Electrostatic speaker - QuickField simulation example
Electrostatic force on the diaphragm of a speaker and the resulting mechanical displacement for the applied bias and audio voltages on the stator plates.
How to calculate the electric force acting on the diaphragm and diaphragm mechanical displacement?
Answer Typical applications Geometry
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Task
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Reference: Wikipedia: Electrostatic loudspeaker
Engineering question
Calculate electrostatic force on the diaphragm at the peak amplifier voltage, transfer the force distribution to the coupled stress model, and solve for diaphragm displacement.
electrostatic loudspeakers, high-voltage audio transducers, diaphragm speaker actuators
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Simulation problem
Problem Type
Axisymmetric multiphysics problem of electrostatics coupled to Stress analysis.
Relative permittivity of diaphragm ε = 3;
Diaphragm thicnkess 40μm;
Power supply voltage V+ = 600 V
Amplifier output voltage V~ = 100 V, peak.
Calculate the electric force acting on the diaphragm and diaphragm mechanical displacement.
To calculate the maximal displacement we should apply the peak value of amplifier voltage. In the model left stator has the potential of -½*|V~| = -50 V, and right stator has the potential of ½*|V~| = 50 V.
The forces distribution is then passed to mechanical problem to calculate the displacement.
Electric force acting on the diaphragm is -0.014 N per 12.5 cm² of diaphragm area. Diaphragm central part displacement is 0.3 mm.
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