Use of Non Destructive Testing (NDT) technique during aircraft maintenance operations is increasing in the last years as well as the tools to perform these inspections are widening their field of application. Damage tolerance design approach has been selected by aeronautic industry for the last years also thanking to the most modern NDT capabilities, like ultrasound and thermography, which have...

Our mechanistic understanding of damage formation in DNA by the direct effect relies heavily on what is known of free radical intermediates studied by EPR spectroscopy. Bridging this information to stable product formation requires methods with comparable sensitivities, a criterion met by the (32)P-post-labeling assay developed by Weinfeld and Soderlind, [Weinfeld,M. and Soderlind,K.-J.M. (1991...

The creep-fatigue interaction has been recognized as the main failure mode of most structural components operating in high-temperature regime. cyclic life (Nf) usually decreases continuously with dwell time their interactions. However, Nf shows an abnormal change, i.e. keeps constant or slightly increases/decreases, present studied Nickel-based superalloy, DZ445. This means that generalized “Nf...

Sometimes it is difficult to choose the most appropriate failure criterion for problem analyzed. For brittle materials, attention must be paid availability of experimental data and calibration representative parameters, within chosen criterion. The work herein presented, starting with an overview on machromechanical criteria, analysed in Haigh-Westergaard Stress Space, investigates suitability ...

Abstract The problem of cyclic loading under pure torsion is an important for numerous different industrial applications, such as shafts, springs, blades, and others. conditions aircraft, railway, automobile industries are often corresponding to long fatigue life. rough estimation shows that the number cycles springs in car engine exceeds 10 8 cycle while blades aircraft turbine may undergo mor...

• A constitutive material model is developed to nonlinear behaviour of timber. Orthotropic stress–strain relationship used in the linear elastic phase. Under compression a based on Hoffman yield criterion and plastic potential used. Isotropic strain hardening during deformation incorporated into criterion. Tensile damages all three grain directions are established using damage factors fracture ...

There have been several reports to suggest that the type of visual field damage in open-angle glaucoma is influenced by intraocular pressure (IOP). This study was undertaken to determine the extent to which patients with normal-tension (NTG) and high-tension glaucoma (HTG) could be differentiated on the basis of some features of their visual fields. The results from 40 pairs of NTG and HTG pati...

Repairing initial slight damage site into stable structures by engineering techniques is the leading strategy to mitigate the damage growth on large-size components used in laser-driven fusion facilities. For KH2PO4 crystals, serving as frequency converter and optoelectronic switch-Pockels cell, micro-milling has been proven the most promising method to fabricate these stable structures. Howeve...

This numerical investigation of an advanced Gurson–Tvergaard–Needleman(GTN) model is an extension of the original work of Ben Bettaieb et al. (2011). The model hasbeen implemented as a user-defined material model subroutine (VUMAT) in the Abaqus/explicitFE code. The current damage model extends the previous version by integrating the threedamage mechanisms: nucleation, growth an...

The effect of tension-tension fatigue (T-T) on carbon/epoxy composites (CFC) has been investigated in this paper. Load controlled fatigue tests were conducted in the tension-tension (T-T) cyclic mode with the R-ratio values of 0.1 and 0.3 and subsequently the specimens with the fatigue life over 10 cycles have been studied by means of tensile testing, ultrasonic inspection and quantitative data...