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Simulation features of the MODELBUILDER

The simulation features will be explained on the Acceleration sensor example discussed in the Example Manual section. The model is similar to the previously discussed example but is extended by additional layout components (e.g. capacitors with gap variation, bottom plate capacitors). The example is given in µMKSV-units.

  • Open the acceleration sensor example with gap varying capacitances
    • Click on the “Open Project” icon.
    • Open the folder “Accelerometer_UsersManual”.
    • Select the “Accelerometer_gap.iromproj” file and open it.

All four types of simulations will be demonstrated on the acceleration sensor model. The simulation examples which are taken from the Example Manual to demonstrate the required simulation commands and post-processing features:

a) Modal analysis, Modal analysis with electrostatic softening
b) Static simulations, DC-voltage sweep with pull-in and pull-out
c) Harmonic response analysis, AC-sweep simulations
d) Transient simulations with pull-in and contact bouncing

  • Click on "Build Solids" and "Build ROM" to generate the simulation model.
  • Run a “Modal analysis” in the mechanical domain
    • Enter SOLV, modal (command-based approach) or click on the “Simulate” icon and “Start Simulation” (GUI-based approach). Compare results with Table 4 of the Example manual.
    • Select mode #4 and apply a scale factor of 0.4.

  • Run a “Modal analysis with electrostatic softening” effects
    • Enter the following commands and compare results with Table 4. 
      COND,sense+,mass,v_sens+;
COND,sense-,mass,v_sens-;
VSCR,mass,0;
VSCR,v_sens+,+100;
VSCR,v_sens-,-100;
SOLV,modal;

Static simulations, DC-sweep simulations with pull-in and pull-out⚓︎

  • Run a “Static simulation” in the mechanical domain
    • Calculate the stiffness of rigid body #1 in uy-direction according to Table 5.
    • The reacting force is 165 µN if voltage loads are still applied from the previous load step (electrostatic softening). Otherwise the force is 175 µN.
LOAD,rb,1,uy,8;
SOLV,stat;

  • Run a “DC-voltage sweep” with pull-in and pull-out effects
    • Enter the following commands and compare results with Table 5. 
COND,sense-,mass,v_sens-;
VSCR,mass,0;
DCSW,vscr,v_sens-,,0,500,501,1;
SOLV,stat;

  • Plot the voltage-displacement-relationship
    • Select sample #501 in the “Datapoint Selection” window.
    • Select "uy" at "RB 1" in the “Solution Item Selection” window for a curve plot.
    • Look at the "DC Sweep" panel to inspect the graph.

  • For a better visualization, drag the edge of the "DC Sweep" panel to make it bigger.

  • Set data point markers at the pull-in and pull-out voltages

    • The left "Select" button of the “DC Sweep” panel must be active.
    • Move the mouse along the orange curve. Datapoint coordinates follow the mouse pointer.
    • Stop at the data point of interest. The yellow label box appears.
    • Click on the left mouse button to place a datapoint. Or click on the right mouse button and select “Create Datapoint”.
    • In this case, a permanent datapoint appears at the pull-out voltage of 200 V.

  • Delete a data point: Go to the data point you want to delete, click on the right mouse button and select “Delete Datapoint”.
  • Click on “Start Animation” of the “3D View” panel to animate the pull-in and pull-out behavior of the 3D-model.
  • The pull-in and pull-out curve consist of 1002 samples. You can use the “Slower” and “Faster” button in the GUI to adapt the speed of the animation. On average, 30-50 samples are processed per second on a PC.

Harmonic response analysis, AC-sweep simulations⚓︎

  • Run a “Harmonic response analysis” of the electro-mechanical system
    • Enter the commands below and compare results with Table 7.
    • Select "uy" at "RB 1" and the electrical current at the “mass” port in the “Solution Item Selection” window for visualization in the “Bode Plot” window.
COND,sense+,mass,v_sens+;
COND,sense-,mass,v_sens-;
VSCR,mass,0,1;
VSCR,v_sens+,+100,0;
VSCR,v_sens-,-100,0;
RDMP,freq,10e3,40e3,0.001,0.001;
HARF,10e3,40e3,5000,log;
SOLV,harm;

  • Select logarithmic x- and y-axes scaling. Click multiple times in the “LOG” icon to toggle between linear and logarithmic x-y-axes.

  • Manipulate the curves (zoom, pan) of the “Bode Plot” window

    • The left “Select” button of the “Bode Plot” window must be active.
    • ZOOM: Move the mouse pointer into the region of the 2D-plot where you want to zoom. Scroll the mouse wheel to zoom in or out.
    • PAN: Zoom into the 2D-plot. Keep the left mouse button pressed and move the mouse to pan the curves in x- or y-direction.
    • Alternatively, you can use the “Zoom-In” and “Zoom-Out” icons.

  • Create a colored amplitude plot of the sample at resonance
    • Select sample #2285 at 18.839 kHz in the “Datapoint Selection” window.
    • The amplitudes of all sample frequencies can be animated.

Transient simulations with pull-in and contact bouncing⚓︎

  • Run a “Transient simulation” of a voltage pulse with contact bouncing
    • Enter the commands below and compare results with Table 9. 
PARA,f0=19.176e+03;
PARA,dmpr=0.15; 
COND,sense+,mass,v_sens+;
VSCR,mass,0;
VSCR,v_sens+,0,+500,puls,5/f0,1/f0;
RDMP,freq,0.8*f0,1.2*f0,dmpr,dmpr;
TIME,5/f0,1/(400*f0);
SOLV,trans;
  • The contact stiffness and damping factor can be changed in the Simulation Settings window of the GUI or directly in the model input file. Stopper data (see STOP command) specified in the user model file have a higher priority.
  • Select sample #400 in the "Datapoint Selection" window.
  • Plot uy-DOF results of rigid body #1 over time.

  • In the Simulation Settings window, enlarge the damping factor from 0.0 to 1.0 to eliminate bouncing.
  • Click on “Build ROM” to create a new simulation model with changed contact settings and re-run the previous simulation.

  • Animate the transient response with contact bouncing effects.