I need to calculate the dimensions of a coil and a permanent magnet which will be used to apply a precise value of force on a test specimen.
i found an expression that defines the force as follows:
F=B*I*L
whereas B is the coil inductance
I: is the current intensity
and L is the length of the cable that constitute the coil
the problem is that the dimensions of the permanent magnet are not taken into consideration in this expression.
is there any other considerations to take in order to use this expression ? or maybe i need to use another that takes in consideration the magnet dimensions ?
the link to the expression: http://www.adetests.com/fr/Portfolio/pot-vibrant-generateur-electrodynamique-shaker
Thanks in advance.
The expression you quote is the force applied on the current carrying coil by
the magneic field. It has nothing to do with the force the mlagnetic field will
induce on a test sample. You must give more details on the samples to evaluate a force. In particular, it must be magnetoic.
Thank you for your answer,
The samples will be undergoing bending efforts on one of its ends, its shape is illustrated in the attached file.
If you need the dimensions of the test sample, i will provide them, provided that there is an expression that determines the force that will be applied on the samples and that will depend on magnet and coil properties.
The problem you have formulated - in mathematics is called the inverse problem. It is very difficult! Especially studied in detail in geophysics.
"B" in your formula for force is the induction of magnetic field, not a coil inductance. Moreover, this formula is correct when all coil windings "feel" the same magnetic field |B| and the current flows in direction perpendicular to B vector. Still more: this formula describes the force acting on a small piece of the winding, being nearly straight line. In addition, the force is perpendicular both to the current and B-vector, so inserting a coil in uniform field, parallel to its axis, will produce only radial forces with net result equal to zero. Thus you coil should feel the radial magnetic field in order to be moved. This means that for best results your coil should be flat and its diameter should be roughly twice as big as the magnet's diameter.
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