Volume 10 (2010): Issue 3 (September 2010)

When bonded joint is subjected to mode I fracture loading, the adhesive joints analytical solutions treats the adhesive layer, usually, as not existing or 1D Hook elastic layer. In the case of 1D elastic layer, represented as Hooks spring element, is acting, only, in direction contrary to the applied load. Basing on the information yielded from sensitive laser profilometry technique, where deflections of bonded part of the joint were measured, within this contribution, 2D Finite Element Method model is introduced. The FEM allows adhesive layer to be simulated as two perpendicular-acting Hook's springs, thus in-plane shear compliance is enabled. Subsequently, appropriate analysis were carried out. Results, in terms of plate deflection, were compared with laser profilometry technique and common analytical solutions. It is concluded that linear 1D model is not sufficient for the asymmetric bonded joint configuration since the adhesive resists actively also in the in-plane shearing direction. Omitting shearing compliance effect can lead to valuable misinterpretation of the fracture energy, up to 20% in cases studied, and thus, cannot be ignored. Finally, power law based, correction factors are given promising fast and reliable data correction.

In this paper characteristic features of metal dusting corrosion in high temperature gas mixtures of high carbon activity in catalytic reforming units, including Continuous Catalyst Regeneration (CCR) platformer are presented. Examples of 2.25Cr-1Mo and 9Cr-1Mo steel tubes at advanced stages of metal dusting process after long-term service in charge heaters are used to prove that destructive examinations are necessary to provide certain information about possible mechanisms of damage, and are helpful in assessment of immediate fitness for purpose and long-term service capability of the components during and following shut-downs.

A cavitation degradation process and fatigue phenomenon were described. Similarly to fatigue phenomenon, cavitation pulses division into three fractions was suggested. The action of each fraction was respectively compared to low-cycle fatigue, high-cycle fatigue and low-amplitude fatigue. The action of each fraction was described separately. Detailed analysis of the influence of each fraction on the degradation process shows that besides mechanical loading also thermal loading occurs. The cavitation erosion is assumed to be the sum of degradation of each fraction. Thus, the model of PVD coatings degradation under action of cavitation pulses include variable-amplitude and variable-temperature fatigue.