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Energy harvesting pzt
Posted 23 ago 2010, 05:01 GMT-4 1 Reply
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hello
i am mtech student in iit doing final project on MEMS energy harveting device . i have drawn geometry of simple unimorph cantilever beam in 2D with two electrode and pzt in between .while givening boundary condition i have fixed one end and applying sine load to other in Fy direction now unit of this is N/m^2 how should i convert it to equivalnet mass if my area is 0.3mm x 0.1mm .if i multiply Fy by area then i am getting force then for mass can i use F=ma formula
then what will be value for a?
another question is that in transient analysis i am getting 75mv we i take voltage from one point then will i get same voltage after fabrication
1 Reply Last Post 23 ago 2010, 05:12 GMT-4
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Posted:
1 decade ago
Hi
one thing in COMSOL; always check carefully the units, loads are in "pressure" (Pa=N/m^2) so you need to be sure you apply them to the corresponding surfaces, edge length or denisty (for body loads) to have correct units.
In 2D you are calculating in fact in 3D with a default depth of typically 1[m] (but you might have defined soemthing else, then you need to mulétiply or divide (depends on your folmular) by this thickness to get coherent units.
In 2D-axi its the "loop length" =2*pi*r one must not forget (in certain cases as for BC's it can be taken in (just as for thicknesses in 2D) by a "click" box
Often you need to integraste the results ofer an area (respective edge*thickness in 2D) to get the total results as forces (except for global reaction forces that are summed up).
The best is to test simple cases, and read the doc (again and again ;)
--
Good luck
Ivar
one thing in COMSOL; always check carefully the units, loads are in "pressure" (Pa=N/m^2) so you need to be sure you apply them to the corresponding surfaces, edge length or denisty (for body loads) to have correct units.
In 2D you are calculating in fact in 3D with a default depth of typically 1[m] (but you might have defined soemthing else, then you need to mulétiply or divide (depends on your folmular) by this thickness to get coherent units.
In 2D-axi its the "loop length" =2*pi*r one must not forget (in certain cases as for BC's it can be taken in (just as for thicknesses in 2D) by a "click" box
Often you need to integraste the results ofer an area (respective edge*thickness in 2D) to get the total results as forces (except for global reaction forces that are summed up).
The best is to test simple cases, and read the doc (again and again ;)
--
Good luck
Ivar