How do you incorporate the boundary conditions and loading scenarios of piezoelectric devices in FEA?

3 How do you define boundary conditions?

Boundary conditions are the constraints or inputs that are applied to the boundaries of the domain. They can be mechanical, electrical or coupled. For example, a mechanical boundary condition can be a fixed displacement, a prescribed force or a symmetry condition. An electrical boundary condition can be a fixed voltage, a prescribed charge or a ground condition. A coupled boundary condition can be a piezoelectric actuation, where a voltage induces a strain, or a piezoelectric sensing, where a strain induces a voltage. To define boundary conditions in FEA, you need to identify the surfaces or nodes where they are applied and specify their values or expressions.

4 How do you define loading scenarios?

Loading scenarios are the combinations of boundary conditions that represent the different situations that the device may encounter in its operation. For example, a piezoelectric sensor may have different loading scenarios depending on the type, direction and magnitude of the external force that it measures. A piezoelectric actuator may have different loading scenarios depending on the frequency, amplitude and phase of the input voltage that it receives. To define loading scenarios in FEA, you need to create different cases or steps and assign the corresponding boundary conditions to each case or step.

5 How do you solve and analyze the results?

To solve the FEA model, you need to choose a suitable solver that can handle the nonlinearities and couplings of the piezoelectric equation. Depending on the software and the element type, you may have different options for the solver, such as direct, iterative or modal. You also need to set the convergence criteria, the time steps and the output variables. After solving the model, you need to analyze the results by plotting the variables of interest, such as stress, strain, electric field, electric displacement, voltage, charge, etc. You can also calculate the performance indicators, such as the piezoelectric coefficients, the resonance frequency, the electromechanical coupling factor, etc.

6 How can you avoid common pitfalls?

FEA modeling of piezoelectric devices can be subject to some common pitfalls, such as mesh errors, material errors, boundary condition errors and solver errors. To mitigate these issues, you can use a fine and uniform mesh that can capture the gradients and discontinuities of the variables. Additionally, you should use accurate and consistent material properties that match the orientation and temperature of the device. Furthermore, realistic and compatible boundary conditions should be used to reflect the actual physical situation and not overconstrain or underconstrain the device. Finally, a robust and efficient solver should be used that can converge to the correct solution and avoid numerical instabilities and spurious modes.