Laminated motor core - material property measurement

[thirumuruga]

Hi,

I am working electric motor stators.Now, the stator core is not a solid metal piece but is a laminated one. How do I proceed with assigning the material data? I feel that the strength would be lesser along the direction in which the lamination has been done.

So how is the material properties along the lamination direction obtained?
Do they do a direct measurement like taking a piece of the core and testing it on a UTM?
Do they do any indirect method to estimate the material properties in that direction?

 

[Tmoose]

I think the laminations are made of steel with particular magnetic properties.

http://www.magneticmetals.com/products/motor-laminations

 

[MikeHalloran]

Because the laminations originate in sheet form, you are asking about measuring mechanical properties of a thin sheet in the through-thickness direction, which is exceedingly difficult. Mechanical properties in the other two directions can be meaasured in a straightforward way, by cutting coupons and gripping them in a testing machine.

There are basically no tensile properties for the assembly in the direction perpendicular to the laminae; they are not intentionally bonded to each other. They are made of a high silicon steel, optimized just for its magnetic properties.

Said properties may be evaluated by setting up an open/air core induction coil in a resonant circuit, then assembling the laminations within the coil and measuring the change in resonant frequency.

That's sort of how many lamination assemblies are made. In transformers and chokes, the coil is wound on a (usually plastic) coil form, then the laminations are slipped into holes in the form, interleaved like a deck of cards, and electrically isolated from each other, for which purposes the individual laminae are coated with a waxlike dielectric.

I think most motors are assembled in a more laborious way, wrapping coil wire around a stack of laminae.

Mike Halloran
Pembroke Pines, FL, USA