In recent years many experimental and numerical studies have been conducted on the fatigue behaviour of CNG storage pressure vessels. The main objective of these studies is to estimate the total fatigue life, which consists of two parts: i) Life till crack nucleation and ii) Crack growth life. Although fatigue evaluation methods for metal cylinders are widely covered in literature including the...

The effects of anisotropy during mixed mode fatigue crack growth were studied in single crystal 316L stainless steel. An anisotropic least-squares regression algorithm using displacements from digital image correlation was developed to find the effective stress intensity factors, KI and KII, and the T-stress. Crack tip plastic zones were determined using an anisotropic yield criterion. Strains ...

Preliminary testing of a complete landing gear under fatigue test has demonstrated the applicability of the test using Acoustic Emission (AE) resonant sensors attached to the outer surface of the landing gear assembly. Attenuation trials were conducted which confirmed that attenuation through the main casing is low and provided data for optimisation of sensor positioning. Background noise level...

The present paper is concerned with the application of a “plasticity-induced” crack closure model to study fatigue crack growth under various load histories. The model was based on the Dugdale model but modified to leave plastically deformed material in the wake of the advancing crack. The model was used to correlate crack growth rates under constant-amplitude loading and then used to predict c...

A numerical technique for planar three-dimensional fatigue crack growth simulations is proposed. The new technique couples the extended finite element method (X-FEM) to the fast marching method (FMM). In the X-FEM, a discontinuous function and the two-dimensional asymptotic crack-tip displacement fields are added to the finite element approximation to account for the crack using the notion of p...

This paper presents a low cycle fatigue life curve by simulating a crack in a cover plate welded moment connection. Initiation of ductile fracture in steel is controlled by growth and coalescence of micro-voids. This research used a numerical method using finite element modeling and simulation of ductile crack initiation by a micromechanical model. Therefore, a finite element model of a cover p...

In this thesis an investigation and modelling of the fatigue crack propagation in the nickel based superalloy Inconel 718, with a special emphasis on the effect of hold times, is presented. The modelling work has been concentrated on describing the hold time fatigue crack propagation by using the concept of a damaged zone in front of the crack tip, which is believed to have a lowered resistance...

 The growth of fatigue cracks at elevated temperatures (25–1300°C) is examined under cyclic loading in an in situ toughened, monolithic silicon carbide with Al-B-C additions (termed ABC–SiC), with specific emphasis on the roles of temperature, load ratio, cyclic frequency, and loading mode (static vs. cyclic). Extensive crack-growth data are presented, based on measurements from an electrical ...

An understanding of the fatigue and fracture behavior of hard tissues (e.g., bone and tissues of the human tooth) is critical to the maintenance of physical and oral health. Recent studies suggest that there are a number of mechanisms contributing to crack extension and crack arrest in these materials, and that they appear to be a function of moisture and age of the tissue. An understanding of ...