In this step by step guide only 2D axiysymmetric models will be considered. This allows for all the main principles to be demonstrated while keeping analysis times and model complexity to a minimum in order to ensure new users can follow the guidelines satisfactorily.
Note: It is strongly advised that all CMUT models be run in the Double Precision
There are two important distinctions that have to be made between traditional OnScale models and Electrostatic CMUT models. They can be grouped into two categories.
Linearity
As we know, most OnScale applications are linear in nature
 Output scales linearly with Input
 Double the Input; double the Output
 Output can be 'corrected' during postprocessing
 Basis for linear systems analyses  using Convolution to extract output from input and impulse response
However, Electrostatic problems are inherently nonlinear
 Coupling efficiency changes with displacement
 Mechanical Nonlinearities exist
 Mechanical 'restoring forces' increase with displacement
Therefore, to accurately analyze a nonlinear problem, all input values must be correct during simulation
 No 'correction' during postprocessing
 Many additional places to make mistakes
 Requires greater knowledge of system being modelled
 Requires greater care during simulation
Large Deformation
Standard OnScale models are considered as small deformation, which is effectively anything less that 1% strain and therefore is fantastically wellsuited to the vast majority of piezoelectric and wavepropagation applications.
 Displacements are small compared to structure size
 Nanometer sized motions on millimeter sized structures

 6 orders of magnitude difference
 Assumption that nodal positions never change
Electrostatic models, however, are very much large deformation in nature
 Displacements are large compared to structure size
 Micron sized displacements on micron sized structures
 Positions are updated every timestep
0 comments
Please sign in to leave a comment.