(-Planning Exercise - Strain gauge Coursework Help -)

[aimi]

hey. i'll leave you to it. i got to go watch a film for english so... hope i have helped. good luck with it.

 

[Thor86]

physics plan

Do we have to mention young’s modulus stress/strain?? Why can't you attach the gauge with epoxy and connects different sized masses to an end the measure the current change then work out the resistance?

 

[Thor86]

a voltage is applied across the wires not masses I thought. I heard of that bridge thing but all I know is it makes it more sensitive

 

[aimi]

the voltage is applied to the strain guage. potential difference over this can be mausured, also current to work out resistance (R=V/I).
Your diagram is a good idea Thor86, i thought of putting it on a table and using a pulley with the mass hanging, i reckon either would work. whatever though. I'm past caring. think i know what I'm doing - in a fasion!

 

[the fugitive]

wot i dnt get...(by the ways hey peepz wot u lot sayin?) well basicly me got the sme exercise to do by thursday...n me ain t got a clue either...so me was wandrin ..insted of jus sayin ''me gota do this n sumbody helpp''...can sum1 ACTUALLY help lolz...if u notice yeh...everyone jus rites that me doing that me need help blah blah but no1's helpin lolz...sumbody out ther...PLEASE HELP ME! (me'll pay u if it thas wot it tkes...or u gurls can ha v lil suming else lolz) nah only messin

 

[the fugitive]

so erm ...me biggin to understand this ****...but wot dus u use to giv a voltage suplly? wer dus the current cum from peeps? (excuse me...me reali dumb) soz

 

[the fugitive]

k erm start from the beginning...me figured out the apparatus n the idagram...got ma voltmeter n ammeter around the strain gauge...and a wire connected to the strain gauge with mass hangin from it...me got a redin for the voltmeter n ammeter...then me add asum mor weights and got mor readins from the voltmeter n ammeter...now wot dus me do with the readings? wots the aim/ i dnt get it proply peepz! please help me please...me can't flop this subject!

 

[Byj]

Hiiii! I put my plan in 2day. Just to make u feel a bit better 'the fugitive' dude, it only counts for 2.5% of your waves theory model, so its a load of bull really. Use a wheatstone bridge, you'll see details about this on a me82 site, R=V/I can be calculated. Every time you add extra load (more Newton weights), you'll have to measure the voltage and current, work out the resistance and tabulate all the readings. You can then plot a graph, the relationship of resistance against force would show u the change in resistance, i'd say it's directly proportional, or resistance increases when force increases most definitely.

I get my plan back on friday so I can alter it, I gave the drapht into mark. If I learn something new, I'll give u the low down boys & girls.
Good luck and **** happens, I think we should all worry more about revising than this waste of time Plan thing. Stupid OCR examining board!

 

[Byj]

Stick the strain gauge with an adhesive to a wire e.g constantan wire, apply force to the constantan wire hanging over a bench. Don't apply too much force or it will snap. No more than 15 Newtons or it will break under the strain !Dangerous!
You don't need the youngs modulus, this I don't think has anythins to do with youngs modulus, it's to do with electrical reisitance!

in the words of Cilla Black " Trraaarr everyone!"

 

[n1ck_w87]

What are you meant to attch the strain gauge to. A wire would be too thin, wouldn't it? Got to hand this thing in nxt week, no idea what i`m doing! Can anyone explain how to use a wheatstone bridge, my physics teacher is probly worse at physics than me!

 

[aimi]

Byj, u r so smart cheers dude! i don't give a **** anymor tho. like u said 5% don't mean ****! L8r! x x

 

[susie28]

i'm doing this experiment too, n i av 2 hand it in in 6 days. i havnt even started. can som1 point me in da drite direction? i have no clue. help me please.

 

[susie28]

r u actually allowed 2 give it 2 ur teach 2 look at? wer not, my teach won't even tell me wat appartus 2 use. som 1 tell me from start 2 finish our 2 do dis, n som1 diagrams 2 wil b helpful. av 2 hand it in in 6 days. dats wen i'v got da practiacl examination. or do u no any websites i can get it from? thanx

 

[the fugitive]

erm...fukin hell me so dumb lol...me been told to attach the strain gauge to a pice of metal...and clamp it horizontally so that its in midair n then hang weight of bout 50 kg etc n measure the resistance across the strain gauge...then a graph of resistance against force ...is that rong? but me dnt kno how big a strain gauge is...sum1 tel me please?

 

[jad_65_2003]

The Experiment Has Nothing To Do With A Crane

 

[the fugitive]

yeh so can sum one please ansa me...? how big is a strain guage? n how big shud the metal strip be? n wot metal shud be used? please tel me !

 

[jad_65_2003]

about 1 cm squared

 

[the fugitive]

wot the metal or the gauge?

 

[sbenj]

Well, aluminium is good cos its young modulus is quite low (that means it is stretchy). a wheatstone bridge is a combination of four resistors, but it is not really necessary, it just makes the measurements more sensitinve than using a multimeter on the resistance range (which is better than using an ammeter and voltmeter and doing loads of calculations), so wheatstone bridge may get an extra mark or two, but not vital. to stik the gauge to the aluminium, use cyanoacrylate. what i am not sure of yet is how to apply the force. any ideas?

 

[sbenj]

quickly ppl, mine is in for 2morro! and i think aluminium foil would b good, as long as it doesn't rip. do u think u could apply the force by clamping the metal horizontally and loading masses on one end? or is that not a tensile force?

 

[the fugitive]

yeh mate that's wot me doin! how big is ur metal strip ?

 

[sbenj]

well, the longer the better, and the thinner, both in width and thickness the better. so it should be quite long, very thin, and as wide as the strain gauge, which i am afraid i have no measurements for

 

[the fugitive]

k...so that dnt reali help me but fanx neway me gota hand it in tomro too...how bout this for measurements for the metal strip: 30mm x 160mm ? that long enuff?

 

[sbenj]

no idea. probably. how r u going to attatch the force?

 

[the fugitive]

at the end of the strip...ther gna be a hole for a weight hanger to han g from it n then aply 0.1 kg weights to it one by one...is that stupid or ok?

 

[arizonian]

Stress is a load applied to an object. Strain is the deformation of the object under stress. Pull a taffy candy strip lengthwise. The pull is the stress and the lengthening of the candy is the strain. Both can be quantified. The load divided by the cross sectional area gives pounds per square inch (psi). The (final length of the candy strip being deformed minus the original length) divided by the original length is the percentage of deformation.
Now that you know stress and strain, you need to take readings with your multimeter while applying different loads and at different locations. The different locations will change the loading on a cantilever beam suspended by a cable. Use trigonometry to calculate the loading in the cable.

On edit, I did not realize that there were 4 pages of posts. I hope this helps those that still have time.

 

[the fugitive]

erm...ell not reali coz it all so complicated n u jus made everyone elses suggestinos that me has had (that sounded good) sound crap...n especially as me understood those ones lolzzzzzz fuk it me jus na stik to wot me originally thought

 

[Fireball]

at the end of the strip...ther gna be a hole for a weight hanger to han g from it n then aply 0.1 kg weights to it one by one...is that stupid or ok?

Thats what I'm thinking of doing and I'm supposed to be doing it this afternoon!

 

[CKLi]

Hi! Try this website to find out more about Strain gauges. www.dur.ac.uk/richard.scott/gauges.html[/URL]

 

[devil_uk]

coursework

i have until wednesday 19th to get mine in, and i am cluless to what to do...i know what a strain gauge is and that the crain has nothing to do with it, but i have no idear how big the gauge is, or how we have/allowed to apply the force to the material, which i have no-idear to what I am using.....lol.....we are all doomed.....

 

[Fireball]

Hi! Try this website to find out more about Strain gauges. www.dur.ac.uk/richard.scott/gauges.html[/URL][/QUOTE]
Thanks for that link, I had no idea what this was all about :confused: before but reading that sorted everything out in my head and helped me to understand the theory behind it all. i now know exactly what I have to do! :smile: :biggrin: :approve: :rofl: :smile:

 

[ashpot86]

I have to write mine up in exam conditions tomorrow(13/5/04), I am trying to plan it now but not much luck, the question asks for any relationship between the force applied to the surface and the electrical resistance, so all that strain and stress doesn't need to be worked out I don't think. I said to use a standard metre rule made of beech wood (i think). Whenever you look for a relationshipe between two things it means plot them in a graph, so i guess that will be a good idea to include. My idea for how the strain gauge is attached to the surface, i just think using a strong adhesive will suffice. For plotting a graph you want a good range of forces to apply, however you want to keep other variables constant. The only thing I haven't thought about yet is what safetly precautions to include. Ah well...

 

[firstkings]

the experiment is in two parts...

stretch a piece of wire . Add a mass, measure the resistance of the strain gauge. No wheatstone bridge, no crane. Glue (superglue) the strain gauge to the wire. keep adding masses (weights), keep measuring V and I. etc

 

[ibnwando]

Thanks for that site CKLI .iT WAS totally relevant!
Im in teh same situation as well. Whats wrong with these OCR people??

 

[m0dm0]

Done mine today. thanks for the help everyone!