Discussion Forum

Hi

I have not found back that model, but in general if you are using a "terminal" and a GND BC, then you can solve and hit the Derived values - Global variable and from the expression list you will find the terminal voltage and current, then their product is the electric power and the U/I ratio gives you the resistance

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Good luck
Ivar

The capability that Ivar mentions above is available in the AC/DC Module, in the MEMS Module, and in the Plasma Module, so make sure you have one of those.

Thanks Ivar and Jean-Francois for the reply.
I shall work on and report back.

BTW, the model number is 366 (Microresistor beam)

Hi Ivar,

I was trying to obtain the resistance by using the derived values function in the result category as you suggested but I couldn't manage to get around this as this is my first time using this function. I wonder if you could elaborate a bit more regarding to this method?

As it is on the microresistor beam model, an electrical potential of 0.2V is supplied through one leg of the microresistor while ground BC is applied to the other end of the microresistor. Should I create a variable in the global definition in order to enter the V/I formula and to be used in the derived values at the result section? If yes, what is the value/equation should I type in the Expression column?

Please kindly advice. Many thanks.

Best Regards,
Tan

Hi
if you apply an electrical potential, with EC you will get some current flowing (and I suppose you do not use the Terminal BC because then you have in the Results section both V and I as global derived values

So add a Definition integration intop1() over the potential boundary (surface for 3D, or edge for 2D physics), or select the GND boundary, then define a variable MyI = intop1(ec.J...) you need to replace the ... by x,y,z . Or use ec.nJ the invard current, but you might need a "-" sign, depends how the normal is defined. Now with the curreent and the applied potential you have easily the electric power and the resistance.

Note check carefully your units if you have a meter hanging by ,it's perhaps because you are in 2D and have forgoten to multiply by the model depth (default 1m, hence the per meter), or in 2D axi you have the loop length = 2*pi*r to add in the integrand (as its not constant !!)

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Good luck
Ivar

Hi Ivar,

Many thanks for your advice. I have managed to obtain the resistance value of my microresistor following your advice.

One question to ask. The next stage of my model is to create four microresistors on a surface plate where all these four microresistors (R1, R2, R3, R4) are connected in a wheatstone bridge configuration. A 5V voltage will be supplied to the circuit and output voltage is then measured.

My question is how to connect four resistors in a wheatstone bridge configuration? Is there a easy way to do it?

Please kindly advice. Many thanks.

Best Regards,
Tan

Hi

what about using 4 ports/terminal, and a circuit link, isnt that what you want. But I'm not sure exactly how to ensure a fixed GND in both physics, or it it's enough with the one in the circuit part. havnt really tried it out.

It would be nice if you could upload your model to show us all, when it works (or a simplified one)

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Good luck
Ivar