Specific features of the formation of optical waveguides, contact pads and electrical interconnections on lithium tantalate substrates

The article considers the formation of titanium channel optical waveguides in LiTaO3 substrates. These structures were obtained by dry etching of grooves in SF6 plasma and magnetron sputtering of titanium film. After that, waveguides were formed by plasma etching using photoresist as mask. Technological features and modes of microstructure production are described. Al contact pads were produced by magnetron sputtering thin metal films on LiTaO3. Aluminum wires were ultrasonically bonded to Al contact pads using Delvotec 5630. The developed technology of formation of contact pads and bonding modes made it possible to obtain a bonded joint with a bond strength of 23-25 Gs.

Comparative study of adhesive fatigue in aeronautical bonded joints: A numerical approach in the frequency domain

The use of adhesively bonded structures has increased over the years, together with the development of composite materials. This work investigates a procedure for fatigue life prediction of an aeronautical bonded joint under random loads, in particular, the cohesive failure of the adhesive layer in a skin-to-stiffener bonded joint. The use of two different adhesives is investigated, and Dirlik’s method is employed to predict the stress response in the adhesive layer, from which the fatigue life is obtained. The effect of damping is also investigated, and it is shown that increases in damping result in higher fatigue life estimations.

Nonlinear 3D Model of Double Shear Lap Tests for the Bond of Near-surface Mounted FRP Rods in Concrete Considering Different Embedment Depth

The utilization of near-surface mounted Fiber Reinforced Polymer (FRP) reinforcement as a method of strengthening in reinforced concrete structures has increased considerably in recent years. Moreover, the application of double-shear lap tests for this rein-forcement method leads to the achievement of a local bond-slip behavior in a bonded joint. This research, therefore, focused on 3-D modeling of this type of test to suitably characterize the bond mechanics between FRP rods and concrete at various embedment depth. The use of different alternatives to represent the interface between the FRP rod and concrete were analyzed after which a comparison was drawn between the numerical finite element (FE) simulations and experimental measurements. The results showed the prediction of the load–slip corresponded with the data obtained from the experiment. Finally, the proposed model has the ability to express the relationship between the penalty stiffness parameters in shear direction Kss = (Ktt) and the embedment depth of FRP rods.