With the aim of increasing the efficiency of maintenance and fuel usage in airplanes, structural health monitoring (SHM) of critical composite structures is increasingly expected and required. The optimized usage of this concept is subject of intensive work in the framework of the EU COST Action CA18203 “Optimising Design for Inspection” (ODIN). In this context, a thorough review of a broad range of energy harvesting (EH) technologies to be potentially used as power sources for the acoustic emission and guided wave propagation sensors of the considered SHM systems, as well as for the respective data elaboration and wireless communication modules, is provided in this work. EH devices based on the usage of kinetic energy, thermal gradients, solar radiation, airflow, and other viable energy sources, proposed so far in the literature, are thus described with a critical review of the respective specific power levels, of their potential placement on airplanes, as well as the consequently necessary power management architectures. The guidelines provided for the selection of the most appropriate EH and power management technologies create the preconditions to develop a new class of autonomous sensor nodes for the in-process, non-destructive SHM of airplane components.

This paper presents a numerical method for calculating the resistance, inductance, and capacitance matrices of transformer windings. Importance of their precise calculation is shown in the simulation of voltage distribution over the windings for a lightning-impulse test. The results obtained in frequency domain analysis are in good agreement with the measurement data. All the parameters are calculated using the self-developed solvers, the theory and the novelty of which are described in this paper. The presented approach allows fast and accurate high-frequency modeling of transformer windings.

A new and extremely fast and precise method for calculating mutual inductance between coaxial circular coils in air with rectangular cross section and uniform current densities is presented. It is thoroughly compared with all recently published methods in the same computing environment, and the results confirm the aforementioned. Along with the high accuracy and low computational time, the emphasis is put on the easiness of implementing the method, using only the elementary functions. The method can be used in all combinations of the coils' radii and heights, from narrow coils to coils with extremely large radii, such as the coils used in superconducting magnets. Excellent numerical stability and agreement with professional software was found in all testing cases.

Calculation of electric field based on integral equations approach and suited to solving large-scale problems is presented. Integral equations are solved by appliance of BEM and Galerkin method. Unknown distribution of the surface charge density is approximated by bicubic splines, which ensure smooth approximation of sources. Accurate calculation of electric fields requires detailed modeling of power system equipment inside substations. This results in large models, which are solved by parallel computing. Numerical results are compared to measured fields inside a 400 kV substation. Comparison shows good agreement, thus approving applicability of the proposed approach in analysis of exposure to electromagnetic fields and electromagnetic compatibility.

In order to minimize eddy current losses in an open-core type of transformer, a lower width-to-thickness ratio of lamination sheets and even varying lamination stacking direction than in the case of standard transformers are used. Consequently, narrow eddy current loops must be considered as a 2D phenomenon, i.e. edge effects and irregular current density distributions cannot be neglected. A two-step method for calculation of eddy currents and eddy current losses in an open-core transformer is presented. In the first step, using the anisotropic surrogate material, the magnetic flux density distribution within the bulk core model is calculated. In the second step, the magnetic flux density obtained in the first step is used as input to calculate eddy currents in a sufficient number of densely meshed 2D slices of the laminated core. Numerical simulation of the method is carried out, and the results are compared with those obtained using a homogenization method and the brute force approach. The results show good agreement and indicate the importance of taking edge effects into account.