Kamran Nikbin¹

Structural Durability & Health Monitoring, Vol.3, No.1, pp. 51-68, 2007, DOI:10.3970/sdhm.2007.003.051

Abstract Weldments and welded regions of components are likely to see failure at elevated temperatures earlier than homogenous parent material. In some cases variable loading could also introduce creep/fatigue crack growth. These weld regions not only contain variable creep properties but are likely to contain residual stresses which could relax in time. There are three key factors which may determine a successful outcome for remaining life assessment of engineering components containing residual stresses in the vicinity of welds. The first is standardized testing and measurement procedures. The second is the development of appropriate and accurate correlating parameters to treat the results… More >

M. Kumosa¹

Structural Durability & Health Monitoring, Vol.3, No.1, pp. 35-50, 2007, DOI:10.3970/sdhm.2007.003.035

Abstract This paper deals with the structural integrity and durability of suspension composite (non-ceramic, polymer) insulators widely used in power transmission systems around the world. Under certain conditions, the insulators can fail in-service both electrically and mechanically resulting in the drop of energized transmission lines and power outages. In this work, predominantly mechanical failures of the insulators are discussed. In particular, the most important characteristics of a catastrophic failure process called brittle fracture are described. Subsequently, two examples of insulator failures by brittle fracture are shown and their causes explained. Finally, several recommendations on how to avoid brittle fracture as well… More >

C.P. Providakis¹

Structural Durability & Health Monitoring, Vol.3, No.1, pp. 29-34, 2007, DOI:10.3970/sdhm.2007.003.029

Abstract Actuators are structures that give micro-electro-mechanical systems (MEMS) the ability to interact with their environment rather than just passively sensing it. Recent studies of MEMS thermal micro-actuators have shown that simple in design and production devices can provide deflection of the order of 10 μm at low voltages. Recently, metals and single-crystal silicon materials were included in the range of materials used for thermal actuators since they operate at lower temperatures than the commonly used (poly)silicon devices. These actuators are liable to meet the loads in service, so the corresponding integrity and stability analysis constitutes a topic of interest on… More >

Abdulnaser M. Alshoaibi^1,2, M. S. A. Hadi², A. K. Ariffin²

Structural Durability & Health Monitoring, Vol.3, No.1, pp. 15-28, 2007, DOI:10.3970/sdhm.2007.003.015

Abstract An adaptive finite element method is employed to analyze two-dimensional linear elastic fracture problems. The mesh is generated by the advancing front method and the norm stress error is taken as a posteriori error estimator for the h-type adaptive refinement. The stress intensity factors are estimated by a displacement extrapolation technique. The near crack tip displacements used are obtained from specific nodes of natural six-noded quarter-point elements which are generated around the crack tip defined by the user. The crack growth and its direction are determined by the calculated stress intensity factors as the maximum circumference theory is also been… More >

M. M. Rahman¹, A. K. Ariffin¹, S. Abdullah¹, N. Jamaludin¹

Structural Durability & Health Monitoring, Vol.3, No.1, pp. 1-14, 2007, DOI:10.3970/sdhm.2007.003.001

Abstract A modern computational approach based on finite element analysis for durability assessment in a two-stroke free piston linear engine component using the variable amplitude loadings is presented. This paper describes the finite element analysis techniques to predict the fatigue life and identify the critical locations of the component. The effect of mean stress on the fatigue life is also investigated. The finite element modeling and analysis has been performed using a computer-aided design and a finite element analysis software package, and the fatigue life prediction was carried out using finite element based fatigue life prediction codes. The fatigue crack initiation… More >

C.P. Providakis¹

Structural Durability & Health Monitoring, Vol.2, No.4, pp. 249-254, 2006, DOI:10.3970/sdhm.2006.002.249

Abstract This paper explores the concept of strain energy density rate in relation to the crack initiation in fracture analysis problems arising in creeping cracked structural components. The analysis of the components is performed by using the boundary element methodology in association with the employment of singular boundary elements for the modeling of the crack tip region. The deformation of the material is assumed to be described by an elastic power law creep model. The strain energy density rate theory is applied to determine the direction of the crack initiation for a center cracked plate in tension which is subjected to… More >

J. Toribio ¹

Structural Durability & Health Monitoring, Vol.2, No.4, pp. 239-248, 2006, DOI:10.3970/sdhm.2006.002.239

Abstract This paper reviews the fracture performance in air and aggressive environment (stress corrosion cracking) of eutectoid prestressing steel wires with different levels of cold drawing. In air environment, a micromechanical model of fracture is proposed to rationalize the results on the basis of the microstructure of the steels after drawing and the model of Miller & Smith of fracture of pearlitic microstructure by shear cracking of the cementite lamellae. In hydrogen assisted cracking (HAC), a microstructure-based model is proposed on the basis of the Miller & Smith model and the mechanism of hydrogen enhanced decohesion or, more properly, hydrogen enhanced… More >