nmac
Electrical
- Apr 26, 2018
- 1
Hello!
I'm a new Abaqus user and mostly self-taught as I'm the first from my organization to use Abaqus. I've been banging my head against the wall for a few months before finding this forum, hoping to get some help.
I'm trying to model a piezoelectric acoustic transducer. It consists of a square piezo film (10cm x 10cm x 110um thick) suspended over a cavity (~10cm deep) and held down by a thin frame (half view):
Everything is tied together with judicious ties. Not shown in above is a sphere of air of 1.5m radius surrounding the system. The air is modeled with acoustic elements, with a skin on the outside which has acoustic infinite elements applied.
The holder is constrained with encastre to prevent rigid body motion, and one side of the piezo film has an electrical boundary condition grounding it. The other side of the piezo film has a constraint so that it's maintained at a constant voltage, because the film I'm modeling is metallized on both sides in real life.
Anyways, onto the question. I have two experiments, both in dynamic steady state. In the first I drive the film with a voltage and measure film velocity. This experiment works great, everything looks exactly as I expect.
The issue comes with the second experiment, where the film is driven by an incident wave, and voltage on the film is measured. The results look as below:
The general shape is what I expect, including resonances at ~480 and ~720Hz, but the "noise" is definitely not expected and clearly indicates an issue with the model. Any ideas as to what could cause this? I feel like I've tried everything!
A few more details: this data comes from a python script which at wach time frequency calculates voltage magnitude from sqrt(data^2 + conjugateData^2). Is this correct?
Also, I believe the issue to be either with the incident wave formulation or the acoustic infinite elements. Do I need to specify some extra impedance condition on the surface of the sphere of air, or are the acoustic infinite elements enough? Regarding the incident wave, I have a source point on-axis to the film, 1m away (inside the sphere of air). The standoff point is on the surface of the box of air which is enclosed by the frame (see above picture). The surface being driven is the top surface of this same box of air (but not the frame surrounding it).
Anything I'm missing here? Could it be a meshing thing? Or maybe the size of the sphere of air? Master/slave selection in ties? I feel like I've tried everything, please help
Thanks!
I'm a new Abaqus user and mostly self-taught as I'm the first from my organization to use Abaqus. I've been banging my head against the wall for a few months before finding this forum, hoping to get some help.
I'm trying to model a piezoelectric acoustic transducer. It consists of a square piezo film (10cm x 10cm x 110um thick) suspended over a cavity (~10cm deep) and held down by a thin frame (half view):
Everything is tied together with judicious ties. Not shown in above is a sphere of air of 1.5m radius surrounding the system. The air is modeled with acoustic elements, with a skin on the outside which has acoustic infinite elements applied.
The holder is constrained with encastre to prevent rigid body motion, and one side of the piezo film has an electrical boundary condition grounding it. The other side of the piezo film has a constraint so that it's maintained at a constant voltage, because the film I'm modeling is metallized on both sides in real life.
Anyways, onto the question. I have two experiments, both in dynamic steady state. In the first I drive the film with a voltage and measure film velocity. This experiment works great, everything looks exactly as I expect.
The issue comes with the second experiment, where the film is driven by an incident wave, and voltage on the film is measured. The results look as below:
The general shape is what I expect, including resonances at ~480 and ~720Hz, but the "noise" is definitely not expected and clearly indicates an issue with the model. Any ideas as to what could cause this? I feel like I've tried everything!
A few more details: this data comes from a python script which at wach time frequency calculates voltage magnitude from sqrt(data^2 + conjugateData^2). Is this correct?
Also, I believe the issue to be either with the incident wave formulation or the acoustic infinite elements. Do I need to specify some extra impedance condition on the surface of the sphere of air, or are the acoustic infinite elements enough? Regarding the incident wave, I have a source point on-axis to the film, 1m away (inside the sphere of air). The standoff point is on the surface of the box of air which is enclosed by the frame (see above picture). The surface being driven is the top surface of this same box of air (but not the frame surrounding it).
Anything I'm missing here? Could it be a meshing thing? Or maybe the size of the sphere of air? Master/slave selection in ties? I feel like I've tried everything, please help
Thanks!