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electromagnet pulling force, Duffing lock simulation, electromagnetic lock simulation

Duffing's electromagnetic lock is a kind of electromagnet used to permanent attraction of magnet keeper and it fast releasing when additional coil will be energized.

A holding coil is constantly supplied with properly chosen current that saturates relatively thin iron core in the surroundings of releasing coil. If additional current flows there, a magnetic field will be significantly reduced. If the force of keeper attraction is comparable with the force of the spring, even small demagnetizing current will release the magnet keeper.

**Problem type**:

Plane-parallel nonlinear magnetostatics.

**Geometry of the electromagnetic lock:**

Model depth 50 mm.

**Given:**

Holding coil total *(n*I)*_{h} = 100 kA-turns;

Releasing coil total current *(n*I) _{r}* = 50 kA-turns;

Force of stretching spring

Core and keeper iron magnetic permeability - nonlinear:

**Results:**

When releasing coil is not energized (*I*=0, edlock_1 case) then the force of keeper attraction is about 295 N/m. Otherwise (*I*>0, edloc_2 case) the attraction force decreases to 225 N and becomes less then stretching force of the spring, and magnet keeper will be unlocked. The force was calculated by means of "Integral calculator" tools.

I, A·turns_{h} |
I, A·turns_{r} |
F, N/m |

100000 | 0 | 295 |

100000 | 50000 | 225 |