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Power electronic equipment regulated by International Thermonuclear Experimental Reactor (ITER) must pass the relevant steady-state magnetic field immunity test. The main body of magnetic field immunity test is magnetic field generator coil. Through mathematical derivation in this article, the magnetic field calculation formulas of four-coil configuration under ideal and actual models are obtained. The traditional method of magnetic field performance calculation is compared with the general formula method under the ideal model. A global parameter optimization method based on Lagrange Multiplier by Karush–Kuhn–Tucker (KKT) conditions is proposed to obtain the coil parameters of high-uniformity magnetic field. The magnetic field distribution in the uniform zone is revealed by the finite-element method. The model analysis is proven to be correct and effective by experimental results. The research of this article provides a practical scheme for the coil design with high magnetic field and high-quality uniformity. [ABSTRACT FROM AUTHOR]

The dc reactor is an important part of the Comprehensive Research Facility for Fusion Technology (CRAFT), which can improve the current quality and reduce the probability of faults. In this article, several common inductance calculation methods are compared, and the more effective row mutual inductance method is selected as the final calculation method of the dc reactor. Using the existing conductor size, the electromagnetic design of the reactor is carried out, and the structural size is determined. The finite-element method (FEM) is used to verify the correctness of the calculation. On the premise of the completion of the electromagnetic structure, to ensure that the temperature rise during the operation of the equipment meets the requirements, a cooling system is needed. The structure and parameters of the waterway are determined by formula calculation, and FEM is used to verify the data. This article provides a preliminary scheme for the related reactor. [ABSTRACT FROM AUTHOR]

A direct Arbitrary Lagrangian Eulerian (ALE) formulation using multi-moment finite volume method for viscous compressible flows on unstructured moving grids has been developed and presented in this paper. High-order polynomials are reconstructed over a compact mesh stencil by making use of both volume integrated average value (VIA) and point values (PV) at the vertices of mesh cells which change in time. By formulating the governing equation in ALE integral form and differential form, the computational variables, VIA and PV, are updated, respectively, by a finite volume scheme and a point-wise discretization using multi-moments (VIA and PV). A simple and efficient formulation is derived for moving mesh which satisfies the geometrical conservation law. In the computations involving moving-body, the PVs of velocity at the vertices of cells adjacent to the body surface are coincided with the motion of the body, which eliminates the numerical approximation to find the cell boundary values on the body surface in conventional finite volume method. Numerical tests are presented to verify the present method as a high-order ALE formulation for compressible flows on both stationary and moving grids. [ABSTRACT FROM AUTHOR]

The effect of off-axis ply on the tensile properties of unbalanced symmetric [0/θ]ns laminates was explored through experimental and numerical analysis. Six CFRP [0/θ]2s plies with different off-axis angles θ were fabricated for tensile tests. In situ observations of the damage to the laminates were conducted to investigate the initiation and progressive growth of the laminates during the tension tests. The fiber fractures, crack initiation, and progressive propagation were analyzed by observing the free edge of the laminates, and the difference in damage behavior caused by different off-axis angles was investigated. All the six [0/θ]2s plies with off-axis angles θ ranging from 15° to 90° showed approximate linear stress–strain responses in the tensile tests. Matrix cracks were not observed prior to the final catastrophic failure in the off-axis layers of the [0/θ]2s laminates with a θ in the range of 15–60°. Finite element analysis (FEA) of the [0/θ]s plies was conducted using a 3D micromechanical model, in which matrix cracking and fiber-matrix debonding in the off-axis layer were simulated using a cohesive interface element. Three micromechanical crack-free, cohesive interface, and initial crack models were analyzed to predict the influence of the matrix cracks inside the off-axis layer on the damage behavior of the [0/θ]s laminates. The numerical results from the initial crack micromechanical model show a lower bound of the tensile strength of the [0/θ]s plies. A high stress concentration is observed adjacent to the cracked off-axis layer, inducing a tensile strength loss of about 20%. [ABSTRACT FROM AUTHOR]

Laminates with unidirectionally arrayed chopped strands (UACS) are one of the advanced short fiber reinforced polymer composites (SFRP) with significant application prospect, which greatly improves mechanical properties compared to the traditional SFRP, meanwhile ensuring excellent flowability. In practice, composite laminate with an open hole is one of the typical connective components, and it is necessary to clarify the allowable load and damage tolerance performance of notched structures. In the present study, UACS laminates were fabricated using the continuous carbon fiber reinforced polymer (CFRP) prepreg, on which regularly arrayed bi-angled slits were introduced by a commercial numerical control cutter. The tensile strength and strain distribution around the open hole of the notched UACS laminate were experimentally investigated, while the damage progression near the open hole of the notched UACS laminate was analyzed by the finite element method (FEM). The tensile strength of the notched UACS laminate was measured at 298 MPa, which is about 60% of the strength of the unnotched UACS laminate. The simulation results match well with the experimental results, although there is a little overestimate on strength, by about 5% and 7%, for unnotched and notched UACS laminates, respectively. The final critical failure mode for the notched UACS laminate is mainly dominated by the delamination instead of the fiber breakage in the unnotched UACS laminate. [ABSTRACT FROM AUTHOR]

• Dynamic model of a rotor-bearing system containing the piezoelectric shunt circuits is established. • The Green's function of an unbalanced rotor-bearing system is derived. • The closed-form solutions with electromechanically coupled boundary conditions are obtained. • Influence of shunt circuits on whirling frequencies and steady-state whirl responses is studied. In this paper, a method based on Green's function is proposed for the dynamic analysis of a rotor-bearing system with electromechanically coupled boundary conditions. The rotor system is supported by two ring-shaped piezoelectric dampers, which has been manufactured in our previous research. Based on the piezoelectric shunt resonant circuits, e.g., current flowing shunt circuit, the rotor system's boundary condition will become complicated and electromechanically coupled. The Laplace transform method is applied to solve the partial governing equations with such boundary conditions and the steady-state whirl Green's function is derived subsequently. Since the Green's functions are fundamental solutions of the system, the steady-state whirl solutions can be obtained by applying the superposition principle. Owing to the solutions' concise form, it is convenient and suitable for analysis and computation. Validation of the proposed method is demonstrated by comparison with the finite element method (FEM). The simulated results show that the analytical solutions possess high accuracy and the piezoelectric damper has significant damping performance. [ABSTRACT FROM AUTHOR]