Simulating a Piezoelectric Transducer (1-3 Composite Array)

In this tutorial you will learn how to set up a simple 3D model of 1-3 Piezocomposite with 100 pillars using the designer mode basic geometry shapes.

You will learn:

• The Basic Simulation Workflow in Onscale Designer
• How to set up a 3D model
• How to create a simple geometry
• How to simulate piezoelectric materials
• How to display and post-process your results

We are building a 1-3 piezo-composite structure in this tutorial.

Problem Definition

Characteristics of the model

Material Data

Why this Simulation?

Modelling and simulating composite array devices with FEA provides a lot of insights to design and fabricate the best ultrasonic sensors. It allows to create designs which are cost-efficient even before starting making some prototypes.

With OnScale, you can set up various geometrical features as parameters that can then be tested virtually by simulation, allowing you to choose the best combination of materials and sizes, while preventing costly design mistakes.

In this simulation we will apply 2 electrodes on both sides of the composite and observe the behaviour of the composite.

This model can be used as a starting point for anyone looking to design a transducer using a composite structure as the active element of the device. This device will have 100 pillars using CTS 3203HD piezoceramic and a hardset epoxy filler. We will build a model with 25 pillars and apply symmetry in X and Z as our thickness will be through Y to achieve a 100 pillar composite.

In the results, the model will appear as a half cylinder when plotted in the post processor.

Step-by-step Video Tutorial

The following video will teach you step by step how to simulate the Piezo Composite transducer model presented in this tutorial:

Note: The Designer interface has changed slightly since this video was recorded. The text that follows has been updated to reflect the interface changes.

All the step are also detailed in text format in the next section. Check it out.

The Simulation Process

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

Step 1 - Create a New Project

1. In the Home tab of the ribbon, click New Project. The New Project window shows.
2. Type a name for the project.
3. If desired, change the save location and/or project file name by clicking … beside Project File.
4. For Analysis, select Mechanical Dynamic.
5. Select the Advanced checkbox.
6. For Distance, select mm.
7. Click OK.

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 hard in this tutorial.

1. Click Project Materials this will open the Materials Database window
2. Expand the Piezoelectric tab
3. Double click pmt3 to add that material to the Project Materials
4. Expand the Epoxy tab
5. Double click hard to add that material to the Project Materials
6. Expand pmt3 tab and then expand the Piezoelectric sub-tab then change the poling direction to Y+
7. Click Done

Step 3 - Create Basic Geometry Shapes

We will make use of the geometric primitives available in Designer. We will use the Cuboid primitive twice. Primitives can be patterned out along the axis so we only need to create one pillar and pattern it out to achieve the full model.

Primitive 1

1. Click the Cuboid icon to add a  primitive
2. Set Material to hard
3. Set End (mm): X (mm) = 0.48, Y (mm) = 1, Z (mm) = 0.48
4. Right click the workspace and select Reset View
5. Click anywhere in the workspace to move rotate and move the model around

Primitive 2

1. Right click primitive_1 and select Duplicate Selection this will create a copy of the primitive called primitive_2
2. Set Material to pmt3 
3. Set X (mm) = 0.08, Y (mm) = 0.0, Z (mm) = 0.08
4. Set X (mm) = 0.40, Y (mm) = 1.0, Z (mm) = 0.40

Step 4 - Pattern out the structure

1. Select both primitives 
2. Change Pattern Type to Linear
3. Set X = 5, Y = 1, Z = 5 
4. Set X = 0.48, Y = 0, Z = 0.48

Step 5 - 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

Step 6 - Choose appropriate meshing

We will now change the mesh settings to use 30 elements per wavelength.

1. Expand Model
2. Expand Mesh
3. Select Configuration
4. Set Definitions to Wavelength Based 
5. Set Elements Per Wavelength to 30
6. Expand Mesh Velocity 
7. Set Mesh Velocity value to 1179

Step 7 - Define loads

Load 1

1. In the Model Tree, expand Boundary Conditions and then, beside Loads, click +.
2. For Creation Mode, select Geometry Interface.
3. For Geometry, select primitive_2 (pmt3) or click it in the model.
4. For Interfacing Item, select side 4 (ymax).
5. For Load Type, select Voltage.
6. For Area Scaling, type 4.
7. For Termination, select timefunc_1.
8. Click Create Load.

Load 2

The Load Definition window should still be open.

1. For Geometry, select primitive_2 (pmt3).
2. For Interfacing Item, select side 3 (ymin).
3. For Load Type, select Voltage.
4. For Termination, select Ground.
5. Click Create Load.

Step 8 - Set domain boundaries

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

1. Click Domain Boundaries
2. Change X Minimum to Symmetry 
3. Change Z Minimum to Symmetry 

Leave all other boundary conditions as there default free

Step 9 - Set the simulation time

We will now set the model simulation time to be 1e-4 seconds

1. Click Analysis 
2. Set Simulation Run Time to 1e-4

Step 10 - Request outputs

We will now define 1 output, we will request the solver generates a mode shape showing displacement in Y

1. Click '+' to add a new output 
2. Change Output Type to Shape Data
3. Change Array Type and Array Component to Displacement and Y
4. Set Frequency to 1e6 Hz

Step 11 - Running your simulation on the cloud

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. Change number of CPUs to 16 (this is to decrease Solve Time, choose what best suits your Core Hour spend)
4. Click Estimate 
5. Click Run

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 

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

Step 12 - Using the post processor to plot results

Switch to the Post Processor

1. Click this icon to access the Post Processor 

Open Results

1. Click File Explorer
2. Expand the job simulation folder that was just downloaded
3. Open the shape.flxdato file (double click)
4. Open the 1-3_Comp.flxhst file (double click)
5. Click Results Manager

Plot Mode Shape (Y Displacement)

1. Right click ydsp and select Plot Shape Movie
2. Click Model Graphics
3. Click Symmetry
4. Apply symmetry on X and Z axis
5. Change Scale Factor to 0.02
6. Enable Save Video
7. Choose an appropriate save location and name the give video a title. Close window
8. Click Play. Watch your Mode Shape. A mode shape video should now be in your save directory

Calculate & Plot Impedance 

1. Click the Reset Viewport Icon and select Reset Current Viewport
2. Select the history 'pize load1: Charge'
3. Select Impedance button 
4. Double click Impd:load1.amp to plot the impedance
5. Click Log yAxis

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 of your own.