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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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#1
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As mentioned in the subject, I'm looking for steel suitable to be used to make an Olympic barbell, 2.2m long and 28mm in diameter. I'm torn between chrome-moly steel and spring steel. Again I'm not a metallurgist and know very little about these things. The bar will be at least 190000 psi tensile strength with 170000 psi yield strength. I'm also looking for decent machining characteristics so that I can put a knurl on it and cut grooves to attach sleeves.
Here are some steels I've thought about SAE 4340 (Heat treated to the required Tensile strength) SAE 4140 EN 47?? Thanks |
#2
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On Sun, 9 Nov 2014 09:47:38 -0800 (PST), Sandarpan Mukherjee
wrote: As mentioned in the subject, I'm looking for steel suitable to be used to make an Olympic barbell, 2.2m long and 28mm in diameter. I'm torn between chrome-moly steel and spring steel. Again I'm not a metallurgist and know very little about these things. The bar will be at least 190000 psi tensile strength with 170000 psi yield strength. I'm also looking for decent machining characteristics so that I can put a knurl on it and cut grooves to attach sleeves. Here are some steels I've thought about SAE 4340 (Heat treated to the required Tensile strength) SAE 4140 EN 47?? Thanks Those are extraordinarily high strength requirements. No steel hardened to those levels will be easy to machine; probably near-impossible to knurl. You can machine it in a normalized or annealed state, and then have it heat-treated. But are you sure you need that level of strength? What kind of load will be put on it to require that much strength? -- Ed Huntress |
#3
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On Sunday, November 9, 2014 12:47:43 PM UTC-5, Sandarpan Mukherjee wrote:
The bar will be at least 190000 psi tensile strength with 170000 psi yield strength. Thanks I can not imagine needing that kind of strength for something that a human in going to use. What diameter is the bar? What is the maximum weight that is going to be on the bar? My guess is that an ordinary barbell is made of something like A36. Dan |
#4
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On Sun, 9 Nov 2014 09:47:38 -0800 (PST), Sandarpan Mukherjee
wrote: snip The bar will be at least 190000 psi tensile st= rength with 170000 psi yield strength. /snip You are talking about very expensive HY210 submarine hull steel. I don't know if this is available in the civilian market. These specs seem excessive for even Olympic class lifters. A quick google search indicates less than 300Kg for any single lift. http://tinyurl.com/lmoxl6a -- Unka' George "Gold is the money of kings, silver is the money of gentlemen, barter is the money of peasants, but debt is the money of slaves" -Norm Franz, "Money and Wealth in the New Millenium" |
#5
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On Sun, 09 Nov 2014 13:05:58 -0600, F. George McDuffee
wrote: On Sun, 9 Nov 2014 09:47:38 -0800 (PST), Sandarpan Mukherjee wrote: snip The bar will be at least 190000 psi tensile st= rength with 170000 psi yield strength. /snip You are talking about very expensive HY210 submarine hull steel. I don't know if this is available in the civilian market. These specs seem excessive for even Olympic class lifters. A quick google search indicates less than 300Kg for any single lift. http://tinyurl.com/lmoxl6a He's around the high end for heat-treated 4340. The thing is, with yield of 170 kpsi and ultimate tensile of 190, when that bar is overloaded, it's going to go "Bang!" It doesn't sound like something you'd want in a barbell. g -- Ed Huntress |
#6
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#7
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On Sun, 09 Nov 2014 13:31:30 -0600, Ignoramus16121
wrote: On 2014-11-09, wrote: On Sunday, November 9, 2014 12:47:43 PM UTC-5, Sandarpan Mukherjee wrote: The bar will be at least 190000 psi tensile strength with 170000 psi yield strength. Thanks I can not imagine needing that kind of strength for something that a human in going to use. What diameter is the bar? What is the maximum weight that is going to be on the bar? My guess is that an ordinary barbell is made of something like A36. It is a thin bar, holding possibly 500 lbs on ends, held possibly in almost one point. i I get 1,026 total pounds of weights to reach yield strength. You're a good guesser, Ig. I think. I had to convert it all to inches, because I get screwed up using metric units for force -- kilogram-force versus Newtons. So don't count on it. -- Ed Huntress |
#8
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#10
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On 11/9/2014 1:31 PM, Ignoramus16121 wrote:
On 2014-11-09, wrote: On Sunday, November 9, 2014 12:47:43 PM UTC-5, Sandarpan Mukherjee wrote: The bar will be at least 190000 psi tensile strength with 170000 psi yield strength. Thanks I can not imagine needing that kind of strength for something that a human in going to use. What diameter is the bar? What is the maximum weight that is going to be on the bar? My guess is that an ordinary barbell is made of something like A36. It is a thin bar, holding possibly 500 lbs on ends, held possibly in almost one point. i And as you might recall - snatching one and press it to the top and let it fall to the ground. Hitting one end and crunch. Martin |
#11
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On Sun, 9 Nov 2014 10:48:21 -0800 (PST), "
wrote: On Sunday, November 9, 2014 12:47:43 PM UTC-5, Sandarpan Mukherjee wrote: The bar will be at least 190000 psi tensile strength with 170000 psi yield strength. Thanks I can not imagine needing that kind of strength for something that a human in going to use. What diameter is the bar? What is the maximum weight that is going to be on the bar? My guess is that an ordinary barbell is made of something like A36. Dan The top end Olympic lifting bars (Elieko) are said to be 215,000 psi tensile strength steel and are heat treated. They claim to test their7 bars in a jig that loads them to 1,500 Kg. (3,306 Lb.) and the bar must withstand that without taking a permanent set. The Men's standard bar is 2.2 M (7.2 ft.) long, the center section is 28 mm (1.1") with a "sleeve" on each end that is 415mm (16.3") long by 50 mm (1.968") in diameter. the sleeves are mounted on bearings so that when lifting the weights do not apply any torque to the center section where the bar is gripped. the complete bar weighs 20 Kg. A quick look seems to show that Hossein Rezazadeh, an Iranian, holds the record at a total weight lifted, in the two events, of 472 Kg, The Clean & Jerk record is 363 kg. and the Snatch record is 214 kg. The maximum that a human can bend over and pickup (Dead Lift) seems to be in the neighborhood of 460 Kg. or 1014 lbs. -- Cheers, John B. |
#12
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On Sun, 09 Nov 2014 19:49:09 -0600, F. George McDuffee
wrote: On Sun, 9 Nov 2014 15:20:59 -0500, "Carl Ijames" wrote: "Ignoramus16121" wrote in message ... On 2014-11-09, wrote: On Sunday, November 9, 2014 12:47:43 PM UTC-5, Sandarpan Mukherjee wrote: The bar will be at least 190000 psi tensile strength with 170000 psi yield strength. Thanks I can not imagine needing that kind of strength for something that a human in going to use. What diameter is the bar? What is the maximum weight that is going to be on the bar? My guess is that an ordinary barbell is made of something like A36. It is a thin bar, holding possibly 500 lbs on ends, held possibly in almost one point. i ================================================ ================================= Just for grins I ran the numbers for a bar 2.2 m long 28 mm dia simply supported at the ends with 1000 lbs concentrated at the center. That is equivalent to supporting the bar at the center and putting 500 lbs at the very end of each side. The deflection at the center if the bar doesn't yield will be 6.44 inches and the maximum stress will be 165,000 psi. I'll never stress a bar that much (at least not using just one hand :-) :-) :-)), but depending on the actual weight (one poster said about 300 kg as a reasonable max which is 660 lbs), and adding in some margin of safety since it will be a live load (3x? like a floor or deck that people walk on), the OP's specs aren't unreasonable as goals and may be low. In reality the center of gravity of the weights will be at least 8-10" from each end, and the lifts with maximum weight will be with two hands probably 24" apart. Using those dimensions (bar 20" shorter supported in two places 24" apart) and 500 lbs at each end gives much more reasonable results, max deflection 2.4" at the center and max stress of 81,000 psi. The real win would be going up in diameter; even 32 mm (1.26") makes the bar 1.7 times stiffer and stronger. If this is a custom bar aimed at world record weights, I think it is reasonable to assume adult-sized hands so think about making the bar bigger unless some sanctioning body has a rule specifying the dimensions. If you can't make it bigger, at least try to squeeze the weights as close to the center as you can. ----- Regards, Carl Ijames =================================== Anything to be gained by pre stressing the bar [assuming it is hollow] by putting some sort of tensioning device in the center such as a high strength (1/2"?) steel rod w/tensioning nuts on the end caps? Ive got an Olympic class bar with my weight set. Its solid bar stock. Get a few hundred pounds on a hollow bar..its called a pipe..and it will bend in a heartbeat. Gunner "At the core of liberalism is the spoiled child, miserable, as all spoiled children are, unsatisfied, demanding, ill-disciplined, despotic and useless. Liberalism is a philosophy of sniveling brats." PJ O'Rourke |
#13
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Carl Ijames wrote:
"Ignoramus16121" wrote in message ... On 2014-11-09, wrote: On Sunday, November 9, 2014 12:47:43 PM UTC-5, Sandarpan Mukherjee wrote: The bar will be at least 190000 psi tensile strength with 170000 psi yield strength. Thanks I can not imagine needing that kind of strength for something that a human in going to use. What diameter is the bar? What is the maximum weight that is going to be on the bar? My guess is that an ordinary barbell is made of something like A36. It is a thin bar, holding possibly 500 lbs on ends, held possibly in almost one point. i ================================================== =============================== Just for grins I ran the numbers for a bar 2.2 m long 28 mm dia simply supported at the ends with 1000 lbs concentrated at the center. That is equivalent to supporting the bar at the center and putting 500 lbs at the very end of each side. The deflection at the center if the bar doesn't yield will be 6.44 inches and the maximum stress will be 165,000 psi. I'll never stress a bar that much (at least not using just one hand :-) :-) :-)), but depending on the actual weight (one poster said about 300 kg as a reasonable max which is 660 lbs), and adding in some margin of safety since it will be a live load (3x? like a floor or deck that people walk on), the OP's specs aren't unreasonable as goals and may be low. In reality the center of gravity of the weights will be at least 8-10" from each end, and the lifts with maximum weight will be with two hands probably 24" apart. Using those dimensions (bar 20" shorter supported in two places 24" apart) and 500 lbs at each end gives much more reasonable results, max deflection 2.4" at the center and max stress of 81,000 psi. The real win would be going up in diameter; even 32 mm (1.26") makes the bar 1.7 times stiffer and stronger. If this is a custom bar aimed at world record weights, I think it is reasonable to assume adult-sized hands so think about making the bar bigger unless some sanctioning body has a rule specifying the dimensions. If you can't make it bigger, at least try to squeeze the weights as close to the center as you can. ----- Regards, Carl Ijames http://www.garage-gyms.com/olympic-b...ing-guide/#Oly -- Steve W. |
#14
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Ed Huntress wrote:
On Sun, 09 Nov 2014 13:05:58 -0600, F. George McDuffee wrote: On Sun, 9 Nov 2014 09:47:38 -0800 (PST), Sandarpan Mukherjee wrote: snip The bar will be at least 190000 psi tensile st= rength with 170000 psi yield strength. /snip You are talking about very expensive HY210 submarine hull steel. I don't know if this is available in the civilian market. These specs seem excessive for even Olympic class lifters. A quick google search indicates less than 300Kg for any single lift. http://tinyurl.com/lmoxl6a He's around the high end for heat-treated 4340. The thing is, with yield of 170 kpsi and ultimate tensile of 190, when that bar is overloaded, it's going to go "Bang!" It doesn't sound like something you'd want in a barbell. g Actually his numbers are at the minimum that are allowed in an Olympic bar. The lower end bars are 170K tensile. The good ones are up around 210K! The idea is that the bar has to flex when you lift, that helps you by storing energy that helps you flip during the lift. The bars also have bearing inside the weight sleeves so that as you lift the plates don't apply any torque to the bar and spoil the lift. I have friends who lift HEAVY and most seem to use Eleiko, York or Werksan bars. They are not cheap but they do seem to last. When they do clean/jerk lifts that bar looks like a wet noodle. -- Steve W. |
#15
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On Mon, 10 Nov 2014 10:43:15 -0500, "Steve W."
wrote: Ed Huntress wrote: On Sun, 09 Nov 2014 13:05:58 -0600, F. George McDuffee wrote: On Sun, 9 Nov 2014 09:47:38 -0800 (PST), Sandarpan Mukherjee wrote: snip The bar will be at least 190000 psi tensile st= rength with 170000 psi yield strength. /snip You are talking about very expensive HY210 submarine hull steel. I don't know if this is available in the civilian market. These specs seem excessive for even Olympic class lifters. A quick google search indicates less than 300Kg for any single lift. http://tinyurl.com/lmoxl6a He's around the high end for heat-treated 4340. The thing is, with yield of 170 kpsi and ultimate tensile of 190, when that bar is overloaded, it's going to go "Bang!" It doesn't sound like something you'd want in a barbell. g Actually his numbers are at the minimum that are allowed in an Olympic bar. The lower end bars are 170K tensile. The good ones are up around 210K! The idea is that the bar has to flex when you lift, that helps you by storing energy that helps you flip during the lift. The bars also have bearing inside the weight sleeves so that as you lift the plates don't apply any torque to the bar and spoil the lift. I have friends who lift HEAVY and most seem to use Eleiko, York or Werksan bars. They are not cheap but they do seem to last. When they do clean/jerk lifts that bar looks like a wet noodle. That's really pushing what you can do without really good material specification and very expert heat treating. You can get the ultimate tensile strength, but avoiding brittleness at that level of tensile strength is a job for the experts. -- Ed Huntress |
#16
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replying to Steve W. , Sandarpan Mukherjee wrote:
csr684 wrote: Actually his numbers are at the minimum that are allowed in an Olympic bar. The lower end bars are 170K tensile. The good ones are up around 210K! The idea is that the bar has to flex when you lift, that helps you by storing energy that helps you flip during the lift. The bars also have bearing inside the weight sleeves so that as you lift the plates don't apply any torque to the bar and spoil the lift. I have friends who lift HEAVY and most seem to use Eleiko, York or Werksan bars. They are not cheap but they do seem to last. When they do clean/jerk lifts that bar looks like a wet noodle. -- Steve W. What you are saying is absolutely true. This link ebay. co m.au/itm/F-OLB-Force-USA-Olympic-Lifting-Bar-20-Kg-Cross-Fit-Warranted-for-Crossfit-Use-/321487232831 (delete the spaces) advertises a bar of 216000 psi TS and it's mentioned that the bar is made from SCM 440 (same as AISI 4140) heat treated steel. What's bothering me is the hardness. Firstly I want to machine the bar and I also don't want it to be too brittle. Even if the yield strength is exceeded, I want the bar to bend not break. Thanks -- -- posted from http://www.polytechforum.com/metalwo...ll-605857-.htm using PolytechForum's Web, RSS and Social Media Interface to rec.crafts.metalworking and other engineering groups |
#17
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On Sat, 15 Nov 2014 18:18:01 +0000, Sandarpan Mukherjee
wrote: replying to Steve W. , Sandarpan Mukherjee wrote: csr684 wrote: Actually his numbers are at the minimum that are allowed in an Olympic bar. The lower end bars are 170K tensile. The good ones are up around 210K! The idea is that the bar has to flex when you lift, that helps you by storing energy that helps you flip during the lift. The bars also have bearing inside the weight sleeves so that as you lift the plates don't apply any torque to the bar and spoil the lift. I have friends who lift HEAVY and most seem to use Eleiko, York or Werksan bars. They are not cheap but they do seem to last. When they do clean/jerk lifts that bar looks like a wet noodle. -- Steve W. What you are saying is absolutely true. This link ebay. co m.au/itm/F-OLB-Force-USA-Olympic-Lifting-Bar-20-Kg-Cross-Fit-Warranted-for-Crossfit-Use-/321487232831 (delete the spaces) advertises a bar of 216000 psi TS and it's mentioned that the bar is made from SCM 440 (same as AISI 4140) heat treated steel. What's bothering me is the hardness. Firstly I want to machine the bar and I also don't want it to be too brittle. Even if the yield strength is exceeded, I want the bar to bend not break. Thanks It's not easy to find specific elongation properties of 4140 when it's heat-treated to 216 kpsi tensile. At the extreme end, 285,000 psi, elongation is 11% and machineability is 65%. Hardness is 578 Brinell or Rc 55. That's more machineable than I expected, although it's carbide-only at 285 kpsi, and I didn't even know that it could develop 285 kpsi tensile strength. That kind of tensile strength, in diameters larger than wire, usually is associated with fairly brittle specialty steels and very low elongation. So, at 216,000, elongation can be expected to be over 11%. That's not terrible. It shouldn't be inclined to break as soon as the yield strength is exceeded. The thing is, heat-treating sounds tricky -- normalize, reheat for time, oil-qnench and extended temper -- and it probably requires real expertise to achieve those extreme properties without brittleness. You can buy it normalized but the time/temperature sounds like a job for carefully controlled furnaces. http://www.matweb.com/search/datashe...a46a1f1 eb1c3 Good luck! -- Ed Huntress |
#18
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replying to Ed Huntress , Sandarpan Mukherjee wrote:
huntres23 wrote: On Sat, 15 Nov 2014 18:18:01 +0000, Sandarpan Mukherjee It's not easy to find specific elongation properties of 4140 when it's heat-treated to 216 kpsi tensile. At the extreme end, 285,000 psi, elongation is 11% and machineability is 65%. Hardness is 578 Brinell or Rc 55. That's more machineable than I expected, although it's carbide-only at 285 kpsi, and I didn't even know that it could develop 285 kpsi tensile strength. That kind of tensile strength, in diameters larger than wire, usually is associated with fairly brittle specialty steels and very low elongation. So, at 216,000, elongation can be expected to be over 11%. That's not terrible. It shouldn't be inclined to break as soon as the yield strength is exceeded. The thing is, heat-treating sounds tricky -- normalize, reheat for time, oil-qnench and extended temper -- and it probably requires real expertise to achieve those extreme properties without brittleness. You can buy it normalized but the time/temperature sounds like a job for carefully controlled furnaces. http://www.matweb.com/search/datashe...a46a1f1 eb1c3 Good luck! -- Ed Huntress Thanks Ed, At this point I'm not overly concerned with heat treatment procedures. Heat treatment in general is a tricky thing. I am just trying to zero in on the actual material. -- -- posted from http://www.polytechforum.com/metalwo...ll-605857-.htm using PolytechForum's Web, RSS and Social Media Interface to rec.crafts.metalworking and other engineering groups |
#19
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http://www.amazon.com/XMark-Commerci.../dp/B00JKM3BZU
The bar in the above link claims to have 240000 psi UTS and made out of a chrome-moly steel? Is it possible for such a high strength steel to be non-brittle enough for the application? |
#20
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On Sat, 22 Nov 2014 07:36:14 -0800 (PST), Sandarpan Mukherjee
wrote: http://www.amazon.com/XMark-Commerci.../dp/B00JKM3BZU The bar in the above link claims to have 240000 psi UTS and made out of a chrome-moly steel? Is it possible for such a high strength steel to be non-brittle enough for the application? "Chrome-moly" usually means AISI 4340 steel or equivalent. 240 kpsi is about the maximum, and elongation falls off sharply above 200 kpsi. At 225, it's down around 5/%. Is that enough for your bar? I don't know. Maybe the real-world application is no problem. At 5%, as a general matter in structural applications, you begin to expect sudden failures. But maybe it's OK for such a bar. -- Ed Huntress |
#21
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On Saturday, 22 November 2014 22:12:46 UTC+5:30, Ed Huntress wrote:
On Sat, 22 Nov 2014 07:36:14 -0800 (PST), Sandarpan Mukherjee wrote: http://www.amazon.com/XMark-Commerci.../dp/B00JKM3BZU The bar in the above link claims to have 240000 psi UTS and made out of a chrome-moly steel? Is it possible for such a high strength steel to be non-brittle enough for the application? "Chrome-moly" usually means AISI 4340 steel or equivalent. 240 kpsi is about the maximum, and elongation falls off sharply above 200 kpsi. At 225, it's down around 5/%. Is that enough for your bar? I don't know. Maybe the real-world application is no problem. At 5%, as a general matter in structural applications, you begin to expect sudden failures. But maybe it's OK for such a bar. -- Ed Huntress Also as far as I can tell from my decaying memories of Strength of Materials 101, thicker materials are more brittle than the same material when thinner? Especially high carbon steels. Is that correct? |
#22
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On Sat, 22 Nov 2014 07:36:14 -0800 (PST), Sandarpan Mukherjee
wrote: http://www.amazon.com/XMark-Commerci.../dp/B00JKM3BZU The bar in the above link claims to have 240000 psi UTS and made out of a chrome-moly steel? Is it possible for such a high strength steel to be non-brittle enough for the application? I'm more of a newb when it comes to metallurgy, but I think the strength of the steel comes from the alloy, while brittleness comes from the temper. Strong steels can be tempered for less brittleness, which is what I think is happening in that bar. /opinion -- "Government is not reason; it is not eloquent; it is force. Like fire, it is a dangerous servant and a fearful master." --George Washington |
#23
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On Sat, 22 Nov 2014 10:09:21 -0800 (PST), Sandarpan Mukherjee
wrote: On Saturday, 22 November 2014 22:12:46 UTC+5:30, Ed Huntress wrote: On Sat, 22 Nov 2014 07:36:14 -0800 (PST), Sandarpan Mukherjee wrote: http://www.amazon.com/XMark-Commerci.../dp/B00JKM3BZU The bar in the above link claims to have 240000 psi UTS and made out of a chrome-moly steel? Is it possible for such a high strength steel to be non-brittle enough for the application? "Chrome-moly" usually means AISI 4340 steel or equivalent. 240 kpsi is about the maximum, and elongation falls off sharply above 200 kpsi. At 225, it's down around 5/%. Is that enough for your bar? I don't know. Maybe the real-world application is no problem. At 5%, as a general matter in structural applications, you begin to expect sudden failures. But maybe it's OK for such a bar. -- Ed Huntress Also as far as I can tell from my decaying memories of Strength of Materials 101, thicker materials are more brittle than the same material when thinner? Especially high carbon steels. Is that correct? Hmmm. I'm rusty on a lot of this (no pun intended g). "Brittleness" is not a term that metallurgists ordinarily use. They look at elongation, and the gap between yield strength and ultimate tensile strength. Charpy and Izod impact strength are additional terms. In discussions of tool steels, you'll also see the term "timbre," which is not well-defined. What you're looking for, I think, is a determination of what happens when the yield strength of the bar is exceeded. Does it bend, or does it quickly reach the ultimate tensile strength, and snap? And if it bends, how much does it bend before it snaps? Right? If that's the case, I don't know the answer. I know that 5% elongation suggests little bending before it snaps. As for thin versus thick, that's a problem of mechanics: a 5% elongation in tension allows more bending, in terms of degrees of bend, in a small wire versus a thicker bar. So a smaller bar should bend more before breaking than a larger one, all other properties being equal. This is discussed in terms of the behavior of the "outermost fibers" (theoretical) of a beam, including a wire or bar. It also explains why a 300 kpsi piece of music wire will bend quite a lot before breaking. I think. g Maybe someone who's more up to date on Statics and the Strength of Materials (that's the title of a good book on the subject) can chime in and correct me on this. -- Ed Huntress |
#24
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On 11/22/2014 10:42 AM, Ed Huntress wrote:
On Sat, 22 Nov 2014 07:36:14 -0800 (PST), Sandarpan Mukherjee wrote: http://www.amazon.com/XMark-Commerci.../dp/B00JKM3BZU The bar in the above link claims to have 240000 psi UTS and made out of a chrome-moly steel? Is it possible for such a high strength steel to be non-brittle enough for the application? "Chrome-moly" usually means AISI 4340 steel or equivalent. 240 kpsi is about the maximum, and elongation falls off sharply above 200 kpsi. At 225, it's down around 5/%. Is that enough for your bar? I don't know. Maybe the real-world application is no problem. At 5%, as a general matter in structural applications, you begin to expect sudden failures. But maybe it's OK for such a bar. Be sure to watch the movie clip in the picture choices. Nice drop tests that passed. Martin |
#25
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On Saturday, November 22, 2014 11:42:46 AM UTC-5, Ed Huntress wrote:
"Chrome-moly" usually means AISI 4340 steel or equivalent. 240 kpsi is about the maximum, and elongation falls off sharply above 200 kpsi. At 225, it's down around 5/%. Is that enough for your bar? I don't know. Maybe the real-world application is no problem. At 5%, as a general matter in structural applications, you begin to expect sudden failures. But maybe it's OK for such a bar. -- Ed Huntress I would think that 4130 would be a better choice than 4340. Dan |
#26
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On Sat, 22 Nov 2014 18:25:32 -0600, Martin Eastburn
wrote: On 11/22/2014 10:42 AM, Ed Huntress wrote: On Sat, 22 Nov 2014 07:36:14 -0800 (PST), Sandarpan Mukherjee wrote: http://www.amazon.com/XMark-Commerci.../dp/B00JKM3BZU The bar in the above link claims to have 240000 psi UTS and made out of a chrome-moly steel? Is it possible for such a high strength steel to be non-brittle enough for the application? "Chrome-moly" usually means AISI 4340 steel or equivalent. 240 kpsi is about the maximum, and elongation falls off sharply above 200 kpsi. At 225, it's down around 5/%. Is that enough for your bar? I don't know. Maybe the real-world application is no problem. At 5%, as a general matter in structural applications, you begin to expect sudden failures. But maybe it's OK for such a bar. Be sure to watch the movie clip in the picture choices. Nice drop tests that passed. Martin The video is interesting, but I was more impressed with the bending test done in a machine. It's hard to tell what the actual load is on the bar in those drop tests. -- Ed Huntress |
#27
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On Sunday, 23 November 2014 06:33:42 UTC+5:30, Ed Huntress wrote:
On Sat, 22 Nov 2014 18:25:32 -0600, Martin Eastburn wrote: On 11/22/2014 10:42 AM, Ed Huntress wrote: On Sat, 22 Nov 2014 07:36:14 -0800 (PST), Sandarpan Mukherjee wrote: http://www.amazon.com/XMark-Commerci.../dp/B00JKM3BZU The bar in the above link claims to have 240000 psi UTS and made out of a chrome-moly steel? Is it possible for such a high strength steel to be non-brittle enough for the application? "Chrome-moly" usually means AISI 4340 steel or equivalent. 240 kpsi is about the maximum, and elongation falls off sharply above 200 kpsi. At 225, it's down around 5/%. Is that enough for your bar? I don't know. Maybe the real-world application is no problem. At 5%, as a general matter in structural applications, you begin to expect sudden failures. But maybe it's OK for such a bar. Be sure to watch the movie clip in the picture choices. Nice drop tests that passed. Martin The video is interesting, but I was more impressed with the bending test done in a machine. It's hard to tell what the actual load is on the bar in those drop tests. -- Ed Huntress The actual load in the drop tests is easy to tell. Each plate is 45 lbs. |
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On Sunday, 23 November 2014 00:08:08 UTC+5:30, Larry Jaques wrote:
On Sat, 22 Nov 2014 07:36:14 -0800 (PST), Sandarpan Mukherjee wrote: http://www.amazon.com/XMark-Commerci.../dp/B00JKM3BZU The bar in the above link claims to have 240000 psi UTS and made out of a chrome-moly steel? Is it possible for such a high strength steel to be non-brittle enough for the application? I'm more of a newb when it comes to metallurgy, but I think the strength of the steel comes from the alloy, while brittleness comes from the temper. Strong steels can be tempered for less brittleness, which is what I think is happening in that bar. /opinion -- "Government is not reason; it is not eloquent; it is force. Like fire, it is a dangerous servant and a fearful master." --George Washington Yes but tempering takes away hardness(brittleness also)as well as strength. Strength and brittleness have a strong correlation. |
#29
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On Sunday, 23 November 2014 06:29:52 UTC+5:30, wrote:
On Saturday, November 22, 2014 11:42:46 AM UTC-5, Ed Huntress wrote: "Chrome-moly" usually means AISI 4340 steel or equivalent. 240 kpsi is about the maximum, and elongation falls off sharply above 200 kpsi. At 225, it's down around 5/%. Is that enough for your bar? I don't know. Maybe the real-world application is no problem. At 5%, as a general matter in structural applications, you begin to expect sudden failures. But maybe it's OK for such a bar. -- Ed Huntress I would think that 4130 would be a better choice than 4340. Dan Dan, 4130 doesn't meet my strength requirements. Remember, I need the bar to resist permanent deformation. That can be achieved only by high yield strength.. The standard is 200000 psi Tensile strength with ~ 180000 psi yield strength. Even then bars bend with abuse. |
#30
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On Sat, 22 Nov 2014 21:14:38 -0800 (PST), Sandarpan Mukherjee
wrote: On Sunday, 23 November 2014 06:33:42 UTC+5:30, Ed Huntress wrote: On Sat, 22 Nov 2014 18:25:32 -0600, Martin Eastburn wrote: On 11/22/2014 10:42 AM, Ed Huntress wrote: On Sat, 22 Nov 2014 07:36:14 -0800 (PST), Sandarpan Mukherjee wrote: http://www.amazon.com/XMark-Commerci.../dp/B00JKM3BZU The bar in the above link claims to have 240000 psi UTS and made out of a chrome-moly steel? Is it possible for such a high strength steel to be non-brittle enough for the application? "Chrome-moly" usually means AISI 4340 steel or equivalent. 240 kpsi is about the maximum, and elongation falls off sharply above 200 kpsi. At 225, it's down around 5/%. Is that enough for your bar? I don't know. Maybe the real-world application is no problem. At 5%, as a general matter in structural applications, you begin to expect sudden failures. But maybe it's OK for such a bar. Be sure to watch the movie clip in the picture choices. Nice drop tests that passed. Martin The video is interesting, but I was more impressed with the bending test done in a machine. It's hard to tell what the actual load is on the bar in those drop tests. -- Ed Huntress The actual load in the drop tests is easy to tell. Each plate is 45 lbs. But that doesn't tell you what the load is on the bar, as a result of being dropped with the weights on it. For example, dropping it straight down and with the bar horizontal imposes very little load on the bar. Dropping it on a 45-degree angle to horizontal imposes a higher, but unknown load. Note that the bar doesn't bend much in that test. The load is not really very high, although it is more of an impact load. -- Ed Huntress |
#31
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On Sat, 22 Nov 2014 21:16:20 -0800 (PST), Sandarpan Mukherjee
wrote: On Sunday, 23 November 2014 00:08:08 UTC+5:30, Larry Jaques wrote: On Sat, 22 Nov 2014 07:36:14 -0800 (PST), Sandarpan Mukherjee wrote: http://www.amazon.com/XMark-Commerci.../dp/B00JKM3BZU The bar in the above link claims to have 240000 psi UTS and made out of a chrome-moly steel? Is it possible for such a high strength steel to be non-brittle enough for the application? I'm more of a newb when it comes to metallurgy, but I think the strength of the steel comes from the alloy, while brittleness comes from the temper. Strong steels can be tempered for less brittleness, which is what I think is happening in that bar. /opinion -- "Government is not reason; it is not eloquent; it is force. Like fire, it is a dangerous servant and a fearful master." --George Washington Yes but tempering takes away hardness(brittleness also)as well as strength. Strength and brittleness have a strong correlation. Yes, it's a balancing act of magic, metallurgically speaking. -- "Government is not reason; it is not eloquent; it is force. Like fire, it is a dangerous servant and a fearful master." --George Washington |
#32
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On Sunday, 23 November 2014 12:32:13 UTC+5:30, Ed Huntress wrote:
On Sat, 22 Nov 2014 21:14:38 -0800 (PST), Sandarpan Mukherjee wrote: On Sunday, 23 November 2014 06:33:42 UTC+5:30, Ed Huntress wrote: On Sat, 22 Nov 2014 18:25:32 -0600, Martin Eastburn wrote: On 11/22/2014 10:42 AM, Ed Huntress wrote: On Sat, 22 Nov 2014 07:36:14 -0800 (PST), Sandarpan Mukherjee wrote: http://www.amazon.com/XMark-Commerci.../dp/B00JKM3BZU The bar in the above link claims to have 240000 psi UTS and made out of a chrome-moly steel? Is it possible for such a high strength steel to be non-brittle enough for the application? "Chrome-moly" usually means AISI 4340 steel or equivalent. 240 kpsi is about the maximum, and elongation falls off sharply above 200 kpsi. At 225, it's down around 5/%. Is that enough for your bar? I don't know. Maybe the real-world application is no problem. At 5%, as a general matter in structural applications, you begin to expect sudden failures. But maybe it's OK for such a bar. Be sure to watch the movie clip in the picture choices. Nice drop tests that passed. Martin The video is interesting, but I was more impressed with the bending test done in a machine. It's hard to tell what the actual load is on the bar in those drop tests. -- Ed Huntress The actual load in the drop tests is easy to tell. Each plate is 45 lbs. But that doesn't tell you what the load is on the bar, as a result of being dropped with the weights on it. For example, dropping it straight down and with the bar horizontal imposes very little load on the bar. Dropping it on a 45-degree angle to horizontal imposes a higher, but unknown load. Note that the bar doesn't bend much in that test. The load is not really very high, although it is more of an impact load. -- Ed Huntress http://www.roymech.co.uk/Useful_Tabl...cs_Impact.html The above page gives approximate formulae to calculate impact stresses. |
#33
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On Sunday, 23 November 2014 20:18:45 UTC+5:30, Larry Jaques wrote:
On Sat, 22 Nov 2014 21:16:20 -0800 (PST), Sandarpan Mukherjee wrote: On Sunday, 23 November 2014 00:08:08 UTC+5:30, Larry Jaques wrote: On Sat, 22 Nov 2014 07:36:14 -0800 (PST), Sandarpan Mukherjee wrote: http://www.amazon.com/XMark-Commerci.../dp/B00JKM3BZU The bar in the above link claims to have 240000 psi UTS and made out of a chrome-moly steel? Is it possible for such a high strength steel to be non-brittle enough for the application? I'm more of a newb when it comes to metallurgy, but I think the strength of the steel comes from the alloy, while brittleness comes from the temper. Strong steels can be tempered for less brittleness, which is what I think is happening in that bar. /opinion -- "Government is not reason; it is not eloquent; it is force. Like fire, it is a dangerous servant and a fearful master." --George Washington Yes but tempering takes away hardness(brittleness also)as well as strength. Strength and brittleness have a strong correlation. Yes, it's a balancing act of magic, metallurgically speaking. -- "Government is not reason; it is not eloquent; it is force. Like fire, it is a dangerous servant and a fearful master." --George Washington Yes. What I would love to know is though, what is the elongation % and reduction in area of the bars at the given strength. Something no manufacturer is willing to tell. |
#34
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On Sun, 23 Nov 2014 08:48:09 -0800 (PST), Sandarpan Mukherjee
wrote: On Sunday, 23 November 2014 12:32:13 UTC+5:30, Ed Huntress wrote: On Sat, 22 Nov 2014 21:14:38 -0800 (PST), Sandarpan Mukherjee wrote: On Sunday, 23 November 2014 06:33:42 UTC+5:30, Ed Huntress wrote: On Sat, 22 Nov 2014 18:25:32 -0600, Martin Eastburn wrote: On 11/22/2014 10:42 AM, Ed Huntress wrote: On Sat, 22 Nov 2014 07:36:14 -0800 (PST), Sandarpan Mukherjee wrote: http://www.amazon.com/XMark-Commerci.../dp/B00JKM3BZU The bar in the above link claims to have 240000 psi UTS and made out of a chrome-moly steel? Is it possible for such a high strength steel to be non-brittle enough for the application? "Chrome-moly" usually means AISI 4340 steel or equivalent. 240 kpsi is about the maximum, and elongation falls off sharply above 200 kpsi. At 225, it's down around 5/%. Is that enough for your bar? I don't know. Maybe the real-world application is no problem. At 5%, as a general matter in structural applications, you begin to expect sudden failures. But maybe it's OK for such a bar. Be sure to watch the movie clip in the picture choices. Nice drop tests that passed. Martin The video is interesting, but I was more impressed with the bending test done in a machine. It's hard to tell what the actual load is on the bar in those drop tests. -- Ed Huntress The actual load in the drop tests is easy to tell. Each plate is 45 lbs. But that doesn't tell you what the load is on the bar, as a result of being dropped with the weights on it. For example, dropping it straight down and with the bar horizontal imposes very little load on the bar. Dropping it on a 45-degree angle to horizontal imposes a higher, but unknown load. Note that the bar doesn't bend much in that test. The load is not really very high, although it is more of an impact load. -- Ed Huntress http://www.roymech.co.uk/Useful_Tabl...cs_Impact.html The above page gives approximate formulae to calculate impact stresses. I really don't think that would answer it for you. When a bar is held at 45 deg. to horizontal and dropped, the impact of the lower weights is not transferred to the bar. It's absorbed by whatever is on the ground. The impact imposed by the upper weights depends on a complex set of forces and deflections, which involve tracing the forces from the upper weights, through the bar, to the lower weights, to where the lower weights contact the ground. Good luck with that. g -- Ed Huntress |
#35
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"Sandarpan Mukherjee" wrote in message
... ... Yes. What I would love to know is though, what is the elongation % and reduction in area of the bars at the given strength. Something no manufacturer is willing to tell. A failed, discarded bar might. If you plan to make these things you need a way to proof test them anyway. |
#36
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On Sun, 23 Nov 2014 08:49:29 -0800 (PST), Sandarpan Mukherjee
wrote: On Sunday, 23 November 2014 20:18:45 UTC+5:30, Larry Jaques wrote: On Sat, 22 Nov 2014 21:16:20 -0800 (PST), Sandarpan Mukherjee wrote: On Sunday, 23 November 2014 00:08:08 UTC+5:30, Larry Jaques wrote: On Sat, 22 Nov 2014 07:36:14 -0800 (PST), Sandarpan Mukherjee wrote: http://www.amazon.com/XMark-Commerci.../dp/B00JKM3BZU The bar in the above link claims to have 240000 psi UTS and made out of a chrome-moly steel? Is it possible for such a high strength steel to be non-brittle enough for the application? I'm more of a newb when it comes to metallurgy, but I think the strength of the steel comes from the alloy, while brittleness comes from the temper. Strong steels can be tempered for less brittleness, which is what I think is happening in that bar. /opinion -- "Government is not reason; it is not eloquent; it is force. Like fire, it is a dangerous servant and a fearful master." --George Washington Yes but tempering takes away hardness(brittleness also)as well as strength. Strength and brittleness have a strong correlation. Yes, it's a balancing act of magic, metallurgically speaking. -- "Government is not reason; it is not eloquent; it is force. Like fire, it is a dangerous servant and a fearful master." --George Washington Yes. What I would love to know is though, what is the elongation % and reduction in area of the bars at the given strength. Something no manufacturer is willing to tell. See Bethlehem Steel's "Modern Steels and Their Properties." This is a scan minus the attribution: http://www.akronsteeltreating.com/do...y/ast-book.pdf -- Ned Simmons |
#37
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On Sun, 23 Nov 2014 17:15:31 -0500, Ned Simmons
wrote: On Sun, 23 Nov 2014 08:49:29 -0800 (PST), Sandarpan Mukherjee wrote: On Sunday, 23 November 2014 20:18:45 UTC+5:30, Larry Jaques wrote: On Sat, 22 Nov 2014 21:16:20 -0800 (PST), Sandarpan Mukherjee wrote: On Sunday, 23 November 2014 00:08:08 UTC+5:30, Larry Jaques wrote: On Sat, 22 Nov 2014 07:36:14 -0800 (PST), Sandarpan Mukherjee wrote: http://www.amazon.com/XMark-Commerci.../dp/B00JKM3BZU The bar in the above link claims to have 240000 psi UTS and made out of a chrome-moly steel? Is it possible for such a high strength steel to be non-brittle enough for the application? I'm more of a newb when it comes to metallurgy, but I think the strength of the steel comes from the alloy, while brittleness comes from the temper. Strong steels can be tempered for less brittleness, which is what I think is happening in that bar. /opinion -- "Government is not reason; it is not eloquent; it is force. Like fire, it is a dangerous servant and a fearful master." --George Washington Yes but tempering takes away hardness(brittleness also)as well as strength. Strength and brittleness have a strong correlation. Yes, it's a balancing act of magic, metallurgically speaking. -- "Government is not reason; it is not eloquent; it is force. Like fire, it is a dangerous servant and a fearful master." --George Washington Yes. What I would love to know is though, what is the elongation % and reduction in area of the bars at the given strength. Something no manufacturer is willing to tell. See Bethlehem Steel's "Modern Steels and Their Properties." This is a scan minus the attribution: http://www.akronsteeltreating.com/do...y/ast-book.pdf Excellent! I see 202 pages of unexpected reading in my near future. Link saved. -- "Government is not reason; it is not eloquent; it is force. Like fire, it is a dangerous servant and a fearful master." --George Washington |
#38
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On Sunday, 23 November 2014 22:44:13 UTC+5:30, Ed Huntress wrote:
On Sun, 23 Nov 2014 08:48:09 -0800 (PST), Sandarpan Mukherjee wrote: On Sunday, 23 November 2014 12:32:13 UTC+5:30, Ed Huntress wrote: On Sat, 22 Nov 2014 21:14:38 -0800 (PST), Sandarpan Mukherjee wrote: On Sunday, 23 November 2014 06:33:42 UTC+5:30, Ed Huntress wrote: On Sat, 22 Nov 2014 18:25:32 -0600, Martin Eastburn wrote: On 11/22/2014 10:42 AM, Ed Huntress wrote: On Sat, 22 Nov 2014 07:36:14 -0800 (PST), Sandarpan Mukherjee wrote: http://www.amazon.com/XMark-Commerci.../dp/B00JKM3BZU The bar in the above link claims to have 240000 psi UTS and made out of a chrome-moly steel? Is it possible for such a high strength steel to be non-brittle enough for the application? "Chrome-moly" usually means AISI 4340 steel or equivalent. 240 kpsi is about the maximum, and elongation falls off sharply above 200 kpsi. At 225, it's down around 5/%. Is that enough for your bar? I don't know. Maybe the real-world application is no problem. At 5%, as a general matter in structural applications, you begin to expect sudden failures. But maybe it's OK for such a bar. Be sure to watch the movie clip in the picture choices. Nice drop tests that passed. Martin The video is interesting, but I was more impressed with the bending test done in a machine. It's hard to tell what the actual load is on the bar in those drop tests. -- Ed Huntress The actual load in the drop tests is easy to tell. Each plate is 45 lbs. But that doesn't tell you what the load is on the bar, as a result of being dropped with the weights on it. For example, dropping it straight down and with the bar horizontal imposes very little load on the bar. Dropping it on a 45-degree angle to horizontal imposes a higher, but unknown load. Note that the bar doesn't bend much in that test. The load is not really very high, although it is more of an impact load. -- Ed Huntress http://www.roymech.co.uk/Useful_Tabl...cs_Impact.html The above page gives approximate formulae to calculate impact stresses. I really don't think that would answer it for you. When a bar is held at 45 deg. to horizontal and dropped, the impact of the lower weights is not transferred to the bar. It's absorbed by whatever is on the ground. The impact imposed by the upper weights depends on a complex set of forces and deflections, which involve tracing the forces from the upper weights, through the bar, to the lower weights, to where the lower weights contact the ground. Good luck with that. g -- Ed Huntress True, what you say, which is why I wrote approximate. |
#39
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On Monday, 24 November 2014 00:09:02 UTC+5:30, Jim Wilkins wrote:
"Sandarpan Mukherjee" wrote in message ... ... Yes. What I would love to know is though, what is the elongation % and reduction in area of the bars at the given strength. Something no manufacturer is willing to tell. A failed, discarded bar might. If you plan to make these things you need a way to proof test them anyway. And therein lies the problem. The driving force behind me wanting to make a bar in the first place is a complete lack of quality equipment in my country. Elite athletes all import Eleikos. However they are sponsored. I am not. |
#40
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On Mon, 24 Nov 2014 07:31:14 -0800 (PST), Sandarpan Mukherjee
wrote: On Sunday, 23 November 2014 22:44:13 UTC+5:30, Ed Huntress wrote: On Sun, 23 Nov 2014 08:48:09 -0800 (PST), Sandarpan Mukherjee wrote: On Sunday, 23 November 2014 12:32:13 UTC+5:30, Ed Huntress wrote: On Sat, 22 Nov 2014 21:14:38 -0800 (PST), Sandarpan Mukherjee wrote: On Sunday, 23 November 2014 06:33:42 UTC+5:30, Ed Huntress wrote: On Sat, 22 Nov 2014 18:25:32 -0600, Martin Eastburn wrote: On 11/22/2014 10:42 AM, Ed Huntress wrote: On Sat, 22 Nov 2014 07:36:14 -0800 (PST), Sandarpan Mukherjee wrote: http://www.amazon.com/XMark-Commerci.../dp/B00JKM3BZU The bar in the above link claims to have 240000 psi UTS and made out of a chrome-moly steel? Is it possible for such a high strength steel to be non-brittle enough for the application? "Chrome-moly" usually means AISI 4340 steel or equivalent. 240 kpsi is about the maximum, and elongation falls off sharply above 200 kpsi. At 225, it's down around 5/%. Is that enough for your bar? I don't know. Maybe the real-world application is no problem. At 5%, as a general matter in structural applications, you begin to expect sudden failures. But maybe it's OK for such a bar. Be sure to watch the movie clip in the picture choices. Nice drop tests that passed. Martin The video is interesting, but I was more impressed with the bending test done in a machine. It's hard to tell what the actual load is on the bar in those drop tests. -- Ed Huntress The actual load in the drop tests is easy to tell. Each plate is 45 lbs. But that doesn't tell you what the load is on the bar, as a result of being dropped with the weights on it. For example, dropping it straight down and with the bar horizontal imposes very little load on the bar. Dropping it on a 45-degree angle to horizontal imposes a higher, but unknown load. Note that the bar doesn't bend much in that test. The load is not really very high, although it is more of an impact load. -- Ed Huntress http://www.roymech.co.uk/Useful_Tabl...cs_Impact.html The above page gives approximate formulae to calculate impact stresses. I really don't think that would answer it for you. When a bar is held at 45 deg. to horizontal and dropped, the impact of the lower weights is not transferred to the bar. It's absorbed by whatever is on the ground. The impact imposed by the upper weights depends on a complex set of forces and deflections, which involve tracing the forces from the upper weights, through the bar, to the lower weights, to where the lower weights contact the ground. Good luck with that. g -- Ed Huntress True, what you say, which is why I wrote approximate. If you really want an engineering analysis of the loads and deflections, this is a job for finite-element analysis (FEA). The tools for doing that today are amazingly good. It would make a good term paper for a mechanical engineering student. However, what you have when you're done is a theoretical set of behaviors based on nominal mechanical properties of the bar. You then need to apply a safety factor, and that wouldn't be a piece of cake for this job, either. I don't know why you're making your own, but if I were doing it, I would copy the material and dimensions of a commercial bar that is known to be safe and successful. "Chrome-moly" is going to be 4340; I would bet on it. But you could confirm it by asking the bar manufacturer. I do that kind of thing all the time, as a writer in the field. Most are forthcoming if it isn't about some proprietary issue, and I can't imagine that this one is. They've publicly stated the class of alloy; all you need to know is the last two numbers, which is the carbon content. Again, that number is almost certainly 40. Good luck with your project. -- Ed Huntress |
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