Additive Manufactured and Topology Optimized Passive Shimming Elements for Permanent Magnetic Systems

Abstract

A method to create a highly homogeneous magnetic field by applying topology optimized, additively manufactured passive shimming elements is investigated. The topology optimization algorithm can calculate a suitable permanent and nonlinear soft magnetic design that fulfills the desired field properties. The permanent magnetic particles are bonded in a polyamide matrix and they are manufactured with a low-cost, end-user 3D printer. Stray field measurements and an inverse stray field simulation framework can determine printing and magnetization errors. The customized shimming elements are manufactured by a selective melting process which produces completely dense soft magnetic metal parts. The methodology is demonstrated on a simple example of two axial symmetric cylindrical magnets, which generates a high inhomogeneous magnetic field. In this case, the maximum magnetic field density is 25 mT and the the homogeneity can be increased by a factor of 35 or down to 6‰. Simulation and measurement results point out a good conformity. Additional topology optimizations of more than one shimming element layer show the opportunity to make the manufactured magnetic system even more homogeneous.

Additive Manufactured Polymer-Bonded Isotropic NdFeB Magnets by Stereolithography and Their Comparison to Fused Filament Fabricated and Selective Laser Sintered Magnets

“…The PBF process can be divided into the heating source. Following commonly used PBF printing techniques are used to investigate the capability to print hard or soft magnets: electron beam melting (EBM) [15], selective laser melting (SLM) [16,17,18,19,20,21], and selective laser sintering (SLS). SLS does not completely melt each powder layer but sinter the particles to retain their original microstructure.…”

Challenges and advances in measuring sap flow in agriculture and agroforestry: A review with focus on nuclear magnetic resonance

“…To overcome this challenge, magnetic arrangement for novel discrete Halbach layout approach is used in numerous designs processes ( Soltner and Blümler, 2010 ). Thus, the final magnetic structure with limited length can have a homogenous field by placing small permanent magnets in an optimal location, which are found by running an optimization algorithm that mostly relies on analytical equations ( Huber et al., 2018 ). Moreover, the mechanical strength of these structures should be considered in the fabricating process.…”

Design and Fabrication of Magnetic System Using Multi-Material Topology Optimization

“…where V f is the volume of the high field area. The target volumes V * P M (18) and V * iron in (19) are set to 0.25 and 0.1, respectively. The total number of discrete target magnetization directions, n, is set as four in this example, and the initial directions of τ i in (15) is set as evenly distributed vectors.…”

“…Despite numerous studies on topology optimization for VOLUME 4, 2016 magnetic system design, few studies have demonstrated the fabrication of a magnetic system that are designed using topology optimization. In [17], [18], single PM block with fixed magnetization direction are fabricated using additive manufacturing of polymer-bonded magnets. A review paper [19] summarizes studies on additive manufacturing of PMs, back-irons, coils (i.e.…”