dimensional (2D) small scale yielding models of fatigue crack growth und...

Abstract: Cracks in solids can be detected by ultrasound if they are open. However, their detection is not easy when they are closed with a closure stress, and it is a fundamental problem in ultrasonic testing. Subharmonics with half the input frequency is potentially useful in the detection and evaluation of such cracks. We developed analytical and numerical theories accounting for the crack p...

In this paper, an equivalent domain integral (EDI) method and the attendant numerical algorithms arc presented for the computation of a near-crack-tip field parameter, the vector Jε-integral, and its variation along the front of an arbitrary three-dimensional crack in a structural component. Account is taken of possible non-elastic strains present in the structure; in this case the near-tip Jε-...

I ′/(x) = I ′/(x) , where x = ∑n i=1 ziai is a generic element for I defined over the polynomial ring R ′ = R[z1, . . . , zn] and I ′ denotes the extension of I to R. This result can be paraphrased by saying that an element is integral over I if it is integral modulo a generic element of the ideal. Other, essentially unrelated, results about lifting integral dependence have been proved by Teiss...

This paper presents a new method for continuum-based shape sensitivity and reliability analyses of a crack in a homogeneous, isotropic, and linear-elastic body subject to mode-I loading. The method involves the material derivative concept of continuum mechanics, domain integral representation of the J-integral, and direct differentiation. Unlike virtual crack extension techniques, no mesh pertu...

Numerical fracture toughness assessment of two types of steel, AISI 420 and AISI 431, has been conducted in this paper. The J-integral is chosen as a criterion for fracture behaviour comparison of compact type (CT) specimens made of investigated materials. The values of J-integral are determined through a newly developed algorithm using finite element (FE) stress analysis results of numerically...

The two-dimensional interface crack problem is investigated for ani-sotropic bodies in the Comninou formulation. It is established that, as in the isotropic case, properly incorporating contact zones at the crack tips avoids contradictions connected with the oscillating asymptotic behaviour of physical and mechanical characteristics leading to the overlapping of material. Applying the special i...