cantilever tutorial for comsol

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Post on 15-Oct-2015

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Tutorial for Cantilever

TRANSCRIPT

Snapshot steps..follow them to complete the tutorial created by me for mems cantilever switch.

Click on next

Select electromagnetic as first physics(for me its recently added you search in all libraries below you will find it in one of them)

Click on the + sign belowto add the select library in the window

Repeat steps to add solid mechanics and moving mesh ale.

Click on finish

So you can see that all there physics that are required for the design of mems cantilever switch are selected.the physics are selected on the need of requirements and not pre defined in manuals.so it comes with experience .Now we have to draw the geometry.so firstly select the units

Right click on geometry and select block

The screen for specifying the details of size and position window will come as shown on the side

So I am drawing a beam that is 180 x 45 x 0.75 microns in length, width and thickness respectively

then the position of the beam is specified so as beam is going to be above all the layers and there has to be a gap between beam and bottom electrode I have specified it as 2.25(that is thickness of bottom electrode 0.75 + gap height 1.5).

then click on build selectedas shown

So you can see the beam formed

You can rename for your continence by doing right click on the block selected as shown..

Repeat the steps and draw the other blocks like bottom electrode and transmission line as required with respective position and sizes

now material selection to aluminum as in my case of evey geometryright click click on materials as shown to select material browser

Now find the material and add it to the model

By default all materials will be selected as the material in browser you can add or remove parts with your desires .

The red sign in the above figure means the value is known for simulation and is desired by the user input if not inputted the simulation will throw as exception

Now for closed domain analysis of moving mesh ale physics selected we require a boundary condition of air surrounding our structure so we have to build one more geometry part air and then select the material air

The boundary air has to removed from aluminum as shown

Now add material air..

Now setting up boundary conditions in physics selected

Ground condition on the boundary you want like for me its 13 domain so user has to add each domain as specified in the box with the help of plus sign

Intial values zero

Initial conservation of temperature and pressure as desired by user

Applying electric potential on beam/bottom electrode

Defining variable force name that is to be carried forward as interface between one physics to otherWe dont consider the air domain for solid mechanics .

Free end for deformation of beam

Fixed domains that wont move that is no effect of displacement due to force

that is no effect of displacement due to force

Most important step .

Value of electrostatic force in solid mechanics to cause displacement

Es stand for the electrostatics physics

nTx is the normal stress developed

and that value Fes multiplied with nTx

hence

es.nTx_Fes and similarly for y axis and z axis.as sown in above figure

next step meshing

Computation takes some time and once its done you can plot the results.

Right click on 3d plot

So above is one of the way of result

So different combinations, possibilities and types are there for result analysis few examples are below..