Issue 32

N. Golinelli et alii, Frattura ed Integrità Strutturale, 32 (2015) 13-23; DOI: 10.3221/IGF-ESIS.32.02

   mrf mrf B A A A

B

(12)

steel

steel

steel

 Determine the magnetic field induction B steel using its B-H relationship.  Find the required number of amp-turns (NI) by using Kirchhoff’s Law of magnetic circuits:     i i mrf steel NI H L H h H L (13) where h is the fluid gap and L is the single length of each links which compose the circuit. The required number of coil wire resulted N = 160, considering a working current of 1 A.

304 Stainless Steel

Air Rubber

430 Stainless Steel

Air

1.276e+000 : >1.343e+000 1.142e+000 : 1.209e+000 1.074e+000 : 1.142e+000 9.401e-001 : 1.007e+000 8.730e-001 : 9.401e-001 8.058e-001 : 8.730e-001 7.387e-001 : 8.058e-001 6.715e-001 : 7.387e-001 6.044e-001 : 6.715e-001 5.372e-001 : 6.044e-001 4.701e-001 : 5.372e-001 4.029e-001 : 4.701e-001 3.358e-001 : 4.029e-001 2.686e-001 : 3.358e-001 2.015e-001 : 2.686e-001 1.343e-001 : 2.015e-001 6.715e-002 : 1.343e-001 <0.000e+000 : 6.715e-002 1.209e+000 : >1.276e+000 1.007e+000 : 1.074e+000

Air

20 AWG [I:153]

1020 Steel

430 Stainless Steel

20 AWG [-I:152]

Rubber

Density Plot: |B|, Tesla

304 Stainless Steel

(a)

(b)

(c) (d) Figure 8 : 2D FEMM Model of the piston head (a) , magnetic field values through the magnetic circuit (b) . Magnification of the central activation area (c) and graph of the magnetic field values B across the activation’s gap along the red line (d) .

M AGNETIC FINITE ELEMENT ANALYSIS

magnetic finite element analysis was performed after the analytical design of the circuit. This operation is a useful method to compare the calculated values with the simulated ones. Furthermore, these simulations allow one to verify that the magnetic saturation will occur in no section of the magnetic circuit. The software FEMM v4.2 [22] A

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