@FEA way:
I am using Inventor-NASTRAN
@driftLimiter:
Imagine a simple frame fixed on the ground with a MOTOR on it.
The motor has a maximum allowable acceleration in its specs. I want to check that the acceleration "seen" by the motor will be lower than that. I then need the ABSOLUTE...
Hi,
I am running a Response Spectrum Analysis (it us actually a DDAM analysis, a "special type" of Spectrum Analysis).
I understand that the acceleration values that I obtain as result in my structure are RELATIVE acceleration values (I see in the postproc that the acceleration at the base of...
Hi,
Does anyone know if there is an equation to calculate the pressure produced by a piezoelectric transducer (maybe in function of electrical power, density of media, etc).
Thanks,
pilafa
- My FEA program has an option to automatically define a "far field".
- Yes, I am modelling an air volume above the tank
- I will try the time-domain test when I have a chance
- Any comment on the previous post (how to choose alpha values)?
Thanks
Hi,
In order to assess my doubt, I built three simple models:
M1:
- Tank of water with oscillating pressure in the bottom
- Surrounding air outside the tank (on the top) with far-field condition on the air domain
M2:
- Only the tank, with a rigid-wall boundary condition on the...
Thanks for your answer btrueblood.
In my FEA, I need to input some Z value. So, I found this formula (I guess it is equivalent to yours):
(Source)
In this formula, alpha is the "absorption coefficient" (I assume that: alpha+R=1)
So, when:
alpha = 1 -> Z=rho_0*C0 -> the energy is perfectly...
Hi,
I have an open tank filled with water, with an ultrasound source in it. I calculate the pressure in the water with FEA.
I would like to study only the water, and avoid meshing surrounding air (which I think is not necessary anyway). For that, I impose an impedance value on the free...
No GregLocock, I think hacksaw agrees with you (see previous answers).
To summarize hacksaw's answers (correct me if I am wrong):
- When working in the frequency domain (with Helmholtz equation): physical pressure is the magnitude of the pressure vector {Re,Im}
- When working in time...
Hi,
Thanks for your help.
Ok...but how to interpret it then? Maybe it does not have a physical interpretation itself, but has sense only for computing the magnitude of P.
Yes, I confirmed with a simple test.
I work with lossless flow. I have a source of pressure in a closed box. If all the...
Hi,
There is a series of acoustic concept I would like to review. My background is rather in the fields of elasticity and CFD.
I read good references explaining the maths. I can understand them, but most of those references don't link it with practical application.
1) Complex and Real part...
Hi Doug,
Thank you for your answer.
Since it's a "noise vibration" problem, I am confident that the amplitudes will be very small.
Now my concern about using the Rule of Mixture is that the properties of a reinforced concrete beam are not isotropic.
I am thinking about using the Rule of...
Hi,
I want to study the dynamic response of a structure subjects to a sine wave acceleration signal.
For that, I will perform an harmonic FEA simulation.
To simplify, let's say that the structure is a column fixed on the ground, and that the ground is moving.
To apply the loads, I am...
Hi,
I want to study vibration on a simple reinforced concrete structure with FEA.
The amplitudes are small, so all the materials stay in the linear domain.
I wonder if it is acceptable to use a Rule of Mixtures to calculate an equivalente Young Modulus (Ec= Ef*Vf+ Em*Vm).
Thanks,
Pierre
Hi,
I’m doing some analysis with SOLID186 and the Mooney-Rivlin hyperelastic material option (TB,HYPER,1,,5,MOONEY). I have a tetrahedral mesh. Ansys gives me this error:
‘Error related to regular shapes of 3D elements with mixed u/P formulation, it should never happen.’
By the way...
