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Strain Gauge on Curved Geometry

Posted 17.03.2015, 17:03 GMT-4 Low-Frequency Electromagnetics, MEMS & Nanotechnology, MEMS & Piezoelectric Devices, Modeling Tools & Definitions, Parameters, Variables, & Functions, Structural Mechanics 6 Replies

Bartu Avci
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Hi all,

I was wondering whether COMSOL would be a good choice to model the behaviour (electrical, mechanical) of metallic strain gauges printed on out-of-plane (curved) structures.

The feature size of the substrate would be in the order of mm; whereas the strain gauge features are much smaller (um range; but surely not nm).

I think with solid deformation and AD/DC module, such simulations are doable. Am I right? Are there any examples (tutorials) similar to this task?

Thank you,
Bartu

PS: I would be happy if you can recommend any other simulation programs, if they are any better.
6 Replies Last Post 01.07.2016, 14:57 GMT-4
Sven Friedel COMSOL Employee

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Posted: 10 years ago 23.03.2015, 10:07 GMT-4
HI Bartu,

have a look here

ch.comsol.com/model/piezoresistive-pressure-sensor-12629

Best regards,
Sven
HI Bartu, have a look here https://ch.comsol.com/model/piezoresistive-pressure-sensor-12629 Best regards, Sven
Nagi Elabbasi Facebook Reality Labs
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Posted: 10 years ago 23.03.2015, 12:52 GMT-4
Hi Bartu,

I think COMSOL is very well suited for this problem, and can handle the different length scales easily. Here is an idea that, if applicable, will simplify your models.

In most cases a strain gauge does not affect the strain state of the underlying structure so it does not need to be explicitly modeled. By the same reasoning, if you need to model the electro-mechanical behavior of the strain gauge you do not need the full structure. You can just find the stress-strain field at the strain gauge location and apply it to a separate strain gauge model. That way you simplify your models and avoid the different length scales.

Nagi Elabbasi
Veryst Engineering
Hi Bartu, I think COMSOL is very well suited for this problem, and can handle the different length scales easily. Here is an idea that, if applicable, will simplify your models. In most cases a strain gauge does not affect the strain state of the underlying structure so it does not need to be explicitly modeled. By the same reasoning, if you need to model the electro-mechanical behavior of the strain gauge you do not need the full structure. You can just find the stress-strain field at the strain gauge location and apply it to a separate strain gauge model. That way you simplify your models and avoid the different length scales. Nagi Elabbasi Veryst Engineering
Bartu Avci
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Posted: 10 years ago 23.03.2015, 13:25 GMT-4
Hi Sven and Nagi,

thank you very much for your replies. Those are really helpful.

In the meantime, I have also decided to simulate the adhesion behaviour between the layers. I have a sandwich-like structure that will experience numerous bending modes during operation. So, I want to check and quantify whether the bonded layers debond or not.

In my research I came across an analytical model called "Cohesive Zone Model". However, I am not entirely sure if it is the best analytical model for this kind of situation.

Are you familiar with some tutorials or analytical model regarding this adhesion issue?

Thanks,
Bartu
Hi Sven and Nagi, thank you very much for your replies. Those are really helpful. In the meantime, I have also decided to simulate the adhesion behaviour between the layers. I have a sandwich-like structure that will experience numerous bending modes during operation. So, I want to check and quantify whether the bonded layers debond or not. In my research I came across an analytical model called "Cohesive Zone Model". However, I am not entirely sure if it is the best analytical model for this kind of situation. Are you familiar with some tutorials or analytical model regarding this adhesion issue? Thanks, Bartu
Nagi Elabbasi Facebook Reality Labs
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Posted: 10 years ago 23.03.2015, 13:36 GMT-4
You're welcome.

In general the Cohesive Zone Model is a suitable approach to simulate debonding. Here is a COMSOL Model Gallery example showing how to implement it: www.comsol.com/model/mixed-mode-debonding-of-a-laminated-composite-19961. You also need to measure several properties that characterize the bond strength.

Nagi Elabbasi
Veryst Engineering
You're welcome. In general the Cohesive Zone Model is a suitable approach to simulate debonding. Here is a COMSOL Model Gallery example showing how to implement it: http://www.comsol.com/model/mixed-mode-debonding-of-a-laminated-composite-19961. You also need to measure several properties that characterize the bond strength. Nagi Elabbasi Veryst Engineering
Bartu Avci
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Posted: 10 years ago 23.03.2015, 16:13 GMT-4
Thanks Nagi,

are there any other easy-to-apply analytical models (other than CZM) that you have experience with?

Bartu
Thanks Nagi, are there any other easy-to-apply analytical models (other than CZM) that you have experience with? Bartu
Jeff Hiller COMSOL Employee

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Posted: 8 years ago 01.07.2016, 14:57 GMT-4
On CZM: this is the approach implemented in the adhesion/decohesion capabilities added into the Structural MEchanics Module at version 5.2a, see www.comsol.com/release/5.2a/structural-mechanics-module .
Best,
Jeff
On CZM: this is the approach implemented in the adhesion/decohesion capabilities added into the Structural MEchanics Module at version 5.2a, see https://www.comsol.com/release/5.2a/structural-mechanics-module . Best, Jeff

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