Serial mechanical sectioning and high resolution X-ray tomography have been used to study the three-dimensional morphology of small fatigue cracks growing in a 12 Cr tempered martensitic steam turbine blade material. A range of surface conditions has been studied, namely polished and shot peened (with varying levels of intensity). In the polished (unpeened) condition, inclusions (alumina and ma...

For many fracture problems of practical engineering importance, the three-dimensional effects are significant and a three-dimensional analysis for the problems is thus required. In this paper, an endochronic theory coupled with anisotropic damage is first established, which is actually an elasto-plastic damage theory coupled with isotropic-nonlinear kinematic hardening. The ductile damage evolu...

The welding heat input has a great influence on the weldments properties. This paper describes the influence of welding heat input on the weld metal toughness of high-carbon steel surface welded joint. The steel is surfaced with self-shielded wire, with three different heat inputs (6.5; 10.5 and 16 kJ/cm). Total impact energy, as well as crack initiation and crack propagation energies, are esti...

Service conditions of turbine blades involve fatigue, creep, and environmental corrosion. Themanner in which these mechanisms interact to initiate cracks is complex. These physicalmechanisms have been observed through observation and measurement of damage in adirectionally-solidified (DS) GTD-111 Ni-base superalloy. Experiments include high temperaturelow cycle fatigue with and ...

An understanding of the evolution of toughness is essential for the mechanistic interpretation of the fracture of cortical bone. In the present study, in vitro fracture experiments were conducted on human cortical bone in order to identify and quantitatively assess the salient toughening mechanisms. The fracture toughness was found to rise linearly with crack extension (i.e., rising resistance-...

Teeth are exposed to cyclic loads due to their physiological functions such as mastication. With age, such repetitive force causes generation of cracks and caries in dentin, and eventually degeneration due to crack initiation and propagation. The degenerative effects are caused by elevated stress levels in cracked zones and also reduction of structural toughness due to presence of microstructur...

The purpose of this research is to determine the resistance to the stress corrosion cracking (SCC) of three unidirectional (pultruded) E-glass/polymer composites based on modified polyester, epoxy and vinyl ester resins. The composites have been subjected to a nitric acid solution of pH 1.2 in a newly designed four-point bend fixture. The stress corrosion process was initiated on the as supplie...

PURPOSE The aim of the present study was to assess the influence of pre-treatments of zirconia by sandblasting and/or heat treatment on the flexural strength of zirconia and debonding/crack-initiation strength of porcelain-veneered zirconia ceramic. MATERIALS AND METHODS Zirconia ceramic specimens were divided into four groups according to treatment (grinding as controls, sandblasting, heat t...

In this work, the uniaxial and biaxial fatigue behaviour of maraging steel (18Ni300) obtained by additive manufacturing was studied. The material evaluated using several load paths different levels. predictive capacity life crack initiation angle critical plane methods Liu (I II), Chu, Conle, Bonnen (CCB) were evaluated. results showed that normal stresses had a strong effect on life. general, ...

The aim of the study was to find the optimum combination of materials and thicknesses to provide a tough, damage resistant multi-layer system with numerical methods to restore the damaged teeth. Extended Finite Element Method (XFEM) was used to assess the critical loads for the onset of damage modes such as radial cracks and plastic deformation in dental prostheses, which consist of a brittle o...