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jt512


May 17, 2010, 5:10 PM
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An online impact force calculator
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I've put an online version of a simple impact force calculator I wrote on my website here.

Here is a screen shot:



The calculator calculates the theoretical maximum impact force of a fall, using the standard model of impact force╣ and a friction-adjusted model▓. Both models depend on a measure of the rope's elasticity called the "rope modulus." If you happen to know the rope modulus, you can enter it directly; otherwise, you can enter the rope's UIAA impact force rating, and the calculator will use it to compute the rope modulus. The "friction factor" is the friction between the rope and the anchor, expressed as a proportion of the impact force on the climber. If you have no idea what that means, accept the default value of 0.33333.

Let me know if you have any questions or comments. In particular, if you find that the calculator does not work, let me know what operating system, browser, and browser version you are using. The calculator should work on any modern browser running javascript, but I'm no expert at this, and I've only tested it on a few combinations of operating system and browser.

Jay

StandardEqn.pdf
Adjusted-impact-force.pdf


(This post was edited by jt512 on May 17, 2010, 5:10 PM)
Attachments: onlinecalc.jpg (75.6 KB)


johnwesely


May 17, 2010, 5:21 PM
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Re: [jt512] An online impact force calculator [In reply to]
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Thanks Jay.


USnavy


May 17, 2010, 11:42 PM
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Re: [] An online impact force calculator [In reply to]
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I am assuming the program assumes a completely static belay?


jt512


May 17, 2010, 11:57 PM
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Re: [USnavy] An online impact force calculator [In reply to]
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USnavy wrote:
I am assuming the program assumes a completely static belay?

Yes.


yokese


May 18, 2010, 12:54 AM
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Re: [jt512] An online impact force calculator [In reply to]
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Thanks jt,
one question though:
how come the friction increases the impact on the belayer?

Would it be possible (and easy) to include a check box for half-ropes, whose published impact force rating is calculated with 55Kg instead of 80Kg?


majid_sabet


May 18, 2010, 12:58 AM
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Re: [jt512] An online impact force calculator [In reply to]
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jt512 wrote:
I've put an online version of a simple impact force calculator I wrote on my website here.

Here is a screen shot:



The calculator calculates the theoretical maximum impact force of a fall, using the standard model of impact force╣ and a friction-adjusted model▓. Both models depend on a measure of the rope's elasticity called the "rope modulus." If you happen to know the rope modulus, you can enter it directly; otherwise, you can enter the rope's UIAA impact force rating, and the calculator will use it to compute the rope modulus. The "friction factor" is the friction between the rope and the anchor, expressed as a proportion of the impact force on the climber. If you have no idea what that means, accept the default value of 0.33333.

Let me know if you have any questions or comments. In particular, if you find that the calculator does not work, let me know what operating system, browser, and browser version you are using. The calculator should work on any modern browser running javascript, but I'm no expert at this, and I've only tested it on a few combinations of operating system and browser.

Jay

StandardEqn.pdf
Adjusted-impact-force.pdf

how about non online version ?

can you email it?


yokese


May 18, 2010, 1:24 AM
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(This post was edited by yokese on May 18, 2010, 1:25 AM)
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johnwesely


May 18, 2010, 4:57 AM
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Re: [yokese] An online impact force calculator [In reply to]
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yokese wrote:
Thanks jt,
one question though:
how come the friction increases the impact on the belayer?

Would it be possible (and easy) to include a check box for half-ropes, whose published impact force rating is calculated with 55Kg instead of 80Kg?

Because friction in the system basically increases the fall factor by lowering rope stretch.


jt512


May 18, 2010, 9:10 AM
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Re: [majid_sabet] An online impact force calculator [In reply to]
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majid_sabet wrote:
jt512 wrote:
I've put an online version of a simple impact force calculator I wrote on my website here.

Here is a screen shot:



The calculator calculates the theoretical maximum impact force of a fall, using the standard model of impact force╣ and a friction-adjusted model▓. Both models depend on a measure of the rope's elasticity called the "rope modulus." If you happen to know the rope modulus, you can enter it directly; otherwise, you can enter the rope's UIAA impact force rating, and the calculator will use it to compute the rope modulus. The "friction factor" is the friction between the rope and the anchor, expressed as a proportion of the impact force on the climber. If you have no idea what that means, accept the default value of 0.33333.

Let me know if you have any questions or comments. In particular, if you find that the calculator does not work, let me know what operating system, browser, and browser version you are using. The calculator should work on any modern browser running javascript, but I'm no expert at this, and I've only tested it on a few combinations of operating system and browser.

Jay

StandardEqn.pdf
Adjusted-impact-force.pdf

how about non online version ?

An online version of the online calculator? Try clicking the link above that says "here."

Jay


jt512


May 18, 2010, 9:11 AM
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Re: [yokese] An online impact force calculator [In reply to]
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yokese wrote:
Mac OS X 10.6.3
Safari 4.0.5

[image]http://www.rockclimbing.com/cgi-bin/forum/gforum.cgi?do=post_attachment;postatt_id=4890;[/image]

Based on your earlier post, it appears that you were able to access the page. Was that by using a different computer, or was this a temporary error?

Jay


yokese


May 18, 2010, 9:37 AM
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Re: [johnwesely] An online impact force calculator [In reply to]
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johnwesely wrote:
yokese wrote:
Thanks jt,
one question though:
how come the friction increases the impact on the belayer?

Because friction in the system basically increases the fall factor by lowering rope stretch.

Yes, but that would increase the force on the climber's end of the rope, not the belayer. I might be misunderstanding Jay's equations, but in the extreme case of friction=1, the impact on the belayer end should be 0...


yokese


May 18, 2010, 9:42 AM
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Re: [jt512] An online impact force calculator [In reply to]
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jt512 wrote:
yokese wrote:
Mac OS X 10.6.3
Safari 4.0.5

[image]http://www.rockclimbing.com/cgi-bin/forum/gforum.cgi?do=post_attachment;postatt_id=4890;[/image]

Based on your earlier post, it appears that you were able to access the page. Was that by using a different computer, or was this a temporary error?

Jay

Nope, I couldn't access it before. I just viewed the screen shot that you attached.
I've also tried with firefox to no avail. Same error (the server is taking too long to respond).
I'll check later on from a different location.


jt512


May 18, 2010, 9:43 AM
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Re: [yokese] An online impact force calculator [In reply to]
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yokese wrote:
how come the friction increases the impact on the belayer?

I think what you're asking is, "Why is the impact force on the belayer higher under the friction-adjusted model than under the standard model?" The reason is that the standard model ignores the effect of friction on the impact force on the climber, whereas the friction-adjusted model takes it into account. Friction increases the impact force on the climber. Thus the impact force on the climber is higher under the friction-adjusted model than under the standard model. However, in both models, the impact force on the belayer is assumed to be a percentage of the impact force on the climber. Therefore, the impact force on the belayer is higher under the friction-adjusted model than under the standard model.

Jay


(This post was edited by jt512 on May 18, 2010, 9:44 AM)


majid_sabet


May 18, 2010, 10:26 AM
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Jay

I want to install in my laptop so I could use without having access to internet


jt512


May 18, 2010, 10:30 AM
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majid_sabet wrote:
Jay

I want to install in my laptop so I could use without having access to internet

I only have one that runs on Linux; nothing for Windows or Mac.

Jay


majid_sabet


May 18, 2010, 11:18 AM
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yokese


May 18, 2010, 11:27 AM
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yokese wrote:
jt512 wrote:
yokese wrote:
Mac OS X 10.6.3
Safari 4.0.5

[image]http://www.rockclimbing.com/cgi-bin/forum/gforum.cgi?do=post_attachment;postatt_id=4890;[/image]

Based on your earlier post, it appears that you were able to access the page. Was that by using a different computer, or was this a temporary error?

Jay

Nope, I couldn't access it before. I just viewed the screen shot that you attached.
I've also tried with firefox to no avail. Same error (the server is taking too long to respond).
I'll check later on from a different location.

it works from my place, so it might be a problem with the firewall at my workplace.


jt512


May 18, 2010, 12:04 PM
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majid_sabet wrote:
jt512 wrote:
majid_sabet wrote:
Jay

I want to install in my laptop so I could use without having access to internet

I only have one that runs on Linux; nothing for Windows or Mac.

Jay

my laptop runs on both windows and linux so can you email the linux version ?

noorkota@hotmail.com

Thanks

Majid,

Are you running 32-bit or 64-bit Linux? The calculator I have was compiled for 64-bit Linux. If you're running a 64-bit operating system, I can email you the calculator right away. If you're running 32-bit, I'll have to compile a 32-bit version first. Let me know.

Jay


Partner cracklover


May 18, 2010, 12:49 PM
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Looks good. You may or may not be interested, but I ran a quick dummy-check. I independently compared the numbers you get for the impact on the climber based on RG's standard model to the numbers I get from the same (I created a simple version of this some months ago).

Varying the parameters climber weight, rope modulus, and fall factor, I consistently got the same numbers as you.

Nice to have this online, especially since Petzl's calculator went away.

Cheers,

GO


JimTitt


May 18, 2010, 1:02 PM
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If I put in a climbers weight I┤m getting 20% higher impact forces than are experienced in reality, maybe you need a correction factor incorporated to take into account that the impact force rating is derived from an already corrected soft body mass. In other words the test 80kg to get the rope impact rating is used as it represents a 100kg climber in a harness. When you put 80kg into the calculator you get the rated impact force of the rope but this is in reality the force experienced by a 100kg climber. Put 100kg in and you get 20% higher impact than will occur.
Jim


majid_sabet


May 18, 2010, 1:14 PM
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jt512 wrote:
majid_sabet wrote:
jt512 wrote:
majid_sabet wrote:
Jay

I want to install in my laptop so I could use without having access to internet

I only have one that runs on Linux; nothing for Windows or Mac.

Jay

my laptop runs on both windows and linux so can you email the linux version ?

noorkota@hotmail.com

Thanks

Majid,

Are you running 32-bit or 64-bit Linux? The calculator I have was compiled for 64-bit Linux. If you're running a 64-bit operating system, I can email you the calculator right away. If you're running 32-bit, I'll have to compile a 32-bit version first. Let me know.

Jay

Jay

I got both 64 and 32 bit on my laptop and on my PC at work so email both if you could, If you could do this on windows, that would be very nice.

Thanks again

Majid


jt512


May 18, 2010, 1:21 PM
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Re: [majid_sabet] An online impact force calculator [In reply to]
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majid_sabet wrote:
jt512 wrote:
majid_sabet wrote:
jt512 wrote:
majid_sabet wrote:
Jay

I want to install in my laptop so I could use without having access to internet

I only have one that runs on Linux; nothing for Windows or Mac.

Jay

my laptop runs on both windows and linux so can you email the linux version ?

noorkota@hotmail.com

Thanks

Majid,

Are you running 32-bit or 64-bit Linux? The calculator I have was compiled for 64-bit Linux. If you're running a 64-bit operating system, I can email you the calculator right away. If you're running 32-bit, I'll have to compile a 32-bit version first. Let me know.

Jay

Jay

I got both 64 and 32 bit on my laptop and on my PC at work so email both if you could, If you could do this on windows, that would be very nice.

Thanks again

Majid

Like I said, I only have a 64-bit Linux version. So, since that should work for you, I'll send it out.

Jay


majid_sabet


May 18, 2010, 1:26 PM
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jt512 wrote:
majid_sabet wrote:
jt512 wrote:
majid_sabet wrote:
jt512 wrote:
majid_sabet wrote:
Jay

I want to install in my laptop so I could use without having access to internet

I only have one that runs on Linux; nothing for Windows or Mac.

Jay

my laptop runs on both windows and linux so can you email the linux version ?

noorkota@hotmail.com

Thanks

Majid,

Are you running 32-bit or 64-bit Linux? The calculator I have was compiled for 64-bit Linux. If you're running a 64-bit operating system, I can email you the calculator right away. If you're running 32-bit, I'll have to compile a 32-bit version first. Let me know.

Jay

Jay

I got both 64 and 32 bit on my laptop and on my PC at work so email both if you could, If you could do this on windows, that would be very nice.

Thanks again

Majid

Like I said, I only have a 64-bit Linux version. So, since that should work for you, I'll send it out.

Jay

jay

you got any calculator for high-line application ?

Something that we could calculate forces on the anchors based on sag , weight of the load and distance between the anchors.


jt512


May 18, 2010, 1:27 PM
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Re: [JimTitt] An online impact force calculator [In reply to]
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JimTitt wrote:
If I put in a climbers weight I┤m getting 20% higher impact forces than are experienced in reality, maybe you need a correction factor incorporated to take into account that the impact force rating is derived from an already corrected soft body mass. In other words the test 80kg to get the rope impact rating is used as it represents a 100kg climber in a harness. When you put 80kg into the calculator you get the rated impact force of the rope but this is in reality the force experienced by a 100kg climber. Put 100kg in and you get 20% higher impact than will occur.
Jim

What are you basing "reality" on? If you can provide a source, I'd consider incorporating it in the application.

Jay


JimTitt


May 18, 2010, 2:53 PM
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If you take a rope and put in the values for the standard drop test you get the impact force back out for that particular rope which is correct for a solid weight BUT the standard drop test includes a correction factor as they use a solid weight instead of a climber in a harness.
If your calculator is meant to be working with a climbers weight this factor has to taken into account. You can see this by putting a climbers weight of 100kg (220lb) in with a rope tested giving 8kN impact. Your calculator gives the impact as 9.03kN but we know the rope tested with a weight representing a climber of 100kg in fact has an impact rating of 8kN.
The UIAA decided way back in the 70┤s that a 80kg solid weight represents the impact of a 100kg (in fact 101 and a little bit if I remember rightly) climber after tests by Troll who made some of the early harnesses. The factor for fall restraint testing is even higher at 1.34:1 but there are moves to reduce this.

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