WRC Deaths

What I mean by it being non-linear is that the amount of stretch is not a simple percent (for a given impact or force). But I also know that the percent is not a linear function of length, either, which rules out anything like 2%/foot. Plus, we know that the function also depends on the impact or force. There's quite a bit to it all and no simple equation or set of pictures or data from a single test will tell you anything close to all of it.

Either use Google Scholar to find some articles on it or let it go. Arguing about some simple function that someone pulled out of his ass is a waste of time.

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Iowa999
Keith -

He's claiming that it's non-linear, which could easily be true. There's no freaking way that it's anything like X%/foot, but it's almost definitely not a simple percent, either.

edit: I find John's participation in a discussion of belt-stretch to be amusingly appropriate in the extreme, given that it isn't acceleration that matters, but the next derivative above, which is known as "jerk"

No trolie No1 and King Troll , I said "we cannot say" since it is dependand on so many factors which should be obvious to anybody except trolls who only come round to troll. x%/foot is X% or whatever per foot..
Shirley you guys cannot be as totally dense as you are pretending, so who do you bring to a discussion when you act like you don't understand?

You guys are the bane of the internet and discussion forums.

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John Vanlandingham
Sleezattle, WA, USA

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www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

Does it ever occur to you that when, for example, people question one your more stupid statements, such as belt stretch is X% per foot, it isn't because we don't understand what you mean, but because we know exactly what you mean and we know that it's wrong, such that repeating it a few more times is really silly?

No?

Thought not.



Edited 2 time(s). Last edit at 09/26/2013 09:06PM by Iowa999.

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john vanlandingham
x%/foot is X% or whatever per foot..
Shirley you guys cannot be as totally dense as you are pretending, so who do you bring to a discussion when you act like you don't understand?

Not Trollin...
It started, simply enough, asking for a clarification - or confirmation - that what you were saying is that with a 2%/ft stretch rate that you are suggesting that a 1' section of belt would stretch 2% but a 2 foot section of belt would stretch 4%.
That is what 2%/foot looks like.

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john vanlandingham
Blame is for idiots. losers.

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alkun

Too.....scared.....to... click

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I find it puzzling that we keep arguing about this as if it is some sort of mystery. This is simple Newtonian physics and the stuff has been known for a long time.

The stretch of the seatbelt is most likely described by a stress-strain diagram, where as you increase the stress (load per unit area) the strain (%elongation) will first increase linearly till you hit the elastic limit and then non linearly till you hit the ultimate strength limit at which point the belt will rupture. If you have high enough stress, the material will get beyond the linear elastic limit. However, it shouldn't be expressed as percent elongation per foot. If it is per foot of belt material, then it is wrong, stress/strain diagram should not change because of the length of the sample, only depend on cross sectional area. If it is per foot of belt stretch, then its probably true, but awfully ambiguous, because foot of belt stretch will be different percent elongation depending on how long the belt is, therefore you have to put in %/foot of 100ft long belt for example. But much better to use strain/stress diagram as engineers have been doing forever.
Here is a pic of stress/strain diagram of some nylon, stuff that goes into some seatbelts:
http://nanotechweb.org/cws/article/tech/27559/1/070408

I found this cool document having a lot of plots of Gs and other things during car crashes:
web.iitd.ac.in/~achawla/public_html/736/crashworthiness_v1.pdf

Finally, here is a very interactive site explaining the physics of normal seat belts:
http://hyperphysics.phy-astr.gsu.edu/hbase/seatb.html

Edit: different stress/strain graph. Link didn't work.

Klim



Edited 2 time(s). Last edit at 09/26/2013 11:24PM by mulik52.

Quote
Morison

Quote
john vanlandingham
x%/foot is X% or whatever per foot..
Shirley you guys cannot be as totally dense as you are pretending, so who do you bring to a discussion when you act like you don't understand?

Not Trollin...
It started, simply enough, asking for a clarification - or confirmation - that what you were saying is that with a 2%/ft stretch rate that you are suggesting that a 1' section of belt would stretch 2% but a 2 foot section of belt would stretch 4%.
That is what 2%/foot looks like.

fuck can't you just shut the fuck up? You are a former used car salesman, former photographer, you can't understand normal thinking and are clueless about anything but arguing.. this is not a fucking treatise or some fucking academic exercise, and nobody cares if you thought it meant anything, just shut up.

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

Quote
mulik52
I find it puzzling that we keep arguing about this as if it is some sort of mystery. This is simple Newtonian physics and the stuff has been known for a long time.

The stretch of the seatbelt is most likely described by a stress-strain diagram, where as you increase the stress (load per unit area) the strain (%elongation) will first increase linearly till you hit the elastic limit and then non linearly till you hit the ultimate strength limit at which point the belt will rupture. If you have high enough stress, the material will get beyond the linear elastic limit. However, it shouldn't be expressed as percent elongation per foot. If it is per foot of belt material, then it is wrong, stress/strain diagram should not change because of the length of the sample, only depend on cross sectional area. If it is per foot of belt stretch, then its probably true, but awfully ambiguous, because foot of belt stretch will be different percent elongation depending on how long the belt is, therefore you have to put in %/foot of 100ft long belt for example. But much better to use strain/stress diagram as engineers have been doing forever.
Here is a pic of stress/strain diagram of some nylon, stuff that goes into some seatbelts:
http://nanotechweb.org/cws/article/tech/27559/1/070408

I found this cool document having a lot of plots of Gs and other things during car crashes:
web.iitd.ac.in/~achawla/public_html/736/crashworthiness_v1.pdf

Finally, here is a very interactive site explaining the physics of normal seat belts:
http://hyperphysics.phy-astr.gsu.edu/hbase/seatb.html

Edit: different stress/strain graph. Link didn't work.

Klim

Klim, overanalyzing again..
I used / as "or"..when i write dimensions I write 0.966"/22mm OR And I said "we cannot say' because of the huge amount of variable that we can only make assumptions...look at your examples where driver's weight is just randomly chose as 160lbs/72,2kg (from USGOV so its probably Obama lying again to steal your freedoms)

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Meanwhile, the average weight for men aged 20-74 years rose dramatically from 166.3 pounds in 1960 to 191 pounds in 2002,

See 191 average weight is a shit ton more stress than random sample, but speed we can't say, duration of decell, how many impacts, just too much

Main point is we cannot say without data, so there must be some other way to try and learn: praxis. And observed results.

---

John Vanlandingham
Sleezattle, WA, USA

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Remember! Pacific Standard Time
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Quote
john vanlandingham
I used / as "or"..when i write dimensions I write 0.966"/22mm OR

See, Keith. A complete waste of time. You're talking about math with a guy who either can't write a simple equation correctly or who thinks that X% is the same as one foot, just a change in the units.

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john vanlandingham
And I said "we cannot say' because of the huge amount of variable that we can only make assumptions...

Narcissism incarnate (or, if you're Freudian, projection writ large). You cannot say, thus you assert that we cannot say, implying that no-one can say. Fortunately, the state of world's knowledge is not limited by what you (think that you) know. There are plenty of people who can say exactly what factors determine belt stretch and write a proper equation to describe it. You're just not one of them.

Deal with it.

I love lamp.

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john vanlandingham
x%/foot is X% or whatever per foot..

[bold added]

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john vanlandingham
I used / as "or"..when i write dimensions I write 0.966"/22mm OR

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john vanlandingham
fuck can't you just shut the fuck up?

And why can't you simply answer an honest question without turning it into drama.

You wrote "Belt stretch should be expressed in % of stretch per length ie 2%/foot or something like that," which sounded very authoritative, but didn't make a lot of sense to me so I asked for clarification. (It really is that simple, you might think otherwise but I don't have any need, or desire, to make you look bad.)

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john vanlandingham
...this is not a fucking treatise or some fucking academic exercise, and nobody cares if you thought it meant anything, just shut up.

No, it's a discussion forum and I was simply looking for clarification of what you said. But no, you have such an ingrained reaction to me that you can't even take a second to answer a simple question. You could have responded more like you did in answering Kilm, but you didn't.

Although what you said in your response to Kilm,

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john vanlandingham
I used / as "or"..when i write dimensions I write 0.966"/22mm

,
doesn't match what you said above, which was explicitly '% stretch per length ie 2%/foot.'

So, a backpedal in what you said - which is fine. So many good people have said, 'that didn't come out right,' or 'that's not what I meant to say,' or 'yah, that didn't make any sense.' It's all part of being human.

---

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Quote
john vanlandingham
Blame is for idiots. losers.

Whoa, dude. He might have been a jerk to you and gone so far as to tell you to fuck off, but that's no reason to suggest that he's merely human. Uncool. Seriously uncool.

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Morison

Quote
john vanlandingham
fuck can't you just shut the fuck up?

And why can't you simply answer an honest question without turning it into drama.

You wrote "Belt stretch should be expressed in % of stretch per length ie 2%/foot or something like that," which sounded very authoritative, but didn't make a lot of sense to me so I asked for clarification. (It really is that simple, you might think otherwise but I don't have any need, or desire, to make you look bad.)

Quote
john vanlandingham
...this is not a fucking treatise or some fucking academic exercise, and nobody cares if you thought it meant anything, just shut up.

No, it's a discussion forum and I was simply looking for clarification of what you said. But no, you have such an ingrained reaction to me that you can't even take a second to answer a simple question. You could have responded more like you did in answering Kilm, but you didn't.

Although what you said in your response to Kilm,

Quote
john vanlandingham
I used / as "or"..when i write dimensions I write 0.966"/22mm

,
doesn't match what you said above, which was explicitly '% stretch per length ie 2%/foot.'

So, a backpedal in what you said - which is fine. So many good people have said, 'that didn't come out right,' or 'that's not what I meant to say,' or 'yah, that didn't make any sense.' It's all part of being human.

Should--that's never authoritative..

Just shut up. It's technical and wasn't directed at you and you are once again derailing and fucking up a thread, again.
Klim is a newbie in this world and he knows he tends to overanalize.. It was conversation--again note a treatise. People don't talk in 100% perfect accuracy, especially when its just wanky talk about shit we have no data about--THAT was the main point to help him understand the piccies don't show us anything useful (because of lack of data and the extreme variability of each and every factor) and to not overanalyze when there's no reason to.
Just shut up.

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.