Modelling and simulation of the hardness profile and its effect on the stress‐strain behaviour of punched electrical steel sheets

We are entering an era of re-electrification, seeking high-power density electrical machines with minimal resource use. Significant performance gains in electrical machines have been achieved through precise manufacturing processes, including the shaping/cutting of soft magnetic materials. However, most studies have evaluated magnetic performance at a macro level, focusing on components, while the fundamental mechanisms, e.g., how the micromagnetic behaviour is affected by mechanical interference, remain unclear. In this study, we examine the impact of sub-micron deformations at opposing strain rates (10−2 to 101 s−1) on the micromagnetic behaviour of soft magnetic non-oriented electrical steel. Using a diamond probe to indent within a single grain of polycrystalline material at different velocities, we induce quasi-static and dynamic mechanical loading. Our analysis, employing magnetic force microscopy, transmission Kikuchi diffraction, and scanning transmission electron microscopy with a pixelated detector, reveals that magnetic texture disturbances rely on the time-dependent dislocation dynamics of the Fe-BCC material. Additionally, we compress micro-pillars to further investigate these effects under bulk-isolated deformation. These findings highlight the importance of considering even ultra-small loads, such as nano-indentations and micro-pillar compressions, in the manufacturing of next-generation electric machines, as they can affect magnetic texture and performance.

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Study of Effect on Structural Strength of Locally Strengthened Rotor Lamination Stack through Virtual Validation

Pawde,

Srimathkandala,

Galande

2024

SAE Technical Paper Series

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<div class="section abstract"><div class="htmlview paragraph">Rotor and Stator are the key constituents of an electric motor that are made of several laminates punched from a sheet metal and stacked together. The rotor stack is inserted with magnets at the punched-out pockets and is assembled with a shaft via press fitting. Rotor assembly being the rotating part of an E-Motor is subjected to centrifugal loads due to masses of magnets, lamination stack and shaft rotating at high speeds, temperatures and assembling loads because of which rotor laminates experience failures as the high strains develop in the regions on the laminate that support magnets. Typically, these high strain locations are the sections of the magnet pockets one on the outer diameter of the laminate and the other at the sections between the magnet pockets. Traditionally, these high strains are addressed by increasing the area of these sections, but this has a detrimental effect on the electromagnetic performance.</div><div class="htmlview paragraph">Instead of increasing the area of these sections, the proposed solution of local strengthening of the magnet pockets influences strength of these sections of the lamination stack. Such localized strengthening can be achieved through surface hardening, grain boundary refinement or using high strength magnet inserts. In this paper, an approach for investigating the effect of localized hardening on improvement in strength of rotor laminate is studied using Finite Element Analysis. A comparison is made between the locally strengthened and non-strengthened rotor laminate in terms of deformations and strains.</div></div>

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Modelling and simulation of the hardness profile and its effect on the stress‐strain behaviour of punched electrical steel sheets

Cited by 3 publications

References 43 publications

Influence of the cutting method on the fatigue life and crack initiation of non-oriented electrical steel sheets

Influence of the cutting method on the fatigue life and crack initiation of non-oriented electrical steel sheets

Effect of sub-micron deformations at opposing strain rates on the micromagnetic behaviour of non-oriented electrical steel

Study of Effect on Structural Strength of Locally Strengthened Rotor Lamination Stack through Virtual Validation

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