Hardness of Hooks
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I did some googling out of curiosity, but I couldn't find any answers...so I measured it my damn self. |
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Interesting info, thanks! |
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Does psi translate into newtons or kilo newtons or some other measurement I might be more familiar with? |
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BBQ wrote:Does psi translate into newtons or kilo newtons or some other measurement I might be more familiar with?Sure, 160 ksi translates to about 1.1 GPa. |
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BBQ wrote:Does psi translate into newtons or kilo newtons or some other measurement I might be more familiar with?N/m^2 is an equivalent. If you are looking for how many KN it will take to break a hook, that is not what the OP is talking about. |
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apoet wrote: N/m^2 is an equivalent.and 1 N/m^2 = 1 Pa, so 160 ksi = 1.1 GPa or 1.1 GN/m^2. |
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Be careful about translating hardness into strength. You can manipulate just the surface hardness without affecting the majority of the base metal. However 150 to 160 ksi is a very reasonable strength for steel. |
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You'd have to do a bunch of math for each hook and configuration to figure out what a kN on the rope would mean for a given tensile strength. Can't help you there; I'm just a software dork with access to a hardness tester that's more than twice my age. |
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NegativeK wrote:You'd have to do a bunch of math for each hook and configuration to figure out what a kN on the rope would mean for a given tensile strength. Can't help you there; I'm just a software dork with access to a hardness tester that's more than twice my age. I really just did the measurement because hooks are advertised as 4130, and I remember seeing somewhere that they're hardened.Doubt you can calculate the strength of a hook and produce a useful number. Maybe to guide design but then after that it is going to be real world testing to see what the finished product can consistently do. |
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King Tut wrote: Doubt you can calculate the strength of a hook and produce a useful number. Maybe to guide design but then after that it is going to be real world testing to see what the finished product can consistently do.Hmm, it´s not exactly rocket science. More like first or second year engineering stuff. |
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Jim Titt wrote: Hmm, it´s not exactly rocket science. More like first or second year engineering stuff.I would bet that a simple FEA simulation would give relatively accurate results. I will try it out if someone gets me a CAD model of a hook they want to test along with its material properties. |
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apoet wrote: I would bet that a simple FEA simulation would give relatively accurate results. I will try it out if someone gets me a CAD model of a hook they want to test along with its material properties.That sounds like pointless fun I can get behind. I'll follow up with hardness measurements of the BD Cliffhanger and Grappling Hook and a Leeper micro cam hook next week, but my CAD skills are best described as "hilariously shitty". Every reference to material I've seen is 4130. If I'd half a mind, I would've gotten the folks with an X-ray fluorescence gun who passed through recently to zap the stuff I have. |
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Rockwell hardness has nothing to do with tensile strength. |
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Jim Titt wrote: Hmm, it´s not exactly rocket science. More like first or second year engineering stuff.Ok, I am happy to be educated in this regard. Its the bend in the material (ie the pointy end) that I am wondering about. Obviously the hole for the sling would be simple I would think. I certainly defer to the real engineers that know this stuff though. :) |
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King Tut wrote: Ok, I am happy to be educated in this regard. Its the bend in the material (ie the pointy end) that I am wondering about. Obviously the hole for the sling would be simple I would think. I certainly defer to the real engineers that know this stuff though. :)With modern CAD/FEA software, this analysis is pretty trivial. That's not to say that actual testing to failure isn't relevant, but with simple geometry and loading the results should be reliable. I am not an expert in this area, but took a few related classes in college and have access to the software at work. If anyone has the means to test hooks to failure, I would love to see the results. I am sure BD has done extensive testing and simulation, but I doubt it is worth the investment for smaller companies to do FEA. |
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apoet wrote: With modern CAD/FEA software, this analysis is pretty trivial. That's not to say that actual testing to failure isn't relevant, but with simple geometry and loading the results should be reliable. I am not an expert in this area, but took a few related classes in college and have access to the software at work. If anyone has the means to test hooks to failure, I would love to see the results. I am sure BD has done extensive testing and simulation, but I doubt it is worth the investment for smaller companies to do FEA.Pretty sure there´s a Talon in the "useless junk I bought once" box, no problem to put it on the tester over the weekend. Bat-hook holes in granite or in a steel block? |
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Jim Titt wrote: Pretty sure there´s a Talon in the "useless junk I bought once" box, no problem to put it on the tester over the weekend. Bat-hook holes in granite or in a steel block?Steel block would probably be easier to simulate. Also, if you can get a picture of how you load it so I can accurately replicate it that would be helpful. Now I need a CAD model of a Talon hook. Any takers? |
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I can also run the simulation, anyone has the alloy and temper treatment? |
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Luc-514 wrote:I can also run the simulation, anyone has the alloy and temper treatment? As for the CAD model... I could but I really don't have the time ;-)4130, Rockwell C 34 -- presumably through thickness, because they aren't that thick, right? I can slap together some (roughly presented) measurements when I do the rest of the hardness tests, to help whoever ends up being the cad. All I've got for rockwell hardness -> tensile strength is stuff like link.springer.com/article/1… and conversion charts that indicate that seem to indicate that people are relying on the approximate correlation. |
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Jim Titt wrote: Pretty sure there´s a Talon in the "useless junk I bought once" box, no problem to put it on the tester over the weekend. Bat-hook holes in granite or in a steel block?Bat-hook holes in granite, please. |
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Though I will need to review how to apply the load on the hook, probably lower third surface of the webbing hole. |