Multilayer Transducer Operating in a Water Load

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In this tutorial, you will learn how to set up a simple 2D transducer model with a backing and matching layer and extract outputs such as impedance, directivity plots and transmit sensitivities.

You will learn:

  • The Basic Simulation Workflow in OnScale Designer
  • How to set up a 2D axi-symmetric model
  • How to create a simple geometry
  • How to simulate piezoelectric materials
  • How to display and post-process your results
  • How to use Extrapolation tool
What is PZT?: Lead zirconate titanate is an inorganic compound with the chemical formula Pb[ZrxTi1-x]O3 (0≤x≤1). Also called PZT, it is a ceramic perovskite material that shows a marked piezoelectric effect, meaning that the compound changes shape when an electric field is applied. It is used in a number of practical applications such as ultrasonic transducers and piezoelectric resonators. It is a white to off-white solid.

Model Definition

Characteristics of the model

Model:

PZT Disc dimensions: 10 mm x 2 mm

Backing dimensions: 10 mm x 5 mm

Matching Layer dimensions: 10 mm x 1/4 Wavelength mm

Water of dimensions: 15mm x 20mm

Mesh Size:

0.1 mm

Output Results:

- Impedance

- Directivity at 1 MHz

- Transmit Sensitivity

Material Data

Name Water at 25C CTS 3203HD Vantico HY1300/CY1301 Backing (20% VF)
Code Name watr pmt3 hard back20
Density 1000 kg.m-3 7820 kg.m-3 1149 kg.m-3 4800 kg.m-3
Bulk Velocity 1496 ms-1 4708.36 ms-1 2536 ms-1 1800 ms-1
Shear Velocity 0 ms-1 1687.891 ms-1 1179 ms-1 962 ms-1

Note: Material Data in OnScale are generally defined using the bulk velocity and the shear velocity parameters instead of the more traditional Elastic Modulus and Poisson's Ratio. You can check this page if you want to understand the relation between those parameters.

Why This Simulation?

Transducer sensors often are constructed using multiple layers to try maximize key performance indicators (KPIs) such as bandwidth. Common ways are to introduce a heavy backing layer and matching layers.

The full design is often tested under specific environmental conditions to measure real-world performance to validate the design.

Important: Make Sure that you select the correct Axis of Symmetry from the beginning in the New project window because it is impossible to change afterwards in the designer mode.

The Simulation Process

Let's go through the step by step tutorial and see how to simulate this in OnScale!

Step 1 - Create a New Project

  1. Click New Project to open up the New Project window
  2. Give the project a name
  3. Set Project working units
  4. Change Model Type to 2D Axi-Symmetric Model
  5. Chose the project save location click '...' and choose an appropriate save location
  6. Click OK to save the dialog window
New_Project.png

Step 2 - Add the Materials from the Material DB

First we will add the materials needed from the material database. We will use pmt3 and water in this tutorial.

  1. Click Project Materials to open the database
  2. Expand Fluid and add watr to the Project Materials (double click)
  3. Expand Epoxy and add hard and back20
  4. Expand Piezoelectric and add pmt3
  5. Expand pmt3 and change the poling direction to Y+
  6. Click Done
Material_Tool.png

Step 3 - Create Basic Geometry Shapes

Note: After making changes to X and Y right click the workspace and select Reset View

  1. Click Rectangle
  2. Change Material to watr
  3. Set End (mm): X (mm) = 15
  4. Set End (mm): Y (mm) = 15
Prim_1__Water.png
  1. Right click primitive_1 and select Duplicate Selection
  2. Click primitive_2
  3. Change material from watr to back20
  4. Set End (mm): X(mm) = 10
  5. Set End (mm): Y(mm) = 5
Prim_2__WBack20ater.png
 
  1. Right click primitive_2 and select Duplicate Selection
  2. Click primitive_3
  3. Change material from back20 to pmt3
  4. Set Begin (mm): Y(mm) = 5
  5. Set End (mm): Y(mm) = 7
Prim_1__Pmt3.png
  1. Right click primitive_3 and select Duplicate Selection
  2. Click primitive_4
  3. Change material from pmt3 to hard
  4. Set Begin (mm): Y(mm) = 7
  5. Set End (mm): Y(mm) = 7.634
Prim_4_hard.png

Step 4 - Define a Time Function

We will now add a Ricker Wavelet drive function for later use as out loads require a time function be set.

  1. Click '+' to open the Define Input Time function window
  2. Change to Ricker Wavelet
  3. Click Insert to close the window. A record called timefunc_1 will be added to the window
time.png

Step 5 - Choose the right Mesh Size

We will now change the mesh settings to use 15 elements per wavelength

  1. Select Configuration
  2. Set Definitions to Wavelength Based
  3. Set Elements Per Wavelength to 15
mesh.png

Step 6 - Create the two electrodes

  1. Click '+' to open the Load Definition window
  2. Change Creation Mode to Geometry Interface
  3. Change Geometry to primitive_3 (pmt3)
  4. Change Interfacing Item to primitive_4 (hard)
  5. Click Create Load
Load_1.png
  1. Click '+' to open the Load Definition window
  2. Change Creation Mode to Geometry Interface
  3. Change Geometry to primitive_3 (pmt3)
  4. Change Interfacing Item to primitive_2 (back20)
  5. Click Create Load
Load_2.png

We will need to edit the loads to create 2 electrodes, where we are driving the top electrode (load_1) and grounding the bottom electrode (load_2).

Change the properties of the electrode 1

  1. Click load_1
  2. Change Load Type to Voltage
  3. Change Termination to timefunc_1
  4. Change Amplitude Scale Factor to 1
Electrode_1.png

Change the properties of the electrode 2

  1. Click load_2
  2. Change Load Type to Voltage
  3. Change Termination to Ground
Electrode_2.png

Step 7 - Define the Boundary Conditions

We will need to change the X minimum boundary condition to Symmetry as this model is symmetrical across that axis.

  1. Click Domain Boundaries
  2. Change the X Minimum boundary condition to Symmetry. All others will be absorbing
  3. Change remaining boundary conditions to Absorbing
Boundary.png

Step 8 - Define the Analysis Simulation Time

We will now set the model simulation time to be 5e-5 seconds

  1. Click Analysis
  2. Change Simulation Run Time (s) to 2e-05
Analysis.png

Step 9 - Define the Output Results

We will now define 1 output, a extrapolation boundary to allow us to generate outputs using the Extrapolation tool

Output Result 1: Extrapolation Data

  1. Click '+' this will create a new output
  2. Change Output Type to  Extrapolation Data
  3. Change Cutting Plane to Y
  4. Change Cutting Point (mm) to 8.5
Output.png

Step 10 - Run on the Cloud

Full_Screen.png

At this point the model is completely set up and it can now be run on the cloud.

  1. Click Run on Cloud
  2. The option to rename your job. This is how it will appear in the storage
  3. Click Estimate
  4. Click Run
Cloud.png

How to Get the Simulation Results?

The simulation results will need to be downloaded from the cloud storage in order to analyse the results in the post processor. More experience users may also be able to process Time Histories in Review.

  1. Click Storage this opens the window shown above
  2. Locate the job
  3. Click Download
  4. Click Download all
Storage.png

Choose an appropriate save location when the file explorer pops up and click Select Folder to close the window.

Step 11 - Check the Simulation Results

Switch to the Post Processor

  1. Click this icon to access the Post Processor
ppswitch.png

Open Results, Calculate and Plot Conductance

  1. In the File Explorer, Locate the Flex History File (.flxhst) & double Left Click
  2. Select the Charge record on load1
  3. Select Real/Imag from the drop down menu
  4. Click Admittance
  5. Two new records will appear, double click on Admt:load1.re to plot
  6. The real part of Admittance (Conductance) will be plotted allowing you to analyze the transducer performance in greater detail.
Output_Admittance.png

Using the Extrapolation Tool

  1. In the Tools tab, Select Extrapolation Tool
  2. Click Open
  3. Select the downloaded extrapolation file (.flxext)
  4. Click Open
Extr_1.png
  1. You will be prompted to open the flxmdl file. Click Yes
Extr_2.png

Directivity (Radial Plot)

  1. Select Radial Plot
  2. Change Y1 origin of directivity to 7.634e-3 m
  3. Change Radius (m) to 1
  4. Change Angular Spread to 180
  5. Change No. of points on line to 181
  6. Change Propagation Vector to Y
  7. Change Drive Frequency (Hz) to 1e6
  8. Click Start to calculate
Radial_1.png

Radial Plot Result

Radial_2.png 

Transmit Sensitivity (TVR)

  1. Select TVR Calculation
  2. Select User Defined
  3. Alter Y reference value to 7.634e-3 m
  4. Change Propagation direction to Y
  5. Click Start to calculate
TVR_1.png

TVR Response

TVR_2.png

Try For Yourself

Now that we have introduced you to the tutorial try have a play around with some of the settings, add some other outputs, or use this model as a starting point for your own.

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