A Dual-Scale Numerical Model for the Diffusive Behaviour Prediction of Biocomposites Based on Randomly Oriented Fibres

This work aims to present a multi-scale numerical approach based on a 2D finite element model to simulate the diffusive behaviour of biocomposites based on randomly dispersed Diss fibres during ageing in water. So, first of all, the diffusive behaviour of each phase (fibres/matrix) as well as of the biocomposite was determined experimentally. Secondly, the microstructure of the biocomposite was observed by optical microscope and scanning electron microscope (SEM), and then regenerated in a Digimat finite element calculation software thanks to its own fibre generator: "Random fibre placement". Finally, the diffusion problem based on Fick's law was solved on the Abaqus finite element calculation software. The results showed an excellent agreement between the experiment and the numerical model. The numerical model has enabled a better understanding of the diffusive behaviour of water within the biocomposite, in particular the effect of the fibre/matrix interface. In terms of durability, the layered structure of this biocomposite has proven to be effective in protecting the plant fibres from hydrothermal transfer, which preserves the durability of the material.

Vibration Band Gap Characteristics of Two-Dimensional Periodic Double-Wall Grillages

In this article, the wave finite element method (WFEM) is used to calculate the band gap characteristics of two-dimensional (2D) periodic double-wall grillages (DwGs), which are verified by the grillage model vibration measurement experiment and finite element calculation. To obtain the band gap characteristics of periodic DwGs, the finite element calculation model is established according to the lattice and energy band theory and the characteristic equation of the periodic unit cell under the given wave vector condition is solved based on Bloch theorem. Then, the frequency transfer functions of finite-length manufactured and finite element models are obtained to verify the band gap characteristics of periodic DwGs. Finally, the effects of material parameters and structural forms on band gap characteristics and transfer functions are analyzed, which can provide a reference for engineering structure vibration and noise reduction design.

Analysis of eddy current loss in magnetic coupling based on three-dimensional finite element calculation

Considering the end effect, the three-dimensional finite element calculation model of the magnetic coupling is established. The three-dimensional distribution nephogram of the induced current and eddy current loss on the isolation cover is obtained, and the distribution trends of the two are consistent. The influence of size, material, and operating condition of magnetic coupling on eddy current loss is studied. The results show that the selection of isolation material with high resistivity and the reduction of isolation thickness are helpful to reduce the eddy current loss. The higher the rotating speed of the magnetic coupling, the greater the eddy current loss. At the same speed, the greater the load, the greater the magnetic declination, the smaller the eddy current loss. The research results can provide a reference for reducing energy loss and cooling structure design of magnetic coupling.

Research on Digital Twin Virtual Model of UHV Core Power Equipment

In this paper, voltage equalization, corona prevention and noise reduction are studied by using finite element calculation method and multi-objective optimization algorithm for UHV substation, series compensation circuit, transmission line, DC valve hall and outdoor field. The calculation model of multi parameter and multi-objective optimization design is established, the optimal configuration parameters of voltage equalizing structure are obtained, the electric field distribution uniformity and structure rationalization are realized, the corona discharge is effectively restrained, the key technology of voltage equalizing and anti corona is solved, the cost is reduced, the efficiency is improved, and a simulation calculation and optimization design platform with independent intellectual property rights is formed. The research results have been successfully applied to UHV projects in China.