Materials - Acoustic Analysis Suite
(FEWaves)
This pull-down will load a material file into the Preprocessing Group database. Using the left mouse button and clicking on this option will result in a File Manager window appearing. The file filter will show all the *.mat files. Choose the file which contains the material information according to the format described below and click OK. A window will appear indicating the material file is being read. If completed successfully, a information icon will appear indicating the number of materials read. If there is an error reading in the file, an error message will appear indicating the trouble, usually the line number where a format error was detected. If this occurs, use the MSTR Technology editor (or another ASCII text editor) to correct the error until you can successfully read in the file.
The *.mat file can be viewed using MSTR Technology file editor available from the File:Edit pull-down menu. Modifications to the materials should be accomplished through the Options:Materials:New, Options:Materials:Modify Existing, and Options:Materials:Delete pull-down menus. The material data file is stored as text to facilitate data transfer between different computer systems. Keep in mind that you may have to convert material parameters from supplier data to fit the FEWaves format. The format for each material follows (any italicized lines are meant as helpful comments and are not included in the file format, also the asterisk lines separate material types for readability and are not included in the file):
Material ID, Material Type
****************************************************
If material type = 0 then the material is a fluid and the format is:
name
In the following material parameters, all values are complex entered as (REAL,IMAG), except the permittivity,
which is REAL only.
density (kg/m**3) velocity (m/s) permittivity(F/m)
****************************************************
If material type = 1 then the material is structural and the format is:
name
In the following material parameters, all values are complex entered as (REAL,IMAG), except the permittivity,
which is REAL only.
density (kg/m3) alpha(1/s) beta(s) conduc(mhos/m) permittivity(F/m)
Stiffness tensor terms (assumed to be symmetric, all units are N/M**2):
C11 C12 C13 C14 C15 C16
C22 C23 C24 C25 C26
C33 C34 C35 C36
C44 C45 C46
C55 C56
C66
****************************************************
If material type = 2 then the material is piezoelectric and the format is:
name
In the following material parameters, all values are complex entered as (REAL,IMAG), except the permittivity,
which is REAL only.
density (kg/m3) alpha(1/s) beta(s) conduc(mhos/m) permittivity(F/m)
Stiffness tensor terms (assumed to be symmetric, all units in N/M**2):
C11 C12 C13 C14 C15 C16
C22 C23 C24 C25 C26
C33 C34 C35 C36
C44 C45 C46
C55 C56
C66
piezoelectric coupling tensor (all terms of the 3X6 tensor in C/M**2
are required):
ex1 ex2 ex3 ex4 ex5 ex6
ey1 ey2 ey3 ey4 ey5 ey6
ez1 ez2 ez3 ez4 ez5 ez6
Permittivity matrix (assumed to be symmetric, all unit in F/M)
exx exy exz
eyy eyz
ezz
****************************************************
If material type = 3 then the material is electrostrictive and the format is:
name
In the following material parameters, all values are complex entered as (REAL,IMAG), except the permittivity,
which is REAL only.
density (kg/m3) alpha(1/s) beta(s) conduc(mhos/m) permittivity(F/m)
Stiffness tensor terms (assumed to be symmetric,
all units in N/M**2):
C11 C12 C13 C14 C15 C16
C22 C23 C24 C25 C26
C33 C34 C35 C36
C44 C45 C46
C55 C56
C66
piezoelectric coupling tensor (all terms of
the 3X6 tensor in C/M**2 are required):
ex1 ex2 ex3 ex4 ex5 ex6
ey1 ey2 ey3 ey4 ey5 ey6
ez1 ez2 ez3 ez4 ez5 ez6
Permittivity matrix (assumed to be symmetric, all unit
in F/M)
exx exy exz
eyy eyz
ezz
Number of D vs. E Terms (NDE)
for I = 1 to NDE:
D(I) E(I) (all units are in C/M**3 and V/M and are REAL quantities)
In addition to the material parameters required for the piezoelectric material, the material type 3 requires a table of Displacement field vs. Electric Field must be entered at the end of the permittivity values. Note: The permittivity is calculated using this table and the Electric Field provided from the preprocessor input and not calculated from these material parameters. The material is assumed to be isotropic regarding the permittivity value. The first line is the number of data points, and each subsequent line follows the format:
Dfield Efield
------- -------
The preprocessor uses this table to interpolate the slope of the D vs. E curve. This slope is the permittivity used in the electrostrictive analysis. In this way the nonlinear behavior of the electrostrictive material has been simplified to a linear case. To understand the nonlinear effects, FEWaves must be run over multiple frequency harmonics of the electrostrictive source. These results can then be coupled to a modeling code specific to the transducers geometry (call for details). The results of the analysis are dependent on the accuracy of this material table.
The following example describes the material properties for the fluid Sea Water with ID = 1.:
1,0
seawater
(1026,0),(1500,0),7.08e-10
The following example describes the material properties of a structural material Steel with ID = 7. All values are input as complex quantities (R,I) as shown, except where indicated above.
7,1
steel
(7700,0),(0,0),(0,0),(0,0),0
(2.493e+11,0),(9.695e+10,0),(9.695e+10,0),(0,0),(0,0),(0,0)
(2.493e+11,0),(9.695e+10,0),(0,0),(0,0),(0,0)
(2.493e+11,0),(0,0),(0,0),(0,0)
(7.617e+10,0),(0,0),(0,0)
(7.617e+10,0),(0,0)
(7.617e+10,0)
The following example describes the material properties of a piezoelectric material PZT-5H with ID = 4. All values are input as complex quantities (R,I) as shown, except where indicated above.
4,2
PZT-5H
(7500,0),(0,0),(6.53e-10,0),(0,0),0
(1.272e+11,0),(8.02e+10,0),(8.47e+10,0),(0,0),(0,0),(0,0)
(1.272e+11,0),(8.47e+10,0),(0,0),(0,0),(0,0)
(1.174e+11,0),(0,0),(0,0),(0,0)
(2.3e+10,0),(0,0),(0,0)
(2.3e+10,0),(0,0)
(2.35e+10,0)
(0,0),(0,0),(0,0),(0,0),(17.03,0),(0,0)
(0,0),(0,0),(0,0),(17.03,0),(0,0),(0,0)
(-6.62,0),(-6.62,0),(23.24,0),(0,0),(0,0),(0,0)
(1.505e-08,0),(0,0),(0,0)
(1.505e-08,0),(0,0)
(1.301e-08,0)
The following is an example of a electrostrictive material call PMN-TEST with ID = 3. All values are input as complex quantities (R,I) as shown, except as indicated above.
3,2
PMN-TEST
(7500,0),(0,0),(0,0),(0,0),0
(8.02e+10,0),(8.47e+10,0),(0,0),(0,0),(0,0),(1.272e+11,0)
(8.47e+10,0),(0,0),(0,0),(0,0),(1.174e+11,0)
(0,0),(0,0),(0,0),(2.3e+10,0)
(0,0),(0,0),(2.3e+10,0)
(0,0),(2.35e+10,0)
(0,0)
(0,0),(0,0),(0,0),(0,0),(0,0),(0,0)
(0,0),(0,0),(0,0),(0,0),(0,0),(0,0)
(0,0),(23.24,0),(0,0),(0,0),(0,0),(0,0)
(1.505e-08,0),(0,0),(0,0)
(1.505e-08,0),(0,0)
(1.301e-08,0)
Options:Materials:Assign to Regions
This option becomes available only after successfully loading the Model Group and the materials file. The model you have created consists of a collection of geometric vertices connected by geometric edges, faces, and surfaces (3D) to form geometric regions. These regions are surfaces in 2D or volumes in 3D. Before your model is fully described, it is necessary to assign material properties to each of these regions. Hence, your finite element model should be constructed so that different materials (they can be the same, of course) are associated with different regions. Clicking on this option enables a window to appear for associating the model regions with the material properties.
The list of materials you have loaded appears in the list box at the top of the window. The table row titles automatically reflect the number of regions found in the model. To assign a material to a region, click in the cell under the Material heading to identify the region, then scroll through the material list until you find the one to assign. Click on this material and the table cell will be filled with the material name. For this example, region 2 has been assigned the material PZT-5H and region 1 the material WATER in the above example. Click SAVE to save your selections and keep the window up, CANCEL to ignore your changes and close the window, and OK to keep your changes and close the window.
Scrolling to the right will reveal the piezoelectric rotation capabilities of FEWaves as shown below.
Typing in an expression of (degree about X-axis, degree about Y-axis, degree about Z-axis) results a piezoelectric material being rotated about the axis by the angle specified. Hence, for the example above, the piezoelectric material PZT-5H in region 2 is rotated 180 degrees about the X-axis. This option only makes sense for piezoelectric materials, which are inherently anisotropic in nature and the orientation of the polarization axes must line up with the model axes.
This option allows you to create a new *.mat material for Acoustic applications. Choosing this option results in the basic edit window used to create a new material or modify an existing material. This window consists of a type field, which had four check boxes: Fluid, Structural, Piezoelectric, or Electrostrictive. Only one box can be checked at a time and the table row titles changes depending on which item is checked. The four cases are looked at separately.
The new material name is given an initialization of materialN, where N is the number of loaded materials + 1. You can edit this name accordingly. In the example below, there are already 14 materials defined in the database. For a fluid material, it is required to define the density, velocity, and DC permittivity, all in MKS units. All materials parameters are assumed to be complex and should be entered using the format (R,I), where R = real part, and I = imaginary part of the complex number. The DC permittivity is a Real quantity.
For this example, a material "MATERIAL15" is defined with density = (1000.0, 0.0) , velocity = (1500.0, 0.0) and zero DC permittivity. Clicking CANCEL disregards the new name you’ve entered but still stores the data. To modify data, simply go into the table and click in the cell of interest and make your change. Exit the cell to keep the change. Clicking OK saves all changes to the material file and the material database.
The new material name is given an initialization of materialN, where N is the number of loaded materials + 1. You can edit this name accordingly. For a structural material, it is required to define the density, alpha, beta, conductivity, DC permittivity, and the 6X6 stiffness tensor C all in MKS units. All materials parameters are assumed to be complex and should be entered using the format (R,I), where R = real part, and I = imaginary part of the complex number. Alpha and beta are the Raleigh loss coefficients which are dependent on the materials mechanical Q (Qm) of the material and the frequency f. In general, the Raleigh loss coefficient Beta is given by the following equation:
When putting in this value, you should calculate the loss using the center of the frequency band. If you change the frequency, you will need to change the loss calculations. The other Raleigh loss term Alpha is much less understood - call MSTR Technology tech support for questions about this term.
For this example, a material "Shell" is defined with density = (7700.0, 0.0) ,and C values as shown. Clicking CANCEL disregards the new name you’ve entered but still stores the data. To modify data, simply go into the table and click in the cell of interest and make your change. Clicking OK saves all changes.
The new material name is given an initialization of materialN, where N is the number of loaded materials + 1. You can edit this name accordingly. For a piezoelectric material, it is required to define the same material parameters as for the structural material and also the 3X6 piezoelectric coupling tensor e, and the 3X3 permittivity tensor. All material parameters are in MKS units. All materials parameters are assumed to be complex and should be entered using the format (R,I), where R = real part, and I = imaginary part of the complex number. Alpha and beta are the Raleigh loss coefficients which are dependent on the resonance factor (Qm) of the material and frequency (see above). The stiffness tensor C and the piezoelectric coupling matrix are the values measured at a constant (zero) electric field. The permittivity tensor is measured at a constant strain.
As above, clicking CANCEL disregards the new name you’ve entered but still stores the data. To modify data, simply go into the table and click in the cell of interest and make your change. Clicking OK saves all changes.
The new material name is given an initialization of materialN, where N is the number of loaded materials + 1. You can edit this name accordingly. For the electrostrictive material, it is required to define the same material constants as for the piezoelectric material above and also input a table of D vs. E values from which to calculate the non-linear permittivity.
To enter this table of data, simply scroll down in the table to the bottom of the Row titles. You can not edit the row "Number D. vs. E." as this is automatically calculated as you enter values. Click in the cell next to "Edit". This for a defined material will show the table values you’ve entered, for a new material you can begin entering the values starting with the row "D(C/m3),E(V/m)" title cell. We have also provided the capability of reading these values from a file. Click in the cell next to "Read from File" and a file manager will appear. Choose the file with the permittivity data. This file must have the format:
first line: number of field points N
lines 2 – N: D,E (real quantities).
Options:Materials:Modify Existing
This pull-down menu brings up a window which requires you to select the material you which to modify. Move the cursor down to the material you which to modify and push the left mouse button.
The material type (whether fluid, structural, piezoelectric, or electrostrictive) is automatically detected and the appropriate material edit window appears. Editing material properties follows the identical procedure as adding a new material described above. Simply click in the table cell of the value you wish modify, make your changes and exit the cell. The cell change indicates the value is saved. Clicking within the check boxes to change from piezoelectric to fluid for example, prompts you with the question "Do you want to continue?." Clicking yes will initialize (zero) all the material values except the name. As before, clicking CANCEL does not save the changes in the material name but does save the material data changes. Clicking OK saves all changes to the material file and the material database.
Clicking this option brings up a window which requires you to choose a material name to delete. Clicking on a material name brings up a notice box verifying you wish to delete this material. Chose YES to delete the material, NO to cancel the operation.
