Improve your relationship

Finite element analysis of ultrasonic transducers is very much like being in a committed relationship - even if you cannot grasp all the physics behind her behavior doesn’t mean you wouldn’t immensely benefit from investing time in getting to a deeper understanding.

Understanding is key

One of the biggest issues that engineers make when doing finite element analysis of ultrasonic devices is that they don't understand the piezoelectric effect. You may think that how could this be true? Could a professional working on ultrasonic device simulation implement the piezoelectric phenomenon but has little to no understanding of it? Well, I have witnessed it on many occasions that the basic effects of the converse and direct piezoelectric effects are not understood by simulation engineers. This is because their previous experience lacks a background in piezoelectric materials, and piezoelectric transducers are not taught at a fundamental level in universities. 

     Engineers coming from different disciplines often don’t have an understanding of the concept of electromechanical coupling. Even more rare is the awareness of the factors which cause differences between simulations and experiments.

Finally, learn your license and learn to drive

FEA tools are powerful, perhaps the most powerful vehicle in development an engineer has. Without “learning to drive,” you can still drive fast, but you will learn by crashing. 

     How do you learn to “drive” piezoelectric simulations? 

STEP 1: Compare theory and FEA

• Firstly, compare finite element simulations with hand calculations of the converse and direct piezoelectric effects. Here are my tutorials on those topics:
• Simulation of the “direct” effect (sensor | input force output voltage)
• Simulation of the “converse” effect (actuator | input voltage output displacement)
• Next, familiarize yourself with the impedance response and factors that change it and what those changes mean to the electrical and mechanical performance. Here is a tutorial to get you started on understanding the impedance response from a theoretical and FEA perspective:
• Impedance Frequency Response of a Piezoelectric Element Using COMSOL

STEP 2: Compare FEA and experiments

• In order to achieve a complete understand of how material properties, boundary conditions, and other parameters affect ultrasonic devices, you must do experiments and compare them with theory and FEA
• Here are some basic experiments that can compare to FEA help you get started on your holistic understanding
• Impedance response of a piezoelectric disk
• Impedance response of ultrasonic cleaning transducer
• Impedance response of a piezoelectric disk bonded (by you) to a substrate
• I recommend using the impedance response for comparison because impedance analyzers are standard tools in most laboratories and provide both electrical and mechanical data in a format that is easy to compare to FEA

Is this just homework?

This may seem like a lot of homework, but the flip-side of not having a holistic understanding is a sub-par competence of your modeling efforts.