EEE Student Seeks Help for Strain Sensing Project

[jendrix]

Hello,

I am a 3rd year EEE student and am working on a project that will go on to form my 3rd year dissertation. I am having trouble formulating a project idea from the guidelines. I was told I should use a strain sensor to form some kind of self sensing smart material that could be used to detect forces acting upon it and maybe some damage too.

The outline was "Monitoring a composite material using strain sensor"

I have reviewed classic strain sensors using the wheatstone bridge in conjunction with an amp to get readings but this doesn't feel like a project. I have seen fibre optics used but this seems more like phd level work. I have also seen a self sensing technique where the material itself self senses. I believe it was a carbon composite the resistance through the material would change with strain/stress. much like a strain sensor. My concern is ending up going too far into the civil/material engineering.

If anyone could offer some pointers of areas to look at I might have missed that would be much appreciated.Thanks

 

[berkeman]

I was told I should use a strain sensor to form some kind of self sensing smart material that could be used to detect forces acting upon it and maybe some damage too

I have a few ideas, but can you post some links to the reading you've been doing about the "detecting damage" part? I think this has been used in a number of recent applications, so it would be good to read through them to see what kind of ideas this can help to bring out.

I'd also be tempted to overlay both a traditional bridge sensor and an optical interference-based sensor, to help to get absolute strain at a course scale, and relative strain at a very fine scale. Have you seen any such combination sensors in your survey so far?

 

[jendrix]

I have a few ideas, but can you post some links to the reading you've been doing about the "detecting damage" part? I think this has been used in a number of recent applications, so it would be good to read through them to see what kind of ideas this can help to bring out.

I'd also be tempted to overlay both a traditional bridge sensor and an optical interference-based sensor, to help to get absolute strain at a course scale, and relative strain at a very fine scale. Have you seen any such combination sensors in your survey so far?

Hello,

So far I have been reading about electrical impedance tomography https://www.sciencedirect.com/science/article/pii/S026635381733186X and have just started to look into fibre optic solutions. The EIT looks promising although it could be a little demanding for a 3rd year project given I have ~5 months to complete it.

I am new to both bridge and optical interence based sensors so will start reading up on both of those too.

 

[anorlunda]

The outline was "Monitoring a composite material using strain sensor"

Is that the complete requirement? That is so thin that almost anything would satisfy it.

So far I have been reading about electrical impedance tomography

You said that using a Wheatstone bridge sounds too easy. But there is also risk to being too ambitious and not finishing. Choosing something that research scientists have just figured out sounds very advanced for a 3rd year student.

I think you need a face-to-face mentor, not advice from the Internet. A mentor can assess your capabilities, and use his knowledge to estimate difficulty and recommend the best match.

 

[jendrix]

Is that the complete requirement? That is so thin that almost anything would satisfy it.

Yes I thought the same, I assumed the mention of it being a composite would mean it would need to be a material that could 'self sense' using the properties of it being a composite material but I may be interpreting that wrong.

You said that using a Wheatstone bridge sounds too easy. But there is also risk to being too ambitious and not finishing. Choosing something that research scientists have just figured out sounds very advanced for a 3rd year student.

I think you need a face-to-face mentor, not advice from the Internet. A mentor can assess your capabilities, and use his knowledge to estimate difficulty and recommend the best match.

I think you are right to be honest, it's hard to gauge the difficulty of some tasks, I do have a mentor at university, I will meet with him again tomorrow and try to get some concrete objectives. I will update then.

I was given this case study on embedded sensors as a potential idea, https://www.uk-cpi.com/login/resources/national-composites-centre-case-study.pdf it covers printable electronics which I thought would require specialist equipment. I would be interested to hear your thoughts on it.

Thanks again

 

[CWatters]

There is a problem with the use of composite materials on aircraft... For example, if someone crashes a service vehicle into a metal aircraft there is usually good visual evidence if damage occurs. Composite aircraft are more like the bumper on your car. The skin can spring back hiding more serious damage. There is concern the vehicle driver may not realize the seriousness of the damage and not report it.

I'm sure there is a lot of research being done into ways that automatic monitoring can be built into the aircraft to address this sort of problem ... If Boeing haven't already solved it!

 

[jendrix]

Hello, I have been able to speak with my supervisor and have a more complete idea of what the aims should be, although there is still scope to change if the circumstances require it.

The reference to a composite material is more to do with the end product which will be an embedded sensor network incorporated into a material giving it additional properties rather than using the properties of a material to detect strain.

The aim is to detect position and magnitude of force on a given piece of material using strain gauges. So I would need to design a circuit that could be integrated into a material to detect the location of any forces. Then I can look for a way to create a prototype, maybe something like 'Direct Write' I have seen or a flexible PCB board. Detecting damage isn't required though additional credit would be awarded.

Does this sound more reasonable for a 3rd year EE? Would be great to hear some feedback.

Thanks