1 Introduction - Finite Element Method Magnetics

Figure 13: Different lamination orientation options.
orientation parameters are used to implement a bulk model of laminated material. The result of
this model is that one can account for laminations with hysteresis and eddy currents in harmonic
problems. For magnetostatic problems, one can approximate the effects of nonlinear laminations
without the necessity of modeling the individual laminations separately. This bulk lamination
model is discussed in more detail in the Appendix (Section A.2).
The dlam edit box represents the thickness of the laminations used for this type of material. If
the material is not laminated, enter 0 in this edit box. Otherwise, enter the thickness of just the iron
part (not the iron plus the insulation) in this edit box in units of millimeters.
Associated with the lamination thickness edit box is the Lam fill factor edit box. This is
the fraction of the core that is filled with iron. For example, if you had a lamination in which the
iron was 12.8 mils thick, and the insulation bewteen laminations was 1.2 mils thick, the fill factor
would be:
Fill Factor = 12.8
= 0.914
1.2+12.8
If a wire type is selected, the Strand dia. and/or Number of strands edit boxes become
enabled. If the Magnet wire or Square wire types are selected, it is understood that there is can
only be one strand, and the Number of strands edit box is disabled. The wire’s diameter (or
width) is then entered in the Strand dia. edit box. For stranded and Litz wire, one enters the
number of strands and the strand diameter. Currently, only builds with a single strand gauge are
supported.
If a wire type is specified, the material property can be applied to a “bulk” coil region each
individual turn need not be modeled. In DC problems, the results will automatically be adjusted
for the implied fill factor. For AC problems, the the fill factor is taken into account, and AC
proximity and skin effect losses are taken into account via effective complex permeability and
conductivity that are automatically computed for the wound region.
3.7.4 Materials Library
Since one kind of material might be needed in several different models, FEMM has a built-in library
of Block Property definitions. The user can access and maintain this library through the
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