Twist extrusion is a processing method involving the extrusion of a sample with a prismatic cross-section using a tool composed of four prismatic parts bisected by a screw component. A beneficial change in mechanical durability is one of the main factors enabling the use of highly durable Al-Mg-Mn-Sc-Zr alloys to construct functional components of non-stationary robots. As part of the present research, ANSYS® software was used to simulate a twist extrusion process. An analysis of a sample entering and passing through the entire twisting area was performed, up to the point of full twisting of the base of the sample. The stress conditions in the sample were analysed as it passed through the twisting area. The highest stress values (reaching up to 600 MPa) were detected at the tips of the sample face as the sample exited the twisting area. The lowest stress values, at around 170 MPa, were detected at the side edges of the sample.

This paper reviews latest developments of substructures for offshore wind turbines focusing on investigations and applications of hybrid foundations. Model tests and numerical analyses were used to simulate the loading of hybrid piles in sand. The results of pile-soil interaction were investigated to confirm the changes in soil stiffness around the hybrid monopile head. The mechanism and factors affecting the change in lateral stiffness of the hybrid foundation were explained by analysing p–y curves for M+H loading conditions in sand. Based on this research, a new shape of p–y curves for hybrid monopiles was established and a method for determining key parameters was proposed. The effectiveness of new p–y curves was verified by comparing back-calculated results with those from numerical simulations. The conducted tests confirmed that the hybrid monopile displacement is 30–50% smaller when compared to a standard monopile with similar dimensions. The gained experiences can be useful for designers and researchers to enhance the design of foundations for offshore wind turbines.

The paper presents the results of numerical analysis of the SAW gas sensor in the steady and non-steady states. The effect of SAW velocity changes vs surface electrical conductivity of the sensing layer is predicted. The conductivity of the porous sensing layer above the piezoelectric waveguide depends on the profile of the diffused gas molecule concentration inside the layer. The Knudsen’s model of gas diffusion was used.

Numerical results for the effect of gas CH4 on layers: WO3, TiO2, NiO, SnO2 in the steady state and CH4 in the non-steady state in recovery step in the WO3 sensing layer have been shown. The main aim of the investigation was to study thin film interaction with target gases in the SAW sensor configuration based on simple reaction-diffusion equation.

The results of the numerical analysis allow to select the sensor design conditions, including the morphology of the sensor layer, its thickness, operating temperature, and layer type. The numerical results basing on the code elaborated numerical system (written in Python language), were analysed. The theoretical results were verified and confirmed experimentally.