Magnetic Damping of Vibrating Conducting Solids
Description: Magnetic Damping of Vibrating Conducting Solids COMSOL Introduction When a conductive solid material moves through a static magnetic field, an eddy current density is induced That induced eddy current density interacts with the static
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slide1. Magnetic Damping of Vibrating Conducting Solids COMSOL<br>
slide2. Introduction When a conductive solid material moves through a static magnetic field, an eddy current density is induced
That induced eddy current density interacts with the static magnetic field and the result is a Lorentz force back on the solid that counteracts the motion
Therefore, a conducting solid that is vibrating in a static magnetic field experiences a structural damping<br>
slide3. Model Definition This example computes the damping effect when a cantilever beam is harmonically excited across a range of frequencies and placed in a strong magnetic field
Assumptions made:
the relative magnitude of the structural displacements are small
the material has isotropic and linear properties A vibrating beam next to a current carrying wire experiences magnetic damping<br>
slide4. Model Definition A vibrating beam next to a current carrying wire experiences magnetic damping the damping Lorentz force can be computed from the static magnetic field and the motion-induced AC eddy current density<br>
slide5. Model Definition Second-order effects arising from the AC magnetic field generated by the eddy currents are not included in the computation
The AC magnetic field is also computed and found to be 2-3Â orders of magnitude smaller than the DC magnetic field A vibrating beam next to a current carrying wire experiences magnetic damping<br>
slide6. Model Definition Solid Mechanics<br>
slide7. Results The figure shows the magnetic flux density computed for the structure The magnetic field around a current carrying wire<br>
slide8. Results The figure displays the magnitude of the displacement of the tip of the beam versus excitation frequency for two different magnetic field intensities for the frequency-domain structural dynamics problem Displacement of the tip of the beam versus excitation frequency for differing magnetic field strengths<br>
slide9. Results The figure shows a snapshot of the induced eddy current distribution in the beam The AC current distribution<br>
slide2. Introduction When a conductive solid material moves through a static magnetic field, an eddy current density is induced
That induced eddy current density interacts with the static magnetic field and the result is a Lorentz force back on the solid that counteracts the motion
Therefore, a conducting solid that is vibrating in a static magnetic field experiences a structural damping<br>
slide3. Model Definition This example computes the damping effect when a cantilever beam is harmonically excited across a range of frequencies and placed in a strong magnetic field
Assumptions made:
the relative magnitude of the structural displacements are small
the material has isotropic and linear properties A vibrating beam next to a current carrying wire experiences magnetic damping<br>
slide4. Model Definition A vibrating beam next to a current carrying wire experiences magnetic damping the damping Lorentz force can be computed from the static magnetic field and the motion-induced AC eddy current density<br>
slide5. Model Definition Second-order effects arising from the AC magnetic field generated by the eddy currents are not included in the computation
The AC magnetic field is also computed and found to be 2-3Â orders of magnitude smaller than the DC magnetic field A vibrating beam next to a current carrying wire experiences magnetic damping<br>
slide6. Model Definition Solid Mechanics<br>
slide7. Results The figure shows the magnetic flux density computed for the structure The magnetic field around a current carrying wire<br>
slide8. Results The figure displays the magnitude of the displacement of the tip of the beam versus excitation frequency for two different magnetic field intensities for the frequency-domain structural dynamics problem Displacement of the tip of the beam versus excitation frequency for differing magnetic field strengths<br>
slide9. Results The figure shows a snapshot of the induced eddy current distribution in the beam The AC current distribution<br>