Magnet study of a sketch

Use More in the Features toolbar › Magnet study of sketches… on a part that has sketches. Each closed shape in the sketches you tick is one region of a flat model; the study works out the magnetic field B, the force and the torque on a body you choose.

Steps

1. Draw the bodies as closed shapes in sketches: an iron yoke, a magnet, a coil. Bodies that touch share an edge, so put them in different sketches; bodies that stand apart, or sit inside one another (a window in a yoke), can share one. Keep the sketches on the same plane.
2. Open the study and tick the sketches to use. Every closed profile gets a row, numbered. Say what it is: Air, Iron (a permeability, or a B–H curve typed as pairs of B in tesla and H in A/m), a Permanent magnet (Br in tesla, its direction as an angle from the sketch's x axis, and its recoil permeability) or a Coil (the total current through its profile, turns times amperes; the sign says which way it runs).
3. Tick Force and torque on this body for the bodies you want them on. Give the depth of the part out of the sketch.
4. Choose the mesh and the air around the model, then Run.

What you should see

• The flux density |B| over the model, dark blue low to red high, with the profiles numbered.
• The strongest field and where it is, the number of triangles, and for each body you ticked the force along x and y and the torque about its middle, for the depth you gave.
• Save results (CSV) writes the numbers.

Good to know

• It is a flat, steady model: everything is per metre of depth, with no eddy currents and no hysteresis, and a magnet is a straight recoil line (it cannot be demagnetised).
• The model sits in a box of air whose edge is a wall. Compare two sizes of the air box, and the Normal and Fine meshes: a force taken from the field round a body is only as good as the mesh there.
• Iron with only a permeability never saturates. When the field passes 2 T the study raises a ⚠ in the Problems list: give the iron a B–H curve. The numbers in a new row are examples (iron μr 2000, a magnet of 1.2 T), not a material's data sheet.
• A body needs room round it to take the force: if another body is too close, the study says so.
• A drafting aid, not an engineering approval.

Next

• Magnetic fields in 2-D (tutorial)